Synthesis of 4-thiosubstituted flavan derivatives and their hypoglycemic activities.

A series of 4-thiosubstituted flavan derivatives (1-44) were designed and synthesized. The target compounds were assayed for inhibitory activity against α-glucosidase in vitro, and the results indicated that all compounds displayed significant effects in the range of IC = 1.03-7.48 μM compared to that of acarbose, the positive control drug. Structure-activity relationship (SAR) studies indicated that the hydroxyl groups in the flavan B ring, the electron withdrawing groups, and the length of the alkyl chains are important for this biological activity. In addition, some compounds were tested for their tolerance to sucrose in mice, and compound 44 exhibited activity comparable to that of acarbose. Docking analysis indicated that compound 44 binds to the enzyme in a pocket close to the catalytic site, similar to acarbose.