Synthesis and biological evaluation of ursolic acid derivatives containing an aminoguanidine moiety

Three series of ursolic acid derivatives containing an aminoguanidine moiety were designed, synthesized, and evaluated for anti-bacterial and anti-inflammatory activity. Some compounds displayed potent anti-bacterial activity against Gram-positive bacterial strains (including multidrug-resistant clinical isolates) and Gram-negative bacterial strains, with minimum inhibitory concentration (MIC) values in the range of 2–64 µg/mL. Compounds 3a, 5a, and 7l showed significant inhibitory activity against the Gram-positive bacterial strain Staphylococcus aureus RN 4220, the Gram-negative bacterial strain Escherichia coli 1924, and four multidrug-resistant Gram-positive bacterial strains, with MIC values of 2 and 4 µg/mL. In anti-inflammatory tests, most of the compounds exhibited potent activity, in particular compound 3a displayed the most potent activity with 81.61% inhibition after intraperitoneal administration, which was more potent than ursolic acid and the reference drugs (ibuprofen and indomethacin). The cytotoxic activity of compound 3a was assessed in HeLa, Hep3B, and A549 cells.