Antifungal activity of a new benzothiazole derivative against Candida in vitro and in vivo

The antifungal activity of 6-amino-2-n-pentylthiobenzothiazole (APB) against 26 strains of the genus Candida in vitro was studied. Susceptibility of 17 strains was IC₅₀ ≤ 40 μmol/ml, of 7 strains IC₅₀ = 40−80 μmol/ml and of 2 strains IC₅₀ = 80−200 μmol/ml. Generalized candidosis of mice was treated with APB (doses 50, 100, 250 mg/kg) and ketoconazole (KET, 50 mg/kg of body weight). The optimal dose of APB was shown to be 100 mg/kg; 25% of mice survived after 14 days as compared to control animals. C. albicans was not found in the kidney of the sacrificed mice. 80% of mice survived after KET therapy. However, C. albicans was present in the kidney in an amount of 10⁵−10⁶ CFU/g of tissue. C. albicans did not reappear in the kidney 7 days after the discontinuation of APB treatment, but it was found there after KET therapy.