Antihyperglycemic Mechanisms of Allium sativum, Citrus sinensis and Persea americana Extracts: Effects on Inhibition of Digestive Enzymes, Glucose Adsorption and Absorption on Yeast Cells and Psoas Muscles

Abstract

Mechanisms by which some plants with antihyperglycemic effects reduce postprandial hyperglycemiaare not fully elucidated. This
study was designed to investigate some action mechanisms of extracts from stem bark of Citrus sinensis, seeds of Persea americana and bulbs of Allium sativum including in vitro inhibition of α-amylase and invertase; glucophagic capacity, absorption capacity on yeast cells and psoas tissues. Methods Ethanolic (EE) and aqueous (AE) extracts were tested on α-amylase and invertase activities. Glucose remaining in the medium was measured after direct interactions of: Glucose-extracts; Glucose-yeast-extracts and Glucose-psoas-extracts at different doses 0, 5, 7.5, 10 mg/ml. Results All extracts inhibited invertase with IC50 varying from 1.92 to 4.81 mg/ml for Allium sativum extracts. α-amylase was inhibited by EE C. sinensis (IC50=0.063 vs 2.73 mg/ml for arcabose) and not by EE of A. sativum and EE of P. americana. Glucophagic capacity of extracts varied signicanty from 47.55 % of AE P. americana (5 mg/ml) to 100% with C. sinensis (5 mg/ml). All extracts stimulated glucose uptake (p<0.05) from 2.62 % AE C. sinensis (2.5 mg/ml) to 54.74% for EE of Persea americana (10 mg/ml). All extracts enhanced glucose uptake by psoas tissues increasing absorption capacity to up to 38.56 % with A. sativum (10.45% insulin, p<0.05). Conclusion Cumulative actions of each plant extract on inhibition of carbohydrates’ digestive enzymes, adsorption of glucose in intestine and blood, stimulation of glucose uptake and insulin action on yeast cells and psoas tissues, contribute to lower hyperglycemia and diabetes related complications. Therefore, extracts from the plants could be good candidates for diabetes therapy.