INTRODUCTION

Herbal therapy denotes the use of plants for the promotion of immunity, maintenance of health and prevention and cure of diseases. In developing countries, more than 80% of human population still relies on Complementary and Alternative Medicine (CAM) for their health related issues (Ernst, 2000; Wanchai et al., 2010; Archana et al., 2011; Umashanker and Shruti, 2011; Mahima et al., 2012; Tiwari et al., 2012; Yarney et al., 2013). In the present era of emerging drug resistance, various kinds of stresses, immune pressures, global warming, liberalized trade, biodiversity variations, increasing population, changing life styles and food habbits and other predisposing factors, several kinds of general health problems and diseases are flaring up with increasing trend worldwide. These include diabetes, obesity, blood pressure, heart problems, arthritis, organ failures, cancers, immunosuppression along with increasing emergence of infectious and non-infectious diseases/disorders (Dhama et al., 2013a, b; Tiwari et al., 2013a). To counter these various diseases and general health problems, nowadays several novel and alternative/complementary therapeutic modalities are getting attention and popularization. These comprises of phages, cytokines, si-RNA, apoptins, nanomedicines, avian egg antibodies, stem cells, probiotics, immunomodulators, antioxidants, panchgavya elements, herbs, phytonutrients, fruits and vegetables (Dhama et al., 2008, 2013c, d, e, 2014; Amarpal et al., 2013; Mahima et al., 2012, 2013a, b; Karthik et al., 2014; Rahal et al., 2014a, b; Tiwari et al., 2012; 2014a, b). Of all these, the wonder world of ancient herbal heritage and the treasure of natural medicine is gaining much popularity due to their low toxicity and costs, changing ethical values, availability worldwide and usefulness as alternative/complementary medicines. Their need and demand is increasing day by day owing to their multi-dimensional health benefits and having several advantages over other medicinal options, possessing useful prophylactic as well as therapeutic potentials with wide practical applications at global level (Mizaei-Aghsaghali, 2012; Mahima et al., 2012; Dhama et al., 2013f; Kumar et al., 2013a; Yarney et al., 2013; Tiwari et al., 2012, 2013b, 2014c, d).

Cancer remains as one of the most dreaded ailments for both human and animals. It claims about 7.6 millions of human lives every year (Ferlay et al., 2010; Dhanamani et al., 2011; Dhama et al., 2013b) in spite of innumerable interdisciplinary approaches efforts invested in cancer diagnosis and treatment. The basis of cancer therapy is surgery when the tumour gets localized, with feasible chemotherapy, radiotherapy, hormonal therapy, targeted therapies and immune therapy. However, these treatment options do not guarantee that cancer will not relapse (Yarney et al., 2013). Moreover, many adverse side effects of chemotherapy and radiotherapy make the life of patients miserable with more sufferings than the cancer alone (Ernst, 2000). Sophisticated therapeutic strategies in modern medicine, though effective but affect humanity and are not reachable to all human populations worldwide. This is because of the problems of affordability and as a consequence, large number of human populations still depends upon traditional herbal medicines as alternatives, to counter many infectious and non-infectious diseases as well as other general health disorders (Ernst, 2000; Mahima et al., 2012; Tiwari et al., 2012; Dhama et al., 2013b). In this context, the dietary plant elements and products and other nutraceuticals restricting the multiplication of cancer cells without showing any adverse effect on normal cells, are being considered as promising regiments for developing novel anti-cancer therapuetics as well as preventive approaches (Wargovich et al., 2001; Diwanay et al., 2004; Balachandran and Govindarajan, 2005; Agarwal et al., 2011; Kitagishi et al., 2012; Yarney et al., 2013).

India has a rich heritage of medicinal plants and herbs and a large number of plant extracts have been reported to be having high utility against several diseases and disorders including of cancers and tumours in medicinal systems of Ayurveda, Siddha and Unani (Archana et al., 2011; Umashanker and Shruti, 2011; Mahima et al., 2012). Among these traditional medicine systems, the Ayurveda is being used since ancient times, mostly utilizing the wealth of herbs to prevent or cure various diseases (Ernst, 2000). In recent times, thousands of herbs and their preparations are being studied worldwide to identify their pharmacologically active components and scientific validation purposes which are playing crucial role in propagating and popularizing the use of these wonderful drugs/medicines (Mizaei-Aghsaghali, 2012; Mahima et al., 2012; Tiwari et al., 2012). The list of useful plants goes endless but most commonly used herbal medicinal plants include Azadirachta indica (neem), Tinospora cardifolia (giloy), Astragalus membranaceus, Withania somnifera (ashwagandha), Emblica officinalis (amla), Ocimum sanctum (tulsi), Piper longum (pipali), Aloe vera, Allium sativum (garlic), Zingiber officinale, (ginger), Curcuma longa, (turmeric) etc., (Archana et al., 2011; Mizaei-Aghsaghali, 2012; Mahima et al., 2012; Dhama et al., 2013b; Kumar et al., 2013a, b, c; Yakout et al., 2013; Midrarullah et al., 2014; Tiwari et al., 2012, 2014c, d). Of these, Morinda citrifolia L., popularly known as Noni, an Indian herb, has been found to offer many health benefits and fight various disease conditions. This plant has also been utilized as potent food supplement since ancient times throughout the globe. The Noni juice had been commercialized in the USA as “functional food” products in 1990s and is increasingly distributed all over the world (Brown, 2012; Singh, 2012). The pharmacologically active compounds derived from M. citrifolia fruits, leaves and roots are nowadays available as readymade capsules, teas and juices, the fruit juice being the most popular. Noni fruit contains alkaloids, scopoletin, damnacanthal and lots of other molecules, as a result the consumption of Noni juice is currently high, not only in US but also in Japan, Europe and India. It is claimed that the marketing of Noni has reached US $ 1.3 billion in annual sales (Chan-Blanco et al., 2006; Singh, 2012). Some companies producing flavoured Noni juices by addition of other fruit juices to render the product more palatable and more acceptable in market (Mathivanan et al., 2005). In response to this demand, some countries including India have increased the commercial cultivation of Noni and this plant has come up as a source of livelihood for farmers especially in Andaman and Nicobar Islands (Singh and Rai, 2007). Noni juice has been recently accepted in European Union as a novel food (EFSA, 2006). Noni plant, by virtue of its immunomodulating and nutritive properties, helps minimize the adverse effects of cancer maladies and side effects of various cancer therapies. Many bio anticarcinogenic agents present in Noni have also been reported to improve the potency of the cancer therapies. This herb also has been found to be beneficial for primary prevention and as a synergistic immune potentiating element in conjunction with common treatment modalities for various ailments (Chan-Blanco et al., 2006; Brown, 2012; Singh, 2012; Gupta and Patel, 2013).

The present manuscript is an updated review compilation on this wonderful herbal plant and its different health beneficial aspects, active phytochemical constituents, pharmacological properties, mechanism of action and various immunomodulatory and therapeutic potentials. A special focus has been made on the potent utility of Noni as a herbal remedy in preventing and treating the deadly malady of cancer. No such review compilation is available on this useful herbal plant having multidimensional health benefits. The manuscript would be highly helpful for pharmaceutists, Ayurveda medicinal system, researchers, medicos, veterinarians, livestock and poultry producers/industry and common man. Altogether, it would help propagate and promote this plant to be used in complementary and alternative medicinal treatment options as a herbal remedy for safeguarduing health of humans and their companion animals.

General description of Morinda citrifolia L. (Noni): An edible and tropical plant Morinda citrifolia L., has been widely used by Polynesians in folk medicine for more than 2,000 years. It is commonly known as great morinda, Indian mulberry, nunaakai and Noni in India, Ba Jitianin in China, dog dumpling in Barbados, mengkudu in Indonesia and Malaysia, Nono in Tahiti, painkiller bush in the Caribbean, cheese fruit in Australia and beach mulberry or Noni in Hawaii (Morton, 1992; Wang et al., 2002a; Cardon, 2003; Serafini et al., 2011). Morinda citrifolia from the coffee family, Rubiaceae is made up of around 80 species. M. citrifolia is a short tropical evergreen plant and is found in open coastal and forest areas upto 1300 feet above sea level. It is native to the Pacific islands, Hawaii, Caribbean, Asia and Australia (Chan-Blanco et al., 2006; Brown, 2012). In Southern India M. citrifolia is found in the coastal regions of the Tamil Nadu and Kerala and also in the Mangalore area of Karnataka. Noni is well suited for extremely broad range of adverse environmental conditions. Noni can grow well in acidic, alkaline and infertile soils and it is also suitable for cultivation in extremely wet to dry areas (Cardon, 2003; Singh, 2012). The leaves are oval shaped, 8-10 inches long, dark green, shiny and with deep veins. The grenade-like yellow fruits can grow to a size of upto 12 cm and it arises due to coalescence of many inferior ovaries of closely packed flowers. The fruit has a lumpy surface with many polygonal shaped areas. The unripened fruit of M. citrifolia is green in colour. As it ripens the fruit becomes white in colour and it simply falls to the ground unless harvested at this stage. When the fruit becomes ripened, it has a very pungent smell, like the odour of blue vein cheese and it has a sour taste. The seeds are triangular in shape and reddish brown in colour, have air sac at one end which makes them buoyant (Wang et al., 2002a; Chan-Blanco et al., 2006). Other species of Morinda used therapeutically include Morinda lucida, Morinda morindoides, Morinda officinalis and Morinda tinctoria. Morinda officinalis (also known as Ba Ji Tian) specifically has been used for antidepressant effects (Schripsema et al., 2006; Mathivanan et al., 2006; Bao et al., 2011). It has also been used to treat kidney disorders in Chinese medicine. Morinda lucida is used in Nigeria for febrile illnesses and sickle cell anemia (Mpiana et al., 2007). Morinda morindoides has been used for anti-cancer treatments. Morinda tintoria has been demonstrated to possess anti-bacterial effects pre-clinically (Alitheen et al., 2010).

Pharmacological activities of Morinda citrifolia: Different parts of the Noni plant have been traditionally used for treatment of various complaints for their therapeutic activities, including hypotensive action (Youngken, 1958, Youngken et al., 1960; Moorthy and Reddy, 1970; Yamaguchi et al., 2002; Gilani et al., 2010), analgesia (Younos et al., 1990; Wang et al., 2002a; Punjanon and Nandhasri, 2005; Basar et al., 2010), antibacterial effects (Atkinson, 1956; Bushnell et al., 1950; Leach et al., 1988; Sundarrao et al., 1993; Dittmar, 1993; Locher et al., 1995; Duncan et al., 1998; Wei et al., 2008; Jayaraman et al., 2008; Selvam et al., 2009; Kumar et al., 2010; Usha et al., 2010; Natheer et al., 2012; Murray et al., 2008; West et al., 2012), antituberculosis properties (Anonymous, 2001; Saludes et al., 2002), anti-inflamatory action (Takahashi et al., 2002; Colville-Nash and Gilroy, 2001; Su et al., 2001; Wang and Su, 2001; McKoy et al., 2002; Li et al., 2003; Akihisa et al., 2007; Deng et al., 2007a; Dussossoy et al., 2011; Palu et al., 2012) and antioxidant effects (Wang and Su, 2001; Wang et al., 2002b; Chow, 1993; Wang et al., 2009a, b; Anitha and Mohandass, 2006; Zin et al., 2002; Liu et al., 2007; Ikeda et al., 2009; West et al., 2009; Thani et al., 2010; Dussossoy et al., 2011; Serafini et al., 2011; West et al., 2011). It is also used for curing osteoporosis and auditory improvement (Langford et al., 2004; Li et al., 2008; Bao et al., 2011), wound healing (Kim et al., 2005; Nayak et al., 2007, 2009; Palu et al., 2010), antiviral activity (Umezawa, 1992; Kamata et al., 2006), anticataract (Gacche and Dhole, 2011; Saminathan et al., 2014), antigout (Palu et al., 2009), antifungal (Banerjee et al., 2006; Usha et al., 2010; Jayaraman et al., 2008; Jainkittivong et al., 2009), neuronal protective (Harada et al., 2010), antidiabetes (Jensen et al., 2005; Nayak et al., 2007, 2011; Horsfall et al., 2007; Kamiya et al., 2008; Owen et al., 2008; Nerurkar et al., 2011), anti-postoperative nausea and vomiting (Prapaitrakool and Itharat, 2010), anti-hypercholesterolemia (Kamiya et al., 2004; Mandukhail et al., 2010), anti-gastric ulcer and reflux esophagitis (Mahattanadul et al., 2011) and anticancer (Hiramatsu et al., 1993; Hirazumi and Furusawa, 1999; Liu et al., 2001; Jayaraman et al., 2008; Arpornsuwan and Punjanon, 2006; Taskin et al., 2009; Hutheyfa, 2010; Thani et al., 2010; Nualsanit et al., 2012; Lv et al., 2011; Clafshenkel et al., 2012; Gupta et al., 2013; Saminathan et al., 2013a, b) effects. Noni is also found useful in cancer chemoprevention (Tepsuwan and Kusamran, 1977; Hirazumi et al., 1992, 1994, 1996; Wang and Su, 2001, Wang et al., 2002c, 2009a, b, 2013; Li et al., 2008; Hazilawati et al., 2010a, b; Stoner et al., 2010; Saminathan et al., 2013c), inhibition of angiogenesis (Hornick et al., 2003) and immune stimulation (Hokama, 1993; Asahina et al., 1994; Hirazumi and Furusawa, 1999; Pansuebchue et al., 2002; Wang et al., 2002a; Brooks et al., 2009; Zhang et al., 2009; Nayak and Mengi, 2010). M. citrifolia prevents the formation and proliferation of tumors, including malignant tumors. It regulates of cell function and regeneration of damaged cells (Singh and Rai, 2007). The major bioactive constituents identified in various parts of M. citrifolia are presented in Table 1.

Table 1:	Major bioactive constituents in various parts of Morinda citrifolia
*Glycosides are primeverosides [=O-β-D-xylopyranosyl-(1-6)-β-D-glucopyranosides], **Glycosides are rutinosides [=O-α-L-rhamnopyranosyl-(1-6)-β-D-glucopyraosides]

Pharmacokinetics of Noni: Wang et al. (2002a) studied the pharmacokinetics of Noni by administration of Noni puree at a dose of 1 mL/100 g body weight, orally in female SD rats. The major component in Noni is scopoletin, a naturally occurring coumarin which was used as a marker and it was estimated from different organs and plasma. The plasma concentration of scopoletin reached maximum at 2 h after administration of Noni and it is decreased to 50% in 4 h. After 12 and 24 h only 12 and 2% of the scopoletin, respectively, was present in the plasma. Absorption was rapid during first 30 min and achieved 50% of maximal concentration. Noni intake at every 2-4 h is must to maintain an elevated blood level of scopoletin. For overall maintenance of health, one-ounce of Tahitian Noni Juice (TNJ) every 12 h is necessary. Overall results indicated that the frequency of drinking of TNJ is more essential than the amount. Estimation of the concentration of scopoletin in various organs indicated that Noni is absorbed into different tissues within 1 h after its administration. The scopoletin level was amusingly higher in breast tissue when compared to other extra GI tract tissues.

Mechanism of action of various compounds present in Noni: Noni has more than 160 phytochemical compounds. The major micronutrients are alkaloids, phenolic compounds, proteins, organic acids, minerals and vitamins. Among phenolic compounds, most important are anthraquinones damnacanthal, nordamnacanthal, morindone, rubiadin-1-methyl ether, alizarin, rubiadin, aucubin, asperuloside and scopoletin (Wang and Su, 2001). The organic acids mainly are caproic and caprylic acids (Dittmar, 1993) while the principal alkaloid is xeronine (Heinicke, 1985). The M. citrifolia fruit contains 90% of water and the chief components of the dry matter are dietary fibers, soluble solids and proteins. The protein content of the fruit is surprisingly high and the main amino acids are glutamic acid, aspartic acid and isoleucine. Noni has six major substances namely anthraquinones, polysaccharides, epigallocatechin gallate (EGCg), coumarins, monoterpenes and terpenoid compounds.which have been shown to fight cancer in different ways (Mathivanan et al., 2005).

Anthraquinones: Morindone, morindin and damnacanthal are important anthraquinone compounds that have a variety of biological activities including anti-inflammatory, anti-oxidant, antibacterial, anthelmintic and immunomodulating effect. Damnacanthal is vital compound found in Noni and prevents the formation of cancers by inhibiting ras gene activation. It has potent inhibitory activity on tyrosine kinases including EGF, Lck, Lyn and Src receptor (Hiramatsu et al., 1993; Hisawa et al., 1999). Alizarin is another anthraquinone compound that shows antiangiogenic function. It prevents blood circulation to malignant cancers results in arrest of the growth of tumour cells. Alizarin also inhibits the activity of cancer producing agent cytochrome C without production of free radicals (Tarasiuk et al., 1996).

Polysaccharides: Ethanol precipitate of Noni contains a unique polysaccharide which is composed of four sugars namely rhamnose, glucoronic acid, arabinose and galactose. It has immunomodulatory effects (Hirazumi and Furusawa, 1999) and blocks the adhesion of mutated cells to other cells and thereby stopping metastasis (Mathivanan et al., 2005).

Epigallocatechin gallate (EGCg): EGCg is a polyphenolic flavonoid that has antioxidant activity and is present in excellent amount in M. citrifolia. EGCg prevents the enzyme quinol oxidase (NOX) in tumours which leads to antiangiogenesis, inhibition of proliferation of cancer cells and death of these cells (Mathivanan et al., 2005).

Coumarins: Scopoletin is a naturally occurring coumarin that was isolated from Noni. It has analgesic activity and also controls the serotonin levels in the body significantly (Duncan et al., 1998; Liu et al., 2007). It also has anti-microbial (Duncan et al., 1998) and anti-hypertensive effects (Solomon, 1999).

Monoterpenes: Monoterpenes prevent the carcinogenic process at both the beginning and progression stages of cancers with no toxic effects on the body. One of the most common monoterpenes found in Noni juice is limonene. It also prevents liver, mammary, lung and other tissue cancers. Stimulation of thymus gland is done by limonene to produce more T cells that demolish the tumour cells. In vitro studies indicate that it is also effective in the treatment of leukaemia (Mathivanan et al., 2005).

Terpenoid compounds: Most common terpenoid compounds found in Noni are beta carotene, eugenol and urosolic acid. Beta carotene reduces various types of cancers and by quenching the free radicals and prevents oxidative damage. Urosolic acid is a penta cyclic terpenoid that has anti carcinogenic effect by preventing the growth of tumour cells and induces apoptosis by enhancing the immune system (Wang et al., 2002a).

Xeronine system: Even though Noni fruits contain slight amount of xeronine in free form, they contain precursor of xeronine called proxeronine in significant quantity. The molecular weight of proxeronine is comparatively large and about 16,000 Da. Proxeronine is converted into xeronine in the body by proxeroninase. Xeronine is a small alkaloid and is physiologically active in the picogram range. Xeronine is present in all healthy cells of animals, plants and microorganisms. The Noni juice should be taken on an empty stomach, the essential proenzyme, proxeroninase does not undergo digestion in the stomach and enters quickly into the intestine, where it may be converted into the active enzyme. If the juice is taken on a full stomach, it will have very little advantageous action. In the stomach, the enzyme, proxeroninase is destroyed by pepsin and acid. The most important function of xeronine is to regulate the rigidity and shape of specific proteins and is also a critical metabolic coregulator. Xeronine will act on abnormal protein and make it fold into its correct conformation that results in properly functioning protein (Heinicke, 1985).

In vitro anticancer effects of Noni: An anthraquinone compound, damnacanthal was separated from the chloroform extract of the root of Morinda citrifolia. It inhibits the ras oncogene function which is associated with signal transduction in leukemia, lung, colon and pancreatic cancers. Damnacanthal induced normal morphology and cytoskeletal structure in K-rasts-NRK cells without changing the localization and amount of ras. This effect was reversible and it had no effect on the morphology of RSVts-NRK cells expressing the src oncogene (Hiramatsu et al., 1993). Sundarrao et al. (1993) reported that Noni has antitumor activity against sarcoma 180 cells in mice.

Noni fruit juice contains a polysaccharide-rich substance which has antitumor activity that increases the production of cytokine IFN-gamma from thymocytes. This polysaccharide-rich substance is a water-soluble, ethanol precipitate containing a gum arabic heteropolysaccharide, composed of the sugars rhamnose, glucuronic acid, arabinose and galactose, however, ethanol-soluble fraction of Noni fruit juice has no antitumor activity. But it has antitumour activity against Lewis lung peritoneal carcinomatosis (LLC) by potentiating the immune system through release of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-10 (IL-10), interleukin-12 (IL-12) p70, interferon-gamma (IFN-γ) and nitric oxide (NO) but had no effect on IL-2 and decreased the IL-4 release (Hirazumi and Furusawa, 1999).

Hisawa et al. (1999) studied the action of damnacanthal on ultraviolet ray-induced apoptosis in ultraviolet-resistant human UVr-1 cells. Damnacanthal has potent inhibitory activity on tyrosine kinases including EGF, Lck, Lyn and Src receptor. Ultraviolet light induces a stress-activated protein kinases and phosphorylated extracellular signal regulated kinases. Stimulatory effect on ultraviolet-induced apoptosis was noticed when the cells were treated with damnacanthal prior to ultraviolet irradiation. This is beneficial effect of damnacanthal because apoptosis eliminates UV radiation induced potential mutagenic or transformed cells. Failure of apoptosis inducing effect of the body results in development of skin cancer. Two novel glycosides NB10 (6-O-(β-D-glucopyranosyl)-1-O-octanoyl-β-D-glucopyranose) and NB11 (asperulosidic acid) had anticancerous activity. They are isolated from the n-butyl alcohol soluble fraction of Noni fruit juice. They suppress the TPA-(12-O-tedtradecanoylphorbol-13-acetate) and EGF-(epidermal growth factor) induced cell transformation and associated AP-1 transactivation in the mouse epidermal JB6 cell line. Growth factors, TPA and UV radiation induce AP-1 transactivation that results in tumorigenesis. These compounds also prevent the phosphorylation of c-Jun (a substrate of JNKs) which suggests that JNKs are a crucial target in mediating the AP-1 activity and cell transformation (Liu et al., 2001).

Morinda citrifolia fruit juice with concentrations of 5% (v/v) or more prevents the initiation of new blood vessel sprouts from placental vein explants and decreases the proliferation and growth rate of newly developing capillary sprouts. Concentration of 2.5% Noni juice in the media was ineffective in blocking initiation of angiogenesis. In human breast tumor explants, 10% Noni juice in growth medium inhibits capillary initiation, vessel degeneration and apoptosis in wells within 2-3 days (Hornick et al., 2003). An anthraquinone with extremely potent quinone reductase-inducing activity, 2-methoxy-1, 3, 6-trihydroxyanthraquinone was isolated from MeOH extract of Noni fruits. It was nearly 40 times more potent than a positive control, l-sulforaphane. It has no discernible cytotoxicity at the highest dose levels (Pawlus et al., 2005). A new saccharide fatty acid ester, 2-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-gluropyranose, four saccharide fatty acid esters and a flavanol glycoside have been separated from a methanol extract of the fruits of Morinda citrifolia. These compounds exhibit inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA) potentiated inflammation (1 μg ear^-1) in mice ear and saccharide fatty acid esters exhibited potent anti-inflammatory activity with ID₅₀ values of 0.46-0.79 mg ear^-1. These compounds also exhibited moderate inhibitory effects against the Epstein-Barr Virus Early Antigen (EBV-EA) activation induced by TPA, with IC₅₀ values of 386-578 mol ratio/32 pmol TPA (Akihisa et al., 2007). The methanolic extract of M. citrifolia fruits have tumour cell suppression potential on human laryngeal epithiloma (Hep2) cells and showed maximum cytotoxicity on Hep 2 cells (50%) followed by ethyl acetate extract. The hexane extract showed no cytotoxic activity on Hep 2 cells (Jayaraman et al., 2008).

Methanol extract of Morinda citrifolia fruits has cytotoxic activity in a concentration dependent manner against various cancer cell lines but it has no cytotoxic activity against normal cell lines. The median lethal concentration (LC₅₀) of the extract in Baby Hamster Kidney (BHK) cells is 2.5 mg mL^-1, African green monkey kidney (Vero) cell is 3 mg mL^-1 and human laryngeal carcinoma (Hep2) cells is 5 mg mL^-1. A concentration of 0.1 mg mL^-1 of crude extract has cytotoxic activity against neuroblastoma (LAN5) cell lines (36%), breast cancer (MCF7) cell lines (29%) and very little cytotoxicity to Hep 2 cells (13%), BHK cells (6%) and has no cytotoxic activity against Vero cells (Arpornsuwan and Punjanon, 2006). Tumour Necrosis Factor (TNF) Related Apoptosis-Inducing Ligand (TRAIL) selectively increases the apoptosis of a wide variety of tumour and transformed cells without damaging normal cells. A new anthraquinone, 1, 5, 15-trimethylmorindol was isolated from the leaves of Morinda citrifolia which has synergistic activity with TRAIL with no side effects. But it did not show significant cytotoxic activity alone (Takashima et al., 2007).

Morinda citrifolia fresh leaf extract also has anticancer activity against human cervical carcinoma (HeLa), human epidermoid carcinoma (KB), human breast carcinoma (MCF-7), vero (African green monkey kidney) and human hepatocellular carcinoma (HepG2) cell lines. The non-aqueous extracts from the leaves of Noni exhibited antioxidant activity with IC₅₀ values of 0.20 to 0.35 mg mL^-1. The median lethal concentration (LC₅₀) of the dichloromethane extract of the fresh leaves of Noni in KB cell line is 21.67 μg mL^-1 and HeLa cell line is 68.50 μg mL^-1. The methanolic extract from the dried leaves of M. citrifolia showed cytotoxic activity against the KB cell line with an IC₅₀ value of 39 μg mL^-1. These two extracts have a higher safety ratio than damnacanthal which provides baseline information for their use as anticancer agents because the extracts prevent the proliferation of tumour cells but not normal cells (Thani et al., 2010).

An anthraquinone compound, damnacanthal, isolated from the roots of Morinda citrifolia, exhibited inhibitory activity on cell growth and enhanced caspase activity in colorectal cancer cells (HCT-116, SW480 and LoVo cells). Damnacanthal showed transcriptional up-regulation of the NAG-1 which is a nonsteroidal anti-inflammatory activated gene-1 and proapoptotic protein which controls cell growth and apoptosis. Damnacanthal promotes the retinoic acid receptor (ERK) pathway and enhances expression of transcription factor CCAAT/enhancer binding protein β (C/EBPβ) that helps in controlling NAG-1 transcriptional activity. This results in enhanced apoptosis in human colorectal cancer cells. It is a potent inhibitor of p56^lck tyrosine kinase activity (Faltynek et al., 1995; Nualsanit et al., 2012). Anthraquinones from the roots of M. citrifolia showed significant proliferation and growth inhibitory activity on human colon and lung cancer cells (Lv et al., 2011).

Gupta et al. (2013) demonstrated that Noni, cisplatin and combination of Noni with cisplatin were able to induce apoptosis through the mitochondrial pathway, in both HeLa and SiHa cells. They demonstrated the anticancerous activity through the p53 and Bax proteins (pro-apoptotic) up regulating pathways and Bcl-2 (anti-apoptotic gene), survivin and Bcl-XL proteins down regulating mechanisms. In addition there was increase in activity of caspases-9 and -3, thus primarily activating intrinsic pathway of apoptosis. Hence, Noni offers can be used as chemo adjuvants for treating cervical cancer specially.

In vivo anticancer effect of Noni: Alcohol-precipitate of Morinda citrifolia fruit juice showed antitumour activity against intraperitoneally injected Lewis Lung Carcinoma (LLC) in C57BL/6 mice. The Noni juice has therapeutic effects from 3-20 mg mouse^-1 and significant anticancerous activity was noticed at the doses of between 6-15 mg mouse^-1. Noni juice also prolonged the life span of the mice for more than 75% (Hirazumi et al., 1992). Ethanol-precipitated fractions of Noni fruit juice (0.8 mg in 0.1 mL of juice) have clear antitumor activity against intraperitoneally implanted LLC in syngeneic C57BL/6 mice. Intraperitoneally injection of Noni ppt (0.1 mL mouse^-1) cured 4 out of 13 mice and increased life span to 119%. Ethanol-soluble fractions of Noni fruit juice (5.2 mg solid in 0.1 mL of juice) have no antitumor activity (Hirazumi et al., 1994). Noni-precipitate prevents ascites in mice (0 out of 5 mice) but untreated mice develops ascites (5 out of 5 mice) (Hirazumi et al., 1996).

Tahitian Noni⁷ Juice (TNJ) 10% made from Morinda citrifolia fruit prevents the DMBA induced mammary gland carcinogenesis in female Sprague-Dawley (SD) rats at the initiation stage of multiple step carcinogenesis. It inhibits DMBA-DNA adduct formation in mammary tissue. DMBA-DNA adduct formation was detected by ³²P-postlabeling assay and it is an important marker for “DNA damage” to examine the preventive effect of Noni juice in a DMBA induced mammary gland carcinogenesis model. The DMBA-DNA adduct levels were reduced to 41% in the lung, 30% in the heart, 80% in the kidney and 42% in the liver of female SD rats. Male C57 BL-6 mice showed more dramatic reduction of DMBA-DNA adduct formation by 50% in the lung, 60% in the heart, 90% in the kidney and 70% in the liver. This preventive effect of TNJ was due to the antioxidant activity by dose-dependent inhibition of both lipid hydroperoxide (LPO) and Superoxide Anion Radicals (SAR) (Wang and Su, 2001). The tumour latency period was delayed to 60-90 days in TNJ group when compared to positive control group. Tumour multiplicity, number of palpable tumours per group and malignancy of lesions were significantly reduced and survival rate of animals was significantly increased in the TNJ group when compared to positive control groups. The DMBA treated control group showed epithelial hyperplasia (12.5%), benign tumours (25%) and in situ carcinomas (25%). In the TNJ group no benign tumours or carcinomas were found and tissues showed normal histology or only mild hyperplasia. These results indicate that TNJ may prevent mammary gland carcinogenesis at the initiation stage of chemical carcinogenesis (Wang et al., 2002c, 2013). Morinda citrifolia fruit juice contains an immunomodulatory polysaccharide-rich substance which possesses both prophylactic and therapeutic activity against the Sarcoma 180 tumour in mice, an immunomodulator sensitive tumour. Intraperitoneal injection of sarcoma tumor cells (S180) in mice followed by treatment with Noni-precipitate (0.5 mg mouse^-1, i.p.) resulted in a cure rate of 25-45%. This therapeutic rate was eliminated by macrophage inhibitors (2-chloroadenosine), T cells (cyclosporine) and Natural Killer (NK) cells (anti-asialo GM1 antibody), whereas interferon increased the survival rate by 71-100%. Noni precipitate shows synergistic beneficial effects with broad spectrum of chemotherapeutic drugs especially, adriamycin, bleomycin, camptothecin, cisplatin, etoposide, 5-fluorouracil, interferon, mitomycin-C and vincristine. Noni precipitate showed antagonistic activity when it is combined with cytosine arabinoside, paclitaxel and immunosuppressive anticancer drugs such as methotrexate, cyclophosphamideand 6-thioguanine. Noni-ppt shows beneficial effects with imexon, a synthetic immunomodulator but not with MVE-2 (Maleic anhydride divinylether) which is a high molecular weight immunomodulator. Noni-ppt also has beneficial effects when combined with Th1 cytokinesinterferon gamma but there is gradual deterioration of activity when combined with Th2 cytokines, interleukin-4 and interleukin-10. So, Noni-ppt potentiates a Th1 predominant immune status in vivo (Furusawa et al., 2003).

Tahitian Noni juice (1% or 1 mg mL^-1) and Noni Fruit Juice Concentrates (NFJC) (5% or 5 mg mL^-1) potentially activate cannabinoid 2 (CB2) receptors but inhibit cannabinoid 1 (CB1) receptors in a concentration-dependant manner. The CB2 receptors are involved in immunomodulation, anti-inflammatory activity by counteracting the proinflammatory signals and inhibiting the neuropathic pain without psychoactive effects (Massa et al., 2004). The CB2 receptors also suppresses the microbial activation and protect hippocampal neurons from excitotoxicity (Ehrhart et al., 2005). Morinda citrifolia potentiates the immune system by activating of the CB2 receptors and increasing the production of IFN-γ cytokines but suppresses IL-4 production (Palu et al., 2008). Fermented Noni Exudate (fNE) has the ability to stimulate both arms of the immune system such as innate and the adaptive immune system to eliminate cancer cells. Intraperitoneally injected fNE significantly increases the amount of NK cells and granulocytes in the peripheral blood, spleen and peritoneum. Surprisingly, the fNE significantly decreases the percentage of B lymphocyte and the percentage of T cells in the spleen and significantly increases the percentages of CD8⁺ T cells and CD25⁺ cells in the peritoneum. The fNE treatment increased the total peritoneal leukocyte counts more than 10 folds. More than 85% of the normal C57BL/6J mice completely rejected S180 tumor cells and 62% of mice rejected Lewis lung carcinoma (LL/2) cells after treatment with three doses of fNE (500 μL/mouse/day, i.p.). In case of C57 nude mice which lack functional lymphocytes, partial tumor rejection was noticed whereas no cancer rejection was noticed in beige mice which are lacking NK cells. So, NK cells are the major quick responders of fNE treatment and innate immune system is the major player for fNE treatment while the adaptive immune system reacts slowly with sustained memory (Li et al., 2008). Noni juice has antigrowth, cytotoxic and apoptosis inducing effects on breast cancer (Ehrlich ascites tumor) in female Balb-c mice. When Noni was administered with the potent anticancer drug doxorubicin, the action was greater than either doxorubicin or Noni alone. It significantly decreased the proliferation rate and size of the tumor about 40-50%. This anti-proliferative effect of Noni was due to stimulation of apoptosis and activation of caspase-3 cells in tissues (Taskin et al., 2009).

Noni prevents chemical induced esophagus tumorigenesis in the rat. In a study tumor incidence was 60% in the Noni group as compared to 95% in the carcinogen group (Stoner et al., 2010). M. citrifolia fruit can reduce the N-Methyl N-Nitrosourea (NMU) induced peripheral T-cell non-Hodgkin’s lymphoma when used as a dietary supplement to Sprague Dawley (SD) rats at a daily dose of 750 mg kg^-1 body weight (Hutheyfa, 2010). M. citrifolia has apoptotic effects against peripheral T-cell Non-Hodgkin’s lymphoma induced by Dibenzo [a,l] pyrene (DBP) in BALB/c mice. DBP is the most powerful genotoxic carcinogenic polycyclic aromatic hydrocarbons (PAHs) and it is found all over the environment in the water, air and soil. M. citrifolia has anti-tumour activity against experimentally induced leukaemia in male SD rats using the NMU. Daily supplementations of M. citrifolia dried fruit at a dose of 5000 mg kg^-1 b.wt. reduced the proliferation of circulating leukaemic cells and 3000 mg kg^-1 reduced the incidence of early stage of leukaemia to 60% (Hazilawati et al., 2010a, 2010b).

Noni juice enhances differentiation of the mammary gland and decreases the mammary cancer proliferation in MMTV-neu transgenic mice. In this model, Mouse Mammary Tumor Virus (MMTV) promoter transcriptionally controls the expression of unactivated rat neu (c-erbB2) gene. This mouse model exhibits various features of similarities to HER2/neu⁺ breast cancer that include onset of stochastic tumor, focal tumors that occurs near the hyperplastic tissue, estrogen-dependent tumor development, long latency period and metastatic progression to the lungs. Prolonged administration of 10% TNJ decreased mammary tumor size, volume and weight, slows the tumor growth kinetics and increased doubling time of tumor. TNJ increases central necrosis in mammary tumors by its antiangiogenic and cytotoxic actions. The anti-inflammatory actions of Noni by directly inhibiting COX-2 activity and its corresponding PGE2 levels are important for the tumor inhibition. TNJ-treatment causes augmented differentiation of mammary gland which has been inversely associated with malignant potential of mammary epithelial cells (Clafshenkel et al., 2012). Saminathan et al. (2013a, b) evaluated the anticancer efficacy of Morinda citrifolia Leaf Extract (MCLE) and fruit juice against N-Methyl-N-Nitrosourea (NMU) induced mammary tumours in female Sprague-Dawley rats. During 28th weeks of experimental period, tumour frequency and average tumour volume was significantly reduced in M. citrifolia treated groups when compared to control. The immunohistochemical expression of cell proliferation marker PCNA, angiogenic markers VEGF and PECAM-1 and anti-inflammatory marker COX-2 expression was significantly (p<0.05) reduced in M. citrifolia treated groups when compared to the control. The TUNEL positive apoptotic cells were significantly higher in Noni treated groups as compared to the control. These results provide promising baseline information for the potential uses of Morinda citrifolia leaf extract in the treatment of cancer. Saminathan et al. (2013c) also studied the chemopreventive activity of Noni fruit juice against N-Methyl-N-Nitrosourea (NMU) induced mammary tumours in female Sprague-Dawley rats. The average latency period was significantly increased (182±0.0 days) in Noni fruit juice treated group whereas in control group decreased to 107±4.1 days. The tumour frequency and tumour incidence were significantly decreased in Noni fruit juice treated groups. Interestingly, in treated groups only benign tumour was observed whereas in control group more malignant tumours were developed.

In vivo anticancer studies in human: Noni juice is used for treatment of gastric cancers. A 69 year old male patient suffering from gastric cancer was expected to die within a few months without surgery. The patient denied surgery and became bedridden and his weight had reduced from 165-79 pounds. Then he started to take household Noni juice regularly. After taking Noni juice his condition improved within a month and after 6 months he was completely cured and did not developed any gastric symptoms during a follow up period of 7 years (Wong, 2004). Another 64 year old male patient underwent surgery, gastrectomy for gastric cancer. The cancer had metastasized to 17 of 28 examined lymph nodes and doctors informed that he would live only for 5 years. The patient consumed home-based Noni juice and lived for 16 more years until he died at age 80 due to starvation that results from gastric cancer (Wong, 2004).

National Institute of Health (NIH) performed phase 1 clinical trials in humans to find the dose and to examine the effect of ripened M. citrifolia fruit extract as dietary supplement in the form of freeze-dried pills in end stage cancer patients. A 29 year old advanced cancer patient was provided with a daily dose of four capsules each containing 500 mg of Noni fruit extract. In consequent days the dosage levels were increased by 2 g daily upto a highest dose level of 10 g daily. After treatment the level of tumour regressions was assessed by using Response Evaluation Criteria in Solid Tumours (RECIST) criteria. The dose response relationship was assessed by measuring the fatigue by using Brief Fatigue Inventory (BFI) and depressed mood by Centre for Epidemiologic Studies Depression scale (CES-D). Finally the results showed that Noni fruit extract has no significant effect on tumour regression and no dose response relationship was noticed. However, there was a significant reduction in sensitivity to pain and no adverse effects to Noni were noticed (Issell et al., 2005).

Tahitian Noni Juice (TNJ) decreases cancer hazard in cigarette smokers by reducing aromatic DNA adducts in peripheral blood lymphocytes. Measurement of aromatic DNA adduct levels are good biomarker for cancer, genotoxicity and DNA damage for all degenerative diseases associated with smoking. After drinking of 1-4 oz of TNJ for 1 a month period of time aromatic DNA adduct levels were significantly reduced to 44.9% in all cigarette smoking participants. Dose-dependent analyses of aromatic DNA adduct levels showed, 49.7 and 37.6% reductions in 1 oz TNJ and the 4 oz TNJ group, respectively. In the gender specific analyses the 4 oz TNJ group showed no significant differences. But interestingly, in the 1-oz TNJ group female smokers showed a reduction of 43.1% when compared to 56.1% in males. The TNJ significantly reduced the levels of Superoxide Anion Radicals (SAR) and lipid hydroperoxide (LOOH) in plasma of the smokers (Wang et al., 2009a, b).

Protective effect of Noni on liver injury induced by a liver carcinogen: Noni Juice (NJ) has preventive effect on carbon tetrachloride (CCl₄) produced liver injury in female SD rats. The placebo and NJ groups showed normal lobular architecture of liver. The placebo+CCl₄ group showed acute liver damage like vacuolated cytoplasm, fatty change, centrilobular necrosis and focal inflammatory cells scattered throughout the lobule. But NJ+CCl₄ group showed significant reduction in swollen, lipid containing and apoptotic hepatocytes. Glycogen depletion, lipid droplets in the plasma membrane, disorganization of Rough Endoplasmic Reticulum (RER) with loss of ribosome and swollen mitochondria were observed in both CCl₄ treated groups at the Electron Microscopic (EM) level. The NJ+CCl₄ group showed golgi complexes with larger vesicles, increased electron density and well developed golgi cisternal stacks. Whereas the placebo+CCl4 group showed golgi complexes with small low-density vesicles (Wang et al., 2002b, 2008; Nayak et al., 2011).

Other pharmacological activities of Noni
Antibacterial activity: Acubin, L-asperuloside and alizarin in the Noni fruit and scopoletin and anthraquinone compounds in Noni roots have antibacterial properties (Atkinson, 1956). M. cirifolia fight against many infectious bacteria like Baciillis subtilis, Staphylococcus aureus, Escherichia coli, Proteus morgaii, Salmonella typhosa, Salmonella montevideo, Pseudomonas aeruginosa, Salmonella schottmuelleri and Shigella paradys. So, Noni is frequently used for treatment of broken bones, bruises, sores and wounds, colds, fevers, skin infections and other bacteria induced ailments (Bushnell et al., 1950; Leach et al., 1988; Sundarrao et al., 1993; Dittmar, 1993; Locher et al., 1995). A coumarin compound scopoletin isolated from Noni plant inhibits the activity of E. coli and also helps in healing of stomach ulcers by inhibiting the bacteria Helicobacter pylori (Duncan et al., 1998). The methanol and aqueous extracts of the Noni fruit have also been reported to possess antibacterial activity against E. coli, Streptococcus sp., Vibrio alginolyticus, Vibrio harveyi, Klebsiella, B. subtilis, Lactobacillus lactis, P. aeruginosa, Salmonella typhi, S. aureus, Streptococcus thermophilus, Shigella flexneri and Chromobacterium violaceum (Wei et al., 2008; Jayaraman et al., 2008; Selvam et al., 2009; Kumar et al., 2010; Usha et al., 2010; Natheer et al., 2012).

Murray et al. (2008) compared the in vitro effectiveness of Noni juice with chlorhexidine gluconate and sodium hypochlorite (NaOCl) to remove the smear layer of Enterococcus faecalis from the canal walls of endodontically instrumented teeth. The result indicated that Noni fruit juice and NaOCl treatment have similar effects. West et al. (2012) reported the antibacterial activity of iridoids (deacetyl asperulosidic acid and asperulosidic acid) in Morinda citrifolia fruits against Candida albicans, E. coli and Staphylococcus aureus.

Anti-tubercular activity: M. citrifolia leaf extract effectively kills 89% of Mycobacterium tuberculosis bacteria, whereas the standard antituberculosis drug Rifampcin has 97% growth inhibition rate at the same concentration (American Chemical Society, 2000; Anonymous, 2001). Various components like E-phytol, stigmasterol, campesta-5,7,22-trien-3beta-ol, beta-sitosterol, ketosteroids stigmasta-4-en-3-one,cycloartenol and stigmasta-4-22-dien-3-one isolated from hexane fraction from M. citrifolia showed pronounced antitubercular activity (Saludes et al., 2002).

Antiviral activity: An anthraquinone compound 1-methoxy-2-formyl-3-hydroxyanthraquinone extracted from M. citrifolia roots reduced the cytopathic effect in MT-4 cells infected with HIV, without inhibiting growth of the cells (Umezawa, 1992). The mechanisms of Vpr have been intensely studied because it is believed that they underlie HIV-1 pathogenesis. Another anthraquinone compound, damnacanthal from Noni inhibits Vpr induced cell death which has major role in HIV-1 pathogenesis. These results formed a novel base for drug screening and development in anti-HIV therapy (Kamata et al., 2006).

Antifungal activity: An aqueous extract of Morinda citrifolia has the ability to hinder the in vitro serum-induced morphological conversion of Candida albicans from the cellular yeast to a filamentous form. The aqueous extract also has inhibiting potential on the germination of Apergillus nidulans spores. The antifungal activity of M. citrifolia aqueous extract may be due to its water-soluble components which have potential therapeutic value against candidiasis and aspergillosis (Banerjee et al., 2006; Usha et al., 2010). Noni has maximum percentage of inhibition against Trichophyton mentagrophytes in the extracts of methanol (79.3%) and ethyl acetate (62.06%). The methanol extract showed 50% inhibition rate against Penicillium sp., Fusarium sp. and Rhizopus sp. Both the extracts were not, however, effective against Candida albicans and Aspergillus species (Jayaraman et al., 2008). Jainkittivong et al. (2009), on the other hand, reported the in vitro antifungal activity of M. citrifolia fruit extract on Candida albicans. In cultures, there was no growth of C. albicans at a concentration of 50 mg mL^-1 of extract for 30 min contact time and at a concentration of 60 mg mL^-1 of extract for 15 min contact time. In broth dilution method, the extract has minimum fungicidal concentration of 40 mg mL^-1 for 90 min contact time and 50 mg mL^-1 for 15 min contact time against C. albicans.

Anthelmintic activity: An ethanolic extract of the immature Noni leaves showed anthelmintic activity by enhancing paralysis and killing of the nematode worm Ascaris lumbricoides, within 24 h (Raj, 1975). At several places such as Philippines and Hawaii Noni has been used as an effective insecticide for control of various arthropod populations (Morton, 1992). The alcoholic extract of M. citrifolia leaves produced more significant anthelmintic activity against adult Indian earthworms (Pheretima posithuma) when compared to petroleum ether extract and the activities were almost equal to activity of the standard anthelminthic drug piperazine citrate (Kumar et al., 2010).

Immunomodulating activity: Alcoholic extract of the Noni fruit at various concentrations has inhibiting effect on tumour necrosis factor-alpha (TNF-α) production. The TNF-α is an endogenous tumor promoter which is responsible for tumour progression (Hokama, 1993; Asahina et al., 1994). Noni fruit juice contains a polysaccharide-rich substance which has anti cancerous activity that increases the release of cytokine IFN-gamma from thymocytes. It has antitumor activity against Lewis Lung Peritoneal Carcinomatosis (LLC) by potentiating the immune system through macrophages to secrete TNF-α, IFN-γ, IL-1β, IL-10, IL-12 and nitric oxide but it had no effect on IL-2 secretion whereas it reduced the secretion of IL-4. These results suggested that the Noni-ppt reduces the tumour growth by potentiating the host immune system (Hirazumi and Furusawa, 1999). Hokama (1993) separated 50% aqueous alcohol and precipitated fractions from the ripe Noni fruit juice that inhibits the Lewis lung tumours in BALB/c mice through activation of the T-cell immune response from thymocytes. In one study, the wet weight of the thymus was increased to 1.7 times than normal, seven days after drinking of 10% TNJ in drinking water. This clearly indicates that TNJ may enhance immune function through stimulation of thymus growth which results in anti-aging and protection from degenerative disease (Pansuebchue et al., 2002; Wang et al., 2002a). Noni fruit juice has potential immune-modulating effects on feeding to neonatal Holstein calves, through increased expression of CD25 on CD4⁺, CD8⁺ and γδ T cells. Noni up regulates IL-1β, TNF-α and IFN-γ in bovine colostrums and results in direct increase in natural cell-mediated immunity through the enhanced activation of CD4⁺ and CD8⁺ T cells (Brooks et al., 2009).

Dendritic Cells (DCs) treated with fermented Noni Exudate (fNE) stimulate proliferation of splenocytes and B cells, promote its differentiation and immunoglobulin class switching to produce IgG and IgM but fNE alone could not directly stimulate B cell proliferation. The fNE contains 0.25 μg mL^-1 of endotoxin. The proliferative response of B cells to fNE-treated DCs was cell contact dependent but CD40L-independent (Zhang et al., 2009). The extracts of M. citrifolia fruits have stimulatory effects on T and B lymphocytes which are the important components of the adaptive immune system. The hydroalcoholic (0.5 and 1.0 mg mL^-1) and aqueous extracts (0.5 and 1.0 mg mL^-1) significantly enhanced the splenocyte proliferation and the cell-mediated immune response. All these results provide baseline information that M. citrifolia fruits have both the humoral and cell mediated immunostimulatory effects (Nayak and Mengi, 2010).

Antioxidant activity: Noni juice has excellent antioxidant activity which may guard individuals from oxygen free radicals and lipid peroxidation induced damage. The Superoxide Anion Radicals (SAR) and quenched lipid peroxides (LPO) scavenging activity of TNJ was estimated in vitro by tetrazolium nitroblue (TNB) assay and LMB assay, respectively. TNJ showed a concentration dependent inhibition of both LPO and SAR. The SAR scavenging activity of TNJ was 2.8 times that of vitamin C, 1.1 times that of grape seed powder and 1.4 times that of Pycnogenol. These results confirmed the antioxidant potential of TNJ by quenching the reactive oxygen free radicals (Wang and Su, 2001; Wang et al., 2002b). The Noni juice also has in vivo antioxidant activity against carbon tetrachloride (CCl₄) induced liver injury model in female SD rats. CCl₄ is a hepatic carcinogen and potent inducer of lipid hydroperoxidation. Administration of 10% of TNJ in drinking water for a period of 12 days suppressed the levels of LPO and SAR in liver to 20 and 50%, respectively 3 hrs after administration of CCl₄ (Wang and Su, 2001; Wang et al., 2002b). In cigarette smoke was reported to contain 227 possible carcinogens and each puff of cigarette smoke contains 1H10¹⁷ oxidant molecules (Chow, 1993). Wang et al. (2009a, b) assessed the antioxidant activity of TNJ on plasma by estimating the SAR and LPO levels in current cigarette smokers. The smokers were provided daily with a dose of two ounces of TNJ twice a day for a period of 30 days. The LPO and SAR levels in the TNJ group showed 23% reduction and 27% reduction, respectively when compared to placebo group. These results indicate that TNJ may guard individuals from tobacco smoke free radical induced damage.

Anitha and Mohandass (2006) reported that oral administration of 50 mg kg^-1 day^-1 of crude methanol extract of M. citrifolia leaves for a period of 14 days significantly enhanced the anti-oxidant enzymes, such as glutathione peroxidase (GSHPx), catalase (CAT) and superoxide dismutase (SOD). Duo to anti-oxidant activity there was reduction in lymphoma in mice. Zin et al. (2002) and Su et al. (2005) reported that various parts of M. citrifolia (leaf, fruit and root) have antioxidative activities. When compared to either leaf or fruit the polar and non-polar extracts of the root exhibited stronger antioxidative potential. Ikeda et al. (2009) observed that both Noni and coumarin derivatives have scavenging activity on ROS such as superoxide (OG₂), singlet oxygen (¹O₂), hydroxyl radical (^.OH) and peroxynitrite (ONOOG) in a dose-dependent manner. Liu et al. (2007) have reported that the antioxidative mechanism of Noni fruit juice was partially attributable to the group of phenolic compounds, such as isoscopoletin, quercetin and aesculetin in the EtOAc (ethanolic) extract. Thani et al. (2010) recorded that the non-aqueous extracts from the leaves of Thai Noni/Yor showed antioxidant properties, giving IC₅₀ values of 0.20-0.35 mg mL^-1. These results suggest that the leaves of M. citrifolia could be preferred as a food supplement for its antioxidative activities in epidermoid and cervical cancers over damnacanthal, rutin and scopoletin. Dussossoy et al. (2011) showed that Noni’s anti-oxidant activities are possibly due to phenolic compounds, iridoids and ascorbic acid. Serafini et al. (2011) investigated the antioxidant activity of aqueous extract from M. citrifolia leaves against lipid peroxidation, hydroxyl and nitric oxide induced radicals. West et al. (2011) evaluated the antioxidant activity of Morinda citrifolia seed extract. The seed extract exhibited significant antioxidant potential against various types of free radical induced damage. West et al. (2009) also evaluated the antioxidant properties of roasted Noni leaf infusion. The infusion has 2, 2-diphenylpicrylhydrazyl (DPPH) radical scavenging activity which was higher when compared to green tea infusion.

Anti-inflammatory activity: Increased expression of COX-2 receptors is associated with development of breast, colon and lung cancer (Takahashi et al., 2002). In chemical carcinogenesis COX-2 is induced at a rapid rate and its over expression may lead to increased signals for angiogenesis and inflammatory reaction (Colville-Nash and Gilroy, 2001). Noni juice selectively inhibits expression of COX-2 receptors resulting in cancer chemoprevention especially colon and breast cancers in a similar way as aspirin, indomethacin and selective COX-2 inhibitor celebrex. Inhibition of COX-2 results in anti-inflammatory activity and decrease angiogenesis. The COX-1 and COX-2 activities were estimated by the Amersham ELA assay which is based on the level of PGE2 produced during the incubation of tested compounds and vehicle with human platelets. The results in this assay provide a strong evidence of its anti-inflammatory activity which may be responsible for cancer prevention (Su et al., 2001). Noni juice has anti-inflammatory activity against CCl₄ induced acute liver damage in female SD rats. The pretreatment with 10% TNJ for a period of 12 days in drinking water reduced inflammatory reaction and lymphocytes around the central vein in the liver were noticed at 6 h post CCl₄ administration (Wang and Su, 2001). McKoy et al. (2002) tested the anti-inflammatory property of an aqueous extract from M. citrifolia fruit juice against local acute inflammatory response induced by potent pro-inflammatory agent bradykinin. He demonstrated that oral drenching of Noni juice extract at a dose of 200 mg quite rapidly prevented the formation of rat paw edema. This anti-inflammatory effect may be due to the inhibition of B2 receptor mediated mechanism of bradykinin. Okusada et al. (2011) reported that damnacanthal isolated from Noni root mediates its anti-inflammatory activity through the histamine H1 receptor. One study showed that ethanol extract of fruit powder has a selective inhibitory effect on cyclooxygenase-1 (COX-1) with IC₅₀ value of 163 μg mL^-1 and it was lower than that produced by aspirin (241 μg mL^-1), whereas much higher than indomethacin (1.2 μg mL^-1) used as the reference COX-1 inhibitors. But it did not exhibit (in vitro and in vivo) Nitric Oxide (NO) scavenging activity, a key mediator in the phenomenon of inflammation (Li et al., 2003).

Several polyphenols belonging to the coumarin, flavonoids, phenolic compounds, iridoids and ascorbic acid present in Noni juice have free radical scavenging activity. These compounds also decrease the carrageenan induced paw edema by directly inhibiting the cyclooxygenase COX-1 and COX-2 activities. The anti-inflammatory activity of Noni may attributed due to inhibition, in a dose dependent manner, of the production of prostaglandins E₂ (PGE₂) and Nitric Oxide (NO) in activated J774 cells. These results showed that Noni’s anti-inflammatory properties are probably due to NO and PGE₂ pathways (Dussossoy et al., 2011). New saccharide fatty acid ester 2-O-(beta-D-glucopyranosyl)-1-O-octanoylbeta-D-gluropyranose isolated from Noni juice exhibited potent anti-inflammatory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA) induced inflammation (1 μg ear^-1) in mice (Akihisa et al., 2007). Song et al. (2010) reported that the methanol extracts of Morinda citrifolia suppressed melittin-induced arachidonic acid release and inhibited phospholipase A2 induced hydrolysis in a concentration and time dependent manner. Therefore, Morinda citrifolia may possess anti-inflammatory activity secondary to Ca²⁺ dependent phospholipase A2 inhibition.

Noni Seed Oil (NSO) has potential beneficial effects in human skin problems like acne. NSO reduced the number of open and closed comedones in the comedogenicity test. NSO has potential anti-inflammatory activity by inhibiting COX-2 and 5-LOX enzymes in a concentration dependent manner. However COX-2 inhibition is more pronounced than 5-LOX. So, Noni seed oil is safe for topical use for skin care applications and is non-comedogenic (Palu et al., 2012). Two new lignans, (+)-3,3'-bisdemethyltanegool and (+)-3,4,3',4'-tetrahydroxy-9,7'alpha-epoxylignano-7 alpha, 9'-lactone as well as seven known compounds isolated from Noni fruits exhibited 5- and 15-lipoxygenase inhibiting activity (IC₅₀ 0.43-16.5 μM). Quercetin exhibited weak inhibitory activity toward COX-2 (Deng et al., 2007a).

Analgesic activity: Extracts from the M. citrifolia plant possess significant tranquilizing and central analgesic activities in a dose related manner. The analgesic effect of the Noni extract is 75% more strong than morphine, however it is non-addictive and absence of side effect (Younos et al., 1990). The analgesic property of TNJ was tested by the hot plate assay and “twisted method” animal model. Administration of antimony potassium tartrate intraperitoneally produces twisting due to pain. The number of twists is counted to assess the level or extent of pain within the first l5 min after injection. The analgesic effect of TNJ is dose dependent and is statistically significant when compared with the control group (Wang et al., 2002a). Punjanon and Nandhasri (2005) evaluated the pain-relieving potential of fruits of Noni and its alcoholic extract by means of acetic acid-induced writhing test in mice. Fifteen min before intraperitoneal administration of acetic acid (0.75%), Noni extract was administered intraperitoneally at the doses of 1, 2, 3 and 4 g kg^-1 b.wt. The alcoholic extracts of Noni produced a significant reduction of acetic acid induced abdominal constriction in a dose dependent manner. At a dose of 4 g kg^-1of extract produces significant analgesic effect which was almost equal to analgesic effect produced by standard analgesic drug morphine at a dose rate of 1.5 mg kg^-1 body weight. The analgesic efficacy of Noni by acetic acid induced writhing test for 15 min was statistically significant until 5 h of administration. These results suggest that the alcoholic extract of fruits have analgesic effect (Okusada et al., 2011). M. citrifolia is used for the treatment of painful inflammatory conditions, such as arthritis. The freeze concentrated Noni fruit puree at a concentration of 10% solution in the drinking water to mice inhibited the pain signals when compared to standard tramadol which was the central analgesic drug. This analgesic action was partially reversed by the drug naloxone, a known morphine antagonist. An alcohol extract of freeze concentrated Noni fruit puree produces reduction of release of MMP-9 from the monocytes of human origin after stimulation with LPS. This effect was comparable to standard drug hydrocortisone. These results proved that extracts of Noni fruits are efficient in inhibiting pain and arthritis (Basar et al., 2010).

Wound healing activity: An anthraquinone, 1, 4-dihydroxy-2-methoxy-7-methylanthraquinone, isolated from the extracts of Noni fruit stimulates production of glycosaminoglycans and type 1 collagen from the normal human fibroblast primary cultures. This compound demonstrated significantly improved biosynthesis of glycosaminoglycans and procollagen type 1 C-terminal peptide. The compound also decreases the production of the collagenase matrix metalloproteinase-1 from the human dermal fibroblasts in a dose-dependent manner. These results indicate that anthraquinone isolated from M. citrifolia fruit extract is a potential candidate for usage as anti-wrinkle agent because of its potent stimulatory action on production of extracellular matrix components (Kim et al., 2005).

Nayak et al. (2007) evaluated the wound regenerating potential of Noni fruit juice in streptozotocin inuced diabetic rats using an excision wound model. The rats were given Noni juice at 100 mL kg^-1 b.wt. in drinking water for 10 days. The wound area reduced to 73% in the Noni treated group as compared to 63% in diabetic controls. The weight of granulation tissue, protein and hydroxyproline content was significant increased in the Noni treated group. Histological findings revealed that deposition of collagen was quicker in the Noni treated group than that in the control group. In the Noni juice treated group, fasting blood glucose values were reduced to 29% when compared to diabetic control animals. They also reported a strong association between the blood glucose level and wound contraction rate. These results demonstrated that Noni fruit juice significantly decreases the blood sugar levels and accelerates wound healing in diabetic rats.

Nayak et al. (2009) evaluated the wound-healing activity of ethanol extract of Noni leaves (150 mg kg/day), using dead space and excision wound models on rats. The rats were administered orally with the ethanol extract by mixing in drinking water. The extract administered group showed 71% reduction in the wound area on day 11, as compared to control group which showed 57% reduction in the wound area. The weight of granulation tissue, protein and hydroxyproline content was significant increased in the dead space wounds in Noni treated animals. Accelerated wound contraction, reduced epithelialization time and improved hydroxyproline contents indicated that Noni leaf extract may have curative potential in wound healing. Palu et al. (2010) reported that M. citrifolia leaves significantly hastened the rate of wound healing in mice due to its possible mechanisms of action of ligand binding to the PDGF and A(2A) receptors .

Hypotensive activity: Ethanolic and hot water extracts of the Noni roots reduced the blood pressure in anesthetized dogs (Dang, 1954; Youngken, 1958; Youngken et al., 1960; Moorthy and Reddy, 1970). Noni fruit juice also has diuretic activity that may have antihypertensive effect. M. citrifolia juice has strong inhibitory activity on Angiotensin I Converting Enzyme (ACE) and thus produces antihypertensive effect. The ACE inhibitory activity of ripened Noni fruit was more potent than that of green immature fruit. Moreover, single administration of the Noni juice orally decreased the systolic blood pressure in hypertensive rats (Yamaguchi et al., 2002). The 70% aqueous-ethanolic extract of M. citrifolia roots (Mc.Cr) has antispasmodic, vasodilator and cardiovascular relaxant effects and can be used in the treatment of gut and cardiovascular disorders (Youngken et al., 1960; Moorthy and Reddy, 1970). The extract also produced a relaxation of spontaneous and high K⁺ induced contractions in a concentration-dependent manner in isolated rabbit jejunum preparations. Like verapamil, it caused the right ward shift in the concentration response curves of Ca⁺⁺. Mc.Cr also produced reduction in both atrial force and the rate of contractions in guinea pig right atria. Similar to verapamil, Mc.Cr also decreased the contractions produced by phenylephrine in rabbit and rat thoracic aortic preparations in which the level of Ca⁺⁺ is normal and the level of K⁺ is high. These results indicate that the vasodilator and spasmolytic activities of M. citrifolia root extract are governed by the inhibition of voltage dependent calcium channels and secretion of intracellular calcium. Taking advantages of these activities, M. citrifolia root extract was used for the trearment of diarrhea and hypertension (Gilani et al., 2010).

Cardiovascular activity: The lignans 3, 3'-bisdemethylpinoresinol, americanol A, morindolin and isoprincepin were isolated from the EtOAc-soluble phase of the fruits of Morinda citrifolia. These compounds prevent arteriosclerosis by inhibiting copper-induced Low-Density Lipoprotein (LDL) oxidation. The MeOH extract showed 88% inhibition and EtOAc-soluble phase showed 96% inhibition. These compounds reduced the low-density lipoprotein levels in a dose-dependent manner. These compounds also showed more potent anti-oxidant activities when compared to standard antioxidant compound 2, 6-di-tert-butyl-p-cresol. The antioxidant activity of these compounds may be attributable mainly to the presence of phenolic hydroxyl groups (Kamiya et al., 2004).

Mandukhail et al. (2010) studied the antidyslipidemic effects of aqueous-ethanolic extracts of Noni fruits (Mc.Cr.F), leaves (Mc.Cr.L) and roots (Mc.Cr.R) in both high fat diet and triton (WR-1339) induced dyslipidemic models in rats. All three extracts caused reduction in triglyceride, total cholesterol, LDL-cholesterol, atherogenic index and TC/HDL ratio. The Mc.Cr.L and Mc.Cr.R caused reduction in body weight gain with a reduction in daily diet consumption whereas Mc.Cr.F had no effect. They concluded that antidyslipidemic effect was governed through the reduction in production absorption and secretion of lipids. This antidyslipidemic effect may be due to the existence of antioxidant compounds in Noni plant.

Hypoglycemic effect: Jensen et al. (2005) treated type 2 diabetes using M. citrifolia leaf extract. Anthraquinones damnacanthol-3-O-beta-D-primeveroside and lucidin 3-O-beta-D-primeveroside were isolated from n-BuOH soluble phase of the MeOH extract of M. citrifolia roots. These compounds exhibited the hypoglycemic effects when administrated orally to streptozotocin (STZ)-induced diabetic mice (Kamiya et al., 2008). Horsfall et al. (2007) examined the antidiabetic potential of M. citrifolia fruit juice alone or in combination with insulin in diabetic rats. Fruit juice of M. citrifolia showed synergistic action with insulin and reduced blood glucose level. Owen et al. (2008) reported that consumption of Noni fruit and extract from leaves showed insulinmimetic activity but had no effect on insulin action. The usual intake of Noni and guava provides better protection against type 2 diabetes (DM2) and betel quid diabetogenicity than cooked mangrove bean. Nerurkar et al. (2011) investigated anti-diabetic potential of fermented Noni fruit juice (fNJ) in High-Fat Diet (HFD) induced model in mice. The fNJ improves glucose metabolism via modulating transcription factor forkhead box O (FoxO1) regulation. One more study suggested that the fermented fruit juice of the M. citrifolia has hypoglycaemic effect in Streptozotocin (50 mg kg^-1 b.wt.) induced diabetic rats. Diabetic rats were administered with M. citrifolia juice at a dose of 2 mL kg^-1 b.wt. and glibenclamide, a known reference hypoglycemic drug, orally for a period of 20 days. There was significant decrease in blood glucose level in both groups when compared to control group. Diabetic rats showed a reduction in body mass on the 10th day of experiment, albeit it was increased significantly in treatment group by the 20th day of the experiment (Nayak et al., 2011).

Anti-obesity effects: Palu et al. (2011) conducted one study to assess the effect of Noni based formulations as dietary supplementation and exercise interventions on body composition in overweight men and women. Body weight, body mass index and percent body fat were measured before and after the trial. The weight reduction and average reduction in fat mass was very significant and resulted in reduction in body mass index and percent body fat. Noni juice caused loss of body weight by 40% in a control diet fed mice whereas it caused 25% loss of body weight in High-Fat-Diet (HFD)-fed mice. Noni juice also increased glucose tolerance and decreased the plasma triglyceride levels. These results suggested that Noni juice has anti-obesity and hypoglycemic effects (Nishioka and Nerurkar, 2007).

Anti-cataract activity: M. citrifolia (IC₅₀ 0.132 mg mL^-1) strongly inhibits Aldose Reductase (AR) which plays an important role in cataractogenesis. Anti-cataract activity was established by means of sugar promoted lens opacity model (Gacche and Dhole, 2011). Saminathan et al. (2014) evaluated the anti-cataract activity of Morinda citrifolia Fruit Juice (MCFJ) and ethanolic leaf extract (MCELE) in N-methyl-N-nitrosourea (NMU) induced cataract in Sprague-Dawley rats. The MCFJ was administered at 10% solution of 5 mL/rat/day and MCELE at 1500 mg kg^-1 b.wt/rat/day, in two divided doses, orally by gavage. The M. citrifolia treated rats showed significant (p<0.05) increase in anti-oxidant enzymes such as Glutathione Reductase (GR), CAT, SOD and significant decrease in LPO enzymes in lens homogenate as compared to NMU control group. These results suggested that M. citrifolia have significant anti-cataract potential.

Mental health and improved high frequency hearing: Langford et al. (2004) conducted a clinical trial in humans to assess the efficiency of TNJ against auditory function and decreased bone mineral density in the patients. They reported that TNJ affords encouraging results on improved high frequency hearing and mental health but this study also showed that excess amounts or prolonged duration of TNJ uptake may be required to overcome these conditions.

Effect on stress-induced impairment of cognitive function: Supplementation of Noni fruit juice safeguards the brain from stress-induced derangement of cognitive function. This defensive beneficial effect may be due to enhancement in stress-induced reduction in blood vessel mass in the area of hippocampal dentate gyrus which was analysed immunohistochemically with BrdU or CD31 antibody (Muto et al., 2010).

Effect on ischemic neuronal damage: Ingestion of 10% Noni juice orally by mixing in drinking water for a period of 7 days in male ddY mice followed by exposure to 2 h of Middle Cerebral Artery Occlusion (MCAO) reduced the progress of neuronal injury. After Noni juice administration MCAO completely disappeared and glucose intolerance abolished on the 1st day. Noni juice administration significantly enhanced the serum insulin levels when compared to the control group on the 1st day but the levels of adiponectin in serum were not changed. These results suggested that Noni juice might enhance insulin secretion after ischemic tension and this may lead to reduction in the progress of post-ischemic glucose intolerance (Harada et al., 2010).

Anxiolytic and sedative effect: Deng et al. (2007b) investigated in vitro anxiolytic and sedative effects of Noni fruit by competitive gamma-aminobutyric acid A (GABAa) receptor-binding assay. They reported that methanol extract of Noni fruit exhibited high specificity to the inhibitory neurotransmitter GABAa receptor and agonist muscimol exhibited 75% inhibition at a concentration of 100 μg mL^-1. These results indicate that Noni fruit is agonistic to the GABAa receptor and thus induces anxiolytic and sedative effects (Kalandakanond et al., 2004).

Prevention of postoperative nausea and vomiting: Prapaitrakool and Itharat (2010) evaluated the preventive potential of Noni against the postoperative nausea and vomiting (PONV) in patients who were at great risk of developing PONV after different kinds of surgery. Administration of Noni extract at a dose of 600 mg which is equivalent to 8.712 μg of scopoletin, significantly reduced the PONV in 48% of the patients during the first 6 h, whereas PONV was recorded in 80% patients in the control group. In all groups no side effects were reported. These results suggested that Noni has an antiemetic property and can be used as prophylactic agent for early postoperative nausea (0-6 h).

Reflux esophagitis and gastric ulcer: Mahattanadul et al. (2011) evaluated the efficiency of aqueous extract of dried mature unripe Noni fruit and its biomarker scopoletin on gastro-esophageal inflammatory model in rats. The aqueous extract at a dose of 0.63-2.50 g kg^-1 b.wt. significantly inhibited the development of acid induced reflux esophagitis, acute gastric lesions induced by ethanol and decreased the serotonin induced gastric lesions. It also hastened the healing of acetic acid-induced chronic gastric ulcer when compared to the standard antisecretory drugs such as lansoprazole and ranitidine. In pylorus ligated rats, aqueous extract of Noni also significantly prevented gastric acid secretion and pepsin activity. Moreover, aqueous extract significantly enhanced the gastrointestinal transit which was better than cisapride. Like of Noni, pure scopoletin also have parallel antisecretory and antiulcer properties but it has a less prokinetic activity. These results suggested that scopoletin can be used as a biomarker ingredient for the quality estimation of Noni fruit based products which are used for the treatment of gastro-esophageal inflammatory disorders.

Antigout activity: In one in vitro study, Noni juice prevented the Xanthine Oxidase (XO) in a concentration dependent manner. A dose of 1, 5 and 10 mg mL^-1 of TNJ (IC₅₀ 3.8 mg) prevented XO by 11, 113 and 148%, respectively, as compared to allopurinol (IC₅₀ 2.4 microm). These results indicated that the Noni fruit juice inhibits XO enzyme which may be the possible mechanism of action of Noni for curative effect against gout (Palu et al., 2009).

Estrogenic activity: M. citrifolia has been reported to have very weak estrogenic activity in vivo. The relative estrogenic potency of alcoholic extract (1:1000) and water extract (1:10,000), indicated that the estrogenic activity is only seen at low doses. It has very low potency as compared to estradiol, suggesting that the beneficial effects of Noni are not closely linked to estrogen mediated action (Chearskul et al., 2004). Basar et al. (2006) conducted two in vitro assays to assess the estrogenic properties of the fruit by the estrogen receptor binding assay using both ER-α and ER-β estrogen receptors. Second, estrogen-receptor dependent induction of alkaline phosphatase has been reported in Ishikawa cells. Hexane extracts prepared from the fruit exhibited high activity in both systems. A preferential binding for ER-β was observed.

Probiotic potential of noni juice: Wang et al. (2009c) assessed the possibility of Noni as a raw substrate for the manufacture of probiotic Noni juice by using lactic acid bacteria such as Lactobacillus plantarum, L. casei and Bifidobacterium longum. After 48 h of fermentation all the strains of bacteria grew luxuriously on Noni juice and attained nearly 10 CFU mL^-1. The production of lactic acid was less in L. casei when compared to L. Plantarum and B. Longum, B. longum and L. plantarum survived under low-pH and cold storage (4°C) conditions for 4 weeks in fermented Noni juice. But after 3 weeks L. casei showed no cell viability. In addition, B. longum fermented Noni juice has highly elevated antioxidant activity. These results suggested that L. plantarum and B. longum are best probiotics for fermentation of Noni juice. A herbal feed additive namely Morical prepared from M.citrifolia fruits has been found to increase the production and improve quality of eggs Japanese quail (Sunder et al., 2013). The probiotic potential of M. citrifolia fruit juice with Lactobacillus acidophilus (LAB) has been evaluated recently by assessing the hisotmorphological changes in the duodenal villi of commercial broiler chick (Ven-cob) (Sunder et al., 2014). In M. citrifolia treated group the villi height and crypt depth showed significant changes in the duodenum when compared to control group. Whereas LAB fed chickens showed significant increase in the villi height and crypt depth as compared to Noni treated group. These results indicate that the administration of Noni fruit juice enhanced the duodenal function which is the major site for the nutrient absorption and development of the immune response.

Safety of Noni juice: A dose of 750 mL of Tahitian Noni juice per day for 28 days was used in a human clinical study. Several parameters were investigated and all parameters were within the range of normal values. Noni juice exhibited no dose-related adverse effects (West et al., 2006). The oral toxicity test for the aqueous extract of Noni fruit was carried out at a dose of 1000 mg kg^-1 body weight for 28 days. There were no changes in weight gain, clinical signs, food consumption, haematological and biochemical values and macroscopic or histopathological findings. In Wistar rats M. citrifolia fruit juice showed significant anxiolytic effects. On the other hand, there was no change in food consumption, weight gain and clinical biochemistry parameters (Kalandakanond et al., 2004). In vitro primary gene mutation potential of Noni juice was assessed in the Chinese hamster V79 cell line. The ethyl acetate extract of the Noni juice showed no gene mutations at the hypoxanthine phosphoribosyl transferase (HPRT) gene locus at a dosage of 0.003-3 μL mL^-1 with 100 fold concentration. These results indicate that the Noni juice does not have any mutagenic potential (Westendorf, 2002a).

An in vivo and in vitro unscheduled DNA synthesis (UDS) assay of Noni juice was performed to examine the DNA damage by estimating the DNA adducts formation. The counting of silver grains in cell nuclei signifies the repair of DNA damage. The Tahitian Noni juice showed normal silver grain count in cell nuclei which was similar to that of the saline control and it was significantly lower when compared to positive controls (N, N-dimethyl nitrosamine and 2-acetyl aminoflourene). Therefore, all these indicate that Noni juice does not have any genotoxic action (Westendorf, 2002b; Westendorf et al., 2007).

The mouse micronucleus test of Noni juice was performed to evaluate the clastogenic activity. The dehydrated Noni juice was administered at a dose of 10 g kg b.wt. The bone marrow of the animals shows no micronucleated polychromatic erythrocytes, clastogenic activity and no evidence of systemic toxicity (Edwards, 2002). Noni juice contains an average potassium content of 56.3±2.5 meq L^-1. This potassium content is almost equal to orange, grapefruit and tomato juices values. The other fruit juices which have same potassium content must be limited in the foods of patients with chronic renal failure. It may causes hyperkalemia in a patient with chronic renal insufficiency kept on a low-potassium diet (Mueller et al., 2000). The Noni fruits have negligible vitamin K content (Palu et al., 2005).

Hepatotoxicity associated with drinking Noni juice has been reported in Austria and southern Germany (Millonig et al., 2005; Stadlbauer et al., 2005; Yuce et al., 2006). A 45 year old man has been reported to suffer from hepatotoxicity, who had been drinking 1 glass day^-1 of Noni juice. After several weeks the patient had highly increased levels of hepatic enzymes such as aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and Gamma Glutamyl Transferase (GGT). Following termination of Noni juice, his hepatic enzyme levels returned to normal within one month. The possible cause of the liver dysfunction could be associated with high level of anthraquinones in Noni fruit juice (Millonig et al., 2005). In another study a 29 year an old man who consumed Noni juice at a rate of 71 mL day^-1 and a 62 year old woman who consumed Noni juice at a rate of 16 mL day^-1 also showed increased bilirubin, alkaline phosphatase (ALP), ALT, AST and GGT. The liver biopsies from both patients confirmed acute hepatitis which may be attributed to idiosyncratic reactions. These enzyme levels were normalized in 11 month after cessation of the juice. The cause of liver dysfunction could be due to herbal toxicity of Noni juice (Stadlbauer et al., 2005; Yuce et al., 2006).

However, West et al. (2006) contradicted the hepatotoxic effect of Noni, as the quantity of anthraquinones in Noni fruits is too small (<1 ppm). Such a small quantity does not have any toxicological significance and does not cause hepatotoxicity. The chemical structures of anthraquinones do not become reduced to reactive anthrone radicals which have a capacity to cause tissue damage. All these results indicate that Noni juice has no toxicological significance on the liver. The hepatotoxic substances pyrrolizidine alkaloids and patulin are absent in Noni juice. Based on all these toxicological assessment, finally they concluded that Noni juice is safe. The European food safety authority reported that there is no association between the undesirable effects recorded on liver and consumption of Noni fruit juice (Potterat and Hamburger, 2007). The hepatic dysfunction recorded in a few studies in aged patients thus may not be attributable to the consumption of Noni fruit juice.

Toxicity, mutagenicity and allergenicity studies of Noni: Acute toxicity of puree of Noni fruit juice was assessed by administering TNJ to Sprague-Dawley rats by oral gavage at a dose of 15,000 mg kg^-1. Following administration, the animals were observed for 14 days. All animals lived the observation period and exhibited no evidences of toxicity. Rather the animals appeared healthy and gained body weight. No signs of gross toxicity were seen in the organs at necropsy. So, it could be inferred that the LD₅₀ of Noni fruit would be greater than 15,000 mg kg^-1. If the acute oral LD₅₀ is greater than 15,000 mg kg^-1 and acute intraperitoneal LD₅₀ is greater than 2,000 mg kg^-1, then the compound may be considered as nontoxic (Product Safety Labs, 2000).

The allergenic risk of Tahitian Noni juice was studied using guinea pigs. Subcutaneous injections of TNJ with Freund=s adjuvant in guinea pigs resulted in no allergic reactions (Kaaber, 2000). A 13 weeks oral toxicity study in Sprague Dawley rats was conducted to assess the systemic safety of TNJ. The rats were administered with daily gavage doses of 0.4, 4, 8, 50 and 80 mL kg^-1 b.wt. There was no significant difference in body and organ weights, clinical signs, food consumption, hematological and biochemical parameters and histological examination of tissues among the groups. Based on the results No Observable Adverse Effect Level (NOAEL) was at least 80 mL TNJ/kg/day. This quantity of Noni juice is equal to 8% of the animal’s body weight (Glerup, 2001). It is confirmed through extensive microbiological, chemical and toxicological analysis that TNJ is safe for human consumption. West et al. (2011) evaluated the potential toxicity of M. citrifolia seed extract by using brine shrimp toxicity test. The result of this test showed that the extract is non-cytoxic (LC₅₀ >1 mg mL^-1). The results of the subacute (28 days) oral toxicity test in SD rats also showed that the extract has no signs of toxicity. Noni seed extract also did not contain genotoxic or mutagenic potential. West et al. (2009) evaluated the toxicity and mutagenicity potential of roasted Noni leaf infusion by using reverse mutation test in Salmonella typhimurium and primary DNA damage test in E. coli PQ37. The infusion showed no mutagenic potential and did not induce any primary DNA damage. In addition, the infusion does not have any cytotoxic potential (LC₅₀ >1 mg mL^-1) and also the freeze-dried infusion does not have any evidence of acute oral toxicity in SD rats (LD₅₀ >2000 mg kg^-1 b.wt.).