Novel 3-O-acyl mesquitol analogues as free-Radical scavengers and enzyme inhibitors: synthesis, biological evaluation and structure–activity relationship

A new isomer of mesquitol (2,3-trans-3′,4′,7,8-tetrahydroxyflavan-3-ol) was isolated from Dichrostachys cinerea in excellent yields. It has shown free-radical scavenging property and α-glucosidase inhibitory activities but, it could not display xanthine oxidase inhibitory property. However, it was observed that acylation of 3-OH group significantly enhanced the α-glucosidase inhibition and displayed xanthine oxidase inhibitory potential. The structure activity relationship revealed that the degree of lipophilicity played a major role in improving enzyme inhibitory activities. A positive correlation was observed between enzyme inhibitory potential and acyl chain length (upto C-16) of aliphatic esters.