In the course of our search for natural antioxidants, the methanol extract of the fruit hulls of mangosteen (Garcinia mangostana L.) originating in Vietnam was found to exhibit a potent radical scavenging effect. By monitoring the radical scavenging effect, two xanthones, α- and γ-mangostins, were isolated together with (-)-epicatechin, procyanidins A-2 and B-2 as active principles. The antioxidative activity of these two xanthones was measured by the ferric thiocyanate method and it was found that γ-mangostin showed more potent antioxidative activity than BHA and α-tocopherol.
