Synthesis and biological evaluation of oleanolic acid derivatives as PTP1B inhibitors

Twenty-four sugar-substituted oleanolic acid derivatives (1a-1f, 2a-2j, and 3a-3h) were synthesized in a concise and efficient strategy and their effects on the inhibition of protein tyrosine phosphatase 1B (PTP1B) and insulin-sensitizing response were evaluated in vitro. Several derivatives showed moderate to good inhibitory activities against PTP1B, and especially compounds 2f, 2h, 3d and 3e exhibited the most potent inhibitory activities with the IC50 values of 1.91, 12.2, 9.21 and 0.56 μM against PTP1B, respectively. Furthermore, compounds 2g-2h and 3b-3e displayed good insulin-sensitizing activities with the response values ranging from 21.52% to 59.58%. Structure-activity relationship study of these sugar-substituted oleanolic acid derivatives demonstrated that PTP1B inhibitory activity and insulin-sensitizing response were strongly influenced by both the carbohydrate moiety at the C-3 position and the long acidic chain at C-28 position of oleanolic acid.