The Chemical Constitutents Research Of Astragalus Variabilis Bunge

Astragalus variabilis Bunge is a kind of poisonous weed vegetating in the pasture land. In my country, it is distributed in Mongolia, Sinkiang, Gansu, Qinghai, Ningxia and so on. Astragalus variabilis Bunge has covered 2.66 million hm2 in all 14 countys(including Jilantai county) in Alasanzuoqi of Mongolia municipality, which has caused 0.2 million head of cattle to dead and leaded to the economic loss of excessive 3 million yuan since 1995. In 2004, Tukemu, Wuliji and Yenensansumu village in the north of Alasanzuoqi was invaded by Astragalus variabilis Bunge spreading 17.85 thousand hm2. As the result, 68 thousand dead of livestock poisoned and even 1.18 thousand died of it, which 1.04 million yuan was lossed. In addition, the poisonous weed acreage reached to 0.3 million hm2 on the whole Alasanzuoqi. It was found that the grassland at Mingqin county in Gansu province almost was covered with Astragalus variabilis Bunge during my investigation at July in 2003. Local herdsman Lu feed 500 head of goats, but 100 of them poisoned and all the poisoning goats died. The mortality is 100%. The chemical constitutents research of Astragalus variabilis Bunge has ever been seen. Through the experiments reaserching chemical constitutents, we can enrich the materials of Astragalus variabilis Bunge, provide the information about realitivity of species and its chemical constitutents, and the poisonous constitutens resesrch. so, the sample was collected and then the poisonous, the chemical constitutes were researched. We got the following results after carrying on the carefully experiments. 1. Pre-experiment on Chemical Composition of Astragalus variabills Bunge The chemical constitutes was preliminary tested though systematic and special pre-experiment. The results indicate that it contains saccharide polysaccharides,glycosides, amino acid, saponins, alkaloids, cardiac glycoside, lipin, flavonoids, steroids, terpenoids, cyanogenetic glycoside, no volatile oils, lactone, coumarin, anthraquinones, nitro compound. 2. GC-MS analysis of chemical constituents of Astragalus variabilis Bunge extracted by petroleum ether The chemical component of Astragalus variabilis Bunge from petroleum ether have been studied by means of the GC-MS. The ion current figure shows 23 peak and 14 of them have been identified. The constitutions include organ acid, ester, ketone, alcohol et al. The compound 9, 12-Octadecadienoic acid (z, z) has highest comparative content, amounting to 79.139%. 3. Extractum preparation of Astragalus variabilis Bunge and its analyse by TLC The air-dried powered whole weed of Astragalus variabilis Bunge were extracted with industrial alcohol. The solvent was removed by rotary evaporation, yielding 422.5g of extract. The extractum was partitioned with petroleum ether, CHCl₃, EtOAc and nBuOH, successively. The respective soluble fractions have 131.4g,16.4g,17.5g and 206.9g. The result indicate that the chemical constituents mainly concentrate on fraction of petroleum ether and nBuOH. TLC analyse show: the fraction of petroleum ether developed with petroleum ether-acetone(8:2) can isolate 8 compounds with ideal effect, so the system consisting of petroleum ether and acetone was elected as the developing system on silica gel column. The fraction of CHCl3 developed with CHCl3-EtOAc(7:3) also can isolate 8 compounds in good condition, so the system consisting of CHCL3 and EtOAc was elected as the developing system on silica gel column. The fraction of EtOAc developed with CHCl3-EtOH-Et2CO(8:2:0.5) and CHCl3-EtOH-H2O(6.5:4.2:1) respectively can get same result isolating 6 compounds. The fraction of nBuOH developed with CHCl3-EtOH-H2O(6.5:4.2:1) can get 6 isolated compounds. Observing the TLC, we come to conclude preliminary that the fraction of nBuOH obtain much flavonoids. 4. The analyse of chemical constituents on fractions The analyse of chemical constituents on fractions were conducted with chromatograph on silica gel column. Five compounds were yielded from the fraction of petroleum ether. Them were identified by IR,MS,m.p as 1-Docosanethiol, Octacosanol, Gamma-sitosterol, β-carotene, Hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester. The fraction of nBuOH was isolated by the chromatograph on associating silica gel with polyamide column. Three compounds were yielded, which were identified by IR,MS, 13CNMR,1HCNMR, m.p as Swainsonine, Narcissin and Rutin. We yielded 8 compounds in the experiment. Except Swainsonine, the others were isolated from Astragalus variabilis Bunge for the first time. In addition, 1-Docosanethiol, Octacosanol, 2-hydroxy-1-(hydroxymethyl)ethyl ester and Narcissin were obtained from the plant of Astragalus Linn. for the first time. We also isolated poisonous constituent-Swainsonine through the systematic analyse of chemical constituent.