FLAVAN-3-OLS ISOLATED FROM SOME MEDICINAL-PLANTS INHIBITING COX-1 ANDCOX-2 CATALYZED PROSTAGLANDIN BIOSYNTHESIS

Extracts from the four plant species Atuna racemosa Raf. ssp. racemosa , Syzygium corynocarpum (A. Gray) C. Muell., Syzygium malaccense (L.) Merr. & Perry and Vantanea peruviana Macbr., traditionally used for in flammatory conditions, were fractionated using a cyclooxygenase-1 cata lysed prostaglandin biosynthesis in vitro assay. The flavan-3-ol deriv atives (+)-catechin, (+)-gallocatechin, 4'-O-Me-ent-gallocatechin, our atea-catechin and ouratea-proanthocynidin A were isolated as active pr inciples. The IC50 values ranged from 3.3 mu M to 138 mu M whilst indo methacin under the same test conditions had an IC50 value of 1.1 mu M. The flavonol rhamnosides mearnsitrin, myricitrin and quercitrin were also isolated. When further tested for inhibitory effect on cyclooxyge nase-2 catalysed prostaglandin biosynthesis, the five flavan-3-ol deri vatives exhibited from equal to weaker inhibitory potencies, as compar ed to their cyclooxygenase-l inhibitory effects. The flavonol rhamnosi des were inactive towards both enzymes.