Isolation,Purification and Antioxidant Activities of Three Kinds of Polyphenol Monomers from Camellia ptilophylla Chang

In this study,Camellia ptilophylla Chang was extracted with 30% ethanol/ethyl acetate,and then three kinds of polyphenol monomers were isolated and purified by Sephadex LH-20 column chromatography and preparative high performance liquid chromatography,and compound structures were identified by high performance liquid chromatography-tandem mass spectrometry,nuclear magnetic resonance and infrared spectroscopy. Antioxidative activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl(DPPH)and 2,2'-azino-bis-(3-ethylbenzothiazole-6-sulfonic acid)diammonium salt(ABTS)radical scavenging ability,iron ion reducing ability(FRAP)and oxygen radical absorbance capacity(ORAC),and L-O₂ hepatocyte oxidative stress model. Result:Three kinds of polyphenol monomers were isolated from the Camellia ptilophylla Chang,namely,gallocatechin gallate(GCG)and 1,2,4,6-tetragalloyl glucose(1,2,4,6-GA-glc),gallocatechin-3,5-digallate(GC-3,5-diGA). Purity was 98%,96% and 97%,yield was 2.45%,0.55% and 0.31%,respectively.DPPH,ABTS and FRAP experiments had bacically the same antioxidant results:GCG > GC-3,5-diGA > 1,2,4,6-GA-glc.In contrast,ORAC method had a stronger effect on 1,2,4,6-GA-glc than GCG and GC-3,5-diGA. After pretreatment with high-dose GCG,1,2,4,6-GA-glc and GC-3,5-diGA,the survival rate of L-O₂ cells under oxidative stress was increased by 26.98%±1.96%,70.87%±3.61% and 35.58%±5.37%,respectively. In conclusion,to obtain high purity GCG and two kinds of special polyphenols 1,2,4,6-GA-glc and GC-3,5-diGA,Sephadex LH-20 column chromatography and preparative high performance liquid chromatography are used to separate,antioxidant results show that GCG has strong chemical antioxidant capacity,1,2,4,6-GA-glc and GC-3,5-diGA have strong cellular antioxidant capacity.