Curbing Key Digestive Enzymes by Three Plant Extracts for Sustainable Management of Postprandial Hyperglycemia

Diabetes mellitus is a chronic metabolic condition marked by persistently elevated blood sugar levels. Key digestive enzymes viz. α-amylase and α-glucosidase, hydrolyze consumed carbohydrates into glucose which raises the postprandial blood glucose level in a diabetic patient. So, the development of α-amylase and α-glucosidase inhibitors procured from medicinal plants to retard starch digestion is an alternative approach for controlling type 2 diabetes mellitus. The current study aimed to evaluate the inhibitory potentials of the key digestive enzymes viz. α-amylase and α-glucosidase by the extracts of three medicinal plants; red dragon fruit (Hylocereus polyrhizus) pulp and peel, bamboo (Bambusa vulgaris) shoot, turnip (Brassica rapa L.) shoot and leaf by performing α-amylase and α-glucosidase inhibition assays in vitro. Inhibition of α-amylase activity was conducted using 3,5-dinitrosalicylic acid method, and 4-Nitrophenyl-α-D-glucopyranoside was used as a substrate to perform α-glucosidase inhibition assay in vitro. Among all the selected sample extracts, red dragon fruit pulp expressed the highest percentage of α-amylase inhibition (59.73±4.33%) at the concentration of 1000 μg/mL which is comparable to standard antidiabetic drug Acarbose (70.59±2.64%), whereas the lowest inhibition was observed in turnip shoot extract (42.48±2.10%) at the same concentration. In terms of α-glucosidase inhibition activity, again, red dragon fruit pulp extract demonstrated the maximum inhibition rate (56.42±2.38%) at 1000 μg/mL concentration. This is respectable in comparison to the reference Acarbose (66.45±1.78%). In contrast, turnip shoot extracts displayed the lowest α-glucosidase inhibition activity (38.27±2.21%) at the same concentration. The current study demonstrated that the red dragon fruit pulp extract possesses substantial antihyperglycemic activity (α-amylase inhibition: 59.73±4.33%, α-glucosidase inhibition: 56.42±2.38%) in vitro, which could be a putative nutraceutical to manage postprandial hyperglycemia.