{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T17:45:59Z","timestamp":1792431959669,"version":"4.5.0"},"posted":{"date-parts":[[2025,1,16]]},"group-title":"Microbiology","reference-count":62,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2025,1,16]],"date-time":"2025-01-16T00:00:00Z","timestamp":1736985600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.biorxiv.org\/about\/FAQ#license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2025,1,15]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  <jats:italic>Acinetobacter baumannii<\/jats:italic>\n                  is a high-priority organism for the development of new antibacterial treatments. We found that the antimalarial medication mefloquine (MFQ) permeabilized the bacterial cell membrane of\n                  <jats:italic>A. baumannii<\/jats:italic>\n                  , decreased membrane fluidity, and caused physical injury to the membrane. MFQ also maintained activity across different pH conditions (PH range 5-8). Structure-activity relationship analysis using MFQ analogs demonstrated that piperidin-2-yl methanol is required for antibacterial activity. Scanning and transmission electron microscopy demonstrated the compromised morphological and membrane integrity in MFQ treated cells. MFQ synergized with the membrane permeabilizers polymyxin B and colistin and the MFQ+polymyxin B combination killed bacterial cells more effectively than either treatment alone. MFQ+polymyxin B was effective against other Gram-negative bacteria including\n                  <jats:italic>Escherisia coli, Burkholderia pseudomallei, Klebsiella pneumoniae,<\/jats:italic>\n                  and\n                  <jats:italic>Pseudomonas auroginosa<\/jats:italic>\n                  . Bodipy-cadaverine displacement assays confirmed the active interaction of MFQ with other membrane lipid components, such as lipopolysaccharide, lipid A, lipoteichoic acids, and fatty acids. In all-atom molecular dynamics simulations, lipid interactions facilitated the permeation of MFQ into the simulated Gram-negative membrane. Additionally, positively charged nitrogen in the piperidine group of MFQ seems to enhance interactions with the negatively charged components of the bacterial membrane. MFQ+polymyxin B caused significantly greater curvature in the simulated membrane, indicating greater damage than standalone drug treatment. Finally,\n                  <jats:italic>in vivo<\/jats:italic>\n                  assays showed that MFQ+polymyxin B rescued\n                  <jats:italic>Galleria mellonella<\/jats:italic>\n                  larvae infected with\n                  <jats:italic>A. baumannii<\/jats:italic>\n                  . In conclusion, membrane-active agents such as MFQ may warrant further investigation as potential component of Gram-negative infection treatment, particularly in combination with polymyxin B.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Importance<\/jats:title>\n                  <jats:p>\n                    Antimicrobial resistance is a threat globally, and new treatments are urgently needed to combat the rise of multidrug-resistant bacteria. However, the development of anti-infectives has declined over the last two decades due to regulatory, financial and long-term requirement related challenges. In this study, we examined the membrane interactions of the antiparasitic agent mefloquine in combination with polymyxin B, using both\n                    <jats:italic>in vitro<\/jats:italic>\n                    and\n                    <jats:italic>in silico<\/jats:italic>\n                    approaches to evaluate their potential efficacy against Gram-negative bacterial infections. We investigated the interaction of MFQ with lipid bilayers to understand the mechanism through which antibacterial activity is exerted. The piperidine moiety of MFQ plays a critical role in its interaction with the lipid bilayer and facilitates membrane permeabilization. In contrast, the membrane permeabilizer polymyxin B is associated with significant neurotoxicity and nephrotoxicity. Our findings highlight the potential of membrane-acting compounds, such as MFQ, to enhance combinatorial activity while mitigating polymyxin B-associated toxicity.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.1101\/2025.01.15.633232","type":"posted-content","created":{"date-parts":[[2025,1,16]],"date-time":"2025-01-16T04:15:13Z","timestamp":1737000913000},"source":"Crossref","is-referenced-by-count":1,"title":["Mefloquine reduces the bacterial membrane fluidity of\n                  <i>Acinetobacter baumannii<\/i>\n                  and distorts the bacterial membrane when combined with polymyxin B"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6107-3754","authenticated-orcid":false,"given":"Nagendran","family":"Tharmalingam","sequence":"first","affiliation":[{"name":"Houston Methodist Hospital and Houston Methodist Research Institute, Houston, TX 77030. The USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Harikrishna Sekar","family":"Jayanthan","sequence":"additional","affiliation":[{"name":"Vanderblit University, Nashville, TN 37240. The USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jenna","family":"Port","sequence":"additional","affiliation":[{"name":"Tufts University, Boston, MA 02111. The USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fernanda Cristina Possamai","family":"Rossatto","sequence":"additional","affiliation":[{"name":"Houston Methodist Hospital and Houston Methodist Research Institute, Houston, TX 77030. The USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4624-0777","authenticated-orcid":false,"given":"Eleftherios","family":"Mylonakis","sequence":"additional","affiliation":[{"name":"Houston Methodist Hospital and Houston Methodist Research Institute, Houston, TX 77030. The USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026041021371284000_2025.01.15.633232v1.1","doi-asserted-by":"publisher","DOI":"10.1016\/J.TIM.2021.11.008"},{"key":"2026041021371284000_2025.01.15.633232v1.2","first-page":"55","article-title":"Biology of Acinetobacter baumannii: pathogenesis, antibiotic resistance mechanisms, and prospective treatment options","volume":"7","year":"2017","journal-title":"Frontiers in cellular and infection microbiology"},{"key":"2026041021371284000_2025.01.15.633232v1.3","doi-asserted-by":"publisher","DOI":"10.1038\/nrmicro.2017.148"},{"key":"2026041021371284000_2025.01.15.633232v1.4","doi-asserted-by":"publisher","DOI":"10.1086\/533452"},{"key":"2026041021371284000_2025.01.15.633232v1.5","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.00058-16"},{"key":"2026041021371284000_2025.01.15.633232v1.6","unstructured":"Organization WH . 2024. WHO bacterial priority pathogens list, 2024."},{"key":"2026041021371284000_2025.01.15.633232v1.7","doi-asserted-by":"publisher","DOI":"10.1016\/j.tim.2023.06.007"},{"key":"2026041021371284000_2025.01.15.633232v1.8","doi-asserted-by":"crossref","unstructured":"Kyriakidis I , Vasileiou E , Pana ZD , Tragiannidis A . 2021. Acinetobacter baumannii Antibiotic Resistance Mechanisms. Pathogens 10.","DOI":"10.3390\/pathogens10030373"},{"key":"2026041021371284000_2025.01.15.633232v1.9","doi-asserted-by":"publisher","DOI":"10.3892\/etm.2023.11908"},{"key":"2026041021371284000_2025.01.15.633232v1.10","doi-asserted-by":"publisher","DOI":"10.1002\/jcla.22976"},{"key":"2026041021371284000_2025.01.15.633232v1.11","doi-asserted-by":"publisher","DOI":"10.1021\/bi5000564"},{"key":"2026041021371284000_2025.01.15.633232v1.12","doi-asserted-by":"publisher","DOI":"10.1016\/j.drup.2010.08.003"},{"key":"2026041021371284000_2025.01.15.633232v1.13","doi-asserted-by":"crossref","unstructured":"Monem S , Furmanek-Blaszk B , \u0141upkowska A , Kuczy\u0144ska-Wi\u015bnik D , Stojowska-Sw\u0119drzy\u0144ska K , Laskowska E . 2020. Mechanisms Protecting Acinetobacter baumannii against Multiple Stresses Triggered by the Host Immune Response, Antibiotics and Outside-Host Environment. Int J Mol Sci 21.","DOI":"10.3390\/ijms21155498"},{"key":"2026041021371284000_2025.01.15.633232v1.14","doi-asserted-by":"crossref","unstructured":"Yin W , Wang Y , Liu L , He J . 2019. Biofilms: The Microbial \u201cProtective Clothing\u201d in Extreme Environments. Int J Mol Sci 20.","DOI":"10.3390\/ijms20143423"},{"key":"2026041021371284000_2025.01.15.633232v1.15","doi-asserted-by":"publisher","DOI":"10.2147\/IDR.S332051"},{"key":"2026041021371284000_2025.01.15.633232v1.16","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.00058-07"},{"key":"2026041021371284000_2025.01.15.633232v1.17","doi-asserted-by":"publisher","DOI":"10.1128\/aac.00310-17"},{"key":"2026041021371284000_2025.01.15.633232v1.18","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2021.790220"},{"key":"2026041021371284000_2025.01.15.633232v1.19","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijantimicag.2021.106309"},{"key":"2026041021371284000_2025.01.15.633232v1.20","doi-asserted-by":"publisher","DOI":"10.1021\/ct4010307"},{"key":"2026041021371284000_2025.01.15.633232v1.21","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jctc.5b01114"},{"key":"2026041021371284000_2025.01.15.633232v1.22","doi-asserted-by":"publisher","DOI":"10.1126\/science.1105787"},{"key":"2026041021371284000_2025.01.15.633232v1.23","doi-asserted-by":"crossref","unstructured":"Ayoub Moubareck C . 2020. Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance. Membranes (Basel) 10.","DOI":"10.3390\/membranes10080181"},{"key":"2026041021371284000_2025.01.15.633232v1.24","doi-asserted-by":"publisher","DOI":"10.1016\/S1473-3099(14)70850-3"},{"key":"2026041021371284000_2025.01.15.633232v1.25","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijantimicag.2016.07.023"},{"key":"2026041021371284000_2025.01.15.633232v1.26","doi-asserted-by":"publisher","DOI":"10.1002\/phar.2209"},{"key":"2026041021371284000_2025.01.15.633232v1.27","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkm357"},{"key":"2026041021371284000_2025.01.15.633232v1.28","first-page":"2391","article-title":"Structure of the antimalarial (\u00b1)-mefloquine hydrochloride","volume":"47","year":"1991","journal-title":"Acta Crystallographica Section C: Crystal Structure Communications"},{"key":"2026041021371284000_2025.01.15.633232v1.29","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1800961115"},{"key":"2026041021371284000_2025.01.15.633232v1.30","doi-asserted-by":"crossref","unstructured":"Eze EC , Chenia HY , El Zowalaty ME . 2018. Acinetobacter baumannii biofilms: effects of physicochemical factors, virulence, antibiotic resistance determinants, gene regulation, and future antimicrobial treatments. Infection and drug resistance:2277\u20132299.","DOI":"10.2147\/IDR.S169894"},{"key":"2026041021371284000_2025.01.15.633232v1.31","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.44.4.848-852.2000"},{"key":"2026041021371284000_2025.01.15.633232v1.32","doi-asserted-by":"publisher","DOI":"10.2147\/IDR.S427232"},{"key":"2026041021371284000_2025.01.15.633232v1.33","doi-asserted-by":"publisher","DOI":"10.1111\/j.1574-695X.2011.00926.x"},{"key":"2026041021371284000_2025.01.15.633232v1.34","doi-asserted-by":"publisher","DOI":"10.1038\/s41522-023-00465-6"},{"key":"2026041021371284000_2025.01.15.633232v1.35","doi-asserted-by":"publisher","DOI":"10.1128\/JB.00647-09"},{"key":"2026041021371284000_2025.01.15.633232v1.36","doi-asserted-by":"publisher","DOI":"10.3389\/fcimb.2021.782733"},{"key":"2026041021371284000_2025.01.15.633232v1.37","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijantimicag.2023.107035"},{"key":"2026041021371284000_2025.01.15.633232v1.38","doi-asserted-by":"publisher","DOI":"10.4155\/fmc-2017-0047"},{"key":"2026041021371284000_2025.01.15.633232v1.39","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2019.01557"},{"key":"2026041021371284000_2025.01.15.633232v1.40","doi-asserted-by":"publisher","DOI":"10.1089\/mdr.2017.0250"},{"key":"2026041021371284000_2025.01.15.633232v1.41","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1904700116"},{"key":"2026041021371284000_2025.01.15.633232v1.42","doi-asserted-by":"crossref","unstructured":"Tharmalingam N , Xu S , Felix LO , Roy B , Xian M , Mylonakis E , Fuchs BB . 2023. Gold complex compounds that inhibit drug-resistant Staphylococcus aureus by targeting thioredoxin reductase. Frontiers in Antibiotics 2.","DOI":"10.3389\/frabi.2023.1179354"},{"key":"2026041021371284000_2025.01.15.633232v1.43","doi-asserted-by":"crossref","unstructured":"Zheng Z , Tharmalingam N , Liu Q , Jayamani E , Kim W , Fuchs B , Zhang R , Vilcinskas A , Mylonakis E . 2017. Synergistic efficacy of Aedes aegypti antimicrobial peptide cecropin A2 and tetracycline against Pseudomonas aeruginosa. Antimicrob Agents Chemother 61.","DOI":"10.1128\/AAC.00686-17"},{"key":"2026041021371284000_2025.01.15.633232v1.44","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkaa376"},{"key":"2026041021371284000_2025.01.15.633232v1.45","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-017-03214-w"},{"key":"2026041021371284000_2025.01.15.633232v1.46","doi-asserted-by":"publisher","DOI":"10.1021\/jp1070264"},{"key":"2026041021371284000_2025.01.15.633232v1.47","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jcim.9b00105"},{"key":"2026041021371284000_2025.01.15.633232v1.48","doi-asserted-by":"publisher","DOI":"10.1002\/jcc.23702"},{"key":"2026041021371284000_2025.01.15.633232v1.49","doi-asserted-by":"publisher","DOI":"10.1016\/j.jcp.2011.04.030"},{"key":"2026041021371284000_2025.01.15.633232v1.50","doi-asserted-by":"publisher","DOI":"10.1016\/j.physleta.2005.04.046"},{"key":"2026041021371284000_2025.01.15.633232v1.51","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jctc.2c01032"},{"key":"2026041021371284000_2025.01.15.633232v1.52","doi-asserted-by":"publisher","DOI":"10.1002\/jcc.20956"},{"key":"2026041021371284000_2025.01.15.633232v1.53","doi-asserted-by":"publisher","DOI":"10.1002\/jcc.540130812"},{"key":"2026041021371284000_2025.01.15.633232v1.54","doi-asserted-by":"publisher","DOI":"10.1016\/j.atmosenv.2023.120282"},{"key":"2026041021371284000_2025.01.15.633232v1.55","doi-asserted-by":"publisher","DOI":"10.1016\/0021-9991(77)90121-8"},{"key":"2026041021371284000_2025.01.15.633232v1.56","doi-asserted-by":"publisher","DOI":"10.1016\/0263-7855(96)00018-5"},{"key":"2026041021371284000_2025.01.15.633232v1.57","doi-asserted-by":"publisher","DOI":"10.1016\/j.str.2016.11.012"},{"key":"2026041021371284000_2025.01.15.633232v1.58","doi-asserted-by":"publisher","DOI":"10.1021\/jp408166m"},{"key":"2026041021371284000_2025.01.15.633232v1.59","doi-asserted-by":"crossref","first-page":"10295","DOI":"10.1021\/acs.jpca.3c05573","article-title":"Benchmarking Basis Sets for Density Functional Theory Thermochemistry Calculations: Why Unpolarized Basis Sets and the Polarized 6-311G Family Should Be Avoided","volume":"127","year":"2023","journal-title":"The Journal of Physical Chemistry A"},{"key":"2026041021371284000_2025.01.15.633232v1.60","doi-asserted-by":"publisher","DOI":"10.1007\/s00214-007-0310-x"},{"key":"2026041021371284000_2025.01.15.633232v1.61","doi-asserted-by":"publisher","DOI":"10.1021\/jp020124t"},{"key":"2026041021371284000_2025.01.15.633232v1.62","doi-asserted-by":"publisher","DOI":"10.1016\/j.dib.2021.106929"}],"container-title":[],"original-title":[],"link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1101\/2025.01.15.633232","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,11]],"date-time":"2026-04-11T04:37:24Z","timestamp":1775882244000},"score":1,"resource":{"primary":{"URL":"http:\/\/biorxiv.org\/lookup\/doi\/10.1101\/2025.01.15.633232"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,1,16]]},"references-count":62,"URL":"https:\/\/doi.org\/10.1101\/2025.01.15.633232","relation":{},"subject":[],"published":{"date-parts":[[2025,1,16]]},"subtype":"preprint"}}