α-Glucosidase inhibitory activity of Syzygium cumini (Linn.) Skeels seed kernel in vitro and in Goto–Kakizaki (GK) rats

Syzygium cumini seed kernel extracts were evaluated for the inhibition of α-glucosidase from mammalian (rat intestine), bacterial (Bacillus stearothermophilus), and yeast (Saccharomyces cerevisiae, baker’s yeast). In vitro studies using the mammalian α-glucosidase from rat intestine showed the extracts to be more effective in inhibiting maltase when compared to the acarbose control. Since acarbose is inactive against both the bacterial and the yeast enzymes, the extracts were compared to 1-deoxynojirimycin. We found all extracts to be more potent against α-glucosidase derived from B. stearothermophilus than that against the enzymes from either baker’s yeast or rat intestine. In an in vivo study using Goto–Kakizaki (GK) rats, the acetone extract was found to be a potent inhibitor of α-glucosidase hydrolysis of maltose when compared to untreated control animals. Therefore, these results point to the inhibition of α-glucosidase as a possible mechanism by which this herb acts as an anti-diabetic agent.