Anti-inflammatory activity of mangostins from Garcinia mangostana

The fruit hull of Garcinia mangostana Linn (Guttiferae) is used as an anti-inflammatory drug in Southeast Asia. Two xanthones, α- and γ-mangostins, were isolated from the fruit hull of G. mangostana, and both significantly inhibited nitric oxide (NO) and PGE₂ production from lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The IC₅₀ values for the inhibition of NO production by α- and γ-mangostins were 12.4 and 10.1 μM, respectively. After iNOS enzyme activity was stimulated by LPS for 12 h, treatment with either α- or γ-mangostin at 5 μg/ml (12.2 and 12.6 μM, respectively) for 24 h did not significantly inhibit NO production. The data show that the inhibitory activities of α- and γ-mangostins are not due to direct inhibition of iNOS enzyme activity. On the other hand, expression of iNOS was inhibited by α- and γ-mangostins in LPS-stimulated RAW 264.7 cells, but not by COX-2. However, the level of PGE₂ production was reduced by the two xanthones. In an in vivo study, α-mangostin significantly inhibited mice carrageenan-induced paw edema. In conclusion, α- and γ-mangostins from G. mangostana are bioactive substances with anti-inflammatory effects.