Goad L J, Holz G G, Beach D H
Mol Biochem Parasitol. 1985 Jun;15(3):257-79. doi: 10.1016/0166-6851(85)90089-1.
Leishmania mexicana mexicana promastigotes grown with cholesterol, supplied in natural products as the free sterol and as cholesteryl esters, were exposed to [2-14C]mevalonate and to the antimycotic drug ketoconazole. Growth was inhibited and cholesterol and 14 alpha-methyl sterols accumulated in free and esterified forms (cholesterol much greater than 4 alpha,14 alpha-dimethylcholesta-8,24-dien-3 beta-ol much greater than 14 alpha-methylcholesta-8,24-dien-3 beta-ol congruent to 14 alpha-methylergosta-8,24(28)-dien-3 beta-ol much greater than 4 alpha,14 alpha-dimethylergosta-8,24(28)-dien-3 beta-ol; identified by capillary gas chromatography/mass spectrometry, and by 1H and 13C nuclear magnetic resonance spectrometry). The 14 alpha-methyl sterols were preferentially labelled with 14C. The cholesterol was unlabelled and substituted for a substantial fraction of the major product of sterol biosynthesis, ergosta-5,7, 24(28)-trien-3 beta-ol (5-dehydroepisterol), but did not replace it and did not offer remarkable protection against either growth inhibition or alteration of sterol biosynthesis. Promastigotes grown with [6-2H]cholesterol or [4-14C]cholesterol did not contain labelled forms of Leishmania sterols, or other sterols. The chromatographic and spectrometric sterol analyses and the isotopic tracer findings suggested that ketoconazole impaired the cytochrome P-450 dependent 14 alpha-demethylation of lanosterol, that cholesterol was neither biosynthesized nor metabolized, and that the physiological functions of 5-dehydroepisterol had sterol structural requirements not entirely met by cholesterol. In all these studies, L. mexicana mexicana demonstrated a sterol biochemistry remarkably similar to that of fungi. This recommends an increase in interest in antimycotic drugs as chemotherapeutic agents for leishmanial infections.
用天然产物中提供的游离甾醇和胆固醇酯形式的胆固醇培养的墨西哥利什曼原虫前鞭毛体，暴露于[2-¹⁴C]甲羟戊酸和抗真菌药物酮康唑中。生长受到抑制，胆固醇和14α-甲基甾醇以游离和酯化形式积累（胆固醇远大于4α,14α-二甲基胆甾-8,24-二烯-3β-醇远大于14α-甲基胆甾-8,24-二烯-3β-醇等同于14α-甲基麦角甾-8,24(28)-二烯-3β-醇远大于4α,14α-二甲基麦角甾-8,24(28)-二烯-3β-醇；通过毛细管气相色谱/质谱以及¹H和¹³C核磁共振光谱鉴定）。14α-甲基甾醇优先被¹⁴C标记。胆固醇未被标记，并替代了甾醇生物合成的主要产物麦角甾-5,7,24(28)-三烯-3β-醇（5-脱氢表甾醇）的很大一部分，但没有完全取代它，也没有对生长抑制或甾醇生物合成的改变提供显著保护。用[6-²H]胆固醇或[4-¹⁴C]胆固醇培养的前鞭毛体不含利什曼原虫甾醇或其他甾醇的标记形式。色谱和光谱甾醇分析以及同位素示踪结果表明，酮康唑损害了细胞色素P-450依赖性羊毛甾醇的14α-去甲基化，胆固醇既不进行生物合成也不进行代谢，并且5-脱氢表甾醇的生理功能具有胆固醇不能完全满足的甾醇结构要求。在所有这些研究中，墨西哥利什曼原虫表现出与真菌非常相似的甾醇生物化学。这建议增加对抗真菌药物作为治疗利什曼原虫感染的化疗药物的关注。
