Studies On Antifungal Agents Targeting On Cell Wall

Fungal cell wall is regarded as an ideal target for antifungal agents. Due to the fact that FKS1-deleted yeast strains are highly sensitive to antifungal agents targeting on glucan synthase, we disrupted FKS1 gene in Saccharomyces cerevisiae whu2a using PCR-mediated one-step gene knockout method, the resultedΔfks1 strain was used to screen glucan synthase inhibitor. Using the same method, CHT020 construced by disrupting CHS1 and CHS3 genes in Saccharomyces cerevisiae whu2a was used to screen inhibitor of chitin synthaseⅡ. And Saccharomyces cerevisiae CHT003 construced by disrupting CHS1 and CHS2 genes was used to screen antifungal agents targeting on chitin synthaseⅢ. The feasibility of these three strains as antifungal agents-screening pattern was proved through a series of specific analysis.The inhibition mechanism of ethanol extract of Coptis chinensis Franch has been studied using these yeast strains as screening models. Calcofluor White (CFW) can inhibit the growth of yeast cells at a certain concentration, but chitin synthase inhibitor can rescue the growth of yeast. Our result showed the ethanol extract of Coptis chinensis Franch functioned as chitin synthase inhibitor, which rescued the growth of yeast. We found that the sensitivity of Saccharomyces cerevisiae CHT003 was four-folds higher to the ethanol extract of Coptis chinensis Franch than the wild-type strain, as for Saccharomyces cerevisiae CHT020, it was two-folds more sensitive than the wild-type strain. The chitin content was also examined, it obviously decreased when treated with the ethanol extract of Coptis chinensis Franch. These results showed that the ethanol extract of Coptis chinensis Franch may contain certain ingredients to inhibit the function of fungal chitin synthase.