Candicidin, A New Antifungal Antibiotic

Abstract

SUMMARY A group of 197 cultures of actinomycetes were tested for their antibiotic activity against Cerastostomella ulmi. This screening program yielded a strain of Streptomyces griseus which produced an antibiotic substance that was very active against yeasts, yeast-like fungi, and C. ulmi; it was not very active against filamentous fungi and had no activity against the bacteria tested. The new antibiotic was different from the known antifungal agents actidione, antimycin A, fradicin, fungicidin, rimocidin and actinone. Because of its marked fungistatic and fungicidal action against Candida albicans, the new antibiotic was designated as candicidin. A crude extract of candicidin could be obtained from liquid culture media, by adsorption on Hyflo-supercel and elution with n-butanol. Crude candicidin could be further fractionated, by solvent extraction and chromatography on cellulose powder, into two very active fractions (A, B) and an almost inactive fraction C. Crude candicidin was fungicidal against growing and resting cells of Candida albicans in the concentration of 1 to 5 mcg/ml. It had no injurious effect upon the germination of pea seeds in concentration of 125 mcg/ml. Spraying young bean plants once a week with an aqueous suspension of crude candicidin (660 mcg/ml) resulted in a decrease of a mildew infection.