Antioxidant Phenolic Compounds Isolated From Wild Pyrus Ussuriensis Maxim.fruit Peels And Leaves

In this study,the fruit peels and leaves of wild Pyrus ussuriensis Maxim.were used as experimental materials,and the activities of petroleum ether,ethyl acetate,n-butanol and raffinate aqueous phase of methanol extracts from pear peels and leaves were detected by DPPH radical scavenging method.silica gel,Sephadex LH-20,reversed-phase RP-18 column chromatography and TLC?thin-layer chromatography?were used to track the active compounds in combination with antioxidant activity.Chemical structures were identified on the basis of mass spectmroetry?EI-MS?ESI-MS?HR-ESI-MS?and nuclear magnetic resonance spectroscopy(¹H-NMR?¹³C-NMR?H-H COSY?HMBC?HMQC?NOESY)along with comparison with literature data.Finally,the result of antioxidant activity of pure compounds was evaluated.Rusults are following behind:?1?Tracing the four extracts activity of pear peels and leaves methanol extracts was found:the antioxidant activity of ethyl acetate fraction was higher than the other fractions.?2?The thirteen isolated compounds from ethyl acetate fractions were identified as rutin?1?,?-?-catechin?2?,orobol?3?,daizein?4?,tricin4'-O-[threo-?-guaiacyl-?7”-O-methyl?-glyceryl]ether?5?,tricin4'-O-[threo-?-guaiacyl-?7”-Omethyl-9”-O-acetyl?-glyceryl]ether?6?,5,7,3',5'-tetrahydroxyflavanone?7?,artselaeroside A?8?,trilobatin?9?,3-?2,4,6-trihydroxyphenyl?-1-?4-hydroxyphenyl?-propan-1-one?10?,quercetin-3-O-?3”-O-galloyl?-?-L-rhamnopyranoside?11?,apigenin?12?and quercetin?13?on the basis of spectrum techniques along with comparison with literature data.Compounds 5-11 were first isolated from Pyrus,and compounds 3-12were identified here for the first time in P.ussuriensis.?3?Finally,antioxidant activity of thirteen pure compounds was evaluated by DPPH radical scavenging assay and ROS level determination.Compounds 13(IC₅₀=6.06?g/mL),11(IC₅₀=9.60?g/mL)and 2(IC₅₀=10.20?g/mL)exhibited potent antioxidant activity.In summary,the antioxidant secondary metabolites of the P.ussuriensis pear peels and leaves were studied and 13 phenolic compounds were isolated which showed different degrees of antioxidant activity.Not only finds significant antioxidants,and also provides a theoretical basis for developing new antioxidant medicine and foods to prevent human aging diseases.