INDONESIAN MEDICINAL-PLANTS .6. ON THE CHEMICAL-CONSTITUENTS OF THE BARK OF PICRASMA-JAVANICA BL (SIMAROUBACEAE) FROM FLORES ISLAND - ABSOLUTE STEREOSTRUCTURES OF PICRAJAVANIN-A AND PICRAJAVANIN-B

Two new quassinoids named picrajavanins A and B were isolated, togethe r with known beta-carboline alkaloids and picrasidine G, from the bark of Picrasma javanica BL. (Simaroubaceae), an Indonesian folk medicine , collected on Flores Island. The absolute stereostructures of picraja vanins A (6) and B (7) have been elucidated on the basis of chemical a nd physicochemical evidence, together with the application of the modi fied Mosher's method.