The study of the hypoglycemic action of extracts from bearberry leaves under experimental insulin resistance in rats

Type 2 diabetes mellitus (DM2) has been increasing steadily all over the world. A large number of medicinal plants that have the hypoglycemic effect are known, but, unfortunately, currently there is very limited choice of antidiabetic herbal medicines. Aim. To design the experiment in order to study the hypoglycemic effect of polyphenolic extracts from bearberry (Arctostaphylos uva-ursi) leaves under the experimental insulin resistance (IR) in rats. Materials and methods. The experimental IR was induced by dexamethasone injections (Dex) and feeding with a high-fructose diet (HFD). Male outbred albino rats were randomized depending on the purpose of the experiment. As the study objects 50 % ethanolic polyphenol extracts obtained from bearberry leaves with addition of arginine (PE50_arg) and cysteine (PE50_cys) were selected. The oral glucose tolerance test (OGTT) was performed in all experimental groups of animals. Results. Dex had a more pronounced effect on tolerance to glucose compared to the HFD. It was shown that PE50_arg and PE50_cys after two weeks of administration revealed the ability to decrease the blood glucose level in rats, as well as reduce IR development and improve tolerance to glucose under the experimental IR. The hypoglycemic activity found did not much differ from the action of Metformin, but exceeded the activity of Arphazetin. These results can be the evidence of activation of glucose utilization processes, and it, in turn, indicates the insulin sensitivity improvement due to the action of the extracts studied. The data obtained indicate that the corrective effect of arginine and cysteine on signal transduction processes in insulin target cells plays an important role in the IR treatment. Conclusions. Bearberry leaves are the promising raw material for creating an anti-diabetic drug. Thus, it is necessary to further study the mechanisms of regulation of metabolic disorders when introducing new polyphenolic extracts.