ISOGAMBOGIC ACID AND ISOMORELLINOL FROM GARCINIA-HANBURYI

Three xanthone derivatives, gambogic acid, isogambogic acid and isomor ellinol, were isolated from the dried latex of Garcinia hanburyi. Two of them, isogambogic acid and isomorellinol, are new. Determinations o f the structures and stereochemistry were achieved independently by a series of NMR experiments including COSY, ROESY, HMQC, HMBC and select ive INEPT. Isolation of isomorellinol from G. hanburyi provided import ant chemical evidence to link this species to G. morella. The presence of gambogic acid and isogambogic acid, however, demonstrated the diff erence between these two species. Cytotoxic evaluation of these isolat es revealed that all three were active against KB and drug-resistant K B-V1 cell lines.