Ahmad Iqbal
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India.
Arch Microbiol. 2024 Dec 7;207(1):11. doi: 10.1007/s00203-024-04209-8.
Antimicrobial resistance (AMR) is an urgent worldwide health concern, requiring the exploration for novel antimicrobial interventions. A Gram-negative bacterium, Chromobacterium violaceum, synthesizes quorum-sensing-regulated violacein pigment, develops resilient biofilms, and is often used for the screening of anti-infective drugs. The aim of this work is to assess the antibacterial and antibiofilm properties of three polyphenols: 1,4-naphthoquinone, caffeic acid, and piperine. The determination of antibacterial activity was conducted by the agar overlay and broth microdilution techniques. Analysis of membrane rupture was conducted by crystal violet uptake and β-galactosidase assay. Inhibition of biofilm was evaluated using a 96-well microtiter plate assay. Biofilm structures were visualized using light, scanning electron microscopy (SEM), and confocal laser scanning electron microscopy (CLSM). Among the phytochemicals, 1,4-naphthoquinone exhibited the highest antibacterial action (25 mm zone of inhibition). The minimum inhibitory concentration of 1,4-naphthoquinone was determined to be 405 µM. Outer and inner membrane permeability was enhanced by 52.01% and 1.28 absorbance, respectively. Violacein production was reduced by 74.85%, and biofilm formation was suppressed by 63.25% at sub-MIC levels (202.5 µM). Microscopic analyses confirmed reduced adhesion on surfaces. Hemolytic activity of 1,4-naphthoquinone showed a concentration-dependent effect, with 32.16% haemolysis at 202.5 µM. Molecular docking revealed significant interactions of 1,4-naphthoquinone with DNA gyrase followed by CviR. These findings highlight 1,4-naphthoquinone's potent antibacterial efficacy against C. violaceum, proposing its use as a surface coating agent to prevent biofilm formation on medical devices, thereby offering a promising strategy to combat bacterial infections.
抗菌耐药性（AMR）是一个紧迫的全球健康问题，需要探索新型抗菌干预措施。革兰氏阴性菌紫色色杆菌能合成群体感应调控的紫菌素色素，形成具有弹性的生物膜，常被用于抗感染药物的筛选。本研究的目的是评估三种多酚类物质：1,4-萘醌、咖啡酸和胡椒碱的抗菌和抗生物膜特性。通过琼脂覆盖法和肉汤微量稀释技术测定抗菌活性。通过结晶紫摄取和β-半乳糖苷酶测定法分析膜破裂情况。使用96孔微量滴定板测定法评估生物膜抑制情况。利用光学显微镜、扫描电子显微镜（SEM）和共聚焦激光扫描电子显微镜（CLSM）观察生物膜结构。在这些植物化学物质中，1,4-萘醌表现出最高的抗菌作用（抑菌圈直径为25毫米）。1,4-萘醌的最低抑菌浓度测定为405µM。外膜和内膜通透性分别提高了52.01%和1.28吸光度。在亚抑菌浓度水平（202.5µM）下，紫菌素产量降低了74.85%，生物膜形成受到63.25%的抑制。显微镜分析证实表面粘附减少。1,4-萘醌的溶血活性呈现浓度依赖性效应，在202.5µM时溶血率为32.16%。分子对接显示1,4-萘醌与DNA促旋酶以及CviR有显著相互作用。这些发现突出了1,4-萘醌对紫色色杆菌的强大抗菌功效，建议将其用作表面涂层剂以防止医疗设备上生物膜的形成，从而为对抗细菌感染提供了一种有前景的策略。
