Studies On Chemical Principals Of Astragalus Strictus Grah Ex Benth And Bacteriostatic Activity Of Its Extractives In Vitro

Astragalus strictus Grah ex Benth belong to the Leguminosae which extensively distributed in Tibet. It's a dominant species of Locoweed in China.The chemical constitutents'systematical research of Astragalus strictus hasn't ever been seen. The research of chemical constitutents can enrich the materials of Astragalus strictus, provide the basic information about dependablity of species and its chemical constitutents, and supply rationale and experiment gist for exploiture and utilization of Astragalus strictus and even Locoweed. The chemical constituents of Astragalus strictus were pretested systematically by means of tube-test and PC-test. Based on the principles of photochemistry, modern chemical isolation and purification methods, some certain compounds were separated and purified from the extractum. Then, structural identification of them was elucidated by the physicochemical properties and spectral analysis, alkaloids was analyzed systemisticly by thin-layer chromatography (TLC). Finally, their bacteriostatic efficacies were tested in vitro with agar diffusion and tube dilution methods. The results were given as follows:1. Pre-experiment on Chemical Composition of Astragalus strictusThe chemical constitutes were preliminary tested through systematic and special pre-experiment. The results showed that plenty of Phenols, tannins, alkaloids, flavones and its glycosides, saccharides polysaccharides and glycosides, amino acids and opypeptides, saponins, organic acids, sterides and triterpenes, volatile oils existed in Astragalus strictus, anthraquinone and its glycoside, lactone, coumarin and its glycoside, cardiotonic glycoside, cyanophoric glycoside and aliphatic series nitrocompound were not involved in.2. The chemical constituents research of n-butanol fraction and water fractionThe chemical constituents were analyzed by TLC, column chromatography, recrystallization and other separation and purification technology. Five compounds were yielded from the fraction of n-butanol, which were identified as swainsonine N-oxide, l-hydroxyindolizidine, Lentiginosine, Rhamnocitrin-3-O-β-D-galactoside and Kaempferol-4-methylether. Other five compounds were also obtained from the fraction of water. Up to now, two compounds were identified as swainsonine and squalene. In a word, except for swainsonine, other compounds isolated from Astragalus strictus yielded in this protocol, were first reported. In addition, Rhamnocitrin-3-O-β-D-galactoside, Kaempferol-4-methylether and squalene were obtained from the plant of Astragalus Linn for the first time.3. The alkaloids analysis of Astragalus strictus by TLCUsing systematic extraction methods and selection eligible development system, alkaloids extracted by different solvent were analyzed by TLC. The results indicated that the major alkaloids in Astragalus strictus were indolizidine compounds. Furthermore, there were minimum, neutral and maximum polarity indolizidine alkaloids, and the last one holded the first place. There were seven, six, four kinds of alkaloids from the chloroform, EtOAc, n-butanol fractions respectively. And swainsonine was contained in all the fractions compared with the standard preparation.4. Experimental study on antimicrobial effects of extractives from Astragalus strictus in vitroIn order to study the bacteriostatic activity of extractives from Astragalus strictus, agar diffusion and tube dilution method were used to observe its bacteriostatic efficacy in vitro. The results showed four kinds of extractives, extracted by petroleum ether, CHCl3, EtOAc and n-butanol, had different bacteriostatic activity to Staphylococcus aureus, Escherichia coli, Streptococcus agalactia, Salmonella and Pasteurella multocida, and the extractum from n-butanol had a significant inhibition capacity in vitro. Advanced test demonstrated that the major activity components from n-butanol existed in 20% and 40% EtoH fraction, especially in the latter one. As to the 40% EtoH fraction, the MIC to five bacteria of is 6.25mg/mL. The MBC to Escherichia coli, Staphylococcus aureus, Salmonella, Pasteurella multocida and Streptococcus agalactia is 6.25mg/mL, 12.25mg/mL, 12.25mg/mL, 12.25mg/mL and 25.00 mg/mL, respectively. Moreover, swainsonine also had significant bacteriostatic activity to five kinds of bacteria in vitro, the MIC to Streptococcus agalactia is 0.50 mg/mL, to other bacteria is 1.00 mg/mL. Rhamnocitrin-3-O-β-D-galactoside has profound property on inhibiting and killing bacteria in vitro excepted Escherichia coli, the MIC to Staphylococcus aureus is 0.50 mg/mL, to other bacteria is 0.25 mg/mL, and the MBC to Salmonella, Streptococcus agalactia, Pasteurella multocida is1.00mg/mL.