Abstract: Extracts of eight kinds of herb (clove,houttuynia,Polygonum cuspidatum,Coptis chinensis,rhubarb,asarum,licorice and scutellaria) were prepared by cellulase method;and their bacterium inhibition efficacy was studied by disc diffusion method and test tube broth dilution method.Formulation study based upon the bacterium inhibition of the aforesaid preservatives was conducted.With reference of the bacterium inhibition efficacy test method of American Personal Care Product Committee (PCPC),microbial challenge tests for cream formulation was processed.The test results demonstrated that in the eight kinds of herbal extract,the extract of Coptis chinensis shows best efficacy on Staphylococcus aureus,Pseudomonas aeruginosa and Escherichia coli.Its diameter of inhibition zone is (12.4±0.4),(11.4±0.6) and (10.7±0.2) mm respectively,and the minimum inhibitory concentration (MIC) is 31.25,31.25 and 15.625 g/L respectively.When the mass fraction of the extract of Coptis chinensis and scutellaria in cream formula is 0.8% and 0.6% respectively,it can inhibit the growth of bacteria and fungi effectively and pass the microbial challenge test meanwhile.

Key words: cosmetics, herbal extract, bacterium inhibition efficacy, cellulase