In vitro and in vivo evaluation of the anticarcinogenic and cancer chemopreventive potential of a flavonoid-rich fraction from a traditional Indian herb Selaginella bryopteris.

Prevention of cancer through nutritional intervention has gained significant recognition in recent years. Evidence revealed from mechanistic investigations coupled with molecular epidemiology show an inverse association of dietary flavonoids intake with cancer risk. The chemopreventive and anticarcinogenic potential of Selaginella bryopteris, a traditional Indian herb referred to as 'Sanjeevani' in the Ayurvedic system of medicine, was examined in the present study. Comprehensive in vitro and in vivo studies were conducted on the flavonoid-rich benzene fraction of the aqueous extract that demonstrated a significant cytoprotective activity. Biomarkers of chemoprevention such as proliferative index and status of cell-cycle regulatory proteins, antioxidant property, anti-inflammatory effect, reversal of stress-induced senescence and genoprotective effect were investigated in human and murine cell cultures. Chemopreventive potential was assessed in benzopyrene-induced lung carcinogenesis and 7,12-dimethyl benz(a)anthracene-mediated skin papillomagenesis test models. Inhibition of DNA fragmentation, unperturbed cell-cycle regulation, maintenance of intracellular antioxidant defence, anti-inflammatory activity, prevention of stress-induced senescence and genoprotective effects against methyl isocyanate carcinogenicity was observed. Medium-term anticarcinogenicity and two-stage skin papillomagenesis tests strongly substantiated our in vitro observations. Results from the present study provide evidence of anticarcinogenic and chemopreventive activities of S. bryopteris hitherto unreported and reaffirm the nutritional significance of flavonoids in cancer prevention.