Characteristics of Polyphenols of Black Hulless Barley Bran and Its Anti-Diabetic Activity

Polyphenols play a crucial role in promoting human health. This study aims to investigate the polyphenols of black hulless barley bran (HBP) and evaluate their anti-diabetic mechanisms in vivo. Using UPLC-QTOF-MS/MS, 27 compounds were identified in HBP, including four phenolic acids, 14 flavonoids, and nine anthocyanidins. High contents of Chrysoeriol 7-O-glucuronide (42.09 mg/g), Cyanidin 3-O-glucoside (21.02 mg/g), and Cyanidin 3-O-(6″-O-malonyl)-glucoside (24.45 mg/g) were quantified via UPLC in HBP. Administration of HBP significantly reduced fasting blood glucose (FBG), improved glucose intolerance and lipid profiles, and alleviated liver and pancreatic damage in type 2 diabetic (T2DM) mice. Furthermore, it enhanced serum antioxidant enzyme activities and modulated inflammatory cytokines. Transcriptomic analysis revealed that HBP influenced signal transduction and the immune system, particularly in key signaling pathways, including Hippo, TGF-beta, HIF-1, and p53, associated with T2DM. Although HBP had minimal impact on gut microbiota diversity and SCFA levels, it presents a promising candidate for T2DM intervention through its multifaceted mechanisms.