| Myrica rubra Sieb.ei Zucc belongs to the branch of Myrica, genus of Myrica. It is widely distributed in China. The root, stem,fruit of myrica nana Ceval has not only been used to cure enteritis, hemostasia, arthralgia, but also be used to cure scald, carbuncle and bellyache etc. The friut of Myrica rubra Sieb.et Zucc contains high content of phenolic compound, which has an important bioactive activity.In order to probe into the bioactive activity of the fruit, this paper focused on the ethanol extract from myrica rubra fruit and its antimicrobial properties,as well as the antimicrobial mechanism.The optimum extracting condition of phenolic from Myrica rubra flesh were stud- ied in this article. Under continuously refluxing treatment, ethanol was used to soak the myrica rubra flesh and distill the phenolic.The result showed that the optimal extraction condition is 5:2 of ethanol to douse the flesh 24h, keep the temperature of 50℃,The extraction rate was 10.34%. Different methods ,such as Agar diffusion assay ,turbidimetric assay and inhibition curves were used to investigate the antimicrobial activity, The results indicated that the ethanol extraction showed significant antimicrobial activity on Staphylococcus aureus,Salmonella typhi ,Streptococcus haemolyc, Shigella dysenteriae ,especially to Staphylococus aureus and Streptococcus haemolyc. But it was not effective to Escherichia coli and A. niger.The minimum inhibition concentration (MIC) was 1.29×10-2 g/mL for Staphylococcus aureus, 5.17×10-2 g/mL for Shigella dysenteriae,5.17×10-2g/mL for Salmonella typhi, 2.59×10-2g/mL for Streptococcus haemolyc, respectively.The influence of several factors was investigated, including temperature, pH , time ,sugar and salt ,enzyme and decoloration. The results indicated that the extraction has a very good temperature stability and it could be effective from pH 5～9. Added with salt or sugar at the same time ,the inhibitory rate was higher. The pretreatment of protease and decolorization with active carbon showed unconspicuous effect.The antimicrobial activity in artificial intestinal juice dramatically differed from in culture medium. The membrane fatty acid of G +( Staphylococcus aureus) was also been effected by GC-MS.By SEM/TEM, the ethanol extraction could destroy the cell integrity and stabilization of Staphylococcus aureus.
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