Studies On Antibacterial Activities Of Three Medicinal Plants

In this thesis, the antibacterial activities of three medicinal plants(the root ofZingiber striolatum Diels, the cone of Platycladus orientalis Franco and the fruit ofSambucus Chinensls Lind1.)were preliminarly investigated. Fourteen compounds havebeen isolated from the root of Zingiber striolatum Diels and the cones of Platycladusorientalis Franco by means of various separating materials and techniques, such assilica gel column chromatography, thin layer chromatography, reverse phasechromatography, Sephadex LH-20, macroporous resin, et al. The structures of these sixcompounds were identified by the modern spectroscopic methods.Polysaccharidessfrom the fruits of Sambucus Chinensls Lind1. were extracted by method of waterextraction and alcohol precipitation, then the content of it was determinated byspectrophotometry. Disc diffusion method was applied to determine the antibacterialactivity against staphylococcus aureus, Bacillus licheniformis, Escherichia coli,Klebsiella pneumoniae and Pseudomonas aeruginosa.The minimum inhibitoryconcentrations (MIC) and the minimum bactericidal concentration (MBC) of the activeextracts, fractions and the compounds were determined by microdilution method. Themain results were as follows:(1)The study on antibacterial activity constituents from the root of Zingiberstriolatum DielsSeven compounds have been isolated from the root of Zingiber striolatum Dielsaccording to bioassay–guided principal. The structures of two compounds wereidentified as β-sitosterol (compound1) and stearic acid (compound2). The antibacterialactivity was determined by disc diffusion method and microdilution method against fivebacteria. The results showed that the petroleum ether and chloroform extracts displayedsignificant antibacterial activities against all bacteria. The ethyl acetate extract exhibitedweak antibacterial activities against Klebsiella pneumoniae, no bacteriostasis towardsother4bacteria. The n-BuOH and water extracts possessed no antibacterial activity.Finally compounds1and2had no antibacterial activity against five bacteria.(2)The study on antibacterial activity constituents of the cones of Platycladusorientalis FrancoSeven compounds have been isolated from the cone of Platycladus orientalisFranco according to bioassay–guided principal. The structures of four compounds were identified as kaempferol-3-O-α-L-rhamnopyranoside (compound1), luteolin-3'-O-α-L-rhamnopyranoside(compound2), Sandaracopimaric acid (compound3), ent-Labda-8(17),13-dien-15,16-olid-19-oic acid methyl ester (compound4). The antibacterialactivities of these four isolates were determined by disc diffusion method andmicrodilution method against five bacteria. The results showed that the compound3displayed significant antibacterial activities against all bacteria with the MIC was62.5μg/mL for staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae,Pseudomonas aeruginosa. While compounds1,2and6displayed weak antibacterialactivities.(3)The study on content determination and antibacterial activity of polysaccharidesfrom the fruit of Sambucus Chinensls Lind1.Polysaccharides from the fruit of Sambucus Chinensls Lind1. was extracted bymethod of water extraction and alcohol precipitation, then the conent of it wasdetermined by spectrophotometry at582nm. The results showed that the content was3.86%, RSD was3.76%(n=5). In conclusion, it showed high repeatability, the averagerecovery was102.55%and RSD was2.51%(n=3) within four hours. The antibacterialactivity was determined by disc diffusion method. The results showed that it had noantibacterial activity against five bacteria.