Antioxidant Activity And Activity Directed Separation Of Alcohol Extract From Water Chestnut Shell

China is rich in rhomboid resources with high nutritional value.It is also a kind of medicinal resources.As a by-product of fresh food or processing,water chestnut shell(WCS)has not been effectively developed and utilized,which has brought a lot of negative effects on the ecological environment.According to the research findings,WCS has antioxidant,antibacterial,hypoglycemic,liver protection and other effects.This is because WCS contains alkaloids,terpenoids,polyphenols,flavonoids and other bioactive components.Based on UPLC-MS/MS tracking and on-line HPLC-ABTS+ activity,antioxidant compounds with high purity were prepared from WCS,and their structures were identified.The specific methods and conclusions are as follows:(1)C18 column chromatography was used to purify the antioxidant target compounds in dicorne hydrochloride ethyl acetate,and it was further prepared by preparative liquid chromatography.The off-line and on-line activities of the crude extract and three extracts were determined.and the antioxidant components of the crude extract were identified by UPLC-MS/MS.The liquid phase analysis and online activity traced 27 chromatographic peaks corresponding to the active compounds in 4 samples.UPLC-MS/MS was used to identify 27 components in the crude extract.The order of antioxidant activity of the three extraction parts is ethyl acetate extract(EAE)>n-butanol extract(BE)>petroleum ether extract(PEE).(2)C18 column chromatography was used to purify the EAE of WCS,and further the target compounds were prepared by preparative liquid chromatography.Different concentrations of ethanol was used to elute the adsorbed samples on the C18 column,successively,and the eluents were detected by HPLC.Semi-preparative liquid chromatography was used to conduct directed separation and preparation of the three fractions,PT-1、PT-2 and PT-3.UPLC-MS/MS was used to confirm the separated compounds.After purification,four monomers with strong antioxidant activity were obtained.Specifically,WZ6 was prepared from PT-1;WZ 15,WZ 16 and WZ 19 from PT-2,and WZ 19 from PT-3.(3)LC-QTOF-MS and NMR(1H-NMR,13C-NMR,H-H COSY,HMBC,HSQC)were used to identify the structures of the four prepared active monomers.The structures of four compounds were identified as gallic acid(WZ 5),1,2,6-tri-galloyl-o-β-D glucose(WZ 15),1,2,3-tri-galloyl-4,6-ellagin-o-β-D glucose(V16)and 1,2,3,6-tetragalloyl-o-β-D glucose(WZ 19).