Discovery of β‐nitrostyrene derivatives as potential quorum sensing inhibitors for biofilm inhibition and antivirulence factor therapeutics against Serratia marcescens

This study was led by Prof. Ai‐Qun Jia (Hainan Affiliated Hospital of Hainan Medical University, Hainan General Hospital, Haikou, China.), Prof. Dayong Wang (Hainan University, Haikou, China.) and their team workers from 2021 - 2024. The team based on biological materials derived from nature, mainly carried out the discovery and evaluation of QSIs derived from drugs and food. So far, more than 40 highly active QSIs have been found, and the structural types involve cyclic peptides, stilbenes, alkaloids, phenolic acids, diterpenes and other compounds. The molecular mechanism of some QSIs, such as resveratrol and hordenine, was investgated in depth. For example, in 2018, it was firstly found that hordenine had a good QS inhibitory activity against Pseudomonas aeruginosa, and this work was highly cited in 2018 (Zhou, J. W., Jia, A. Q., et al., 2018, JAFC, 66(7), 1620). Subsequently, QS inhibition of hordenine on S. marcescens was the cover article in 2019 (Zhou, J. W., Jia, A. Q., et al., 2019, JAFC, 67(3), 784). In order to enrich the molecular diversity and possible other pharmaceutical activities of QSIs, the team conducted in-depth and systematic research on the synthesis of indole-azepines based on classical organic synthesis methodologies. As a result, the team successfully published the cover article in the J. Org. Chem. in 2022. (Wang, J., Jia, A. Q., et al., J. Org. Chem. 2022, 87, 15, 9663–9674). In short, the team rooted in QS field for a long time and gave some achievements.

This work mainly focuses on synthesis of β-nitrostyrene derivatives as QSI against S. marcescens, investgated by by Jiang Wang, Dayong Wang, Ai-Qun Jia et al. for the great work and successfully publish in mLife recently. In detail, QS inhibition has emerged as a promising target for directed drug design, providing an appealing strategy for developing antimicrobials, particularly against infections caused by drug‐resistant pathogens (Figure 1). In this study, they designed and synthesized a total of 33 β‐nitrostyrene derivatives using 1‐nitro‐2‐phenylethane (NPe) as the lead compound, to target the facultative anaerobic bacterial pathogen S. marcescens. The QS‐inhibitory effects of these compounds were evaluated using S. marcescens NJ01 and the reporter strain Chromobacterium violaceum CV026 (Figure 2). Among the 33 new β‐nitrostyrene derivatives, (E)‐1‐methyl‐4‐(2‐nitrovinyl)benzene (m‐NPe, compd. 28) was proven to be a potent inhibitor that reduced biofilm formation of S. marcescens NJ01 by 79% (Figure 3). Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) results revealed that treatment with m‐NPe (50 μg/mL) not only enhanced the susceptibility of the formed biofilms but also disrupted the architecture of biofilms by 84% (Figure 4). m‐NPe (50 μg/mL) decreased virulence factors in S. marcescens NJ01, reducing the activity of protease, prodigiosin, and extracellular polysaccharide (EPS) by 36%, 72%, and 52%, respectively (Figure 5). In S. marcescens 4547, the activities of hemolysin and EPS were reduced by 28% and 40%, respectively, outperforming the positive control, vanillic acid (VAN) (Figure 6). The study also found that the expression levels of QS‐ and biofilm‐related genes (flhD, fimA, fimC, sodB, bsmB, pigA, pigC, and shlA) were downregulated by 1.21‐ to 2.32‐fold. Molecular dynamics analysis showed that m‐NPe could bind stably to SmaR, RhlI, RhlR, LasR, and CviR proteins in a 0.1 M sodium chloride solution (Figure 7). Importantly, a microscale thermophoresis (MST) test revealed that SmaR could be a target protein for the screening of a QSI against S. marcescens. Overall, this study highlights the efficacy of m‐NPe in suppressing the virulence factors of S. marcescens, identifying it as a new potential QSI and antibiofilm agent capable of restoring or improving antimicrobial drug sensitivity.

How to cite this article:

Wang J, Yang J‐Y, Durairaj P, Wang W, Wei D‐Y, Tang S, et al. Discovery of β‐nitrostyrene derivatives as potential quorum sensing inhibitors for biofilm inhibition and antivirulence factor therapeutics against Serratia marcescens. mLife. 2024; https://doi.org/10.1002/mlf2.12135