Synthesis and cytotoxic screening of beta-boswellic acid derivatives

Abstract

Beta-boswellic acids are triterpenoids being generic to the plants of genus boswellia. Although they were shown to exhibit different biological activities, the cytotoxic potential of b-boswellic acid derivatives remained by and large unexploited. To expand the potential of these compounds we developed simple procedures for the interconversion of the most important b-boswellic acids 1-4 and prepared several other derivatives 5-48. These compounds were screened for their cytotoxic activity in sulforhodamine B assays employing several human tumor cell lines and nonmalignant mouse fibroblasts. One of these compounds, a difluoromethylester of 3-O-acetyl-11-keto-beta-boswellic acid 23, was cytotoxic for human breast adenocarcinoma cells MCF-7 (EC50 = 6.5 mM) while being significantly less cytotoxic for the mouse fibroblasts.