In Vitro Antioxidation, α-Glucosidase, and α-Amylase Inhibitory Activities of Different Solvent Extracts of Thai Traditional Diabetic Medicine

Abstract

Globally, interest in the treatment of diabetes mellitus with medicinal plants is growing. Treatment of diabetes mellitus  using traditional recipes in the Royal Textbook of King Rama V has been widely documented. The present study was  aimed at investigating the effects of the recipe extracts of a Thai traditional diabetic medicine on antioxidation,  α-glucosidase, and α-amylase inhibitory activities. Recipe-I comprised 6 Thai medicinal plants without any additional  medicinal material, while Recipe-II was composed of 6 Thai medicinal plants with 2 additional medicinal components (ammonium alum and potassium nitrate). Constituent plants of the 2 recipes were extracted with aqueous (H₂O), 50%  ethanol (HE), and 95% ethanol (E). Phytochemical screening was conducted on the various extracts to determine the  total flavonoid content (TFC) and total phenolic content (TPC). Three different assays, including FRAP (ferric reducing  antioxidant power), DPPH (2,2- diphenyl-1-picrylhydrazyl), and ABTS (2,2′-azino-bis-[3-ethylbenzothiazoline-6-sulfonic]  acid) radical scavenging were used to evaluate the antioxidant potential of the various extracts. The inhibitory activities  of the recipe extracts against α-glucosidase and α-amylase enzymes were also evaluated. The results showed that  Recipe-II-E was significantly higher in both TPC and TFC. The antioxidant activity of Recipe-I-E and Recipe-II-E was more  potent in DPPH and FRAP assays, while Recipe-II-E was significantly more potent in the ABTS assay. Concerning the  αglucosidase and α-amylase inhibitory activities, Recipe-I-H₂O was significantly (p < 0.05) more effective among the test  extracts. The findings of this study revealed that the test recipe extracts possess noticeable in vitro antioxidant potential  and α-glucosidase and α-amylase inhibitory activities.