® Bioremediation, Biodiversity and Bioavailability ©2011 Global Science Books Ruta graveolens Cultures as Screening Resources for Phyto-Pharmaceuticals: Bio-prospecting, Metabolic Phenotyping and Multivariate Analysis Renuka Diwan • Nutan Malpathak* Department of Botany, University of Pune, Pune: 411007 Maharashtra, India Corresponding author : * [email protected] ABSTRACT Ruta graveolens is a folklore plant, used by ancient Egyptians and Greeks and used in traditional medicine systems like Unani, Ayurveda and traditional Chinese medicine. The plant has potent anti-inflammatory, anti-cancer and anti-HIV activity. In this study, R. graveolens and six in vitro cultures (with varying degrees of differentiation) were screened for biologically active compounds by GC-MS analysis. Non-targeted comprehensive analysis, directed towards extracting broad spectrum biochemical information was used for bioprospecting. The relationship between metabolic components and lines was interpreted with the help of multivariate analysis (hierarchical cluster analysis and principal component analysis). The characteristic metabolic traits underlying clustering and separation of culture lines were also elucidated. Bio-prospecting based on GC-MS analysis indicated the presence of several metabolites with a wide range of bioactivities: photobilogical, anti-microbial, anti-viral, anti-oxidative, anti-proliferative, anti-inflammatory, anti-tumour, anti-platelet aggregation, anti- HIV, immunomodulatory, estrogenic activity, among others with potential economic importance. Multivariate analysis demonstrated that metabolic traits enabled the discrimination of genotypes that exhibited marked differences in pharmaceutically important metabolites. With the use of metabolic phenotyping, in vitro cultures can be used as novel screening resources for new or improved phyto- pharmacueticals. _____________________________________________________________________________________________________________ Keywords: metabolic profiling, hierarchical cluster analysis, principal component analysis Abbreviations: FC, furanocoumarin; HCA, hierarchical cluster analysis; Ia3, transformed clone; PCA, principal component analysis; RC1, dispersed cell line; RS2, shoot line; RC3, aggregated cell line; RC6, differentiated cell line INTRODUCTION derived from the Greek “reuo” (to set free), because this herb is so efficacious in various diseases. Ancient Egyptians Natural products have provided inspiration for most of the and early Greeks used Ruta to improve eyesight. In Chinese active ingredients in medicines: around 80% of medicinal medicine, it is used for its antifungal, antibacterial and anti- products up to 1996 were either directly derived from natu- inflammatory properties. Ruta has been reported to be rally occurring compounds or were inspired by a natural useful for the treatment of multiple sclerosis and also pos- product, and more recent analysis confirms the continuing sesses hypotensive activity (Korengath et al. 2008). It has a importance of natural products for drug discovery (Harvey long history of use in homeopathic, Ayurvedic and Unani 2001, 2004, 2007). The search for active phytocompounds preparations (Elia 2003). It has traditionally been used in will be greatly advanced by the combination of various treatment of leucoderma, vitiligo, psoriasis, multiple sclero- metabolomic approaches to differentiate between plant spe- sis, cutaneous lymphomas, and rheumatic arthritis. Recently cies, tissues, or phytopreparations, and to identify novel its extracts were shown to have potent anti-inflammatory lead compounds for future development. Though the use of and anti-cancer activity (Pathak et al. 2003; Preethi et al. metabolomics in the development of active secondary meta- 2007; Diwan and Malpathak 2009). Plant parts contain bolites from medicinal plants as novel or improved phyto- more than 120 compounds of dierent classes of natural therapeutic agents is still limited, it can offer a comprehen- products such as acridone alkaloids, coumarins, essential sive overview of the identity and quantity of metabolites in oils, \avonoids, and furoquinolines (Feo et al. 2002; Oliva biological materials. Wang et al. (2005) pointed out that et al. 2003). Many of these compounds are physiologically metabolomics could provide the needed links between the active and therefore of immense pharmaceutical interest. complex chemical mixtures used in traditional medicines With the success achieved in increasing culture produc- and molecular pharmacology. In a complementary develop- tivity, in vitro cultures are now being promoted as alterna- ment, the use of metabolome-refined herbal extracts with tive source and screening resources (bio-prospecting) for other biochemical components in combination, rather than new or improved phyto-pharmacueticals. Reports describing as isolated single compound(s), may prove to be very useful the successful use of R. graveolens culture for furanocou- as broader and holistic therapeutic or pharmacological marin (FC) production (Ekiert et al. 1998, 2001) have made agents for a variety of human health care applications them promising alternatives with potential for large-scale (Shyur and Yang 2008). Even though such approaches have production (Gontier et al. 2005; Diwan and Malpathak been employed for traditional Chinese medicines (TCM), 2008). Enhanced production of FCs was achieved by mani- its applications for traditional Indian medicine are yet to be pulations of media constituents (Massot et al. 2000) and realized. culture conditions (Ekiert and Gomóka 1999; Ekiert et al. Ruta graveolens (Rutaceae), a folklore plant, is used as 2001). Effective elicitation by biotic and abiotic elicitors traditional medicine for various ailments. The name Ruta is (Bolhmann et al. 1995; Orlita et al. 2007a, 2007b, 2008), Received: 5 April, 2010. Accepted: 10 September, 2010. Original Research Paper Bioremediation, Biodiversity and Bioavailability 5 (1), 1-9 ©2011 Global Science Books for enhanced FC production was recently reported. Besides vested, dried at 40°C and pulverized. Roots were also dried and coumarins, Ruta cultures have several biologically active powdered as described above. In vitro plant material was harves- metabolites present like protocatechuic, vanillic, syringic ted on the 21st day after culture initiation, dried at 40°C and pow- and p-coumaric acid (Ekiert et al. 2009), triglycerides (Asil- dered. Extraction of in vivo and in vitro material was carried out as bekova 2001), lipids (Asilbekova 2000), furacridone alka- follows. Finely pulverized in vivo/in vitro plant material (100 mg) loids (Nahrstedt et al. 1985), volatile oils (Kuzovkina et al. was sonicated (33 Mhz) for 20 min at room temperature and cold- 2009), acridone alkaloids (Sidwa-Gorycka et al. 2009), and extracted in ultra-pure methanol overnight. The extract was centri- arbutin (Piekoszewska et al. 2010). fuged at 10,000 rpm for 20 min and the supernatant was filtered Therefore R. graveolens and selected in vitro cultures (using a 0.45 μM membrane filter; Laxbro, India). After filtration, were screened for biologically active compounds by GC- the extract was evaporated to dryness at room temperature and MS analysis. In this study, six in vitro cultures with varying dissolved in ethyl acetate (ultra-pure). The final concentration of degrees of differentiation were screened for biologically all crude extracts was 1 mg ml-1. Methanolic extracts of in vivo active compounds by GC-MS analysis. Shoot line RS2 was plant material (stems and roots) were used as reference during pro- selected for its rapid growth rate and high FC productivity filing. (Diwan and Malpathak 2008). R. graveolens cell cultures that displayed a wide range of cellular differentiation were Metabolic phenotyping selected. Such a range of organization is rarely observed, making it a model system for examining the relation be- Plant extracts were subjected to GC-MS analysis. tween cellular differentiation and secondary metabolite pro- duction. 1. GC-MS conditions This non-targeted comprehensive analysis was directed towards extracting a broad spectrum of biochemical infor- GC-MS analyses were performed using a gas chromatograph mation of the metabolome of selected culture lines. The (Varian 3800 GC, USA) with a data handling system and FID relationship between culture lines and metabolic compo- coupled to ion trap detector, equipped with a DB-5 fused-silica nents was interpreted with the help of multivariate analysis. column (30 m, 0.32 mm ID and 0.25 μM film thickness). Injection The characteristic metabolic traits underlying the clustering temperature was 300°C. Oven temperature was programmed from and separation phenomenon in culture lines were elucidated 50°C for 2 min then increased by 20°C/min until it reached 150°C, using high factor scores of principal component analysis followed by 3°C/min until it reached 225°C and finally increased (PCA). by 15°C/min until it reached 280°C, then held for 9 min with a total run time of 45 min. Helium was used as the carrier gas at a MATERIALS AND METHODS flow rate of 1 ml/min. Injection was done in split mode (4:1) with a volume of 1.0 μl. Plant material 2. MS conditions R. graveolens plants were established from Pune, Kolhapur and Kerela then screened for furanocoumarin productivity. Plants Analysis was performed on a Varian 4000 (USA), ion trap mass having furanocoumarin content higher than 8 mg g-1 DW were spectrophotometer. MS was scanned from 10 to 1000 m/z at a scan