ANTIOXIDANT ACTIVITY OF TANNINS AND FLAVONOIDS IN EUCALYPTUS-ROSTRATA

Antioxidant activity of an extract from Eucalyptus rostrata was the hi ghest among 16 Eucalyptus species tested. From the leaves of Eucalyptu s rostrata nine active compounds were isolated: 1,2,6-tri-O-galloyl-be ta-D-glucose and tellimagrandin 1 as tannins; spiraeoside, hyperoside, isoquercitrin, and myricetin 3-O-alpha-L-arabinopyranoside as flavono l glycosides; quercetin 3-O-alpha-arabinopyranoside-2''-gallate, kaemp ferol 3-O-a-arabinopyranoside-2''-gallate, quercetin 4'-O-beta-D-gluco pyranoside-6''-gallate as acylated flavonol glycosides. Antioxidant ac tivity of the tannins and acylated flavonol glycosides, all with gallo yl groups, was much higher than that of a synthetic antioxidant. Two o f the compounds, spiraeoside and quercetin 4'-glucosylgallate, showed high superoxide dismutase activity.