Synthesis of New .ALPHA.-Glucosidase Inhibitors Based on Oleanolic Acid Incorporating Cinnamic Amides

A series of α-glucosidase inhibitors with the oleanolic acid core and different cinnamic amide ligands were designed and synthesized. Their preliminary structure–activity relationships were analyzed. In general, the compounds with 3,28-disubstituted oleanolic acid exhibited stronger activity than those 28-monosubstituted analogues, and variation of cinnamic amide substitution significantly affected α-glucosidase inhibition activities. Most of the compounds showed potent inhibitory activity against α-glucosidase with much greater efficacy than a typical α-glucosidase inhibitor, acarbose.