{"title":"Polygonum tinctorium extract suppresses the virulence of methicillin-resistant Staphylococcus aureus by disrupting its extracellular vesicles","authors":"Naoko Watabe , Phawinee Subsomwong , Kyosuke Yamane , Krisana Asano , Akio Nakane","doi":"10.1016/j.jep.2024.118933","DOIUrl":null,"url":null,"abstract":"<div><h3>Ethnopharmacological relevance</h3><div>Methicillin-resistant <em>S. aureus</em> (MRSA) is a significant global health concern, causing both hospital- and community-acquired infections. The extracellular vesicles released by <em>S. aureus</em> (SaEVs) contain essential factors related to the bacterial survival and pathogenicity. <em>Polygonum tinctorium</em> is traditionally used as a natural dye (indigo) and for treating various infectious diseases caused by microorganisms. However, the effect of <em>P. tinctorium</em> extract (Indigo Ex) and its mechanism on SaEVs is unknown.</div></div><div><h3>Aim of the study</h3><div>We investigated the effect and mechanism of Indigo Ex on SaEVs, which could be used in controlling <em>S. aureus</em>, especially MRSA infection.</div></div><div><h3>Materials and methods</h3><div>Indigo Ex was prepared from pesticide-free <em>P. tinctorium</em>, which was dried, powdered, and extracted with <em>d</em>-limonene. SaEVs were isolated and purified from MRSA culture supernatant by step-gradient ultracentrifugation. The effect of Indigo Ex on SaEVs morphology was observed by both transmission and scanning electron microscopy after incubating the Indigo Ex and SaEVs under shaking conditions. The cytotoxicity of Indigo Ex was performed using mouse macrophage cell line, RAW 264.7. In addition, the ability of Indigo Ex-treated SaEVs to stimulate the immune response and cytotoxicity in RAW 264.7 cells were evaluated by ELISA and WST-1 assay, respectively.</div></div><div><h3>Results</h3><div>SaEV particles were disrupted when treated with undiluted Indigo Ex in a time-dependent manner. For the cytotoxicity of Indigo Ex on RAW 264.7 cells, over 50% of the cell viability decreased when diluted Indigo Ex 1000-fold and no cytotoxic effect was observed at a 25,000-fold dilution of Indigo Ex. Interestingly, the Indigo Ex-treated SaEVs showed less cytotoxic effect than SaEVs alone. Similarly, SaEVs treated with Indigo Ex reduced stimulation of pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory cytokine (IL-10) in RAW 264.7 cells compared to untreated SaEVs. Our results indicate that Indigo Ex disrupted SaEV particles, resulting in reduced virulence and stimulation of immune response.</div></div><div><h3>Conclusions</h3><div>This study reveals that the low concentration of Indigo Ex can suppresses the virulence of SaEVs without causing cytotoxicity to the host cells. Therefore, Indigo Ex may have the potential to be used to control <em>S. aureus</em> infection.</div></div>","PeriodicalId":15761,"journal":{"name":"Journal of ethnopharmacology","volume":null,"pages":null},"PeriodicalIF":4.8000,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of ethnopharmacology","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0378874124012327","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MEDICINAL","Score":null,"Total":0}
引用次数: 0
Abstract
Ethnopharmacological relevance
Methicillin-resistant S. aureus (MRSA) is a significant global health concern, causing both hospital- and community-acquired infections. The extracellular vesicles released by S. aureus (SaEVs) contain essential factors related to the bacterial survival and pathogenicity. Polygonum tinctorium is traditionally used as a natural dye (indigo) and for treating various infectious diseases caused by microorganisms. However, the effect of P. tinctorium extract (Indigo Ex) and its mechanism on SaEVs is unknown.
Aim of the study
We investigated the effect and mechanism of Indigo Ex on SaEVs, which could be used in controlling S. aureus, especially MRSA infection.
Materials and methods
Indigo Ex was prepared from pesticide-free P. tinctorium, which was dried, powdered, and extracted with d-limonene. SaEVs were isolated and purified from MRSA culture supernatant by step-gradient ultracentrifugation. The effect of Indigo Ex on SaEVs morphology was observed by both transmission and scanning electron microscopy after incubating the Indigo Ex and SaEVs under shaking conditions. The cytotoxicity of Indigo Ex was performed using mouse macrophage cell line, RAW 264.7. In addition, the ability of Indigo Ex-treated SaEVs to stimulate the immune response and cytotoxicity in RAW 264.7 cells were evaluated by ELISA and WST-1 assay, respectively.
Results
SaEV particles were disrupted when treated with undiluted Indigo Ex in a time-dependent manner. For the cytotoxicity of Indigo Ex on RAW 264.7 cells, over 50% of the cell viability decreased when diluted Indigo Ex 1000-fold and no cytotoxic effect was observed at a 25,000-fold dilution of Indigo Ex. Interestingly, the Indigo Ex-treated SaEVs showed less cytotoxic effect than SaEVs alone. Similarly, SaEVs treated with Indigo Ex reduced stimulation of pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory cytokine (IL-10) in RAW 264.7 cells compared to untreated SaEVs. Our results indicate that Indigo Ex disrupted SaEV particles, resulting in reduced virulence and stimulation of immune response.
Conclusions
This study reveals that the low concentration of Indigo Ex can suppresses the virulence of SaEVs without causing cytotoxicity to the host cells. Therefore, Indigo Ex may have the potential to be used to control S. aureus infection.
期刊介绍：
The Journal of Ethnopharmacology is dedicated to the exchange of information and understandings about people''s use of plants, fungi, animals, microorganisms and minerals and their biological and pharmacological effects based on the principles established through international conventions. Early people confronted with illness and disease, discovered a wealth of useful therapeutic agents in the plant and animal kingdoms. The empirical knowledge of these medicinal substances and their toxic potential was passed on by oral tradition and sometimes recorded in herbals and other texts on materia medica. Many valuable drugs of today (e.g., atropine, ephedrine, tubocurarine, digoxin, reserpine) came into use through the study of indigenous remedies. Chemists continue to use plant-derived drugs (e.g., morphine, taxol, physostigmine, quinidine, emetine) as prototypes in their attempts to develop more effective and less toxic medicinals.
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