Abstract: In spite of the many achievements in health care delivery in the current century as evidenced by the rapid progress and expansion of orthodox medicine, people in Nigeria like in most of the developing countries lack regular access to essential medicines. For these people, faith in and popularity of traditional methods have not decreased because modern medicine is unlikely to be a tenable treatment alternative primarily because of its high cost. The cost of modern medicine is constantly increasing with improvements in modern health technology and in many cases is inappropriate to the immediate needs of people in developing and underdeveloped countries. On the other hand, medicinal herbs are widely available and affordable, even in remote areas. In addition, consumers believe that herbal medicines are safe because they are “Natural”. The constant resort to medical herbalism has however, thrown up certain health challenges arising from the side and unwanted effects of these herbs on the human anatomy and physiology. One such health condition is male infertility or sub-fertility as a result of the effect of medicinal herbs on the male reproductive organs. This review attempts to document those nigerian medicinal plants that possess the potentials to reduce male fertility particularly as demonstrated from the results of basic and allied medical sciences research and published in the peer reviewed scientific literature.
INTRODUCTION
Complementary and Alternative Medicine (CAM) is defined as "A group of diverse medical and health care systems, practices and products that are not presently considered to be part of conventional medicine". It interprets "Complementary" medicine as being used together with conventional medicine, whereas "Alternative" medicine is used in place of conventional medicine (Hoffman and Fox, 2006).
The CAM therapies are classified into four categories or domains (May, 2011):
| • | Biologically-based practices |
| • | Energy therapies |
| • | Manipulative and body-based methods and |
| • | Mind-body medicine |
Biologically based therapies in CAM use substances found in nature, such as herbs, foods and vitamins. Some examples include dietary supplements, herbal products and the use of other so-called natural but as yet scientifically unproven therapies (for example, using shark cartilage to treat cancer) (Ruggie, 2004; Shealy and Dawson, 2006).
Medical herbalism or simply, herbalism or herbology, is "The study of herbs and their medicinal uses". This definition can be extended to include the cultivation, collection or dispensing of aromatic plants, especially those considered to have medicinal properties.
Other terms substituted for medical herbalism, include herbal or botanical medicine or phytotherapy, previously defined as "The use of plant materials to prevent and treat ill health or promote wellness" (Bekalo et al., 2009).
Medicinal plants play a crucial role in health care needs of people around the world especially in developing countries (Rao et al., 2004; Bekalo et al., 2009). About 80% of the populations of most developing countries still depend on the use of traditional medicine derived from plants (Cunningham, 1993).
The African continent has a long history with the use of plants for medicinal purposes (Metz, 1991). Traditional medicine was the only source of health care in Nigeria in historical times.
Orthodox medicine was not formally introduced into Nigeria until 1860s when Sacred Heart Hospital was established by the Roman Catholic Missionaries in Abeokuta (Bekalo et al., 2009).
In the past two decades, there has been a global resurgence of interest in traditional medicine for the treatment of ailments that defile orthodox medicine principally because many diseases have defiled or developed resistance to conventional drugs as well as a health system closer to the rural poor. As a result of this renaissance in unorthodox medicine, a lot of interest and attention have been drawn to the curative claims and norms (ethics) of herbal plants in different parts of the globe especially Africa and Asia.
Characteristics of herbal medicine: Herbal medicine has some characteristics that make them unique and different from synthetic drugs (Calixto, 2000). These include:
| • | The active principle is frequently unknown |
| • | The availability and quality control are frequently problematic |
| • | Standardization, stability and quality control are feasible but not easy |
| • | They have a wide range of therapeutic use and are suitable for chronic treatments |
| • | Well-controlled double blind clinical and toxicological studies to prove their efficacy and safety are rare when compared with synthetic drugs but well-controlled randomized clinical trial revealed they do exist |
| • | They are cheaper than synthetic drugs |
The medical systems in developing countries involve both traditional herbal systems and orthodox medicine. Due to the economic predicament of these countries, the people resort to the traditional herbal system for primary health care. In Africa, particularly West Africa, new drugs are not often affordable thus up to 80% of the population use medicinal plants as remedies (Kirby, 1996; Hostettmann and Marston, 2002). World bank data on African development indicators 2003 revealed that the ratio of medical doctors to total population for 1990-2000 in Nigeria was 1:5208. This condition and the fact that international commercial orthodox medicines are becoming increasingly out of reach for most Nigerians have contributed to the dependence of a large percentage of the Nigerian people on local herbal medicine (Sofowora, 1992).
Treatment offered by traditional herbal healers at the primary health care leveled has greatly sustained the Nigerian Society before and after colonization.
IMPORTANCE OF MEDICAL HERBALISM IN AFRICA
World Health Organization (WHO) estimates that around 80% of the population in Africa-use traditional medicines. About 85% of traditional medicine involves use of plant extracts (Farnsworth and Soejarto, 1985). This would imply that the reliance on herbal medicine is immense. To appreciate the extent of this dependence, it is estimated that in Sub-Saharan Africa there is one traditional healer for every 500 people, whereas there is only one medical doctor for every 40,000 people. Therefore the importance of herbal medicines in the life of Africans cannot be overemphasized. The re-insurgence of interest of herbal medicines in Africa is backed by several reasons namely, the increasingly expensive and unavailability of orthodox drugs to average income earners (Sofowora, 1992). Another reason is that many ailments are developing resistance to orthodox drugs, for instance, the increasing resistance of malaria parasites to chloroquine which is the cheapest and the most commonly used drugs for treating malaria in Nigeria (Odugbemi et al., 2007). Bacterial resistance to antibiotics is another classical example. The inability of Western orthodox medicine to provide cure for some diseases and infections (e.g., HIV/AIDS) is a possible reason also. The ascendancy of the human immune deficiency virus has spurred intensive investigation into plant derivatives which may be effective especially for use in developing and underdeveloped nations. The little or no side effects with use of herbal medicines are other factors often stated in favour of herbalism.
Demand for herbal medicine: For years, public interest has increased for natural therapies (mainly herbal medicine) all over the world including Africa (Grunwald, 1995; Robbers et al., 1996; Blumenthal, 1999). According to Grunwald (1995), there are several factors that lead to the preference and growth of phytotherapeutic market worldwide and they include:
| • | Preference of consumers for natural therapies |
| • | Great interest in alternative medicine |
| • | The belief that herbal medicine is devoid of side effect since millions of people all over the world have been using herbal medicine for thousands of years |
| • | The belief that herbal medicine is used for the treatment of certain diseases where conventional medicine fails |
| • | Improvement in the quality, proof of efficacy and safety of herbal medicine and |
| • | High cost of synthetic drugs |
EFFECTS OF HERBAL MEDICINES ON MALE REPRODUCTIVE ANATOMY AND PHYSIOLOGY
Male reproduction anatomy is a complex structure that involves the testes, epididymis, accessory sex glands and associated hormones. Testes perform two highly organized and intricate functions, called spermatogenesis and steroidogenesis, which are crucial for the perpetuation of life. Spermatogenesis, a highly dynamic and synchronized process, takes place within the seminiferous tubules of the testis with the support of somatic Sertoli cells, leading to the formation of mature spermatozoa from undifferentiated stem cells (Hess and de Franca, 2008). The interstitial compartment, which comprises leydig cells, is the site of steroidogenesis in the testis (Osinowo, 2006).
Several plants are reported to enhance reproductive processes in laboratory animal models. This has been severally demonstrated in our laboratory. This include the findings that; grapefruit seed extract demonstrates profertility effects in male rats (Saalu et al., 2008, 2010a, b), extract of Sesame radiatum enhances fertility in male Sprague dawley rats (Ukwenya et al., 2008), Moringa oleifera lamark (drumstick) leaf extract modulates testicular toxicity in rats (Saalu et al., 2011), aqueous extract of date (Phoenix dactylifera) protects testis (Akunna et al., 2012), Laurus nobilis preserves testicular functions in crytorchid rat (Akunna et al., 2012), stem bark extract of Enantia chlorantha has testiculo-protective effect on Lead-induced toxicity in adult wistar rat (Oyewopo et al., 2012), bitter leaf has a modulating role on spermatogenic and steroidogenesis functions of the rat testis (Saalu et al., 2013), Cissus populnea extract and Jatropha curcas extract has ameliorating effect on the rat testis (Oyewopo et al., 2014) and Croton zambesicus leaf extract has ameliorating capabilities on the testis of rats exposed to pyrethroid-based insecticide (Akunna et al., 2014).
However, many basic science researches have shown several medicinal plants that hinder testicular functions.
The aim of this review is to collate all available data on nigerian medical plants with antifertility effects reported in the scientific literature.
The list of potential male antifertility Nigerian medicinal plants is presented with their photo, scientific name, common name and the local nigerian names of the country in which they are available are indicated. The description of methods used in the experiment model animals and the effect of antifertility, doses, duration of exposure, the part used, the folkloric usage and phytochemical composition are also included. Plants which did not show any significant antifertility effect were not included.
A total of 40 medical plants are reported in this review as having different antifertility activities. The collected information are given below and also summarized in Table 1 and 2.
| Table 1: | Medicinal plants in Nigeria with potential antifertility pontentials |
| Table 2: | Basic medical science research demonstration of the male anti-fertility potentials of Nigerian medicinal plants |
| • | Abrus precatorius (Fig. 1) | |
| • | Common name: | |
| • | Jumble beads | |
| • | Local nigerian name: | |
| • | Oju ologbo (Yoruba) | |
| • | Damar Zaya (Hausa) | |
| • | Anya Mumu (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Cough | |
| • | Convulsion | |
| • | Anemia | |
| • | Aphrodisiac | |
| • | Ulcer | |
Testicular degeneration characterized by reduced number of cells in the epithelium along with reduction in the number of sperm cells was observed when the aqueous extract of Abrus precatorious was administered to male rats at doses of 400, 800 and 1600 mg kg–1 b.wt. for 18 days (Adedapo et al., 2007). The alcoholic seed extracts of Abrus precatorious at a dose of 100 mg kg–1 b.wt. for 60 days significantly lowered cauda epididymal sperm motility and brought about a decrease in the levels of succinate dehydrogenase and ATPase in the sperm of albino rats. Scanning electron microscopic studies on sperm morphology revealed decapitation, acrosomal damage and formation of bulges on the mid piece region of sperms following exposure to Abrus precatorious seed extracts (Rao, 1987). Irreversible impairment of the motility of human spermatozoa at a concentration of 20 mg mL–1 of the methanol extract of Abrus precatorious seed extracts was reported, which may be due to the decline in cAMP and enhanced generation of reactive oxygen species (Ratnasooriya et al., 1991).
| Fig. 1: | Abrus precatorius |
Dose-dependent decrease in the enzyme activity of 3α, 3β, 17β-hydroxysteroid dehydrogenases and degeneration of leydig cells were reported when Abrus precatorius was administered to male rats (Sinha and Mathur, 1990).
Administration of methanolic extract of the seeds of A. precatorius (Fabaceae) (20 and 40 mg kg–1 b.wt. day–1) for 45 days in adult male mice caused a significant decrease in caudal sperm motility, count and viability. There was a complete suppression of fertility at 40 mg kg–1 dose level. The decrease in weights of testes and Cauda epididymis of mice at 40 mg kg–1 level was also observed (Bhatt et al., 2007).
Methanolic extract of A. precatorius seeds (5.0 and 20.0 mg mL–1) showed inhibitory effects on the motility of washed human spermatozoa. The extract caused a concentration-related impairment of percentage sperm motility. With the highest concentration tested (20.0 mg mL–1), the onset of the antimotility action was almost immediate. In addition, this concentration impaired the functional integrity of the plasma membrane (hypo-osmotic swelling test) and viability (nigrosin-eosin stain) of spermatozoa (Ratnasooriya et al., 1991).
Oral administration of crude mixture of A. precatorius seeds at dose of 50 mg kg–1 b.wt., caused reduction in the epididymal sperm count and reduced level of testosterone was also observed (Gigani et al., 2012):
| • | Albizzia lebbeck (Fig. 2) | |
| • | Common name: | |
| • | Siris | |
| Fig. 2: | Albizzia lebbeck |
| Fig. 3: | Acacia auriculaeformis |
| • | Local nigerian name: | |
| • | Lgbagbo (Yoruba) | |
| • | Esheye shege (Bini) | |
| • | Therapeutic/folkloric use: | |
| • | Diarrhea | |
| • | Low back pain | |
In male rats the methanolic extract of Albizzia lebbeck pods causes spermatogenic arrest and brought about a significant decrease in sperm motility and density. There was a marked reduction in the numbers of primary spermatocytes, secondary spermatocytes and spermatids (Gupta et al., 2004). Further, administration of saponins isolated from Albizzia lebbeck L. (50 mg kg–1 b.wt. day–1) for 60 days caused a significant decrease in the weights of reproductive organs of rats. The population of various spermatogenic cells in seminiferous tubules decline significantly (Gupta et al., 2005):
| • | Acacia auriculaeformis (Fig. 3) | |
| • | Common name: | |
| • | Auri | |
| • | Local nigerian name: | |
| • | Kasisa eleti (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Astringent | |
In male rats, triterpene extract of the bark of Acacia auriculaeformis at 20 and 50 mg kg–1 b.wt., for 40 days caused a sperm immobilizing effect (Pakrashi et al., 1991):
| Fig. 4: | Acacia concinna |
| • | Acacia concinna (Fig. 4) | |
| • | Common name: | |
| • | Velvet bean | |
| • | Local nigerian name: | |
| • | Yerepe (Yoruba) | |
| • | Therapeutic/folkloric usage: | |
| • | Ant-dandruff | |
| • | Skin diseases | |
Acacia concinna is a climbing shrub. The tree is food for the larvae of butterfly.
Methanolic extract of the bark of Acacia concinna 20 and 50 mg kg–1 b.wt., for 40 days was shown to have spermicidal and semen coagulating effects in the rat (Kamboj and Dhawan, 1982):
| • | Allamanda cathartica (Fig. 5) | |
| • | Common name: | |
| • | Golden Trumpet | |
| • | Local nigerian name: | |
| • | Orogbo-erin (Yoruba) | |
| • | Izeni (Edo) | |
| • | Therapeutic/folkloric use: | |
| • | Cough | |
| • | Waist pain | |
| • | Yellow fever | |
Allamanda cathartica L. (Apocyanaceae) is widely growing perennial shrub. The leaves are smooth and thick (Islam et al., 2010).
| Fig. 5: | Allamanda cathartica |
| Fig. 6: | Allium sativum |
The roots are used against jaundice, complications with malaria and enlarged spleen in traditional medicine. The flowers act as a laxative. Moreover, yellow Allamandah as also antibiotic action against Staphylococcus (Nayak et al., 2006).
All parts of the plant contain allamandin, a toxic iridoid lactone. Leaves and stems yield ursolic acid, β-amyrin and β-sitosterol. Plumericin and isoplumericin are extracted from stem and root-bark, also from leaves and roots, besides plumieride and long chain esters (Nithya and Muthumary, 2011).
The oral administration of aqueous leaf extract of A. cathartica (150 mg kg–1 b.wt. day–1 for 14, 28 and 42 days) induces infertility and changes in various male reproductive endpoints in Parkes strain mice. Histologically, testes in extract-treated mice showed non-uniform degenerative changes in the seminiferous. The treatment also had adverse effects on motility, viability, morphology and on number of spermatozoa in the cauda epididymidis. Fertility of the extract-treated males was also suppressed (Singh and Singh, 2008):
| • | Allium sativum (Fig. 6) | |
| • | Common name: | |
| • | Garlic | |
| • | Local nigerian name: | |
| • | Ayuu (Yoruba) | |
| • | Tafarnawa (Hausa) | |
| • | Ayo (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Stroke | |
| • | Eye pains | |
Allium sativum, commonly called garlic is a species in the onion genus.
The crude aqueous extract of Allium sativum bulb possesses spermicidal activity and showedthe most promising results by instantimmobilization of the epididymal sperm at 0.25 g mL–1 and human ejaculated sperm at 0.5 g mL–1.
More than 50% reduction in sperm viability occurred in treated sperm, indicating the possibility of plasma membrane disintegration which was further supported by the significant reduction in the activity of membrane bound nucleotidase and acrosomal acrosin (Chakrabarti et al., 2003). On the testes, use of garlic has been noted to compromise some male reproductive functions, as it affects spermatogenesis and testosterone levels, which are vital to reproduction (Hammami et al., 2008, 2009).
Administration of aqueous extract of garlic different doses (500 and 1000 mg kg–1 day–1) to the wistar rats caused reduction in the percentage of morphologically normal spermatozoa as well as sperm concentration (Omotoso et al., 2010):
| • | Aloe barbadensis (Fig. 7) | |
| • | Common name: | |
| • | Aloe vera | |
| • | Local Nigerian name: | |
| • | Alon erin (Yoruba) | |
| Fig. 7: | Aloe barbadensis |
| Fig. 8: | Anethum graveolens |
| • | Ibube agu (Igbo) | |
| • | Tinya (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Cancer eczema | |
| • | Wounds | |
| • | Acne | |
| • | Ulcer | |
| • | Impotence | |
| Fig. 9: | Aspillia Africana |
Aloe babadensis is a succulent plant species. About 50% ethanolic extract Aloe barbadensis leaf extract 70 and 100 mg kg–1 b.wt. day–1 for 56 days showed antiandrogenic activity in the dog (Dixit and Joshi, 1983):
| • | Anethum graveolens (Fig. 8) | |
| • | Common name: | |
| • | Soya | |
| • | Local nigerian name: | |
| • | Alasisede (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Headache | |
| • | Malaria | |
About 70 mg and 100 mg kg–1 b.wt. day–1 for 32 days of acqueos extract of Anethum graveolens seed extract exhibited antispermatogenic effects in the rat (Malihezaman and Sara, 2007):
| • | Aspillia Africana (Fig. 9) | |
| • | Common name: | |
| • | Bush marigold | |
| • | Friend of pepper | |
| • | Local nigerian name: | |
| • | Yun yun (Yoruba) | |
| • | Kalankwa (Hausa) | |
| • | Urangila (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Stop bleeding | |
| • | Promotes healing | |
| • | Antimalarials | |
| Fig. 10: | Ananas comosus |
Methanol leaf extract of Aspillia africana 100, 200, 400 mg kg–1 b.wt. day–1 for 52 days showed antispermatogenic effect in rat (Ruth et al., 2015):
| • | Ananas comosus (Fig. 10) | |
| • | Common name: | |
| • | Pineapple | |
| • | Local nigerian name: | |
| • | Ogede-oyibo (yoruba) | |
| • | Akwu-oyibo (Igbo) | |
| • | Mbuer u buter (Tiv) | |
| • | Eyop mbakara (Efik) | |
| • | Therapeutic/folkloric use: | |
| • | Purgative | |
| • | Stomach upset | |
Ananas comosus also called pineapple is a tropical plant with multiple fruit consisting of coalesced berries. Ethanol extract of unripe fruit of Ananas cosmosus 200 mg kg–1 b.wt. day–1 for 60 days showed antispermatogenic activity in rat (Satyawati, 1983):
| • | Azadirachta indica (Fig. 11) | |
| • | Common name: | |
| • | Neem | |
| • | Local nigerian name: | |
| • | Dogonyaro (Hausa)/(Yoruba)/(Edo)/(Tiv) | |
| • | Therapeutic/folkloric use: | |
| • | Malaria | |
| • | Chicken pox | |
| Fig. 11: | Azadirachta indica |
| • | Antifungal | |
| • | Antibacterial | |
| • | Antihelminths | |
Administration of A. indica are reduced the fertilizing activity and administration of dry powder of leaves of A. indica at the dose level of 20, 40 and 60 mg rat–1 day–1 results in a decrease in weight of seminal vesicle and decrease in the sperm count (Shaikh et al., 1993).
Histopathological and biochemical changes in the testis of rats treated with the leaf powder of A. indica were reported (Joshi et al., 1996). It suggested a possible reversible antiandrogenic property of the leaves of A. indica in male albino rats. Neem seed extract is reported to induce abnormality in spermatogenesis and sperms production in some of the seminiferous tubules (Meymand et al., 2002). Ultrastructural changes like intracellular spaces and vacuolization in sertoli cells and defects in the mitochondrial sheath of late spermatids were induced by leaves of A. indica (Neem) in the testis of albino rats (Kasturi et al., 2002). Neem oil proved spermicidal against rhesus monkey and human spermatozoa in vitro. Antifertility effect of neem oil has also been studied and suggested to be a novel method of contraception (Biswas et al., 2002). Contraceptive effects of A. indica leaves (500 mg kg–1 b.wt. day–1) on testosterone (0.25 mg kg–1 b.wt. day–1) were also studied in male rats (Aladakatti and Ahamed, 2005).
| Fig. 12: | Bambusa arundinaecea |
Inclusion of neem leaf meal up to 15% in the ration of matured rabbit bucks could cause mild supressive effect on the spermatogenesis, semen quality and seminiferous tubule diameter male albino rat treated with low dose (0.6 mL of neem oil/animal) and high dose (1.2 mL of neem oil/animal) of neem oil revealed significant decrease in the seminiferous tubular diameter and number of spermatozoa (Shaikh et al., 2009):
| • | Bambusa arundinaecea (Fig. 12) | |
| • | Common name: | |
| • | Common bamboo | |
| • | Local nigerian name: | |
| • | Gora (Hausa) | |
| • | Kewal, kewe (Fulfude) | |
| • | Songough (Tiv) | |
| • | Otosi (Ibo) | |
| • | Therapeutic/folkloric use: | |
| • | Stomach upset | |
| • | Antimalarial | |
Bamboo buds ethanolic extract given 100 and 200 mg kg–1 b.wt. daily for 60 days demonstrated impaired structural and functional activity of the epididymis in the rat (Manonayagi et al., 1989):
| • | Barleria prionitis (Fig. 13) | |
| • | Common name: | |
| • | Porcupine flower | |
| • | Local nigerian name: | |
| • | Sinkinmini (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Fever | |
| • | Antimalarial | |
| Fig. 13: | Barleria prionitis |
Also known as the porcupine flower is a species in the family Acanthaceae.
Male rats treated with isolated fractions of the B. prionitis root methanolic extract (100 mg kg–1 for 60 days) showed a significant reduction on spermatogenesis without affecting general body metabolism. Sperm motility as well density in cauda epididymides was reduced significantly. The population of various spermatogenic cells such as primary spermatocytes, secondary spermatocytes and round spermatids were declined significantly in treated animals (Verma et al., 2005).
Oral administration of root extract of B. prionitis L. to male rats (100 mg rat–1 day–1) for the period of 60 days did not cause body weight loss. The root extract brought about an interference with spermatogenesis. The round spermatids were decreased by 73.6% (p≤0.001). The extract reduced the fertility of male rats by 100%. Cross sectional surface area of Sertoli cells and mature leydig cell numbers were significantly reduced (36.9%). Testicular glycogen contents were low. Antifertility effects of Barleria seemed to be mediated by disturbances in testicular somatic cells functions (Leydig and sertoli cells) resulting in the physio-morphological events of spermatogenesis (Gupta et al., 2000):
| Fig. 14: | Calotropis procera |
| Fig. 15: | Cannabis sativa |
| • | Calotropis procera (Fig. 14) | |
| • | Common name: | |
| • | Apple of sodom | |
| • | Local nigerian name: | |
| • | Bomubomu (yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Measles | |
| • | Diaphoretic emetic | |
| • | Asthma | |
| • | Antipyretic | |
| Fig. 16: | Carica papaya |
This plant is also popularly referred to as giant milk weed. It is used to treat headache, painful swellings and carious tooth (Iwu, 1993). It was found to decrease testicular weight and it caused testicular degenerative changes in Wistar rat (Akinloye et al., 2002):
| • | Cannabis sativa (Fig. 15) | |
| • | Common name: | |
| • | Ganja | |
| • | Indian hemp | |
| • | Local nigerian name: | |
| • | Igbo (Yoruba) | |
| • | Nwonkaka (Igbo) | |
| • | Ikya (Tiv) | |
| • | Therapeutic/folkloric use: | |
| • | Mood stimulant | |
| • | Sedative | |
Cannabis sativa is an annual herbaceous plant in the cannabis genus, a species of the cannabaceae family.
Methanolic leaf extract of Cannabis sativa 25 mg kg–1 b.wt. day–1 given for 30 days caused testicular lesion with atrophy of the leydig cells in the mouse (Sailani and Moeini, 2007):
| • | Carica papaya (Fig. 16) | |
| • | Common name: | |
| • | Pawpaw | |
| • | Local nigerian name: | |
| • | Ibepe (Yoruba) | |
| Fig. 17: | Celastrus paniculatus |
| • | Gwanda (Hausa) | |
| • | Okwuru bekoe (Igbo) | |
| • | Mpuer (Tiv) | |
| • | Therapeutic/folkloric use: | |
| • | Constipation | |
| • | Stomach upset | |
The benzene chromatographic fractions of chloroform extract of the seeds of C. papaya possess reversible male contraception potential and the effect appears to be mediated through the testis without adverse toxicity (Pathak et al., 2000). Even aqueous extract of papaya bark has potential contraceptive activity. Further studies revealed that the inhibition of sperm motility may be due to ultrastructural changes in epididymis (Manivannan et al., 2004):
| • | Celastrus paniculatus (Fig. 17) | |
| • | Common name: | |
| • | Intellect tree | |
| • | Local nigerian name: | |
| • | Rimi (Hausa) | |
| • | Vambe (TIv) | |
| • | Therapeutic/folkloric use: | |
| • | Convulsion | |
| • | Headache | |
Celastrus paniculatus is a woody liana commonly known as black oil plant, climbing staff tree and intellect tree.
Ethanolic extract of Celastrus paniculatus seed 20 mg kg–1 b.wt. day–1 for 30 days showed antispermatogenic activity in rat (Bidwai et al., 1990):
| Fig. 18: | Citrullus colocynthis |
| • | Citrullus colocynthis (Fig. 18) | |
| • | Common name: | |
| • | Bitter gourd | |
| • | Wild gourd | |
| • | Local Nigerian name: | |
| • | Kwantowa (Hausa) | |
| • | Egwusi (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Laxative | |
| • | Sexually transmitted diseases | |
| • | Epilepsy | |
Administration of crude 50% ethanol extract of C. colocynthis schrad roots to male albino rats at dose levels of 50, 100 and 200 mg kg–1 b.wt. day–1 for a period of 60 days caused a significant decreases in cauda epididymal sperm motility, density, number of pups and fertility (Mali et al., 2001). The 50% ethanolic extract of C. colocynthis extract showed an antiandrogenic nature, thereby reduced reversible infertility in male albino rats. The testes showed degenerative changes in the seminiferous epithelium and arrest of spermatogenesis at the secondary spermatocyte stage (Chaturvedi et al., 2003):
| • | Chromolaena odoratum (Fig. 19) | |
| • | Common name: | |
| • | Siam weed | |
| • | Local nigerian name: | |
| • | Akintola/Awolowo (Yoruba) | |
| • | Obiarakaka (Igbo) | |
| • | Ebe Awolowo (Edo) | |
| Fig. 19: | Chromolaena odoratum |
| • | Therapeutic/folkloric use: | |
| • | Stops bleeding heals wounds | |
| • | Indigestion | |
| • | Stomach upset | |
Chromolaena odorata (Asteraceae) commonly known as Siam weed is a fast-growing perennial and invasive weed.
Oral administration of aqueous extract of C. odoratum leaves (250 and 500 mg kg–1 b.wt.) for 14 days in male albino rats revealed a significant reduction (p<0.05) in testicular body weight ratio and histological examination revealed disruption in the arrangement of seminiferous tubules with no distinct basement membrane. These changes were accompanied by reduction in the number of spermatozoa. All these results indicated that aqueous extract of C. odoratum leaves possesses antiandrogenic property by interfering with steroidogenesis at the testicular level and this will adversely affect the functional capacity of the testes and the fertility of the animal (Yakubu et al., 2007):
| • | Curcurma longa (Fig. 20) | |
| • | Common name: | |
| • | Tumeric | |
| • | Local nigerian name: | |
| • | Ata-Ile Pupa (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Heart | |
| • | Liver and chest problems | |
| • | Fever ringworm | |
| Fig. 20: | Curcurma longa |
Rats fed with Curcuma longa aqueous and 70% alcoholic extract for 60 days (500 mg kg–1 day–1) showed a reduction in sperm motility and density. C. longa may have affected the androgen synthesis either by inhibiting the Leydig cell function or the hypothalamus pituitary axis and as a result, spermatogenesis is arrested (Ashok and Meenakshi, 2004).
Male mice of the Parkes (P) strain were orally administered aqueous rhizome extract of C. longa (600 mg kg–1 b.wt. day–1 for 56 and 84 days) showed adverse effect of on various male reproductive organs and fertility. The treatment had adverse effects on motility, viability, morphology and number of spermatozoa in the cauda epididymidis, serum level of testosterone and on fertility. By 56 days of treatment withdrawal, however, the above parameters recovered to control levels. The results show that C. longa treatment causes reversible suppression of spermatogenesis and fertility, thereby suggesting the potential of this plant in the regulation of male fertility (Mishra and Singh, 2009a):
| • | Daucus carota (Fig. 21) | |
| • | Common name: | |
| • | Carot | |
| • | Local nigerian name: | |
| • | Karoti (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Anti-inflammatory | |
| • | Anti-rheumatic | |
| • | Fever | |
| Fig. 21: | Daucus carota |
| Fig. 22: | Fadogia agrestis |
Aqueous extract of Daucus carota tuber 0.5 g kg–1 b.wt. day–1 given for 60 days exhibited anti-spermatogenic activity in the rat (Shah and Varute, 1980):
| • | Fadogia agrestis (Fig. 22) | |
| • | Common name: | |
| • | Black magic | |
| • | Local Nigerian name: | |
| • | Bakin gagai (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Black aphrodisiac | |
| Fig. 23: | Gossypol herbaceum |
Aqueous extract of the Fadoga agrestis stem 18, 50, 100 mg kg–1 b.wt. day–1 for 28 days showed reduced testicular function in rat (Yakubu et al., 2008).
| • | Gossypol herbaceum (Fig. 23) | |
| • | Common name: | |
| • | Cotton | |
| • | Local nigerian name: | |
| • | Mou (Tiv) | |
| • | Auduga (Hausa) | |
| • | Owu (Igede) | |
| • | Ro afor (Igbo) | |
| • | Igi-ora (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Wound dressing | |
| • | General infertility | |
| • | Ailments | |
Gossypol, a yellow polyphenolic compound present in the stem, seeds and roots of Gossypium species. It is known to exert unique and selective effects upon reproduction in various species such as rats, mice, hamsters, rabbits, monkeys and human beings (Coutinho, 2002). The contraceptive effect of gossypol was first discovered in China. Gossypol was reported to invoke antifertility effects in rats at 30 mg kg–1 b.wt., whereas a much lesser dose, 0.3 mg kg–1 b.wt., could incite infertility in humans, making the compound very efficient in humans than in rats (Udoh et al., 1992).
Several studies affirm that gossypol treatment reduced the level of serum testosterone and luteinizing hormones in dose and duration dependent manner (Zhuang et al., 1986).
| Fig. 24: | Leptadenia hastata |
Gossypol acts directly on testes and induces azoospermia or oligospermia (Zhuang et al., 1986):
| • | Leptadenia hastate (Fig. 24) | |
| • | Common name: | |
| • | Tears | |
| • | Local nigerian name: | |
| • | Yaadiya (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Cancer | |
| • | Antimicrobials | |
Aqueous leaf and stem extract of Leptadenia hastata 100, 200, 400, 800 mg kg–1 b.wt. day–1 given for 60 days showed anti-spermatogenic activity in rat (Bayala et al., 2011):
| • | Momordica charantia (Fig. 25) | |
| • | Common name: | |
| • | African cucumber | |
| • | Local nigerian name: | |
| • | Daddagu (Hausa) | |
| • | Ejinrin (Yoruba) | |
| • | Alaban adene (Ibo) | |
| • | Dagdaye (Kanuri) | |
| • | Therapeutic/folkloric use: | |
| • | Asthma | |
| • | Cough | |
| • | Liver problems | |
| Fig. 25: | Momordica charantia |
Petroleum ether, benzene and alcohol extracts of the seeds of Momordica charantia tested in rats at the dose level of 25 mg/100 g b.wt. for 35 days showed antispermatogenic activity as the number of spermatocytes, spermatids and spermatozoa decreased.
Increase in cholesterol level and sudanophilic lipid accumulation indicates inhibition in the steroidogenesis. Out of the three extracts, the alcohol extract was more potent in its antispermatogenic, antisteroidogenic and androgenic activities (Naseem et al., 1998). It has been shown that oral administration of M. charantia root extract (5 mg kg–1 b.wt. day–1 for 60 days) showed 100% antifertility in the rats (Yama et al., 2011). There was marked decline in testicular germ cell population, leydig cell number and nuclear area as comported to controls. Serum testosterone level also reduced after extract treatment:
| • | Morinda lucida (Fig. 26) | |
| • | Common name: | |
| • | Brimestone tree | |
| • | Local nigerian name: | |
| • | Oruwo (Yoruba) | |
| • | Njisi (Hausa) | |
| • | Eze Ogu (Igbo) | |
| • | Ufu ogile (Igede | |
| • | Therapeutic/folkloric use: | |
| • | Fever | |
| • | Antimalarial | |
| • | Diabetes | |
| • | Heart diseases | |
| Fig. 26: | Morinda lucida |
| Fig. 27: | Mucuna urens |
Morinda lucida is an evergreen shrub or small to medium-sized tree bearing a dense crow of slender, crooked branches.
Aqueous leaf extract of Morinda lucida 400 mg kg–1 b.wt. day–1 for 13 weeks had antispermatogenic properties on the rat (Raji et al., 2005):
| • | Mucuna urens (Fig. 27) | |
| • | Common name: | |
| • | Cow itch plant | |
| • | Velvet bean | |
| Fig. 28: | Nicotiana tabacum |
| • | Local nigerian name: | |
| • | Ewe-ina | |
| • | Yerepe (Yoruba) | |
| • | Agba Ohia (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Blood tonic | |
| • | Intestinal worms | |
| • | Genito-urinary disease | |
Ethanolic seed extract of Mucuna urens 70, 140, 210 mg kg–1 b.wt. day–1 for 14 days exhibited anti-spermatogenic activity in the rat (Etta et al., 2009):
| • | Nicotiana tabacum (Fig. 28) | |
| • | Common name: | |
| • | Tobacco | |
| • | Local nigerian name: | |
| • | Ewe (Yoruba) | |
| • | Taba (Hausa) | |
| • | Anwere (Igbo) | |
| • | Itaba (Edo) | |
| • | Taav (Tiv) | |
| • | Therapeutic/folkloric use: | |
| • | Convulsion | |
| • | Epilepsy, | |
| • | Toothache | |
| • | Ringworm | |
| • | Cold | |
| • | Ulcers | |
| Fig. 29: | Piper nigrum |
Ethanolic leaf extract of Nicotiana tabacum 100, 200 mg kg–1 day–1 for 60 days showed anti-androgenic effect in the rat (Londonkar et al., 1998):
| • | Piper nigrum (Fig. 29) | |
| • | Common name: | |
| • | Black pepper | |
| • | Local nigerian name: | |
| • | Iyere (Yoruba) | |
| • | Uzize (Igbo) | |
| • | Masooroo (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Constipation | |
| • | Anti-inflammatory | |
Piper nigrum L. commonly known as black pepper belongs to family Piperaceae. The fruits of P. nigrum are not only important as a spice or flavoring agent but have also been prescribed for cholera, dyspepsia, diarrhea, various gastric ailments and paralytic and arthritic disorders.
Oral administration of fruit powder of P. nigrum (25 and 100 mg kg–1 b.wt. day–1 for 20 and 90 days) to male mice of the Parkes (P) strain adversely affects sperm parameters and also caused marked alterations in male reproductive organs (Mishra and Singh, 2009b).
Piperine (1-piperoylpiperidine) is an alkaloid present in the fruits of black pepper (Piper nigrum), long pepper (Piper longum) and other piper species. Epididymal sperm count and motility decreased at 10 and 100 mg kg–1 and sperm viability decreased significantly at 100 mg kg–1.
| Fig. 30: | Pterocarpus santalinus |
Piperine could damage the epididymal environment and sperm function (D’Cruz and Mathur, 2005):
| • | Pterocarpus santalinus (Fig. 30) | |
| • | Common name: | |
| • | Red sandal | |
| • | Local nigerian name: | |
| • | Gbengbe (Yoruba), | |
| • | Gunduruu (Hausa), | |
| • | Nturukpa (Igede) | |
| • | Therapeutic/folkloric use: | |
| • | Skin diseases | |
| • | Antipyretic | |
| • | Antidiarrhoea | |
Aqueous extract of Pterocarpus santalinus stem 100 mg kg–1 day–1 for 60 days demonstrated semen coagulating activity in mice (Dhawan et al., 1980):
| • | Ricinus communis (Fig. 31) | |
| • | Common name: | |
| • | Castor bean | |
| • | Local nigerian name: | |
| • | Lara pupa (Yoruba) | |
| • | Kulakula Nkpikpi (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Veneral diseases | |
| Fig. 31: | Ricinus communis |
| Fig. 32: | Syzygium aromaticum |
Ethanolic extract of Ricinus communis seed 100 mg kg–1 day–1 for 60 days showed alteration in motility, mode of movement and morphology of sperms in rat (Sandhyakumary et al., 2003):
| • | Syzygium aromaticum (Fig. 32) | |
| • | Common name: | |
| • | Clove | |
| • | Local nigerian name: | |
| • | Kanum fari (hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Cough and catarrh | |
| Fig. 33: | Syzygium cuminii |
Syzygium aromaticum L. commonly known as clove belongs to family Myrtaceae. It is used as a spice to add flavor to exotic food preparations.
Oral exposure of hexane extract of flower buds of S. aromaticum in three doses (15, 30 and 60 mg kg–1 b.wt.) for a single spermatogenic cycle (35 days) in Parkes (P) strain mice induced non-uniform degenerative changes in the seminiferous tubules associated with decrease in daily sperm production and depletion of round and elongated spermatids population (Mishra and Singh, 2008):
| • | Syzygium cuminii (Fig. 33) | |
| • | Common name: | |
| • | Skeels | |
| • | Local nigerian name: | |
| • | Ori (Yoruba) | |
| • | Malmoo (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Purgative | |
Alcohol extract of the seed of Syzygium cuminii 100 mg kg–1 day–1 for 60 days showed anti-spermatogenic effect in rat (Shad et al., 2014):
| • | Tecoma stans (Fig. 34) | |
| • | Common name: | |
| • | Yellow bells | |
| • | Local nigerian name: | |
| • | Awun (Yoruba) | |
| • | Ukhu (bini) | |
| • | Therapeutic/folkloric use: | |
| • | Antimalarial | |
| Fig. 34: | Tecoma stans |
| Fig. 35: | Terminalia superba |
Ethanol leaf extract of Tecoma stans 500 mg kg–1 day–1 for 60 days demonstrated anti-spermatogenic effect in rat (Mathur et al., 2010):
| • | Terminalia superba (Fig. 35) | |
| • | Common name: | |
| • | Black limba | |
| Fig. 36: | Thevetia peruviana |
| • | Local Nigerian name: | |
| • | Afara (Yoruba) | |
| • | Baushe (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Antimalarial | |
Ethanol extract of the fruit of Terminalia superba 50 and 100 mg kg–1 day–1 for 60 days showed anti-androgenic effect in rat (Srivastav et al., 2010):
| • | Thevetia peruviana (Fig. 36) | |
| • | Common name: | |
| • | Yellow oleandar | |
| • | Suicide tree | |
| • | Local nigerian name: | |
| • | Olomojo (Yoruba) | |
| • | Therapeutic/folkloric use: | |
| • | Anti -measles | |
| • | Anti-diabetics | |
Methanol extract of stem bark of Thevetia peruviana 100 mg kg–1 day–1 for 60 days showed ant-spermatogenic effect (Gupta et al., 2011):
| • | Tinospora cordifolia (Fig. 37) | |
| • | Common name: | |
| • | Hearth leaves | |
| • | Local nigerian name: | |
| • | Epaikum (Yoruba) | |
| Fig. 37: | Tinospora cordifolia |
| Fig. 38: | Trigonella foenum-graecum |
| • | Therapeutic/folkloric use: | |
| • | Anti-inflammatory | |
Tinospora cordifolia (Willd.) belongs to the Menispermaceae family. It is reported to possess anti-spasmodic, antiinflammatory, anti-allergic, anti-diabetic, antioxidant properties (Premanath and Lakshmidevi, 2010):
| • | Trigonella foenum-graecum (Fig. 38) | |
| • | Common name: | |
| • | Wild yam | |
| Fig. 39: | Vigna Ungiculata |
| • | Local nigerian name: | |
| • | Osanwene (Yoruba) | |
| • | Lemu (Hausa) | |
| • | Olofa-nta (Igbo) | |
| • | Therapeutic/folkloric use: | |
| • | Antimalarial | |
| • | Chest diseases | |
| • | Abdominal upset | |
Trigonella foenum-graecum (Fenugreek) is a member of the Fabaceae family. Fenugreek is native to the area from the eastern Mediterranean to Central Asia and Ethiopia and much cultivated in Pakistan, India and China. Its dried ripe seeds are variously referred to as Trigonella seeds or as Fenugreek.
Trigonella foenum-graecum tends to reduce the male fertility by reducing testosterone concentration, sperms concentration and inhibiting mass and individual motility of the sperms (Kassem et al., 2006):
| • | Vigna ungiculata (Fig. 39) | |
| • | Common name: | |
| • | Cowpea | |
| • | Local Nigerian name: | |
| • | Owi-ahun (Yoruba) | |
| • | Wakia-tunka (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Toothache | |
Aqueous extract of leaf of Vigna ungiculata 200 mg kg–1 day–1 for 30 days showed anti-spermatogenic effect in rat (Umapathy, 1993):
| Fig. 40: | Zizyphus mauritiana |
| • | Zizyphus mauritiana (Fig. 40) | |
| • | Common name: | |
| • | Indian plum | |
| • | Local nigerian name: | |
| • | Magarya (Hausa) | |
| • | Therapeutic/folkloric use: | |
| • | Antimalarial | |
| • | Abdominal upset | |
Ziziphus belongs to the kingdom; plantae, order; roasles, division; magnoliophyta, class; magnoliopsida, family; rhamnaceae, genus, Ziziphus. Z. mauritiana is a fast growing small to medium-sized, single or multi-stemmed, spiny shrub or tree, which is almost evergreen but is deciduous during the dry season. It can reach up to 12 m tall and 30 cm diameter at breast height but is highly variable in size and general appearance. The bark is dark grey, dull black or reddish with long vertical fissures, reddish and fibrous inside. The branches are spreading and droop at the ends.
Acqueous bark extract of Zizyphus mauritiana 0.1 and 0.5 mg/mL/60 days showed spermicidal properties (Dubey et al., 2011).