Anti-hyperglycemic activity of Aegle marmelos (L.) corr. is partly mediated by increased insulin secretion, α-amylase inhibition, and retardation of glucose absorption

Abstract

Background: Aegle marmelos (commonly known as Bael, golden apple) was formerly described to have anti-hyperglycemic activity. The present study aimed to explore the possible effects, in depth, of A. marmelos extracts on carbohydrate absorption, glucose utilization, and α-amylase inhibition and insulin content in pancreases of type 2 diabetic rats.

Methods: This research begins with fasting blood glucose and oral glucose tolerance test (OGTT) to evaluate the primary anti-hyperglycemic effect in chemically induced type 2 diabetic rats. Furthermore, the plasma insulin concentration and serum glucose level were studied, which include measuring the sucrose content in six different segments of the gastrointestinal (GI) tract of the rats following oral sucrose feeding. An in situ, perfused, intestinal model in rats and glucose-fiber binding assay were conducted to find the effects of A. marmelos extracts on glucose absorption. Extract effects on carbohydrate breakdown, intestinal disaccharidase enzyme activity, and α-amylase inhibition were assessed. Effect on GI motility was evaluated using BaSO4 milk traverse test.

Results: Treatment of extracts suppressed blood glucose elevation after oral sucrose (2.5 g/kg) administration and significantly (p<0.05) improved oral glucose tolerance in type 2 diabetic rats. Aegle marmelos extracts showed remarkable (p<0.05) changes in plasma insulin secretion at 30 min and 60 min, respectively. A noticeable reduction in glucose absorption was observed in the in situ perfused rat intestinal model at two different doses (250 and 500 mg/kg). The extract was also found to inhibit the action of both α-amylase and intestinal disaccharidase enzyme, and this study was affirmed again by the sucrose malabsorption test, where sucrose digestion was inhibited throughout the length of the GI tract. During this chronic study, body mass of rats became normal and their polydipsic and polyphagic conditions were ameliorated also.

Conclusions: The findings demonstrate that anti-hyperglycemic activity of A. marmelos is mediated by the inhibition of carbohydrate digestion and absorption, and improvement of insulin action to uptake glucose in peripheral tissue. Additional study is required to correlate A. marmelos extracts' specific mechanism of glucose-fiber binding capacity and glucose transporters.