Phytochemical Investigation of Active Compounds from Celastrus orbiculatus Thunb. with α-Glucosidase Inhibitory Activity

Diabetes, characterized by elevated blood glucose levels, has a significant impact on cardiovascular, neural, and vascular systems. α-Glucosidase inhibitors have emerged as potential therapeutic agents for type 2 diabetes, as they slow carbohydrate digestion and reduce postprandial blood sugar levels. In this study, we investigated the phytochemical and pharmacological properties of Celastrus orbiculatus Thunb., renowned for its diverse phytochemical constituents and potential medicinal applications. Through the application of chromatographic and spectroscopic techniques, we successfully isolated and structurally elucidated 16 compounds from the stems of C. orbiculatus. The in vitro α-glucosidase inhibitory activity of these compounds was evaluated. Notably, celaphanol A (1) and (+) lariciresinol (7) exhibited strong α-glucosidase inhibition, with IC₅₀ values of 8.06 ± 0.30 and 48.02 ± 0.47 µM, respectively. Enzyme kinetics analysis revealed that the most active compound 1 acted as a non-competitive inhibitor against α-glucosidase, with a K_i value of 7.77 ± 0.16 µM. These findings underscore C. orbiculatus as a valuable source for discovering and developing new α-glucosidase inhibitors. Furthermore, compound 1 shows promise as a candidate for natural herbal therapy targeting α-glucosidase inhibition. This suggests the potential for further investigation into its effectiveness through in silico or in vivo studies using a diabetes model.