Antibacterial Component And Mechanism Of Toddalia Asiatica (LINN)Lam

With the extensive application of antibiotics,bacterial resistance is getting more and more serious,it is very vibrant to find active natural products in Chinese herbal medicine as antimicrobial agents. Not only that the majority of Chinese herbal medicine with Qingrejiedu effect have played the role of the resistance to infection for a long time,but also the bacteria have little resistance to traditional Chinese medicine.Therefore, it is an important significance for screening antibacterial components from Chinese herbal medicine.This paper is composed of four chapters. The chapter one studies the antibacterial activity of the isolated fractions from T. asiatica against Staphylococcus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA) and beta-Lactamase-producing Staphylococcus aureus in vitro.The second chapter establishes a method for determination of chelerythrine in Toddalia asiatica (Linn) Lam. by HPLC. The third chapter expounds the mechanism of chelerythrine by studying the changing of alkaline phosphatase, the extracellular protein content, sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE), scanning electron microscope(SEM) and transmission electron microscope(TEM). The fourth chapter summarizes the advance in studies on pharmacological activities of chelerythrine.Chapter I the Antibacterial activity of the isolated fractions from T. asiatica in vitroDisc diffusion methods were employed to determine the IZ, MIC and MBC of the isolated fractions from T. asiatica against the tested bacteria. The IC50were measured by liquid culture methods. The results indicated that petroleum ether extracts and ethyl acetate extracts of the roots extracts of T. asiatica all had certain suppression to SA and MRSA, but had no activity to beta-Lactamase-producing Staphylococcus aureus.Chapter II Determination of chelerythrine in Toddalia asiatica by HPLCThe chapter measured the content of chelerythrine in T. asiatica by HPLC and carried out the method validation study. The results showed that the ethyl acetate fractions of the roots of T. asiatica had the highest chelerythrine content (1.97mg/g) and the petroleum ether fractions of T. asiatica were the lowest that were only0.04mg/g.Chapter III The mechanism of Chelerythrine isolated from Toddalia asiatica(Linn) Lam. Disc diffusion methods were employed to determine the IZ, MIC and MBC to the tested bacteria. The IC50were measured by liquid culture methods. The results showed chelerythrine had strong antibacterial activity against SA, MRSA and beta-Lactamase-producing Staphylococcus aureus.The mechanism of chelerythrine against SA,MRSA and beta-Lactamase-producing Staphylococcus aureus were investigated to detect the changing of alkaline phosphatase, conductivity, the extracellular protein content, SDS-PAGE,SEM and TEM.Results suggested that the chelerythrine might partially destroy the structures of bacterial cell walls and cell membranes,bringing about increased permeability and leaking contents to the outside of the cell.Meanwhile it also had some impact on the synthesis and expression of bacterial protein,so that the protein was fewer and fewer, eventually, the bacterial cells were damaged and even death.Chapter IV Advance on pharmacological activities of chelerythrineThe progress of pharmaceutical research of chelerythrine were summarized.