Preliminary Studies On The Antimicrobial Mechanism Of Chinese Herbal Medicine Houpu On Saccharomyces Cerevisiae And Candida Albicans

In this study, we used the well-studied model organism budding yeast (Saccharomyces cerevisiae) to study the possible mechanisms for the effect of Chinese medicine on killing pathogenic fungi. We found Chinese medicine Houpu (ethanol-extract of bark of Magnolia officinalis Rehd. Et Wils) can kill Saccharomyces cerevisiae and Candida albicans at the lowest concentration of2.5g/L ethanol-extract in YPD medium among the tested Chinese medicine ethanol-extracts. The general effect trends of these Chinese medicines on yeasts are consistent to the results reported on small experimental animals or mammol/Lal cells. We further tested the changes in Saccharomyces cerevisiae at cellular level with low concentration of Houpu ethanol-extract and honokiol (pure major component in Houpu ethanol-extract) treatment. Our results showed that Houpu can disrupt GFP-Sncl transport and FM4-64dye intake in Saccharomyces cerevisiae, which represents the general exocytosis pathway and endocytosis pathway, respectively. We also found a specific physiological process, autophagy, was impaired in the honokiol treated Saccharomyces cerevisiae. The effects of honokiol on vacuolar and nuclear morphology are shown in both Yeasts. The effects of honokiol on fungi are significantly different from those of transition metal ions on fungi. We postulated that Chinese medicines may kill pathogenic fungi through disrupting protein trafficking and physiological process such as autophagy. The GFP tagged strains in this study can be used for screening Chinese medicines for anti-microorganisms.