Screening for biological activity of crude methanol extract and its fractions showed that all extract and
fractions possessed radical scavenging activity by DPPH test with SC50 values from 23.94 – 167.43
μg/mL, in which the crude extract was the most active sample with SC50 = 23.94 μg/mL. From the ethyl
acetate fraction, five compounds were isolated including methyl gallate (1), blumenol A (2), (6S,9R)-
roseoside (3), kaempferol-3-O-α-rhamnoside (4), and vitexin (5). Their structures were determined by
MS, NMR, analysis and in comparison with previous publications. Compounds (1), (2) and (4) were
isolated for the first time from Sonneratia ovata Backer.