INDOLE ALKALOIDS FROM PESCHIERA-LAETA THAT ENHANCE VINBLASTINE-MEDIATED CYTOTOXICITY WITH MULTIDRUG-RESISTANT CELLS

Coronaridine [1], conoduramine [2], and voacamine [3], three indole al kaloids isolated from Peschiera laeta, have been found to enhance the cytotoxic response mediated by vinblastine [4] with multidrug-resistan t KB cells. Inhibition of vinblastine binding with membrane vesicles i solated from this cell line was also assessed, and the bisindole alkal oids conoduramine [2] and voacamine [3] were found to be more potent i nhibitory agents than the monomeric alkaloid, coronaridine [1]. Thus, these compounds appear to function by binding with P-glycoprotein.