Insect Antibacterial Screening Method And Research On The Antibacterial Activity And Secondary Metabolite From Periplaneta Americana (Blattidae)

In recent years, it has become urgent problems that effective antibacterial andanti-viral substances are sought in the antibacterial activity study of nature productswith the pathogenic bacteria continuous mutation and increasing of drug resistance.The first part of this investigation used several kinds of common insect pests,antibacterial activity was measured in liquid medium by screenning of air pollutionbacteria strains （Bacillus subtilis、 Escherichia coli、 Staphlococcus aureus andpseudomonas aeruginosa） and clinical pathogenic bacteria strains （Methcillin-resistantStaphylococcus aureus、Staphylococcus epidermidis、Acinetobacter baumannii andEnterobacter cloacae）. Liquid plate inoculation method evaluated for the insects crudeextracts and set up the different concentrations antibacterial of dose group. Thisantibacterial results laid the foundation for the subsequent separation.The second part of this investigation used Periplaneta Americana （Blattaria,commonly known as cockroaches）, antibacterial activity of the crude extraction wasmeasured in liquid medium using four kinds of air pollution bacteria and four kinds ofclinical pathogenic bacteria as the tested strains.70%methanol extract of PeriplanetaAmericana has antibacterial activity by screening. Under the guidance of theantibecterial activities, the secondary metabolite of Periplaneta Americana wereanalysed and separated. Column chromatography and thin layer chromatography wereused as the main isolation means, combined with the reversed phase high performanceliquid chromatography （RP-HPLC）. The secondary metabolites from70%methanolextract was studied in searching for the new antibacterial compounds.Three antibacterial compounds were obtained. Two of them inhibited the growthof the Gram-positive bacteria Bacillus subtilis. Both of them have a MIC value of10mg·mL^-1and a MIZ value of φ=6.0mm. There are two compounds were identified as isoflavone derivatives including a new one. The other one was sterol compound. Andall of compounds were separated for the first time from Periplaneta Americana.Based on the medicinal values of secondary metabolites of PeriplanetaAmericana （Blattaria） in antibacterial activity, they were preliminarily explored in thiswork. The result revealed that a new structure of the antibacterial compounds is frominsects. Meanwhile, it provided the basis for entomogical classification and ecology.