Thymol Mediates Bactericidal Activity against Staphylococcus aureus by Targeting an Aldo–Keto Reductase and Consequent Depletion of NADPH

Abstract

Staphylococcus aureus is a common pathogen that can cause life-threatening infections. Treatment of antibioticresistant S. aureus infection needs effective antibacterial agents. Thymol, a generally recognized safe natural compound, has potential as an alternative to treat S. aureus infections. However, the targets and mechanisms of action of thymol were not fully understood. Bioinformatics analysis showed that IolS, a predicted aldo−keto reductase (AKR) in S. aureus, could be a potential target of thymol. Isothermal titration calorimetry (ITC) analysis demonstrated that thymol directly binds IolS and amino acid residues (Y30 and L33) are essential for such binding. Deletion of IolS or mutation of Y30A and L33A reduced the bactericidal activity of thymol at the concentration of 200 μg/mL, suggesting that thymol mediates bactericidal activity via binding with IolS. Biochemical analysis showed that addition of thymol significantly increased AKR activity of IolS from 1.6 ± 0.1 to 2.4 ± 0.2 U (p < 0.05). The content of NADPH within S. aureus cells decreased significantly from 105 ± 5 to 72 ± 3 pmol/10 8 cells (p < 0.05) following thymol treatment at the concentration of 200 μg/mL. Importantly, addition of NADPH could alleviate the bactericidal effect of thymol on S. aureus, indicating that the depletion of NADPH is responsible for thymol-mediated bactericidal activity. Overall, these results demonstrated that thymol could directly bind IolS and increase its AKR activity, leading to the depletion of NADPH and bactericidal effect. AKR activity of IolS could be a promising target for the development of new antimicrobials.

Antifungal activities and mechanisms of trans‐cinnamaldehyde and thymol against food‐spoilage yeast Zygosaccharomyces rouxii

“…T-CNM causes cell membrane shrinkage and invagination, while THY results in perforation in cell membrane. Zhou et al (2019) reported that THY interacted with the potassium ion channel protein β subunit-KcNAb on the inner side of the cell membrane, resulting in perforation injury of the cell membrane of S. aureus. Whether THY causes the perforated membrane injury of Z. rouxii through the reported mechanism still needs further confirmation in the future work.…”

Thymol Inhibits Biofilm Formation, Eliminates Pre-Existing Biofilms, and Enhances Clearance of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Mouse Peritoneal Implant Infection Model

“…The traditional Chinese medicine, 2-isopropyl-5-methylphenol (IPMP), commonly known as thymol, is a monoterpene phenol isolated from plants. It is a component of the essential oils extracted from various plants in the Lamiaceae, Verbenaceae, and Scrophulariaceae families, and it exhibits anti-inflammatory, antioxidant and potent antimicrobial properties [22][23][24]. In our previous studies [25] we showed the potent effects of thymol against MRSA infections.…”

Currently Applied Extraction Processes for Secondary Metabolites from Lippia turbinata and Turnera diffusa and Future Perspectives

“…It is classified as a generally recognized as safe (GRAS) compound by the US Food and Drug Administration. It possesses notable antimicrobial activities against bacteria and fungi [76], and is used in edible films [77] and other areas. In phenolic compounds, the main identified compound was quercetin (Figure 1).…”