Liendo A, Lazardi K, Urbina J A
Seccion de Parasitología, Instituto de Zoología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Caracas.
J Antimicrob Chemother. 1998 Feb;41(2):197-205. doi: 10.1093/jac/41.2.197.
We investigated the in-vitro antiproliferative effects and mechanism of action of both enantiomers of the bis-triazole derivative ICI 195,739 against epimastigotes and amastigotes of Trypanosoma cruzi, the aetiological agent of Chagas' disease. It has recently been shown that the R(+) enantiomer, D0870, can induce radical parasitological cure in murine models of the acute and chronic forms of the disease. D0870 dose-dependently affected the growth rate of the epimastigote form (IC50 = 0.1 microM; MIC = 1-3 microM). The S(-) enantiomer was much less active (IC50 = 3 microM). Growth arrest and cell lysis induced by D0870 coincided with the complete depletion of endogenous 4,14-desmethyl sterols and their replacement by 4,14-trimethyl and dimethyl sterols. The S(-) enantiomer produced qualitatively similar changes but to a lesser extent. D0870 inhibited the incorporation of radioactivity from [2-14C]acetate into the epimastigote's 4,14-desmethyl sterols with an IC50 of 50 nM while the corresponding concentration for the S(-) enantiomer was 3 microM. D0870 eradicated the intracellular (amastigote) form of the parasite from cultured Vero cells at 10 nM; a 100-fold higher concentration of the S(-) enantiomer was required to produce a similar effect, and deleterious effects of the host cells were observed at > 100 nM. At the MIC of D0870 the endogenous amastigote sterols (ergosta-7-en-3beta-ol, 24-ethyl-cholesta-7-en-3beta-ol and ergosta-7, 24(24[1])-dien-3beta-ol) were also largely replaced by lanosterol and 24-methyl-dihydrolanosterol. Combinations of D0870 and inhibitors of sterol delta24(25) sterol methyltransferase (such as 22,26-azasterol and 24(R,S),25-epiminolanosterol) acted synergically against the intracellular forms. Taken together these results indicate that, although both enantiomers have anti-T. cruzi activity, the specific activity of the R(+) enantiomer (D0870) is nearly two orders of magnitude higher than that of its S(-) analogue. However, as the in-vitro activity of D0870 is comparable to that of standard azoles, such as ketoconazole, its remarkable in-vivo antiparasitic activity may only be explained by its particular pharmacokinetic properties.
我们研究了双三唑衍生物ICI 195,739的两种对映体对恰加斯病病原体克氏锥虫的前鞭毛体和无鞭毛体的体外抗增殖作用及作用机制。最近研究表明，R(+)对映体D0870可在急性和慢性疾病的小鼠模型中诱导寄生虫学上的彻底治愈。D0870剂量依赖性地影响前鞭毛体形式的生长速率（IC50 = 0.1微摩尔；MIC = 1 - 3微摩尔）。S(-)对映体的活性则低得多（IC50 = 3微摩尔）。D0870诱导的生长停滞和细胞裂解与内源性4,14 - 去甲基甾醇的完全耗尽以及它们被4,14 - 三甲基和二甲基甾醇替代同时发生。S(-)对映体产生了定性相似但程度较小的变化。D0870抑制[2 - 14C]乙酸盐的放射性掺入前鞭毛体的4,14 - 去甲基甾醇中，IC50为50纳摩尔，而S(-)对映体的相应浓度为3微摩尔。D0870在10纳摩尔时可从培养的Vero细胞中根除寄生虫的细胞内（无鞭毛体）形式；S(-)对映体需要高100倍的浓度才能产生类似效果，并且在>100纳摩尔时观察到对宿主细胞的有害作用。在D0870的MIC下，内源性无鞭毛体甾醇（麦角甾 -7-烯 -3β -醇、24 - 乙基 - 胆甾 -7-烯 -3β -醇和麦角甾 -7,24(24[1]) - 二烯 -o3β -醇）也很大程度上被羊毛甾醇和24 - 甲基 - 二氢羊毛甾醇替代。D0870与甾醇δ24(25)甾醇甲基转移酶抑制剂（如22,26 - 氮杂甾醇和24(R,S),25 -环氧氨基羊毛甾醇）联合使用对细胞内形式具有协同作用。综上所述，这些结果表明，尽管两种对映体都具有抗克氏锥虫活性，但R(+)对映体（D0870）的比活性比其S(-)类似物高近两个数量级。然而，由于D0870的体外活性与标准唑类（如酮康唑）相当，其显著的体内抗寄生虫活性可能仅由其特殊的药代动力学性质来解释。
