Inhibition of sterol 4-demethylation in Candida albicans by 6-amino-2-n-pentylthiobenzothiazole, a novel mechanism of action for an antifungal agent.
The effects of 6-amino-2-n-pentylthiobenzothiazole (APB), a new antifungal agent, on ergosterol biosynthesis in Candida albicans and Saccharomyces cerevisiae were studied, using [14C]acetate incorporation. In C. albicans, the inhibition of growth was accompanied by a marked inhibition of acetate incorporation in 4-desmethylsterols, with a significant portion of the radiolabel being incorporated in 4,4-dimethylsterols, lanosterol, and 4,4-dimethylzymosterol and minor amounts being incorporated in 4-methylsterols and squalene. The data are interpreted as evidence of a block of the ergosterol biosynthesis pathway at the level of 4-demethylation of 4,4-dimethylzymosterol, with partial inhibition of lanosterol 14-dimethylation and squalene epoxidation also being possible. In 6-amino-2-n-pentylthiobenzothiazole-treated S. cerevisiae, a significant amount of the radiolabel was incorporated also in 4-methylsterols, 4-methylzymosterol, and 4-methylfecosterol, indicating that in this microorganism there are different sensitivities of the two 4-demethylations and that the pathway is blocked at the level of 4-demethylation of 4-methylsterols.
D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D004875:Ergosterol / Q000097:blood*; D008745:Methylation / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology*
D000935:Antifungal Agents; D013844:Thiazoles; C078412:6-amino-2-n-pentylthiobenzothiazole; D004875:Ergosterol