Enhanced extraction of polyphenols from persimmon peel via subcritical solvent-assisted method: Targeting α-amylase/α-glucosidase inhibition and mechanistic elucidation.

Persimmon peel is a valuable source of polyphenols with anti-hyperglycemic potential. This study aimed to identify key α-amylase/α-glucosidase (α-AMY/α-GLU) inhibitors within persimmon peel polyphenols and to enhance their inhibitory activity. Using affinity ultrafiltration, LC-MS, and molecular docking, hyperin, isoquercitrin, and quercetin were identified as dual-target inhibitors. Subcritical solvent-assisted extraction (SAE) parameters (solvent, temperature, and time) were optimized, with 50 % ethanol at 130 °C for 10 min yielding the highest phenolic (531.8 mg GAE/g) and flavonoid (636.1 mg RE/g) contents and the strongest enzyme inhibition. Furthermore, kinetic studies revealed three distinct stages during SAE: Solubilization Zone (100 °C), Critical Conversion Zone (130 °C), and Degradation Zone (160-190 °C). The enhanced inhibition was attributed to the dissolution of key inhibitors and the conversion of hyperin/isoquercitrin into quercetin, within the Critical Conversion Zone. These results demonstrate that SAE, by controlling temperature and time, effectively valorizes persimmon peel and enhances its polyphenol bioactivity.