title: Sterols of ketoconazole-inhibited Leishmania mexicana mexicana promastigotes.
abstract: 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.
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D002849:Chromatography, Gas; D003577:Cytochrome P-450 Enzyme System / Q000494:pharmacology; D007654:Ketoconazole / Q000494:pharmacology*; D007810:Lanosterol / Q000378:metabolism; D007891:Leishmania / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008798:Mevalonic Acid / Q000378:metabolism; D013261:Sterols / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D013261:Sterols; D007810:Lanosterol; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D007654:Ketoconazole; D008798:Mevalonic Acid