Luya Wang

Background: Reducing postprandial blood glucose (PBG) is a crucial strategy for treating diabetes and minimizing the risk of complications. Developing efficient and safe α-glycosidase inhibitors from natural products to lower PBG has attracted much attention. Silphium perfoliatum L. (SP), a traditional herbal medicine of North American Indigenous tribes, has efficacy of treating metabolic diseases, but its hypoglycemic activity and bioactive components have not been fully studied. Methods: In vitro α-glucosidase inhibition and in vivo sucrose/maltose/starch tolerance assays were performed to assess the hypoglycemic effects of SP extracts, and UPLC-Triple-TOF-MS/MS analysis was used to tentatively identify its chemical structure composition. In vitro enzyme inhibition and molecular docking were used to verify the effective ingredients. Results: In vitro hypoglycemic activities of four extracts of SP (SP-10/SP-40/SP-60/SP-C) showed that SP-10 exhibited strong α-glucosidase (sucrase and maltase) inhibitory effects with IC₅₀ of 67.81 μg/mL and 62.99 μg/mL, respectively. Carbohydrate tolerance assays demonstrated that SP-10 could significantly reduce the PBG levels of diabetic mice, with a significant hypoglycemic effect at a dosage of 20 mg/kg. A total of 26 constituents, including 11 caffeoylquinic acids (CQAs) and 15 flavonol glycosides, were tentatively identified by mainly analyzing secondary MS fragmentation. Moreover, three CQAs rich in SP-10, namely chlorogenic acid (CGA), neochlorogenic acid (NCGA), and cryptochlorogenic acid (CCGA), may be the main hypoglycemic substances, as evidenced by their inhibitory effects on sucrase and maltase. Conclusions: The α-glucosidase inhibitory effects of SP extract both in vitro and in vivo and its active ingredients were systematically studied for the first time. Results indicated that SP extract, rich in CQAs, had significant hypoglycemic activity, supporting the considerable potential of SP as hypoglycemic functional food or cost-effective therapeutic agents for diabetes treatment.