Oil palm leaf protein hydrolysate and its novel peptides as alternative plant-based α-glucosidase inhibitors

Diabetes, particularly type II, is a global health concern, with current treatments like α-glucosidase inhibitors often causing gastrointestinal side effects. This study explored the antihyperglycemic potential of crude protein hydrolysate from oil palm leaves (OPL) as a plant-based α-glucosidase inhibitor. OPL protein hydrolysate was extracted under acidic, neutral, and alkaline conditions, and their α-glucosidase inhibitory activity was assessed. OPL hydrolysate obtained under neutral conditions for 2 h showed the highest inhibitory activity, comparable to the standard drug, acarbose. Bioassay-guided fractionation of the most potent extract revealed that peptides from sub-fractions C1 and C9 exhibited stronger inhibition, with IC50 values of 66.3 and 62.0 μg/mL, respectively. Seven novel peptides were identified from these fractions, and molecular docking confirmed stable interactions between these peptides and the α-glucosidase enzyme via hydrogen bonds and salt bridges. These findings suggest that OPL protein hydrolysate is a plant-based promising natural α-glucosidase inhibitor with potential as an antidiabetic agent. Future studies should focus on in vivo validation of its efficacy and safety for therapeutic use.