Identification of a novel α-glucosidase inhibitor from Melastoma dodecandrum Lour. fruits and its effect on regulating postprandial blood glucose

• Published in: Food chemistry 2023-01, Vol.399, p.133999-133999, Article 133999
• Main Authors: Xu, Yang, Rashwan, Ahmed K., Ge, Zhiwei, Li, Yuting, Ge, Hengju, Li, Jiaxin, Xie, Jiahong, Liu, Shiyu, Fang, Jie, Cheng, Kejun, Chen, Wei
• Format: Article
• Language: English
• Subjects: Casuarictin; Melastoma dodecandrum Lour. fruits; Postprandial blood glucose; UPLC-Q-TOF-MS/MS; α-Glucosidase
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2022.133999

•Chemical constituents of Melastoma dodecandrum Lour. (MDL) fruit were identified.•Anthocyanins and proanthocyanidin derivatives were discovered for the first time in MDL.•A novel α-glucosidase inhibitor was identified as casuarictin.•Casuarictin bound α-glucosidase competitively, occupying the catalytic site. Melastoma dodecandrum Lour. (MDL) extracts have shown potent α-glucosidase inhibitory activity, suggesting MDL might be a good source of α-glucosidase inhibitors. The aim of the study was to identify compounds in MDL extracts with α-glucosidase inhibitory activities and evaluate their effect on postprandial blood glucose as well as elucidating the underlying mechanisms of inhibition. A total of 34 polyphenols were identified in MDL fruits, among which 10 anthocyanins and three proanthocyanidin derivatives were discovered for the first time. Dosing mice with MDL extracts (100 mg/kg body weight, by gavage) was associated with a significantly decrease in postprandial blood glucose concentrations after oral administration of maltose. The most potent α-glucosidase inhibitor was identified as casuarictin (IC50 of 0.21 μg/mL). Casuarictin bound competitively to α-glucosidase, occupying not only the catalytic site but also forming strong hydrogen bonds with α-glucosidase residues. Therefore, casuarictin derived from MDL fruits might be used as novel α-glucosidase inhibitor in functional foods or other dietary products.