EVALUATION OF Α-AMYLASE AND Α-GLUCOSIDASE INHIBITORY ACTIVITY OF FLAVONOIDS

A number of phenolic acids and flavonoids were screened for inhibitory activity against rat intestinal α-glucosidase and porcine pancreatic α-amylase. The phenolic acids were not inhibitory to both enzymes at 1 mM. Inhibition of α-amylase by flavonoids mirrored the inhibition of α-glucosidase in that both baicalein and myricetin inhibited the enzyme most strongly, but differs in that spectrum of flavonoid inhibition for α-amylase only restricted to these two flavonoids while it was more wide spread for the inhibition of α-glucosidase. Baicalein inhibited α-amylase and α-glucosidase activity by 41.1±2.6% and 56.9±1.7% at 1 mM, respectively. Myricetin inhibited α-amylase and α-glucosidase activity by 35.9±3.8% and 47.7±2.4% at 1 mM, respectively. The IC50 (concentration required for 50% reduction activity) of baicalein (0.713±0.034 mM) and myricetin (1.030±0.026 mM) confirmed that baicalein is the most potent flavonoid inhibitor against α-glucosidase in the flavonoid series studied.