Anti‐complement activity of isolated compounds from the roots of Clerodendrum bungei Steud

To determine the anti‐complement activity of natural diterpenes, chromatographic separation of the acetone‐soluble fraction from the roots of Clerodendrum bungei (Verbenaceae) led to the isolation of five diterpenoids. An acetone‐soluble extract of the roots of C. bungei exhibited significant anti‐complement activity on the classical pathway complement system, which was expressed as total hemolytic activity. Five compounds isolated from the roots of C. bungei, namely 12‐O‐β‐d‐glucopyranosyl‐3,11,16‐trihydroxyabieta‐8,11,13‐triene (1), 3,12‐O‐β‐d‐diglucopyranosyl‐11,16‐dihydroxyabieta‐8,11,13‐triene (2), ajugaside A (3), uncinatone (4) and 19‐hydroxyteuvincenone F (5). Compounds 1, 2, 3, 4 and 5 showed inhibitory activity against complement system with 50% inhibitory concentrations (IC₅₀) values of 24 µm, 138 µm, 116 µm, 87 µm and 232 µm. Among the compounds tested, 1 showed the most potent anti‐complement activity (IC₅₀, 24 µm). Copyright © 2010 John Wiley & Sons, Ltd.