Isolation, Purification, Structure Identification, And Bioactivities Of Active Components In Usnea Montis-fuji

Usnea montis-fuji,belonging to the Ascolichens Lecanorales Usneaceae Usnea,contains a variety of active substances,such as lichen polysaccharides,usnic acid,barbatic acid and ethyl haematommate,which have a high medicinal and economic values.In this study,we systematically studied the chemical composition,structure identification,and activity of Usnea montis-fuji.The following are main results.The Usnea montis-fuji were collected from Sichuan province.The methyl 2,4-dihydroxy-3,6-dimethylbenzoate(UAE5)and ethyl haematommate(UAS1)were obtained by ethyl acetate extraction,water extraction at 80°C,and silica gel column chromatography.Then the antioxidant and antibacterial activity tests of the extracts were performed,showed that the UAE5 had higher bioactive.The Usnea polysaccharides were extracted with hot water.DEAE-52-cellulose column chromatography and Sephadex G-100 were adopted to purify the polysaccharides from Usnea montis-fuji.Four polysaccharide fractions(UPL-0.0,UPL-0.1,UPL-0.3,UPL-0.5)were analyzed by high performance anion exchange liquid chromatography(HPAEC),nuclear magnetic resonance(NMR),infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC).The determination of reducing power method were used to analyze antioxidant activity.The results showed that the molecular weight and the monosaccharides of the four polysaccharide fractions were quite different,and all the four polysaccharide fractions had some antioxidant activity.The sugar composition of UPL-0.1 is glucose,mannose,galactose,xylose,and arabinose.The UPL-0.1 mainly consist of(1→3)-(1→4)-α-glucan and galactomannan.The four polysaccharide fractions(UPS15,UPS30,UPS50,UPS70)were obtained by graded precipitation from Usnea polysaccharide at the ethanol concentration of 15%,30%,50%,and 70%,respectively.The differences in the composition,molecular weight,and antioxidant activity of the polysaccharides were explored,as well as the reasons affecting the antioxidant activity were investigated.The results showed that the relative average molecular weight of the four polysaccharides were all above 10~5Da,and the proportion of the monosaccharides was different.The antioxidant activity showed that all the four polysaccharide fractions had antioxidant activity,and were significantly related to the content of mannose and glucose.