Antioxidant activity and constituents of extracts from the root of Garcinia multiflora

The methanolic extract of the root of Garcinia multiflora and its derived soluble fractions, namely those soluble in ethyl acetate (EtOAc), n-butanol, and water, were screened for their antioxidant activities. Among them, the EtOAc-soluble fraction exhibited the highest scavenging activity against the 1,1-dipheny1,2-picrylhydrazyl radical, the highest superoxide radical scavenging activity, and the strongest reducing power. In addition, according to the bioactivity-guided isolation, 26 specific phytocompounds, including 3 aromatics, 3 benzophenones, 3 flavonoids, 3 isocoumarins, 1 phloroglucinol, 6 steroids, and 7 xanthones, were isolated from the EtOAc-soluble fraction and identified. Of these, 2,4,3′,4′-tetrahydroxy-6-methoxybenzophenone and 1,3,6,7-tetrahydroxyxanthone were found to be the major bioactive constituents, present in the crude extract in concentrations of 3.9 and 15.6 mg/g, respectively. These two compounds had similar antioxidant activities to (+)-catechin, a well-known antioxidant.