Hegazy Ahmed M, Shehat Michael G, Abouelfetouh Alaa, Teleb Mohamed, Khattab Sherine N, Haiba Nesreen S
Chemistry Department, Faculty of Science, Alexandria University Alexandria 21321 Egypt
Department of Materials Science, Institute of Graduate Studies and Research, Alexandria University Alexandria Egypt.
RSC Adv. 2025 Jan 20;15(3):1665-1679. doi: 10.1039/d4ra06367h. eCollection 2025 Jan 16.
A novel series of azo dyes was successfully synthesized by combining amino benzoic acid and amino phenol on the same molecular framework azo linkage. The structural elucidation of these dyes was carried out using various spectroscopic techniques, including UV-vis, FT-IR, NMR spectroscopy, and HRMS. Surprisingly, the aromatic proton in some dyes exhibited exchangeability in DO, prompting a 2D NMR analysis to confirm this phenomenon. Furthermore, comprehensive density functional theory (DFT) calculations were conducted to unravel synthetic dyes' geometrical and electronic properties. Meanwhile, the reactivity of various sites was further investigated through Frontier Molecular Orbitals (FMOs) analysis and molecular electrostatic potential mapping. Besides, the experimental NMR spectra were interpreted by incorporating theoretically computed NMR spectrum and reduced density gradient (RDG) function. These computations revealed a pronounced intramolecular hydrogen bond through O-H⋯N interaction that significantly influenced the proton chemical shift. The dyes were assessed for their antimicrobial activities using agar diffusion, micro broth dilution, and biofilm inhibition assays. Interestingly, one of the synthetic dyes showed promising antibacterial effects against (ATCC-6538) as well as against a multidrug-resistant MRSA clinical isolate with a MIC (minimum inhibitory concentration) of 78.12 μg mL. Moreover, that dye inhibited biofilm formation of the strong biofilm former clinical MRSA isolate with a concentration as low as 0.25 MIC (19.53 μg mL). Indeed, our qPCR data suggest that inhibiting the SaeS/SaeR system is another potential mechanism by which D4 exerts its antibacterial and anti-virulence effects. Altogether, this shows these synthetic azo dyes' promising antibacterial and anti-virulence activities concerning MRSA clinical infections.
通过在同一分子骨架的偶氮键上结合氨基苯甲酸和氨基酚，成功合成了一系列新型偶氮染料。使用各种光谱技术对这些染料进行结构解析，包括紫外可见光谱、傅里叶变换红外光谱、核磁共振光谱和高分辨质谱。令人惊讶的是，某些染料中的芳族质子在重水中表现出可交换性，因此进行了二维核磁共振分析以证实这一现象。此外，还进行了全面的密度泛函理论（DFT）计算，以揭示合成染料的几何和电子性质。同时，通过前线分子轨道（FMO）分析和分子静电势映射进一步研究了各个位点的反应性。此外，通过结合理论计算的核磁共振光谱和密度降低梯度（RDG）函数来解释实验核磁共振光谱。这些计算揭示了通过O-H⋯N相互作用形成的明显分子内氢键，这对质子化学位移有显著影响。使用琼脂扩散法、微量肉汤稀释法和生物膜抑制试验评估了这些染料的抗菌活性。有趣的是，其中一种合成染料对金黄色葡萄球菌（ATCC-6538）以及对耐多药的耐甲氧西林金黄色葡萄球菌临床分离株显示出有前景的抗菌效果，其最低抑菌浓度（MIC）为78.12 μg/mL。此外，该染料对强生物膜形成的临床耐甲氧西林金黄色葡萄球菌分离株的生物膜形成具有抑制作用，浓度低至0.25 MIC（19.53 μg/mL）。实际上，我们的定量聚合酶链反应数据表明，抑制SaeS/SaeR系统是D4发挥其抗菌和抗毒力作用的另一种潜在机制。总之，这表明这些合成偶氮染料在耐甲氧西林金黄色葡萄球菌临床感染方面具有有前景的抗菌和抗毒力活性。
