Comparative Studies On Chemical Components And Biological Activities Of Flavonoids And Volatile Oils Of Hawk Tea From Different Botanical Origins

Hawk tea,a medicinal and edible plant,is one of the most popular herbal teas in the southwest of China for thousands of years.The infusion of Hawk tea,yellowish-red with a slight camphor-aromatic smell,has the effects of detoxification and detumescence,improvement of eyesight,antioxidation,reduction of blood sugar and blood lipid.Hawk tea is mainly produced from buds or leaves of Litsea coreana Levl.var.lanuginose.However,many other material plants,for example,Machilus chuanchienensis S.Lee,Actinodaphne cupularis(Hemsl.)Gamble,Machilus rehderi Allen,Litsea pungens Hemsl and Lindera communis Hemsl are also used as the plant source of Hawk tea in Guizhou and Sichuan regions.The use of different varieties leads to a confusion of the botanical origin of Hawk tea,blocking the establishment of uniform quality standards and further product development for Hawk tea.So it is necessary to compare the chemical components and biological activities of six kinds of Haw tea to screen the most suitable botanical origins of Hawk tea,which can lay the foundation for further development of this characteristic resource.1.Comparative analyses of flavonoids compositions and antioxidant activities of Hawk tea from six botanical originsThe aim of this study was to compare the flavonoids compositions,content and antioxidant activities of Hawk tea from six botanical origins for screening the most suitable botanical origins.The main flavonoids of Hawk teas from Litsea coreana Levl.var.lanuginose were identified,and six high contents of individual flavonoids(hyperin,isoquercitrin,quercitrin,astragalin,quercetin and kaempferol)were quantitative and comparative analysis.Moreover the potential antioxidant capacity of Hawk tea was measured by using in vitro antioxidant assays.The above experimental data were all used for the principal component analysis.The statistical results showed that the extracts from Actinodaphne cupularis(Hemsl.)Gamble and Litsea coreana Levl.var.lanuginose appeared closely positioned in the positive regions,indicated the higher flavonoids and antioxidant activity compared with other species.Thus,they were temporarily considered as good sources of Hawk tea.2.Comparative evaluation of the chemical composition,antioxidant and antimicrobial activities of the volatile oils of Hawk tea from six botanical originsIn this study,volatile oils of six Hawk tea varieties were studied for their chemical composition,antioxidant and antimicrobial activities to screen the most suitable botanical origins of Hawk tea.A total of 72 components were separated and identified from the six oils.The major constituents of the volatile oils were: ?-pinene,camphene,limonene,1,8-cineole,linalool,cis-nerolidol,germacrene B.Moreover,the volatile oils were evaluated for antioxidant potential and antimicrobial activities.The results showed that all volatile oils exhibited acceptable antioxidant and antimicrobial activities,which suggested that these volatile oils may serve as natural alternatives to synthetic antioxidants and preservatives to be applied in food and pharmaceutical industries.Principal component analysis results denoted that some major compounds may be closely related to the antioxidant and antimicrobial activities.It also showed that the volatile oils from Litsea coreana Levl.var.lanuginose and Litsea pungens Hemsl were characterized by positive values of first two principal components,indicating higher active chemical compounds and antioxidant and antimicrobial activities compared with other species.Thus,they were temporarily considered as good sources of Hawk tea.