Chinese folk mecicine, Melastoma dodecandum Lour. (Melastomaceae) has been used as a traditional antipyretic, antitoxic, ciuretic, hemostatic and anti-rheumatic medcine. An extract of the whole plant with 80% aqueous acetone (MDL)and compounds isolated from this plantwereexamined foranti-allergic activety in the Passive Cutaneous Anaphylaxis (PCA) activity, and toward histamine and leukottiene (LT) release from rat peritoneal mast cells in vitro and nitric oxide (NO) production by a murine macrophage-like cell line, RAW264.7, activated with lipopolysaccharide (LPS) and interferon-gamma (lFN-gamma).
1) MDL inhibited rat PCA, histamine release, LT release and NO production.
2) Nene compounds, plerocarinin C (1), casuarictin (2), pedunculagin (3), casuarinin (4), nobotannin B(5), vitexin (6), isoquercitrin (7), 4-O-[beta-D-glucopyranosyl]-3, 3', 4'-tri-O-methyl ellagic acid (8) and gallic acid 3-O-beta-D(6'-O-galloyl)-glucopyranoside (9) were isolated from MDL.
3) Major inhibitory compounds on PCA were considered by hydrolyzable tannins because hydolyzable tannins 1, 2, 3, 4 and 5 inhibited strongly PCA and a flavonol 7 inhibited also it.
4) Compounds 1, 2, 3 and9 showed strong inhibitory activities on histamine releasinhibitory test. Dimeric hydrolyzable tannin 5 and compounds 7 and 8 showed moderate inhibitory activities, but compound 4 did not show such inhibitory activity.
5) Compounds 1, 2, 3, 4, 5 and 7 showed strong inhibitory activities on LT release inhibitory test.
6) Compound 5, a dimeric tannin, was a stronger inhibitor than yhe other monomeric tannins 2, 3 and 4 in NO production by macrophages activated with LPS and IFN-gamma. However, compound I showed cytoloxic activity.