Bifidenone: Structure-Activity Relationship and Advanced Preclinical Candidate.

Bifidenone is a novel natural tubulin polymerization inhibitor that exhibits antiproliferative activity against a range of human cancer cell lines, making it an attractive candidate for development. A synthetic route was previously developed to alleviate supply constraints arising from its isolation in microgram quantities from a Gabonese tree. Using that previously published route, we present here 42 analogues that were synthesized to examine the structure-activity relationship of bifidenone derivatives. In addition to in vitro cytotoxicity data, data from murine xenograft and pharmacokinetic studies were used to evaluate the analogues. Compounds 45b and 46b were found to demonstrate promising efficacy in murine xenograft experiments, and 46b had significantly more potent in vitro antiproliferative activity against taxane-resistant cell lines compared to that of paclitaxel.