Marichal P, Gorrens J, Coene M C, Le Jeune L, Vanden Bossche H
Division of Medicinal Chemistry and Pharmacology, Janssen Research Foundation, Beerse, Belgium.
Mycoses. 1995 Mar-Apr;38(3-4):111-7. doi: 10.1111/j.1439-0507.1995.tb00032.x.
Two Candida krusei isolates were used to compare the effects of fluconazole, ketoconazole and itraconazole on growth and ergosterol synthesis, and to measure intracellular drug contents. Fifty per cent inhibition (IC50) of growth was achieved at 0.05-0.08 microM itraconazole and 0.56-1.2 microM ketoconazole, whereas 91-->100 microM fluconazole was needed to reach the IC50 value. Similar differences in sensitivity to these azole antifungal agents were seen when their effects on ergosterol synthesis from [14C]acetate were measured after 4 h and 24 h of growth. However, when the effects of the azoles on ergosterol synthesis from [14C]mevalonate by subcellular fractions were measured, fluconazole was only 2.3-6.1 times less active than itraconazole, and the IC50 values for ketoconazole were almost similar to those obtained with itraconazole. These results indicate that differences in susceptibility to itraconazole and ketoconazole are unrelated to differences in affinity for the C. krusei cytochrome P450. The much lower growth-inhibitory effects of fluconazole can also be explained partly only by a lower affinity for the P450-dependent 14 alpha-demethylase. The differences in sensitivity of both C. krusei isolates appeared to arise from differences in the intracellular itraconazole, ketoconazole and fluconazole contents. Depending on the experimental conditions, these isolates accumulated 6-41 times more itraconazole than ketoconazole and the intracellular ketoconazole content was 3.0-19.0 times higher than that of fluconazole.
使用两株克鲁斯假丝酵母菌分离株比较氟康唑、酮康唑和伊曲康唑对生长及麦角甾醇合成的影响，并测定细胞内药物含量。伊曲康唑浓度为0.05 - 0.08微摩尔/升、酮康唑浓度为0.56 - 1.2微摩尔/升时可实现50% 的生长抑制（IC50），而达到IC50值则需要91→100微摩尔/升的氟康唑。在生长4小时和24小时后测量这些唑类抗真菌药对[14C]乙酸盐合成麦角甾醇的影响时，观察到对这些唑类抗真菌药的敏感性存在类似差异。然而，当测量唑类对亚细胞组分由[14C]甲羟戊酸合成麦角甾醇的影响时，氟康唑的活性仅比伊曲康唑低2.3 - 6.1倍，酮康唑的IC50值与伊曲康唑几乎相似。这些结果表明，对伊曲康唑和酮康唑敏感性的差异与对克鲁斯假丝酵母菌细胞色素P450亲和力的差异无关。氟康唑较低的生长抑制作用部分也只能通过对P450依赖性14α-脱甲基酶较低的亲和力来解释。两株克鲁斯假丝酵母菌分离株敏感性的差异似乎源于细胞内伊曲康唑、酮康唑和氟康唑含量的差异。根据实验条件，这些分离株积累的伊曲康唑比酮康唑多6 - 41倍，细胞内酮康唑含量比氟康唑高3.0 - 19.0倍。
