Synthesis and antitumor activity of alkylated bile acids and oxazolines

Abstract

Bile acid derivatives with a free carboxylic group or an oxazoline ring in the side chain and with different lengths of alkyl chains on steroid skeleton were synthetized and their antitumor activity against six human cancer cell lines was investigated. Methyl, ethyl, butyl or octyl chains were introduced stereoselectively by Grignard reaction at C-7 of acid and oxazoline, and at C-12 of oxazoline. Carbonyl group at C-12 of acid compound gave addition product only with methyl Grignard reagent, and complex mixture of products with other used reagents. Due to enolization, the C-3 carbonyl group did not participate in the Grignard reaction. Steric reasons are a main cause of this chemical behavior. Compounds with a butyl chain at the C-7 position showed very good antitumor activity with IC50 < 5 μM.