In vitro α-amylase and α-glucosidase enzyme inhibition and antioxidant activity by capsaicin and piperine from Capsicum chinense and Piper nigrum fruits.

In the present study, α-amylase and α-glucosidase inhibitory effect and antioxidant activity of capsaicin and piperine from the ethanolic extract of Capsicum chinense (EECch) and Piper nigrum (EEPn) fruits were investigated. Results revealed that EECch exhibited the highest phenolic (154 mg GAE/100 g of tissue) and flavonoid content (75 mg RtE/100 g of tissue) in comparison with EEPn. The predominant compound detected in EECch and EEPn by GC-EIMS analysis was the capsaicin and piperine, respectively. The capsaicin and piperine showed the highest α-amylase and α-glucosidase inhibitory effect and antioxidant activity rather than extracts. The EEPn (IC50= 216 µg/mL) and piperine (IC50= 105 µg/mL) present a highest α-amylase inhibitory effect, while the EECch (IC50= 225 µg/mL) and capsaicin (IC50= 117 µg/mL) showed highest anti-α-glucosidase activity. Molecular docking established that capsaicin and piperine bind at the α-glucosidase and α-amylase through hydrophobic interactions, hydrogen bond, and charge interactions with amino acid residues. The enzyme inhibitory activity and antioxidant properties exhibited by EECch and EEPn could be attributed to the capsaicin and piperine content and other compounds present such as phenolic compounds and flavonoids. These fruits are potential sources of natural antioxidant agents and α-amylase and α-glucosidase inhibitors.