Inhibitors of the arachidonate cascade from Allium chinense and their effect on in vitro platelet aggregation.

N- (p-trans-Coumaroyl) -and N- (p-cis-coumaroyl) tyramines (1, 2), lunularic acid (3) and p-coumaric acid (4), which are inhibitors of prostaglandin (PG) and thromboxane synthetases, were isolated from the bulb of Allium chinense G. DON, a Chinese medicinal drug. Stilbene derivatives structurally related to lunularic acid (3) were tested for inhibitory effect on prostaglandin synthetase. The compounds that inhibited PG biosynthesis also showed significant inhibitory effects on platelet aggregation induced by arachidonic acid and collagen.