This study for the first time constructs a complete temporal mechanism chain from initial membrane damage and rapid metabolic disorder to downstream cellular dysfunction for the CAR-ε-PL synergy, providing a novel theoretical basis for developing natural antimicrobial strategies in food preservation.
Abstract
This study aims to explore the synergistic bactericidal interaction of carvacrol (CAR) combined with ε-polylysine (ε-PL) against Staphylococcus aureus and its underlying mechanism. The combination of CAR (12.50 µg mL−1) and ε-PL (7.66 µg mL−1) exhibited synergistic bactericidal and antibiofilm activities, primarily attributed to combined destruction of the bacterial cell membrane, as evidenced by increased membrane permeability, time-dependent depolarization, and reduced cell surface hydrophobicity after 3 h of treatment. Membrane damage facilitated intracellular accumulation of CAR, which rapidly triggered energy depletion and early metabolic disturbances. Using metabolomics, the combination after 0.5 h was found to primarily perturb three key pathways, including tryptophan metabolism, cofactor biosynthesis (thiamine, biotin, nicotinamide), and nucleotide metabolism. These early metabolic changes, along with ATP decline, occurred prior to full membrane depolarization, oxidative stress, and pH imbalance at 3 h. Ultimately, the synergy caused irreversible energy depletion, membrane disruption, and severe oxidative damage. Furthermore, the combination reduced S. aureus counts by approximately 1.0 log10 CFU g−1 in raw beef under refrigeration, supporting its practical potential. This study for the first time constructs a complete temporal mechanism chain from initial membrane damage and rapid metabolic disorder to downstream cellular dysfunction for the CAR-ε-PL synergy, providing a novel theoretical basis for developing natural antimicrobial strategies in food preservation.
The emergence of methicillin-resistant Staphylococcus aureus (MRSA) calls for novel antibiotic adjuvants. Carvacrol (Car), a natural monoterpene phenol derived from the essential oils of aromatic plants, exhibits membrane-active properties and has potential as an antibacterial adjuvant. Here, we found that Car markedly enhanced the bactericidal activities of Gentamicin (Gen) against MRSA. Mechanistically, Car dissipated membrane potential, inhibited respiratory chain dehydrogenase activity, and depleted intracellular ATP. Moreover, Car promoted membrane lipid peroxidation, ultimately leading to structural and functional membrane damage and bacterial death. Notably, pharmacological perturbation of respiratory and metabolic pathways further supported that this synergistic effect depends on bacterial respiratory bioenergetics. In addition, the combination showed favorable in vivo antibacterial efficacy in both Galleria mellonella and murine infection models, without apparent toxicity under the tested conditions. Collectively, these findings indicate that Car may serve as a natural antibacterial adjuvant for combination therapy against drug-resistant infections.
The results of clinical studies from the last decade are reviewed, demonstrating the potential of NAC as an adjuvant in urinary tract infections, chronic rhinosinusitis, diabetic osteomyelitis, and cystic fibrosis.
Anastasia N. Golub, N. N. Mikhailova, M. V. Pomytkina et al.· Life· 0 citations
Acne vulgaris is a chronic inflammatory skin disorder in which Cutibacterium acnes contributes to disease persistence through biofilm formation, lipid metabolism, and production of inflammatory metabolites within the pilosebaceous unit. Targeting bacterial physiological pathways that sustain these processes represents a potential therapeutic strategy beyond conventional antibiotic approaches. In this study, we evaluated a panel of halogenated indole derivatives and identified 6-bromo-4-iodoindole as a potent inhibitor of C. acnes growth and biofilm formation. The compound exhibited a minimum inhibitory concentration of 20 μg/mL and disrupted biofilm architecture. Further analyses revealed that treatment markedly altered several virulence-associated phenotypes, including reductions in extracellular lipase activity, cell-surface hydrophobicity, extracellular polymeric substance production, and porphyrin levels, accompanied by increased intracellular reactive oxygen species. Because lipase activity plays a central role in sebum metabolism and follicular colonization by C. acnes, molecular docking was performed to evaluate potential target engagement. Docking simulations suggested that 6-bromo-4-iodoindole occupies the catalytic pocket of C. acnes triacylglycerol lipase, providing a structural basis for the observed suppression of lipase-dependent phenotypes. Importantly, the compound retained biofilm inhibitory activity in polymicrobial C. acnes + Staphylococcus aureus biofilms, exhibited broad-spectrum growth inhibition extending to S. epidermidis, and significantly reduced bacterial recovery in an ex vivo porcine skin model. In silico pharmacokinetic analyses further indicated physicochemical properties compatible with localized topical delivery. Together, these findings demonstrate that a dihalogenated indole reduces lipase-associated virulence related phenotypes in C. acnes and suppresses biofilm formation in skin-relevant environments, supporting further investigation of this scaffold as a therapeutic strategy targeting acne-associated microbial physiology.
S. Angulmaduwa, G.G. Roshan Pradeep Ratupaskatiye, Yong-Guy Kim et al.· Microbial Pathogenesis· 0 citations
Efficiently eradicating superbacteria without harming normal cells and inducing bacterial drug-resistance holds significant importance in safeguarding human health. Herein, we discovered a novel selective bactericidal material synthesized from natural cellulose as the backbone, with cationic groups introduced via a deoxygenation process. Compared to conventional ester-type cationic cellulose derivatives (CCDs), deoxy-type CCDs exhibit high selective bactericidal activity. Through tailored cationic structure and substitution degree modulation, these derivatives achieve targeted bacterial eradication at low concentrations while maintaining mammalian cell biocompatibility. Specifically, deoxy-type CCDs, C-Ts-BenA0.80 and C-Ts-TBuP0.83, demonstrate minimum inhibitory concentrations (MICs) of 16 μg/mL and 4 μg/mL against E. coli and S. aureus, respectively, with corresponding selectivity indices of 312 and 50. Deoxy-type CCDs have strong cell-membrane depolarization ability owing to the unique surface charge distribution, thus leading to bacterial death. Based on the physical membrane-disruption mechanism, deoxy-type CCDs do not induce the emergence of drug-resistant bacteria and can effectively kill a variety of superbugs, including ESKAPE bacteria. The synergistic effect between the linkage bond and cations offers a new approach for constructing highly efficient and nontoxic inactivating materials.
Xi Wang, Hailong Zhuo, Chunchun Yin et al.· ACS Macro Letters· 0 citations
ABSTRACT The global proliferation of methicillin-resistant Staphylococcus aureus (MRSA) persists as a significant contributor to challenging infections, highlighting the urgent necessity for therapies that utilize novel mechanisms. Aspartate transcarbamoylase (ATCase), which catalyzes the initial committed step of de novo pyrimidine biosynthesis, represents a promising metabolic target with potential relevance to MRSA fitness and persistence. Through structure-based virtual screening and experimental validation, we identified the flavonoid isokurarinone as a compound targeting ATCase, demonstrating potent anti-MRSA activity. Docking and molecular dynamics simulations, along with surface plasmon resonance and differential scanning fluorimetry, provided evidence for direct binding, which was accompanied by a decrease in pyrB expression and a reduction in ATCase activity. Non-targeted metabolomics revealed a disruption of pyrimidine nucleotide homeostasis, coinciding with impaired membrane integrity, reduced proton motive force, decreased intracellular ATP levels, and increased oxidative stress. Isokurarinone also showed an additive interaction with vancomycin in vitro, inhibited biofilm formation and altered the expression of virulence-associated genes. Safety evaluation showed cell-type-dependent cytotoxicity in mammalian cells, while no obvious acute oral toxicity was observed in mice at a single dose of 2 g/kg. In a murine model of MRSA-infected wounds, isokurarinone accelerated wound closure, reduced bacterial burden, and attenuated local inflammatory mediators. Collectively, these findings support the notion of ATCase as a metabolism-guided target for MRSA and nominate isokurarinone as a promising lead scaffold for therapeutic development.
Xinyuan Cao, Xiaorong Yang, Lixia Dai et al.· Virulence· 0 citations
The spoilage of blue honeysuckle during storage is mainly caused by specific dominant microorganisms, while most antimicrobial systems are developed without considering these target spoilage species. In this study, dominant spoilage yeasts were isolated from blue honeysuckle berries, and an antimicrobial system was constructed using these yeasts, along with common foodborne bacteria as target strains. The results showed that the antimicrobial system exhibited significant synergistic antimicrobial activity. Further analysis indicated that the essential oils disrupted the cell membrane structure and increased membrane permeability, thereby promoting the interaction of ε-PL with intracellular components. Multiple physiological alterations were detected after treatment, including membrane depolarization, leakage of intracellular components, accumulation of intracellular reactive oxygen species, and suppression of cellular metabolism. These observations suggested that damage to microbial cells might be synergistically induced by the composite system. Application of the system to blue honeysuckle berries effectively inhibited the growth of endogenous spoilage microorganisms and delayed quality deterioration during storage, and significantly reduced weight loss and decay rates, as well as changes in color, anthocyanin content, and vitamin C content. These results indicate that constructing antimicrobial systems based on dominant spoilage microorganisms can improve preservation efficiency and provide a useful approach for the storage of blue honeysuckle and similar fruits.
Yang Yu, Jiayuan Luo, Mingjie Jia et al.· Foods· 0 citations