Fleeman Renee, Van Horn Kurt S, Barber Megan M, Burda Whittney N, Flanigan David L, Manetsch Roman, Shaw Lindsey N
Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, USA.
Center for Drug Discovery and Innovation, University of South Florida, Tampa, Florida, USA.
Antimicrob Agents Chemother. 2017 May 24;61(6). doi: 10.1128/AAC.00059-17. Print 2017 Jun.
We previously reported a series of ,-disubstituted quinazoline-2,4-diamines as dihydrofolate reductase inhibitors with potent and antibacterial activity against methicillin-resistant (MRSA) strains. In this work, we extended our previous study to the Gram-negative pathogen We determined that optimized ,-disubstituted quinazoline-2,4-diamines are strongly antibacterial against multidrug-resistant strains when the 6-position is replaced with a halide or an alkyl substituent. Such agents display potent antibacterial activity, with MICs as low as 0.5 μM, while proving to be strongly bactericidal. Interestingly, these compounds also possess the potential for antibiofilm activity, eradicating 90% of cells within a biofilm at or near MICs. Using serial passage assays, we observed a limited capacity for the development of resistance toward these molecules (4-fold increase in MIC) compared to existing folic acid synthesis inhibitors, such as trimethoprim (64-fold increase) and sulfamethoxazole (128-fold increase). We also identified limited toxicity toward human cells, with 50% lethal doses (LDs) of ≤23 μM for lead agents 4 and 5. Finally, we demonstrated that our lead agents have excellent efficacy, with lead agent 5 proving more efficacious than tigecycline in a murine model of infection (90% survival versus 66%), despite being used at a lower dose (2 versus 30 mg kg). Together, our results demonstrate that ,-disubstituted quinazoline-2,4-diamines have strong antimicrobial and antibiofilm activities against both Gram-positive organisms and Gram-negative pathogens, suggesting strong potential for their development as antibacterial agents.
我们之前报道了一系列α,β-二取代喹唑啉-2,4-二胺作为二氢叶酸还原酶抑制剂，对耐甲氧西林金黄色葡萄球菌（MRSA）菌株具有强效抗菌活性。在这项工作中，我们将之前的研究扩展至革兰氏阴性病原体。我们确定，当6位被卤化物或烷基取代基取代时，优化后的α,β-二取代喹唑啉-2,4-二胺对多重耐药菌株具有强效抗菌作用。这类药物显示出强效抗菌活性，最低抑菌浓度（MIC）低至0.5 μM，同时被证明具有强效杀菌作用。有趣的是，这些化合物还具有抗生物膜活性的潜力，在MIC或接近MIC时可根除生物膜内90%的细胞。通过连续传代试验，我们观察到与现有的叶酸合成抑制剂（如甲氧苄啶（MIC增加64倍）和磺胺甲恶唑（MIC增加128倍））相比，这些分子产生耐药性的能力有限（MIC增加4倍）。我们还确定了对人类细胞的毒性有限，先导化合物4和5的半数致死剂量（LD50）≤23 μM。最后，我们证明我们的先导化合物具有出色的疗效，在小鼠感染模型中，先导化合物5比替加环素更有效（存活率分别为90%和66%），尽管使用的剂量较低（2 mg/kg对30 mg/kg）。总之，我们的结果表明，α,β-二取代喹唑啉-2,4-二胺对革兰氏阳性菌和革兰氏阴性病原体均具有强大的抗菌和抗生物膜活性，表明其作为抗菌剂开发具有很大潜力。
