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Antidiabetic agents simultaneously inhibiting hepatic glucose production and stimulating hepatic glucose consumption could apply a better control over hyperglycemia. A series of oleanolic acid derivatives with bulky substituents at C-3 position were designed and synthesized in order to search for this kind of agents. All of the compounds were evaluated biologically in vitro using glycogen phosphorylase and HepG2 cells. The results indicated that several derivatives exhibited moderate-to-good inhibitory activities against glycogen phosphorylase. Compound 8g showed the best inhibition with an IC50 value of 5.4 μ m. Moreover, most of the derivatives were found to increase the glucose consumption in HepG2 cells in a dose-dependent manner. The possible binding mode of compound 8g with glycogen phosphorylase was also explored by docking study. 8g was found to have hydrogen bonding interactions with Arg193, Arg310, and Arg60 of the allosteric site. [ABSTRACT FROM AUTHOR]

Abstract: To explore the molecular mechanisms of oleanolic acid, two novel photoaffinity probes were synthesized based on the structure–activity relationship reported previously. Their potency were evaluated in an enzyme inhibition assay against rabbit muscle glycogen phosphorylase a (RMGPa), a known target protein of oleanolic acid. The inhibitory activity of probe 2 was only about two-fold less potent than the mother compound oleanolic acid. The photoaffinity labeling experiments were also performed and two proteins were specifically tagged by probe 2. The results suggest that the synthesized probes could be used as powerful tools to isolate and identify the target proteins of oleanolic acid. [Copyright &y& Elsevier]