Unlocking the potential of Polygonatum odoratum protein hydrolysate: identification, characterization, and...

Polygonatum odoratum is a traditional medicinal food used for diabetes management, yet most studies have focused on its polysaccharides and largely overlooked its protein fraction. Here, we investigated the antidiabetic activity and potential mechanisms of a Polygonatum odoratum protein hydrolysate (POP) for the first time. POP was produced by simulated gastrointestinal digestion and consisted mainly of oligopeptides (<1.5 kDa) enriched in leucine and valine. In HFD/STZ-induced type 2 diabetic mice, POP intervention significantly reduced hyperglycemia, improved glucose tolerance and insulin sensitivity, and alleviated dyslipidemia. Histological analyses showed that POP mitigated pancreatic β-cell injury, hepatic steatosis, and renal damage. POP also attenuated hepatic oxidative stress, as indicated by lower ROS and MDA levels and higher activities of antioxidant enzymes (SOD, CAT, and GSH-Px). Consistently, immunofluorescence indicated activation of the Nrf2/Keap1 pathway, with enhanced Nrf2 nuclear translocation and increased HO-1 expression. Therefore, POP improves glucose and lipid homeostasis and tissue damage in diabetic mice by enhancing Nrf2-dependent antioxidant defense mechanisms. These findings highlight the underexplored value of the P. odoratum protein fraction and support POP as a promising functional food ingredient for T2DM management.