Synthesis of new N-substituted aminoquercitols from naturally available (+)-proto-quercitol and their α-glucosidase inhibitory activity

Aminocyclitols have been recognized as alpha-glucosidase inhibitors due to their close structural relationship with sugar. The inhibitory effect can be improved by modifying the cyclic core and N-substituted moiety. In the present investigation, a series of new N-alkyl and N-acyl aminoquercitols have been synthesized using a natural chiral building block, (+)-proto-quercitol, and evaluated for alpha-glucosidase inhibition. N-Alkyl aminoquercitols encompassing medium alkyl chains (hexyl to decyl chains) showed highly improved inhibition against rat intestinal maltase, 3-6 fold more potent than antidiabetic drug acarbose. Kinetic study of potent N-substituted aminoquercitols indicated that they retarded maltase function in a competitive manner.