Objective To determine the susceptibility of yeasts and to explore the
antifungal m echanismof
Lisea cubeba oil,so as to provide evidence for the development of antifungal medicinal herbs.Methods The minimuminhibitory concentrations(MIC)of Lisea cubeba oil and fluconazole were determined by broth microdilution method according to the National Com mittee on Clinical Laboratory Standards(NCCLS)reference method for broth dilution antifungal susceptibility testing of yeasts.Ultra-structur al
changes of C.
krusei were observed by electron microscopy before and after Lisea
Cubeba oil treatment.Results Five previously identified quality control(QC)strains(Candida albicans,Candida tropical is,Candida glabrata,Candida parapsilosis,Candida krusei)were susceptible to Lisea cubeba oil,their MICs were 14.14±3.64μg /mL,23.22±2.85μg /mL,31.24±2.88μg /mL,76.19±4.40μg /mL,28.30±2.54μg /mL,respectively.After treatmen t with Lisea cubeba oil the mor-phology and ultrastructure of Candida krusei showed obvious changes:their cell wall and cytoplasmic membrane ruptured;intracellar components dissolved;organellae swollen and di ssolved.There were no changes observed in the morphology and ultrastructure of C.krusei treated with fluconazole.Conclusions The data indicate that Lisea cubeba oil has antifungal effect not only on C.albican and other medically important Candida spp.,but also on fluconazole resistant isolates such as C.krusei and thus has great clinical importan ce.The antifungal mechanismof Lisea cubeba oil may be that the structure of cell w all and cell membrane of C.krusei being inhibited.