Pharmacological Activities and Chemical Constituents of Ferula szowitsiana DC

INTRODUCTION

Ferula (means “rod” in Latin) is a genus of about 170 different species that belongs to the Umbelliferae (Apiaceae) family. The plants grow mostly in arid climate such as the Mediterranean area and central Asia. Ferula species are 1-4 m tall herbaceous plants, with tripinnate leaves and yellow flowers on large umbels. Many species of this genus are used to produce essential oils or aromatic resins which have unique therapeutic values in traditional medicine (Chen et al., 2000). Around 15 species are indigenous in Iran and the Persian name for most of these species is known as “Koma” (Mozaffarian, 1966, 1983).

The chemical constituents derived from Ferula sp. (aerial parts and roots) have been extensively investigated by a few research groups (Diab et al., 2001; Iranshahi et al., 2004a; Abd El-Razek et al., 2003). Phytochemical studies revealed that the plant is a potential source of sesquiterpene derivatives especially sesquiterpene coumarins (Shahverdi et al., 2006; Iranshahi et al., 2004b, 2007a, b, 2008; Ahmed, 1999; Abd El-Razek et al., 2001) humulanes, daucanes, guainanes, germacranes, eudesmanes and himachalanes (Gonzalez and Barrera, 1995; Appendino et al., 1997; Kojima et al., 1999; Su et al., 2000a, b).

Ferula szowitsiana DC is an ethnomedicinal plant found in Iran, Turkey and Afghanistan. This plant is widely used as anti-helminthics and anti-septic in traditional medicine of these countries. A vast variety of biological activities and pharmacological effects of the extracts or pure compounds isolated from F. szowitsiana have been reported by many investigators, including anti-cancer (Barthomeuf et al., 2008; Hanafi-Bojd et al., 2011; Soltanzad et al., 2012), anti-oxidant (Soltani et al., 2010), anti-genotoxicity (Gooshchi et al., 2012), anti-inflammation (Kohno et al., 2011), anti-microbial (Iranshahi et al., 2007a; Ozek et al., 2008) and antibiotic activities (Shahverdi et al., 2007; Bazzazz et al., 2009; Bazzaz et al., 2010) (Fig. 1). In this review, we will discuss about the chemical contents and the medicinal properties of F. szowitsiana.

Chemical Constituents of F. szowitsiana DC: Over the years, many groups have isolated an array of bioactive compounds from different species of Ferula. The plant is known to be rich in coumarins, particularly sesquiterpene coumarins (Abd El-Razek et al., 2003). The phytochemical investigations of F. szowitsiana DC have resulted in isolation and identification of various types of compounds including monoterpene coumarins, sesquiterpene coumarins, phenylpropanoid derivatives and steroidal compounds (Table 1). The isolation of the compounds was obtained by column chromatographic techniques while identification of compounds was done by spectroscopic methods including ¹H and ¹³C-NMR, mass experiments. Essential oils of the aerial, leaves and stems of F. szowitsiana DC were also extracted by hydrodistillation and analyzed by GC and GC/MS methods.

Anti-cancer property: Malignant melanoma is the most common form of fatal skin cancer and the eighth most common cancer in the United States (Parker et al., 1996; Landis et al., 1999).


Fig. 1:	Overview of biological effects and targeted signaling pathways by F. szwotsiana

Table 1:	Essential oils and compounds isolated from F. szowitsiana

Its incidence among Caucasian population is in a rise in the past 20 years (Rigel et al., 1996; Greenlee et al., 2001). Barthomeuf et al. (2008) studied the anti-cancer property of F. szowitsiana on malignant melanoma. They reported high inhibitory activity of umbelliprenin isolated from F. szowitsiana roots against human M4Beu metastatic pigmented malignant melanoma cell line. They purified umbelliprenin (C₂₄H₃₀O₃, MW: 366) and auraptene (C₁₉H₂₂O₃, MW: 298.4) to test against a number of melanoma cells using Resazurin Reduction Test (RRT). Umbelliprenin (IC₅₀ = 12.4±0.5 μM) significantly inhibited the growth of M4Beu cells at a lower dose, compared to auraptene (IC₅₀ = 17.2±0.7 μM) and the standard drug, cisplatin (IC₅₀ = 23.1±0.8 μM). They also showed the ability of umbelliprenin to reduce the serum-induced proliferation of M4Beu at 25 mM through cell cycle blockade in G1 and induction of dose-dependent apoptosis (Barthomeuf et al., 2008).

In addition to M4Beu, they tested the activity of umbelliprenin and auraptene in human primary fibroblasts to evaluate the selectivity index of the compounds and also in other cancer cells including PA1 (ovary teratocarcinoma), MCF7 (breast adenocarcinoma), PC3 (androgen-resistant prostate carcinoma), DLD1 (colon adenocarcinoma) and A549 (non-small cell lung carcinoma). Both compounds exhibited high inhibitory activity against all carcinoma cell lines. At concentration of 25 mM, minimal cytotoxic effect of umbelliprenin was observed in primary fibroblasts, suggesting its significant selectivity between normal and malignant cells. However, some cytostatic effects were observed at that concentration (Barthomeuf et al., 2008).

Multi-Drug Resistance (MDR) is a phenomenon of tumor cells exhibiting resistance to different anti-cancer drugs (Liscovitch and Lavie, 2002). One of the major cellular mechanisms that mediate MDR is the over-expression of a 170 kDa plasma membrane protein, named ABCB1 or P-gp (Ambudkar et al., 1999). In the study by Hanafi-Bojd et al. (2011), P-gp-over-expressing cell line MCF7/Adr was used to evaluate the inhibitory activity of galbanic acid isolated from F. szowitsiana roots and farnesiferol A isolated from F. Persica roots, against P-gp for two exposure times (15 and 30 min). Galbanic acid exhibited high potential to serve as a proper MDR inverting candidate, due to its significant inhibitory effect for both exposure times (Hanafi-Bojd et al., 2011). Meanwhile, farnesiferol A at 0.5 μg mL^-1 inhibits P-gp transporter at 15 min after treatment. At this exposure time, it demonstrated higher activity compared to standard drug, verapamil. Of note, Farnesiferol A has been successfully isolated from F. szowitsiana (Kohno et al., 2011).

Cytotoxicity and anti-cancer activity of methanolic fraction of F. szowitsiana was also examined on lung cancer (Soltanzad et al., 2012). Lung cancer is the most frequent cancer in the world, which ranked as the major cause of world-wide cancer death (Haugen, 2008; Skarda et al., 2008). Malignant lung cancer may spread into nearby tissue and other parts of the body through metastasis. The major difficulty faced in treating lung cancer is the resistance of lung cancer to chemotherapeutic drugs. Thus, discovery of novel drug with new targets will ease drug resistance problem in lung cancer (Shanker et al., 2010).

Soltanzad et al. (2012) showed that the F. szowitsiana methanolic extract inhibited the proliferation of A549 cells in a dose-dependent manner using MTT assay. They also studied the expression of apoptosis related genes such as Bcl-2, Bcl-XL, Bax and p53 in comparison to 18s housekeeping gene using reverse transcriptase-qPCR. The results from the qPCR confirmed the significant cytotoxicity and growth inhibitory activity of the methanolic extract of F. szowitsiana. This suggests its high potential for further clinical evaluations (Soltanzad et al., 2012).

Anti-inflammation property: Inflammation is a biological response initiated by innate immune response in an individual against harmful stimuli such as pathogen. It is also common condition present in many diseases such as cardiovascular diseases and diabetes mellitus (Mueller et al., 2010). It can be related to the excessive production of Nitric Oxide (NO) which initiates leucocytes recruitment (Laroux et al., 2001). Study by Kohno et al. (2011) proved that one of the terpenoid coumarins isolated from F. szowitsiana, methyl galbanate, demonstrated marked reduction of NO production in lipopolysaccharide (LPS)- or interferon-γ (IFN-γ)-stimulated RAW264.7 macrophage cells. From their findings, methyl galbanate treated RAW264.7 cells exhibited decreased level of LPS/IFN-γ-induced iNOS mRNA expression. Besides, methyl galbanate was capable of preventing NO-induced apoptosis in neuronally differentiated tsAM5NE cells (Kohno et al., 2011).

Antioxidant and anti-genotoxicity property: Reactive Oxygen Species (ROS) had been recognized to enhance the effects of inflammation via activation of inflammatory cascades (Conner and Grisham, 1996). Thus, discovery of the capability of F. szowitsiana in reducing ROS supports its anti-inflammation property as well. Soltani et al. (2010). demonstrated antioxidant capacity in auraptene isolated from F. szowitsiana. Auraptene was proved to decrease genotoxicity of H₂O₂ and its activity was higher than ascorbic acid. They suggest that auraptene suppress the generation of superoxide anion due to the presence of prenyl moiety (Soltani et al., 2010). The antioxidant property of F. szowitsiana was further supported by Gooshchi et al. (2012). In their study, antioxidant activity of the methanol extract of F. szowitsiana was proved by using DPPH (1,1-diphenyl-2-picryl-hydrazyl) assay where it demonstrated remarkable radical scavenging activity (8.85x10^-2 mg mL^-1) comparable with rutin (5.12x10^-2 mg mL^-1) (Gooshchi et al., 2012).

Anti-microbial property: Human leishmaniasis is a severe parasitic infection, caused by different species of Leishmania, a genus of trypanosomatid protozoa, with high mortality and morbidity rates in Asia, Africa and Latin. These intracellular pathogens can accumulate in dogs, rodents and other small mammals and are normally transmitted via mosquitoes from Lutzomia and Phlebotomus genera. Although leishmaniasis is difficult to treat due to the intramacrophagic location of the infectious form, many natural products have been reported to show anti-leishmanial activity. Due to the side effects of the alternative drugs used for leishmaniasis treatment, they have been replaced over the last few years, by plant extract and plant-derived compounds such as lignans, chalcones, naphthoquinones, alkaloids, triterpenoids and neolignans (Sauvain et al., 1996; Balana-Fouce et al., 1998; Torres-Santos et al., 1999; Kayser et al., 2000; Barata et al., 2000; Camacho et al., 2000; Delorenzi et al., 2001; De Carvalho and Ferreira, 2001).

Iranshahi et al. (2008) isolated a number of compounds, as shown in Table 1 and evaluated the inhibitory activity of the acetone extract of F. szowitsiana roots, prenylated coumarins, szowitsiacoumarin A and szowitsia coumarin B, auraptene, umbelliprenin and galbanic acid against promastigotes of L. major compared with amphotericin B, as the positive control (Iranshahi et al., 2008). They employed stationary-phase promastigotes to evaluate the anti-leishmanial activity of the compounds via in vitro leishmanicidal assay (Jaafari et al., 2006). The acetone extract and all of the evaluated compounds indicated inhibitory activity against L. major promastigotes, especially umbelliprenin and auraptene which efficiently inhibited the parasite at IC₅₀ values of 13.3 μM and 17.1 μM, respectively (Iranshahi et al., 2008). Coumarins and auraptene had been previously reported to show anti-leishmanial and growth inhibitory activities against the tropical parasite, L. major (Oketch-Rabah et al., 1997; Bravo et al., 1999; Napolitano et al., 2004) .

Modulation of antibiotic activity: Antibiotics include a substantial portion of medications, frequently used in modern medicine. The most significant problem associated with application of antibiotics is the ability of some important community and hospital-acquired pathogens, to acquire resistance to these therapeutic agents. The upward trend in the existence of resistant Gram-positive bacteria affirms the urgent need for development of new drugs and/or a combination of different therapies to control the resistant pathogens (Bazzazz et al., 2009). During the recent decades, many investigations on combinations of plant extracts and antibiotics have been conducted in order to find a solution for the problem of emerging resistance in clinical isolates.

Shahverdi et al. (2007) showed that the combination of cephalexin or penicillin G with galbanic acid isolated from from the acetone extract of F. szwotsiana roots demonstrated marked decrease in the MIC of the two antibiotics against S. aureus (Shahverdi et al., 2007). Later, Bazzazz et al. (2009), also demonstrated a reduction of MIC by antibiotics ciprofloxacin, methicillin and tetracycline against resistant isolates of S. aureus with galbanic acid from F. szwotsiana. Meanwhile, no inhibitory effect was observed on high concentration of galbanic acid. This suggests that the positive inhibitory effects demonstrated could be due to the combination of antibiotics and galbanic acid (Bazzazz et al., 2009).

CONCLUSION

Different medicinal potentials of F. szwotsiana in various diseases have been reported by many investigators. However, there is a definite requirement of more detailed mechanistic and clinical studies on the mechanisms of these properties. The current state of research on F. szwotsiana implicates great potential of the isolated bioactive compounds in treating diseases. With the advancement in medicinal chemistry and bioinformatics, the ethnomedicinal usage of F. szwotsiana can be scientifically explained and proved through in vitro or in vivo studies and may consequently be developed as potential plant-based drugs.

ACKNOWLEDGMENT

This study was supported by UM Research grant (RG434-12HTM) from University of Malaya.