The Study On Chemical Composition And Antioxidant Ability Of Essential Oil From Tree Peony Petal

The objective of this study was to explore the health care and medical values of essential oils（EOs）from petals of various tree peonies originated from China,to comprehensively develop the tree peony EO resources,and to further screen and obtain the cultivars which were suitable for EO application.In the present study,supercritical CO₂ method was used to extract the EOs from petals of three wild species and 11 cultivars of tree peonies,and gas chromatography-mass spectrometry（GC-MS）method was used to analyze chemical composition of EOs.Combined with analysis of hierarchical cluster,principle component,and correspondence,the chemical composition of EOs was then deeply assessed.Moreover,the free radical-scavenging capacity of different tree peony petal EOs for DPPH and ABTS was tested.The results are shown as follows:1.The EO extraction of tree peony petals was carried out using supercritical CO₂ method.The results indicated that extraction rates of EOs among various wild species and cultivars of tree peonies were significantly different.The average extraction rate was 0.94%,with the highest one of 1.25% being P.rockii and the lowest one of 0.63% being P.delavayi.A total of 163 components were identified from the composition of EOs,mainly including linalool oxide,（Z）-3-heptadecene,Z-5-dodecen-1-yl acetate,palmitic acid,nonadecane,Z-5-nonadecene,palmitic acid ethyl ester,heneicosane,phytol,linolenic acid methyl ester,linoleic acid ethyl ester,linolenic acid ethyl ester,and etc.The statistics of chemical classification for EO compostion demonstrated that the order of contents of diverse compounds in the majority of tree peony petal EOs was as follows: hydrocarbons and their derivatives> high-level fatty acids and their derivatives>monoterpenoids>diterpenoids>sesquiterpenoids>benzene ring compounds> others.2.163 components of EOs from tree peony petals were investigated through hierarchical cluster,principle component,and correspondence analysis.Three wild species and 11 ornamental cultivars of tree peonies could be classified into four groups,including group one: ‘Bai Xue Ta’,‘Yin Hong Qiao Dui’,‘Er Qiao’,‘Dou Lv’,and ‘Da Zong Zi’;group two: P.rockii,‘Ying Ba Yang Fei’,‘Guan Yin Mian’,and ‘Fen Yin Hui’;group three: ‘Feng Dan’ and ‘Jing Yu’;and group four: ‘Hign Noon’,P.delavayi,and P.lutea.Among the four groups,the petal EOs of group three had sweet fragrance and of group four had fresh herb fragrance.The members of these two groups possessed great potential to be flavours and fragrances.3.The functional ingredients in the EO composition of tree peony petals were further studied,and we found that the EOs of tree peony petals contained abundant nutrient ingredients,such as phytol,linalool,farnesol,beta-eucalyptol,DL-alpha-tocopherol,and etc.These ingredients are medically valuable for anticancer,antiinflammatory,antioxidation,and others.4.Assessment of antioxidant ability of tree peony petal EOs was performed,and the results showed that all the EOs from petals of different wild species and culivars of tree peonies had certain antioxidant activities.The ones with relatively strong antioxidant abilities were P.lutea,P.delavayi,and ‘Da Zong Zi’,which were highly potential to be natural antioxidant substances.Particularly,P.lutea exhibited the strongest free radical-scavenging capacity for DPPH and ABTS,and it was about twice higher than the mean of scavenging capacity of all tree peony petal EOs tested.Based on the experimental results above,we concluded that the EOs of tree peony petals were riched in nutrient and aroma components and possessed great antioxidant activities.In terms of functional component content,furthermore,a significant variation among various wild species and cultivars existed.Our data demonstrated that the EOs from tree peony petals could be valuable as natural antioxidants for pharmacy,and as flavours and fragrances for daily chemicals.