Synthesis and Cytotoxicity of Triterpenic Acids Modified at C3 and C28 Positions

Series of N-, S- and Br-derivatives of betulinic, oleanolic, and ursolic acids have been synthesized and screened for their in vitro antitumor activity (cytotoxicity). N-Methylpiperazinylamide of 2-[3-pyridinylidene]-ursolic acid and methyl 2-methylideneureido-betulonate have shown significant cytotoxic activity against the PC3 cancer cells (IC50 = 8 μM) and HCT-116 cell line (IC50 = 5.7 μM).