Anti-inflammatory principles from Heritiera littoralis bark

Compounds from the hexane, dichloromethane and acetone extracts of Heritiera littoralis bark were investigated for their nitric oxide (NO) inhibitory effects using RAW264.7 macrophage cells. The result indicated that ergosterol peroxide (13) exhibited the highest activity against NO release with an IC50 value of 2.5 μM, followed by 6-α-hydroxystigmast-4-en-3-one (11, IC50 = 9.5 μM) and stigmast-4-en-3-one (9, IC50 = 15.9 μM), whereas other compounds showed moderate and mild effects (25.4- > 100 μM). Ergosterol peroxide (13) and 6-α-hydroxystigmast-4-en-3-one (11) were also tested against prostaglandin E2 (PGE2) and tumor necrosis factor alpha (TNF-α) releases. It was found that ergosterol peroxide (13) possessed marked activity against PGE2 release with an IC50 value of 28.7 μM, while 6-α-hydroxystigmast-4-en-3-one (11) was 86.7 μM. However, these two compounds were inactive towards TNF-α release (IC50 > 100 μM). The mechanism in transcriptional level of ergosterol peroxide (13) was found to down regulate mRNA expressions of iNOS and COX-2 in dose-dependent manners.