Urea derivates of ursolic, oleanolic and maslinic acid induce apoptosis and are selective cytotoxic for several human tumor cell lines

2,3-Di-O-acetyl-maslinic acid benzylamide (5) has previously been shown to possess high cytotoxicity for a variety of human tumor cell lines while being of low cytotoxicity to non-malignant cells. Structural modifications performed on 5 revealed that the presence of these acetyl groups in 5 and the presence of (2 beta,3 beta)-configurated centers seems necessary for obtaining high cytotoxicity combined with best selectivity between malignant cells and non-malignant mouse fibroblasts. Compounds carrying an ursane skeleton showed weaker cytotoxicity than their oleanane derived analogs. In addition, the benzylamide function in compound 5 should be replaced by a phenylurea moiety to gain better cytotoxicity while retaining and improving the selectivity. Thus, maslinic acid derived N-[2 beta,3 beta-di-O-acetyl-17 beta-amino-28-norolean-12-en-17-yliphenylurea (45) gave best results showing EC50 = 0.9 mu M (for A2780 ovarian cancer cells) with EC50 > 120 mu M for fibroblasts (NIH 3T3) and triggered apoptosis while caspase-3 was not activated by this compound. (C) 2016 Elsevier Masson SAS. All rights reserved.