The Study On The Chemical Constitents And Antioxidation Activity Of Ipomoea Batatas

Ipomoea Batatas belongs to the family Convolvulaceae, it's a new brand of sweet potato, it was purple, with a color, nutrition and health effect. Previous study were concentrated in anthocyanin and phenolic compounds, phenolic compounds have been reported as caffeic acid and chlorogenic acid isomers. In this study, eight compounds were isolated and identified by ESI-MS,1H-NMR and 13C-NMR.The powered of I. Batatas was extracted with 95% ethanol aqueous, the ethanol extracts were combined and evaporated to dryness to afford a gummy residue. This residue was suspended in H2O and extracted with EtOAc and n-BuOH, successively, which were used for the chemical study.The EtOAc extract was subjected to column chromatography on silica gel eluted with an EtOAc:petroleum ether gradient to afford five fractions (Fr.l-Fr.5). Compound I and II were obtained from Fr.l and Fr.3 by stallization and recry-stallization, respectively. Fr.2 was separated by high-speed countercurrent chromatography (HSCCC) equipped with a biphasic solvent system composed of petroleum ether-EtOAc-mathanol-water(1:1.5:1:1,V/V/V/V) to afford fractions A-G.Fractions C-D were further chromatographic purification on Sephadex LH-20 and prep-HPLC to afford compoundsⅢ,Ⅳ,ⅤandⅥ。The. EtOH extract was separated by high-speed countercurrent chromatography (HSCCC) with a biphasic solvent system composed of EtOH-EtOAc-water (1:1:1,Ⅴ/Ⅴ/Ⅴ) to afford fractions H-O. The fraction L was further chromatographic purification on Sephadex LH-20 and prep-HPLC to afford compounds VII and VIII.The structures of compounds I-VIII were elucidation by ESI-MS,'H-NMR and 13C-NMR, and their antioxidant activity was assayed by DPPH method.They are as follows:β-sitosterol(compoundⅠ) seopoletin (compoundⅡ)cis methyl caffeate(compoundⅢ)trans methyl caffeate(compoundⅣ)cis ethyl caffeate(compoundⅤ) trans ethyl caffeate(compoundⅥ)scopolin (compoundⅦ)adenosine(compoundⅧ)They were all isolated from I. Batatas for the first time, trans ethyl caffeate(VI)> trans methyl caffeate(Ⅳ)> cis ethyl caffeate(Ⅴ)> cis methyl caffeate(Ⅲ)> adenosine(Ⅷ)>β-sitosterol(Ⅰ)> seopoletin(Ⅱ)> scopolin(Ⅶ).The results of present study will be useful to further phytochemical and biology activity investigation on I. Batatas, and provide a scientific basis for comprehensive utilization of I. Batatas.