ANTIPLATELET AGGREGATION PRINCIPLES FROM THE STEM AND ROOT BARK OF MELICOPE TRIPHYLLA

Fifteen compounds including five furoquinoline alkaloids, dictamine (1 ), evolitrine (2), pteleine (3), skimmianine (4) and kokusaginine (5); two coumarins, imperatorin (6), phellopterin (7); four flavonoids, ,5 ,8-trimethoxy-6,7;3',4'-bismethylenedioxyflavone (8), meliternin (9), melisimplexin (10) and meliternatin (11); three sesquiterpene lactones , melicophyllone-A (12), -B (13) and -C (14); a steroid mixture of P-s itosterol and stigmasterol were isolated and characterized from the st em and root barks of Melicope triphylla. Their structures were determi ned by spectral analysis. Most of the Isolated compounds shouted poten t inhibitory activity on rabbit platelet aggregation induced by arachi donic acid (100 mu M) and collagen (10 mu g/mL). Compounds 1, 2, 3 and 6 were found to possess medium inhibitory activity toward ADP-induced platelet aggregation. Compounds 1 and 2 also inhibited rat aorta toni c contraction induced by NE (3 mu M) and K+ (80 mM) + Ca2+ (1.9 mM). O n the other hand, meliternin (9) exhibited 80.6% inhibition of tonic c ontraction induced by high K+ (80 mM) + Ca2+ (1.9 mM). (C) 1998 John W iley & Sons, Ltd.