In-vitro and In-vivo Studies of 5,7 Dihydroxy Flavones

Alpinia galanga (L.) also known as greater galangal is a traditional medicinal herb found in the tropical regions of Asia (Verma et al. 2011). It belongs to Zingiberaceae family and extensively used in food flavouring, cosmetics, dietary intake and also used as medicine by tribal communities. Plants of Zingiberaceae are considered to be safe for human consumption and these species have proved as excellent candidates for the development of novel therapeutics (Ramesh et al. 2015; Mazaheri et al. 2014; Jaju et al. 2010). Several studies reported that the rhizomes, leaves and stems of A.galanga are having medicinal properties such as anti-inflammatory, anti-bacterial, anti-fungal, anti-oxidant, anti-malarial, anti-allergic, anti-ulcer etc and are officially reported in pharmacopoeias (Sawangjaroen et al. 2005; Victorio et al. 2011; Jiang et al. 2006). Rhizomatous root of A.galanga has more medicinal properties as compared to shoot and other parts due to high concentration of various bioactive compounds like alkaloids, tannins, phenolic compounds, flavonoids, essential oils etc (Jiang et al. 2006). Studies effectively optimized new harvesting method of A.galanga suitable for Kerala climatic conditions to obtain better yield from rhizomes (Joy et al. 2002). Most of the characterized bioactive compounds from A.galanga are 1,8 cineol, beta-selinene, trans-p-hydroxycinnamyl acetate, 4,6-heptatrien-3-one and 5,7 dihydroxy flavones and is mainly studied in the treatment of different human ailments (Al-snafi 2010; Someya et al. 2001). Flavonoids are low molecular weight, secondary metabolites present in plants with poly-phenolic structure. It has a major role in growth and creates a defence mechanism against plaque formation in plants (Maria et al. 2012).

The chemical investigation of A.galanga has led to the isolation of 5, 7 dihydroxy flavone (pinocembrin) (Kumar et al. 2007). This flavonoid derivative is abundantly present in honey, propolis and few herbs and has previously reported to possess anti-cancer activities (Samarghandian et al. 2011; Visweswara et al. 2017). Zingiberaceae family is reported to contain flavonoids which are rich in anti-oxidants, henceforth taking leads from traditional medicine, A.galanga was used as a source to isolate compounds with anti-tumour activity in multiple types of cancer (Mosa-Al-Reza et al. 2014; Hadjzadeh et al. 2009). Medicines from plant origin are more studied since it has least side effects and production cost is cheap as compared to synthetic chemistry formulations. Kumar MA et al reported that pinocembrin, the oxidised form of chrysin isolated from A.galanga triggers apoptosis and cell death in various cancer cells (Kumar et al. 2007). At present A.galanga is gaining interest because of its antitumor activity and in-vitro cytotoxicity on various cell lines (Hadjzadeh et al. 2009; Phan et al. 2011; Matsuda et al. 2003). The flavonoids have potent anticancer activity by inhibition of the detoxification enzyme CYP1A1 and also by aryl hydrocarbon receptor modulation, depletion of GSH etc (Ciolino et al. 1999). Previous studies have concluded that the flavanoid extract induces apoptosis in human breast cell lines especially MCF-7, hepatic cells, oral squamous cell carcinoma, hepatocellular carcinoma, human melanoma etc (Priya et al. 2013).

Present studies are more focused on chrysin derivatives along with combinations of different synthetic or semi-synthetic chemicals that yield better anti-tumour activity like chrysin salicylate derivatives and dimethoxyflavone (Li et al. 2017; Mohammed et al. 2011). Chrysin is also reported to be very potent flavonoid which can induce good activity against leukaemia cells and prostate cancer cells. The effects of chrysin on apoptosis and its mechanism of action is well documented and reported on colon, breast, prostate, hepatocellular carcinoma and leukemia cells. The current cancer treatment has certain limitations such as drug resistance, high cost, toxicity effects and suppression of the immune system. Therefore our intention is to isolate and characterize chrysin from Alpinia galanga and to develop an alternative therapy or adjuvant therapy for the treatment of daltons lymphoma ascites and human lung cancer.