Antioxidant flavonoid glycosides from Evolvulus alsinoides

Oxidative damage is an established outcome of chronic stress. Thus, the present study was designed to investigate the modulatory role of ethanolic extract of Evolvulus alsinoides (EA) in terms of oxidative alterations at peripheral and central level in rats subjected to chronic unpredictable stress (CUS). CUS exposure for 7 days reduced Cu, Zn superoxide dismutase and catalase activity with increase in glutathione peroxidase activity and lipid peroxidation, while decrease in reduced glutathione level in blood plasma, frontal cortex and hippocampus regions of brain. Oral administration of EA extract at 200mg/kg p.o. normalized these stress induced oxidative alterations with an efficacy similar to that of melatonin. Further, EA extract was taken up for detailed chemical investigation. Two new flavonol-4'-glycoside, kaempferol 4'-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside (3) and kaempferol 4'-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (5) were isolated, along with eight known compounds (1, 2, 4 and 6-10). The structures of new compounds were established by detailed spectroscopic studies, while known compounds were characterized by direct comparison of their reported NMR data. All these compounds were evaluated for their in vitro antioxidant activity. Compounds 3, 5, 9 and 10 at 100 and 200 microg/ml showed significant in vitro antioxidant activity. Therefore, EA may hold great potential in preventing clinical deterioration in stress induced oxidative load and related disorders.