Study On The Constituents Of Swertia Yunnanensis

The plant Swertia yunnanensis Burk.belongs to Swertia genera of Gentianaceae family, It has the effect of febrifuge and dehumidification.The xanthones,flavaoids,iridoids and triterpenoids,which are rich in Swertia genera,are reported to possess antioxygented activity, cardiovascular and cerebrovascular protection,lowing blood sugar and liver protection activities.In China,there is a rich resource of Swertia yunnanens Burk.,but the studies on chemistry and pharmacology about this plant are seldom reported.For the purpose of making full use of the medicinal plant,this study focuses on the constituents of Swertia genera.The constituents of the methanol extracts from this plant are systematically investigated. Thirteen compounds are obtained by means of solvent partition and various kinds of column chromatography including silica gel,polymeric adsorbents,Sephadex LH-20,C-18 and so on. On the basis of MS,1D and 2D-NMR and physical properties,their structures are elucidated respectively as Oleanolic acid(Ⅰ),Bellidifolin(Ⅱ),β-Sitosterol(Ⅲ),Stigmasterol(Ⅳ), Demethylbellidifolin(Ⅴ),Gentisin(Ⅵ),Deacetylcentapicrin(Ⅶ),Swertianolin(Ⅷ),1,3, 5,8-tetrahydroxyl-5,6,7,8-tetrahydroxanthone(Ⅸ),Vittadinoside(Ⅹ),Decussatin(Ⅺ), 9-deoxy-9-(1,3,5,8-tetrahydroxyxanthone-7-yl)-gentiolactone(Ⅻ) and Mangiferin(ⅩⅢ). CompoundsⅠ～ⅩⅢare all firstly isolated from this plant while compoundⅨandⅫare new compounds.DPPH free radical method is used to evaluate the antioxidant activity of compoundⅡ,Ⅴ～ⅩⅢ,with Trolox a standard reference.The results show that compoundsⅡ,Ⅴ,Ⅺ,ⅫandⅩⅢhave different levels of antioxygented activity.Furthermore,compoundⅫis more active than Trolox.Some of the isolated compounds are screened for their effects on rabbit blood platelet aggregation induced by ADP in vitro.The test results show that compoundⅡ,Ⅸcan decrease platelet aggregation rate at a low concentration,and stimulate platelet aggregation at a high concentration,while compoundⅫ,on the contrary,can stimulate platelet aggregation rate with a low concentration,and decrease platelet aggregation with a high concentration.It can be deduced that the mechanisms of these effects are complicated and a further research is still needed.