Bile acids lithocholic acid (LCA) and ursodeoxycholic acid (UDCA) together with trametenolic acid (TMA) were used as starting materials for the preparation of new derivatives bearing a guanidine moiety in their side chain. The derivatives were synthesized through modification at the oxygenated carbon C-3/C-7 and at the carbonyl carbon C-24/C-21. The reactions showed yields ranging from 40 % to 96 %. The structures of all compounds obtained were identified on the basis of their spectral data (IR, MS, 1D- and 2D-NMR). The activity of bile acids, trametenolic acid and derivatives was evaluated against the growth of S. aureus, B. subtilis and M. smegmatis. The derivative 3α-hydroxy-23-guanidino-5β-cholane showed the best activity, with MIC values of 12.5 μM against S. aureus, 5 μM against B. subtilis and 50 μM against M. smegmatis. The cytotoxic activity of bile acids, trametenolic acid and derivatives was also evaluated against HT-29 cell line.
