Whalen Kristen E, Poulson-Ellestad Kelsey L, Deering Robert W, Rowley David C, Mincer Tracy J
‡College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States.
J Nat Prod. 2015 Mar 27;78(3):402-12. doi: 10.1021/np500775e. Epub 2015 Feb 3.
Members of the resistance nodulation cell division (RND) of efflux pumps play essential roles in multidrug resistance (MDR) in Gram-negative bacteria. Here, we describe the search for new small molecules from marine microbial extracts to block efflux and thus restore antibiotic susceptibility in MDR bacterial strains. We report the isolation of 3,4-dibromopyrrole-2,5-dione (1), an inhibitor of RND transporters, from Enterobacteriaceae and Pseudomonas aeruginosa, from the marine bacterium Pseudoalteromonas piscicida. 3,4-Dibromopyrrole-2,5-dione decreased the minimum inhibitory concentrations (MICs) of two fluoroquinolones, an aminoglycoside, a macrolide, a beta-lactam, tetracycline, and chloramphenicol between 2- and 16-fold in strains overexpressing three archetype RND transporters (AcrAB-TolC, MexAB-OprM, and MexXY-OprM). 3,4-Dibromopyrrole-2,5-dione also increased the intracellular accumulation of Hoechst 33342 in wild-type but not in transporter-deficient strains and prevented H33342 efflux (IC50 = 0.79 μg/mL or 3 μM), a hallmark of efflux pump inhibitor (EPI) functionality. A metabolomic survey of 36 Pseudoalteromonas isolates mapped the presence of primarily brominated metabolites only within the P. piscicida phylogenetic clade, where a majority of antibiotic activity was also observed, suggesting a link between halogenation and enhanced secondary metabolite biosynthetic potential. In sum, 3,4-dibromopyrrole-2,5-dione is a potent EPI and deserves further attention as an adjuvant to enhance the effectiveness of existing antibiotics.
外排泵的耐药结节化细胞分裂（RND）家族成员在革兰氏阴性菌的多药耐药性（MDR）中起着至关重要的作用。在此，我们描述了从海洋微生物提取物中寻找新的小分子以阻断外排，从而恢复多重耐药细菌菌株对抗生素的敏感性。我们报告了从海洋细菌杀鱼假交替单胞菌中分离出3,4 - 二溴吡咯 - 2,5 - 二酮（1），它是一种RND转运蛋白抑制剂。在过表达三种典型RND转运蛋白（AcrAB - TolC、MexAB - OprM和MexXY - OprM）的菌株中，3,4 - 二溴吡咯 - 2,5 - 二酮使两种氟喹诺酮类、一种氨基糖苷类、一种大环内酯类、一种β - 内酰胺类、四环素和氯霉素的最低抑菌浓度（MIC）降低了2至16倍。3,4 - 二溴吡咯 - 2,5 - 二酮还增加了野生型菌株中Hoechst 33342的细胞内积累，但在转运蛋白缺陷型菌株中未增加，并阻止了H33342的外排（IC50 = 0.79 μg/mL或3 μM），这是外排泵抑制剂（EPI）功能的一个标志。对36株假交替单胞菌分离株的代谢组学调查表明，主要溴化代谢物仅存在于杀鱼假交替单胞菌的系统发育分支内，在该分支中也观察到了大部分抗生素活性，这表明卤化与增强的次级代谢物生物合成潜力之间存在联系。总之，3,4 - 二溴吡咯 - 2,5 - 二酮是一种有效的EPI，作为增强现有抗生素有效性的佐剂值得进一步关注。
