Studies on the Anti-Inflammatory Effects of Clerodendron trichotomum Thunberg Leaves

Clerodendron trichotomum Thunberg Leaves (CTL) have been used for centuries in Chinese folk medicine for their anti-inflammatory properties. We have studied the anti-inflammatory effects of CTL extracts in rats, mice and in Raw 264.7 cells. 1 mg/kg solutions of the 30％ and 60％ methanol extracts of CTL were used and a 1 mg/kg of indomethacin was used as a positive anti-inflammatory standard; these were then administrated to rats. Carrageenan was injected subcutaneously to induce hind paw edema in rats. The result of carrageenan-induced rat paw oedema showed that a 1 mg/kg of the 30％, and 60％ methanol fraction of CTL and 1 mg/kg of indomethacin inhibited the hind paw edema by 19.5％, 23.0％, and 20.5％ respectively. The effect of CTL on inflammation in mice by a capillary permeability assay was examined by detecting Evans blue leakage from capillaries after the intraperitoneal injection of acetic acid, a potent inflammatory stimulus. The 60％ methanol fraction of CTL inhibited Evans blue dye leakage by 47.0％, which was 10％ higher than that of the inhibition of 1 mg/kg of indomethacin. Also, the 60％ methanol fraction of CTL suppressed the prostaglandin $E_2$ ($PGE_2$) generation in RAW 264.7 macrophage cells after treatment with lipopolysaccharide (LPS) by as much as the inhibition of 1 mg/kg of indomethacin and this led to the synthesis of $PGE_2$ by COX-2 induction. The inhibition of the carrageenan-induced rat paw oedema, vascular permeability and the $PGE_2$ generation demonstrates that the 60％ methanol fraction of CTL contains a potent anti-inflammatory activity.