Sanan Subhadhirasakul, Bamrung Jankeaw, and Apai Malinee

pp. 351 - 357

Abstract

Chloroform and n-butanol extracts from the leaves of Dyera costulata exhibited EC₅₀ values for
DPPH radical scavenging activity of 79.8±0.2 and 12.0±0.1 µg/ml, respectively. Chemical investigation of the
extracts was conducted by means of column chromatography. β-Amyrin and rhamnazin were isolated from
the chloroform extract and quercetin-3-O-α-L-rhamnopyranoside was isolated from the n-butanol extract.
The chemical structures of the isolated compounds were identified by comparison of their spectroscopic data
with those reported in the literature. The EC₅₀ value of quercetin-3-O-α-L-rhamnopyranoside in DPPH
radical scavenging activity was 9.37±0.02 µM. Its antioxidative activity is therefore about 8 times higher than
that of the well known antioxidant, BHT, which has an EC₅₀ value of 80.78±0.01 µM.