Antifungal action of Carica papaya latex: isolation of fungal cell wall hydrolysing enzymes.

Carica papaya latex inhibits the growth of Candida albicans. Latex proteins appear to be responsible for this antifungal effect. The minimum protein concentration for producing a complete inhibition was estimated to be about 138 micrograms ml-1. Exploration of different glycosidic activities shows that only alpha-D-mannosidase and N-acetyl-beta-D-glucosaminidase were present in latex in important levels and they were partially purified. The two enzymes show a limited inhibitory effect on yeast growth, alpha-D-mannosidase being more efficient than N-acetyl-beta-D-glucosaminidase. A mixture of the two enzymes showed a synergistic action on the inhibition of the yeast growth. Scanning and transmission electron microscopy observations showed a lack of polysaccharidic content on outermost layers of yeast cell walls when alpha-D-mannosidase was added to the culture medium. When C. albicans was cultured in medium supplemented with N-acetyl-beta-D-glucosaminidase a lack of polysaccharides was noted not only in the outermost layers of fungal cell wall but also in the inner layers. The potential utilization of latex glycosidases in combination with antifungals such as polyenes and azoles involving the formation of protoplasts is discussed.