Antiplatelet aggregation principles from Glycosmis citrifolia

Twelve acridone alkaloids, citracridone-I (1), atalaphyllidine (2), noracronycine (3), des-N-methyl-noracronycine (4), 5-hydroxynor-acronycine (5), des-N-methylacronycine (6), N-methyl severifoline (7), 5-hydroxy-N- methyl severifoline (8), glycocitrine-II (9), 3-O-methyl-glycocitrine-II (10), glycocitrine-I (11) and pyranofoline (12); one 2-quinolone alkaloid, 4,8-dimethoxy-1-methyl-3(3-methylbut-2-enyl)2-quinolone (13) were isolated and characterized from the stem and root barks of Glycosmis citrifolia. Their structures were determined by spectral analyses. On bioactive evaluation, compounds 1 and 2 almost completely inhibited platelet aggregation induced by arachidonic acid (100 μM), collagen (10 μg/mL) and PAF (2 ng/mL). Compounds 2, 4 and 13 also showed an inhibitory effect on AA and collagen-induced rabbit platelet aggregation. In the structure and activity relationship of acridone alkaloids, the acridone nucleus bearing a pyranyl moiety is a most important factor for the antiplatelet aggregation activity.