Trösken Eva R, Adamska Magdalena, Arand Michael, Zarn Jürg A, Patten Christopher, Völkel Wolfgang, Lutz Werner K
Department of Toxicology, University of Würzburg, Versbacher Str 9, Würzburg, Germany.
Toxicology. 2006 Nov 10;228(1):24-32. doi: 10.1016/j.tox.2006.08.007. Epub 2006 Aug 12.
Inhibition of fungal lanosterol-14 alpha-demethylase (CYP51) is the working principle of the antifungal activity of azoles used in agriculture and medicine. Inhibition of human CYP51 may result in endocrine disruption since follicular fluid-meiosis activating steroid (FF-MAS), the direct product of lanosterol demethylation, is involved in the control of meiosis. To investigate the specificity of antifungal agents for the fungal enzyme, assays to determine inhibitory potencies of 13 agricultural fungicides and 6 antimycotic drugs were established. FF-MAS product formation was measured by LC-MS/MS analysis in the incubations using lanosterol as substrate. Recombinant human enzyme (hCYP51) was available from BD Gentest. CYP51 of Candida albicans (cCYP51) was co-expressed with Candida tropicalis oxidoreductase in the baculovirus system. IC(50) values of 13 fungicides for cCYP51 ranged about six-fold (0.059-0.35 microM); for hCYP51 the range was about 30-fold (1.3-37.2 microM). The most favourable IC(50) ratio human to Candida was observed for imazalil (440-fold), while the specificity of epoxiconazole and tebuconazole for cCYP51 was only by a factor of 10. For the antimycotic drugs, the range of IC(50) values for cCYP51 was similar to those of fungicides (0.039-0.30 microM). For the inhibition of hCYP51, IC(50) values split into two classes: the newer drugs fluconazole and itraconazole showed little inhibition (> or = 30 microM) while the older drugs were even more potent than the agricultural fungicides, with miconazole being the most potent (0.057 microM). No correlation was seen between the IC(50) values determined for the two enzymes, indicating that a housekeeping gene can show significant diversity if inhibition is concerned. Our data indicate that fungicide residues in food are unlikely to exert a relevant inhibition of CYP51 in humans whereas systemic use of some antimycotic drugs, e.g. ketoconazole or miconazole, should be carefully considered regarding disturbance of human steroid biosynthesis.
抑制真菌羊毛甾醇-14α-脱甲基酶（CYP51）是农业和医学中使用的唑类抗真菌活性的作用原理。抑制人CYP51可能导致内分泌紊乱，因为羊毛甾醇去甲基化的直接产物卵泡液减数分裂激活类固醇（FF-MAS）参与减数分裂的控制。为了研究抗真菌剂对真菌酶的特异性，建立了测定13种农用杀菌剂和6种抗真菌药物抑制效力的试验。在以羊毛甾醇为底物的孵育中，通过LC-MS/MS分析测定FF-MAS产物的形成。重组人酶（hCYP51）购自BD Gentest。白色念珠菌的CYP51（cCYP51）与热带念珠菌氧化还原酶在杆状病毒系统中共表达。13种杀菌剂对cCYP51的IC50值范围约为6倍（0.059 - 0.35 microM）；对hCYP51而言，范围约为30倍（1.3 - 37.2 microM）。抑霉唑观察到最有利的人与念珠菌的IC50比值（440倍），而环氧唑和戊唑醇对cCYP51的特异性仅为10倍。对于抗真菌药物，cCYP51的IC50值范围与杀菌剂相似（0.039 - 0.30 microM）。对于hCYP51的抑制，IC50值分为两类：新型药物氟康唑和伊曲康唑显示出几乎没有抑制作用（≥30 microM），而较老的药物甚至比农用杀菌剂更有效，咪康唑最有效（0.057 microM）。两种酶的IC50值之间未发现相关性，表明如果涉及抑制作用，管家基因可能表现出显著的多样性。我们的数据表明，食品中的杀菌剂残留不太可能对人体中的CYP51产生相关抑制作用，而对于某些抗真菌药物的全身使用，例如酮康唑或咪康唑，在考虑对人体类固醇生物合成的干扰时应谨慎。
