Study On The Chemical Constituents And Hypoglycemic Activity Of Urtica Laetevirens Maxim.

Urtica laetevirens Maxim. is a perennial herb belonging to Urticaceae genus Urtica（Urtica L.）.In this study,Urtica laetevirens was selected as the research object.Liquid-liquid extraction,silica gel and macroporous resin column chromatography were firstly used to preliminarily separate the crude extracts,and the obtained fractions were further purified by high performance liquid chromatography,semi-preparative high performance liquid chromatography and recrystallization method.29 compounds were obtained and the chemical structures of 19 compounds were identified.Meanwhile these 19 compounds were analyzed by molecular docking againstα-glucosidase to screen target compounds withα-glucosidase inhibitory activity.The inhibitory activity of compounds screened by docking were further confirmed by in-vitro enzyme inhibitory experiments.The main results were as follows:1.The crude extract of Urtica laetevirens Maxim. was treated by liquid-liquid extraction to obtain three parts:petroleum ether part,ethyl acetate part and water part.Petroleum ether part did not conduct further separation due to its complex composition.Water part was treated by macroporous adsorption resin to obtain 6subfractions and ethyl acetate part was treated by silica gel column chromatography to obtain 709 subfractions.High performance liquid chromatography was employed to analyze each fraction obtained by macroporous adsorption resin and silica gel column chromatography.9 fractions were chosen to conduct further purification based on the HPLC analysis results.Finally,29 compounds with satisfied purity were obtained.The chemical structures were identified by mass spectrometry（MS）,nuclear magnetic resonance spectroscopy（NMR）.The chemical structures of 19 compounds were clearly identified:2-dimethyl-Penidilamine（1）,Indole-3-carboxaldehyde（2）,Scopoletin（3）,p-Coumaric Acid（4）,methyl 4-hydroxylbenzoate（5）,thymine（6）,uracil（7）,grasshopper ketone（8）,phaseic acid（9）,isovitexin（10）,1’-O-chlorogenoyl-neochlorogenic acid（11）,5-O-caffeoylshikimic acid（12）,1,3-di（4-methoxycinnamoyl）glycerol（13）,Isoorientin（14）,Butanediamide（15）,protocatechuic acid（16）,neochlorogenic acid methyl ester（17）,3,4-di-O-caffeoylquinic acid methyl ester（18）,caffeic acid（19）.Among them,compound 1 is a new compound,and compounds 4,5,6,8,9,10,11,12,13,14,15,16,17,18,and 19 are isolated from Urtica laetevirens Maxim.for the first time.2.The molecular docking analysis was conducted by selecting the 19 identified compounds as ligands andα-glucosidase as receptor protein to simulate the interaction.Five active compounds were screened to exhibitα-glucosidase inhibitory activity by docking:Isovitexin（minimum binding energy is-9.4 kcal/mol）;1’-O-chlorogreen acyl-neochlorogenic acid（minimum binding energy is-8.8kcal/mol）;5-caffeoyloxyshikimic acid（minimum binding energy is-8.6 kcal/mol）;isoorientin（minimum binding energy is-8.6 kcal/mol）;caffeic acid（minimum binding energy is-7.2 kcal/mol）.Using acarbose as a positive control,the above five compounds were tested for theirα-glucosidase inhibitory activity in vitro,and four compounds were confirmed to exhibitα-glucosidase inhibitory activity:Isovitexin(IC₅₀=7.42μM);1’-O-chlorogreen acyl-neochlorogenic acid(IC₅₀=26.24μM);isoorientin(IC₅₀=71.31μM);caffeic acid(IC₅₀=172.55μM),Among them,isovitexin exhibits the strongestα-glucosidase inhibitory activity.