Mycoversilin, a new antifungal antibiotic. III. Mechanism of action on a filamentous fungus Trichophyton rubrum.

Mycoversilin is active against filamentous fungi, being specifically inhibitory to Trichophyton rubrum, minimum inhibitory concentration being 15 micrograms/ml. Mycoversilin inhibits sporulation to the extent of 28.5% even at the growth inhibitory concentration whereas inhibition of spore germination requires higher concentration. It has no effect on radial growth. Further it shows no action either on the release of UV absorbing materials or on the respiration of T. rubrum. However, the antibiotic inhibits in vivo synthesis of protein fairly strongly, DNA moderately and RNA slightly at the minimum inhibitory concentration. Cell-free protein synthesis is also strongly inhibited, the site of action being the inhibition of leucyl-tRNA formation by the antibiotic which has no action on leucine activation.