Two series of piperazinyl-pyrrolo[1,2-a]quinoxaline derivatives were prepared via a Buchwald–Hartwig cross-coupling reaction and then evaluated for their ability to inhibit the drug efflux activity of CaCdr1p and CaMdr1p transporters of Candida albicans overexpressed in a Saccharomyces cerevisiae strain. In the initial screening of twenty-nine piperazinyl-pyrrolo[1,2-a]quinoxaline derivatives, twenty-three compounds behaved as dual inhibitors of CaCdr1p and CaMdr1p. Only four compounds showed exclusive inhibition of CaCdr1p or CaMdr1p. Further biological investigations were developed and for example, their antifungal potential was evaluated by measuring the growth of control yeast cells (AD1-8u⁻) and efflux pump-overexpressing cells (AD-CDR1 and AD-MDR1) after exposition to variable concentrations of the tested compounds. The MIC₈₀ values of nineteen compounds ranging from 100 to 901 μM for AD-CDR1 demonstrated that relative resistance index (RI) values were between 8 and 274. In comparison, only seven compounds had RI values superior to 4 in cells overexpressing Mdr1p. These results indicated substrate behavior for nineteen compounds for CaCdr1p and seven compounds for CaMdr1p, as these compounds were transported via MDR transporter overexpressing cells and not by the AD1-8u⁻ cells. Finally, in a combination assay with fluconazole, two compounds (1d and 1f) have shown a synergistic effect (fractional inhibitory concentration index (FICI) values ≤ 0.5) at micromolar concentrations in the AD-MDR1 yeast strain overexpressing CaMdr1p-protein, indicating an excellent potency toward chemosensitization.

中文翻译：

---

Buchwald-Hartwig 交叉偶联反应合成新的哌嗪基-吡咯并[1,2-a]喹喔啉衍生物作为白色念珠菌多药转运蛋白的抑制剂

通过Buchwald-Hartwig 交叉偶联反应制备了两个系列的哌嗪基-吡咯并[1,2- a ]喹喔啉衍生物，然后评估它们抑制在酵母菌中过表达的白色念珠菌的 CaCdr1p 和 CaMdr1p 转运蛋白的药物流出活性的能力酿酒酵母菌株。在29个哌嗪基-吡咯并[1,2- a ]喹喔啉衍生物的初步筛选中，23个化合物表现为CaCdr1p和CaMdr1p的双重抑制剂。只有四种化合物显示出对 CaCdr1p 或 CaMdr1p 的排他性抑制作用。开展了进一步的生物学研究，例如，通过测量对照酵母细胞 (AD1-8u ^-) 和外排泵过表达细胞 (AD-CDR1 和 AD-MDR1) 在暴露于不同浓度的测试化合物后。对 AD-CDR1 的 100 至 901 μM 范围内的 19 种化合物的 MIC ₈₀值表明，相对抗性指数 (RI) 值在 8 至 274 之间。相比之下，在过表达 Mdr1p 的细胞中，只有 7 种化合物的 RI 值优于 4。这些结果表明了 19 种 CaCdr1p 化合物和 7 种 CaMdr1p 化合物的底物行为，因为这些化合物是通过MDR 转运蛋白过表达细胞而不是 AD1-8u ^-细胞转运的。最后，在与氟康唑的联合试验中，两种化合物（1d和1f) 在过表达 CaMdr1p 蛋白的 AD-MDR1 酵母菌株中在微摩尔浓度下显示出协同效应（分数抑制浓度指数 (FICI) 值 ≤ 0.5），表明对化学增敏作用具有极好的效力。