The aim of this study was to investigate the phenolic profiles, antioxidant activities and α-glycosidase inhibitory activities of three different phenolic fractions from water caltrop (Trapa quadrispinosa Roxb.) husk and to further explore the predominant compounds and their mechanisms on α-glycosidase inhibition by virtual screening and molecular dynamics. A total of 29 substances were identified and quantified in this study. Tannins were the main constituents of water caltrop husk extract. All of the free phenolic (FP), esterified phenolic (EP) and insoluble-bound phenolic (BP) fractions exhibited good antioxidant activities, and the BP had the highest radical scavenging ability with IC₅₀ values of 0.82 ± 0.12 μg/mL (ABTS) and 1.15 ± 0.02 μg/mL (DPPH), respectively (p < 0.05). However, compared with the EP and BP, the FP showed the strongest inhibition towards the α-glycosidase and the IC₅₀ value of FP was 1.43 ± 0.12 μg/mL. The 1,2,6-trigalloylglucose and α-glycosidase complex had better root mean square deviations (RMSD) stability via molecular dynamics simulation study. Results obtained from this study may provide a good potential natural resource for the improvement of oxidative stress injury and blood glucose control in diabetes mellitus, which could expand the use of water caltrop husk and improve its economic value.

中文翻译：

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菱角 (Trapa quadrisinosa Roxb.) 壳改善糖尿病患者的氧化应激和餐后血糖：通过体外和计算机分析对不同馏分的酚类成分、抗氧化活性和 α-糖苷酶抑制作用

本研究的目的是研究菱角 ( Trapa quadrispinosa Roxb.) 壳中三种不同酚类组分的酚类成分、抗氧化活性和 α-糖苷酶抑制活性，并进一步探索主要化合物及其抑制 α-糖苷酶的机制通过虚拟筛选和分子动力学。本研究共鉴定并量化了 29 种物质。单宁是菱角皮提取物的主要成分。所有游离酚类 (FP)、酯化酚类 (EP) 和不溶性结合酚类 (BP) 组分均表现出良好的抗氧化活性，其中 BP 具有最高的自由基清除能力，IC 50 值为 0.82 ± 0.12 μg/mL ₍ ABTS ) 和 1.15 ± 0.02 μg/mL (DPPH)，分别为 ( p< 0.05)。然而，与EP和BP相比，FP对α-糖苷酶的抑制作用最强，FP的IC ₅₀值为1.43±0.12μg/mL。通过分子动力学模拟研究，1,2,6-三没食子酰葡萄糖和α-糖苷酶复合物具有更好的均方根偏差（RMSD）稳定性。本研究结果可为改善糖尿病氧化应激损伤和血糖控制提供良好的潜在天然资源，从而扩大菱角壳的用途，提高其经济价值。