The chemical constituents of different polar fractions of the leaves of Litchi chinensis Sonn were analyzed using ultra-performance liquid chromatography-quadrupole-electrostatic orbitrap high-resolution mass spectrometry(UPLC-Q-Orbitrap HRMS),and the p-nitrophenyl-α-D-glucopyranoside(PNPG)and 3,5-dinitro salicylic acid(DNS)methods were used to compare the sites of hypoglycemic activity of lychee leaves in vitro.The inhibitory activities against α-glucosidase and α-amylase of different polar fractions of the leaves were investigated using PNPG and DNS methods.The results of chemical composition identification revealed 29 compounds from different polar fractions of the leaves of L.chinensis,including eight organic acids,ten flavonoids and their glycosides,three procyanidins,five nitrogen-containing compounds,one coumarin,one glycoside,and one compound of another class.The ethyl acetate extract of the leaves exhibited the strongest inhibitory activity against α-glucosidase and α-amylase,with IC50 values of 54.50 and 122.20 μg/mL,respectively.Protocatechuic acid,luteolin,epicatechin,kaempferol and other components are potential pharmacodynamic factors contributing to the in vitro hypoglycemic activity of ethyl acetate extracts.These results establish a foundation for further investigations on the quality control of L.chinensis.
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