A reinvestigation of Maprounea triterpenes.

Anti-HIV activity and the inhibition of phorbol ester receptor binding activity in two species of Maprounea were traced to small amounts of highly potent phorbol esters of the daphnane type. The triterpenes previously isolated from this genus were found to be devoid of biological activity when scrupulously purified. Four new triterpene esters were elucidated; two [3,4] were found in M. africana, while three [4,6,7] were found in M. membranacea. Nmr assignments have also been made for two previously known compounds [2,5] in this group.