{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T10:46:03Z","timestamp":1789469163228,"version":"build-2803163510"},"reference-count":54,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T00:00:00Z","timestamp":1789430400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100009687","name":"the Medical University of Wroclaw","doi-asserted-by":"publisher","award":["SUBK.D230.26.006"],"award-info":[{"award-number":["SUBK.D230.26.006"]}],"id":[{"id":"10.13039\/501100009687","id-type":"DOI","asserted-by":"publisher"}]},{"award":["SUBK.D230.26.006"],"award-info":[{"award-number":["SUBK.D230.26.006"]}],"id":[{"id":"https:\/\/ror.org\/00yae6e25","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>\u03b2-thujaplicin (BTJ) is an organic compound with medicinal potential. Its activity against pathogenic Streptococcus species has been insufficiently investigated. This study aimed to evaluate the antimicrobial activity of \u03b2-thujaplicin against more than 30 reference and clinical isolates of Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae, and to assess its effect on the intrinsic low-level resistance of these bacteria to aminoglycosides. Susceptibility of \u03b2-thujaplicin and selected aminoglycosides was determined using the broth microdilution method. The modulatory effect of \u03b2-thujaplicin on aminoglycoside activity was assessed using the checkerboard assay, with interactions evaluated based on the fractional inhibitory concentration index (FICI). \u03b2-thujaplicin exhibited antimicrobial activity against S. pyogenes and S. pneumoniae, with minimum inhibitory concentration (MIC) values ranging from 16 to 32 \u00b5g\/mL, exceeding the activity of amikacin (AN). Synergistic interactions between \u03b2-thujaplicin (2\u20138 \u00b5g\/mL) and aminoglycosides were observed in 100% of S. pneumoniae strains tested, 50% of S. pyogenes, and 80% of S. agalactiae isolates. In the presence of \u03b2-thujaplicin, aminoglycoside MICs decreased by 2- to 64-fold depending on the species. \u03b2-thujaplicin demonstrates in vitro bactericidal activity against most tested Streptococcus strains and exhibits synergistic effects when combined with aminoglycosides. These findings suggest that \u03b2-thujaplicin may reduce the natural resistance of strepto-cocci to these antibiotics.<\/jats:p>","DOI":"10.3390\/pathogens15090978","type":"journal-article","created":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T09:31:57Z","timestamp":1789464717000},"page":"978","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Anti-Streptococcal Activity of \u03b2-Thujaplicin and Its Effect on Natural Low-Level Resistance of Streptococcus Species to Aminoglycoside Antibiotics"],"prefix":"10.3390","volume":"15","author":[{"given":"Adriana","family":"Marcin\u00f3w","sequence":"first","affiliation":[{"name":"Student Scientific Association of Pharmaceutical Microbiology \u201cMICRO&Pharm\u201d, Faculty of Pharmacy, Wroclaw Medical University, 50-556 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3630-0289","authenticated-orcid":false,"given":"El\u017cbieta","family":"Pi\u0105tkowska","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Microbiology and Parasitology, Faculty of Pharmacy, Wroclaw Medical University, 50-556 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2812-4702","authenticated-orcid":false,"given":"Krzysztof","family":"Kujawa","sequence":"additional","affiliation":[{"name":"Statistical Analysis Centre, Wroclaw Medical University, 50-556 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"698","DOI":"10.1002\/ardp.201600095","article-title":"Antimicrobial\/antibiofilm activity and cytotoxic studies of \u03b2-thujaplicin derivatives","volume":"349","author":"Fotopoulou","year":"2016","journal-title":"Arch. Pharm."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1016\/j.micres.2012.12.007","article-title":"In vitro antimicrobial and anticancer potential of hinokitiol against oral pathogens and oral cancer cell lines","volume":"168","author":"Shih","year":"2013","journal-title":"Microbiol. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1093\/chromsci\/45.5.281","article-title":"Analysis of Western Redcedar (Thuja plicata Donn) Heartwood components by HPLC as a possible screening tool for trees with enhanced natural durability","volume":"45","author":"Daniels","year":"2007","journal-title":"J. Chromatogr. Sci."},{"key":"ref_4","first-page":"783","article-title":"A stepwise protocol for induction and selection of prominent coniferous cell cultures for the productin of \u03b2-thujaplicin","volume":"10","author":"Ogita","year":"2015","journal-title":"Nat. Product. Commun."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1111\/1348-0421.12688","article-title":"Antibacterial activity of hinokitiol against both antibiotic resistant and susecptible phatogenic bacteria that prodominate in the oral cavity and upper airways","volume":"63","author":"Domon","year":"2019","journal-title":"Microbiol. Immunol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"964","DOI":"10.1038\/eye.2015.62","article-title":"Anti-inflammatory effects of hinokitiol on human corneal epithelial cells: An in vitro study","volume":"29","author":"Ye","year":"2015","journal-title":"Eye"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"El Hachlafi, N., Lakhdar, F., Khouchlaa, A., Bakrim, S., El Omari, N., Balahbib, A., Shariati, M.A., Zengin, G., Fikri-Benbrahim, K., and Orlando, G. (2021). Health benefits and pharmacological properties of hinokitiol. Processes, 9.","DOI":"10.3390\/pr9091680"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"100527","DOI":"10.1016\/j.prmcm.2024.100527","article-title":"Mechanistic insights and therapeutic applications of hinokitiol in inflammation, antimicrobial therapy, and cancer","volume":"13","author":"Karunakar","year":"2024","journal-title":"Pharmacol. Res.-Mod. Chin. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.freeradbiomed.2025.06.034","article-title":"Hinokitiol modulates Nrf2\/HO-1 signaling, autophagy, and URAT1 in hyperuricemia and oxidative stress models of renal injury","volume":"238","author":"Chiang","year":"2025","journal-title":"Free Radic. Biol. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e202401904","DOI":"10.1002\/cbdv.202401904","article-title":"Therapeutic efficacy studies on the monoterpenoid hinokitiol in the treatment of different types of cancer","volume":"22","author":"Bhuia","year":"2025","journal-title":"Chem. Biodivers."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Ohara, H., Odanaka, K., Shiine, M., and Hayasaka, M. (2023). Antimicrobial effect of oral care gel containing hinokitiol and 4-isopropyl-3-methylphenol against intraor.al pathogenic microorganisms. PLoS ONE, 18.","DOI":"10.1101\/2023.03.07.531591"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Isono, T., Domon, H., Nagai, K., Maekawa, T., Tamura, H., Hiyoshi, T., Yanagihara, K., Kunitomo, E., Takenaka, S., and Noiri, Y. (2020). Treatment of severe pneumonia by hinokitiol in a murine antimicrobial-resistant pneumococcal pneumonia model. PLoS ONE, 15.","DOI":"10.1371\/journal.pone.0240329"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2793","DOI":"10.1111\/jam.15139","article-title":"Development of Hinoline\u00ae as a natural preservative for cosmetic product using bioinspiration and Greenpharma Database","volume":"131","author":"Bernard","year":"2021","journal-title":"J. Appl. Microbiol."},{"key":"ref_14","unstructured":"World Health Organization (2024). WHO Bacterial Priority Pathogens List, 2024: Bacterial Pathogens of Public Health Importance to Guide Research, Development and Strategies to Prevent and Control Antimicrobial Resistance, World Health Organization."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"991","DOI":"10.1007\/s15010-024-02413-8","article-title":"Post-COVID-19-pandemic changes and clinical characteristics of invasive group a streptococcal infections from 2015 to 2023","volume":"53","author":"Nurjadi","year":"2025","journal-title":"Infection"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"107415","DOI":"10.1016\/j.ijantimicag.2024.107415","article-title":"The longitudinal trend and driving factors of antimicrobial resistance among Streptococcus pneumoniae worldwide","volume":"65","author":"Shi","year":"2025","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Zakerifar, M., Kaboosi, H., Goli, H.R., Rahmani, Z., and Peyravii Ghadikolaii, F. (2023). Antibiotic resistance genes and molecular typing of Streptococcus agalactiae isolated from pregnant women. BMC Pregnancy Childbirth, 23.","DOI":"10.1186\/s12884-023-05380-4"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"001822","DOI":"10.1099\/jmm.0.001822","article-title":"Characterization of invasive Group B Streptococcus isolates from Western Australian infants, 2004\u20132020","volume":"73","author":"Hilpipre","year":"2024","journal-title":"J. Med. Microbiol."},{"key":"ref_19","unstructured":"(2026, February 12). EUCAST Expected Resistant Phenotypes v.1. Available online: www.eucast.org\/expert_rules_and_expected_phenotypes."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3085","DOI":"10.1093\/jac\/dkx265","article-title":"Synergistic antibiotic activity against planktonic and biofilm-embedded Streptococcus agalactiae, Streptococcus pyogenes and Streptococcus oralis","volume":"72","author":"Trampuz","year":"2017","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1128\/AAC.47.1.144-147.2003","article-title":"Vancomycin acts synergistically with gentamicin against penicillin-resistant pneumococci by increasing the intracellular penetration of gentamicin","volume":"47","author":"Cottagnoud","year":"2003","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"101","DOI":"10.4265\/bio.12.101","article-title":"The mechanism of the bactericidal activity of hinokitiol","volume":"12","author":"Morita","year":"2007","journal-title":"Biocontrol Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"110178","DOI":"10.1016\/j.abb.2024.110178","article-title":"Searching for the role of membrane lipids in the mechanism of antibacterial effect of hinokitiol","volume":"761","author":"Olechowska","year":"2024","journal-title":"Arch. Biochem. Biophys."},{"key":"ref_24","unstructured":"The European Committee on Antimicrobial Susceptibility Testing (2025, December 08). Breakpoint Tables for Interpretation of MICs and Zone Diameters. Version 15.0. Available online: https:\/\/www.eucast.org\/fileadmin\/eucast\/pdf\/breakpoints\/v_15.0_Breakpoint_Tables.pdf."},{"key":"ref_25","unstructured":"(2019). Susceptibility Testing of Infectious Agents and Evaluation of Performance of Antimicrobial Susceptibility Test Devices\u2014Part 1: Broth Micro-Dilution Reference Method for Testing the In Vitro Activity of Antimicrobial Agents Against Rapidly Growing Aerobic Bacteria Involved in Infectious Diseases (Standard No. ISO 20776-1:2019)."},{"key":"ref_26","unstructured":"The European Committee on Antimicrobial Susceptibility Testing (2025, November 22). Routine and Extended Internal Quality Control for MIC Determination and Disk Diffusion as Recommended by EUCAST. Version 15.0. Available online: https:\/\/www.eucast.org\/fileadmin\/eucast\/pdf\/disk_test_documents\/archive\/v_15.0_EUCAST_QC_tables_routine_and_extended_QC.pdf."},{"key":"ref_27","unstructured":"European Committee on Antimicrobial Susceptibility Testing (2025, January 26). Data from the EUCAST MIC Distribution Website. Available online: https:\/\/mic.eucast.org\/search\/."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1093\/jac\/dkae380","article-title":"Bactericidal versus bacteriostatic antibacterials: Clinical significance, differences and synergistic potential in clinical practice","volume":"80","author":"Ishak","year":"2025","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Leber, A.L. (2016). Synergism testing: Broth microdilution checkerboard and broth macrodilution methods. Clinical Microbiology Procedures Handbook, John Wiley & Sons.","DOI":"10.1128\/9781683670438.CMPH"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"7571","DOI":"10.21608\/ejhm.2022.276689","article-title":"Determination of fractional inhibitory concentration (FIC) index as a measure of synergy of antibiotics in E. coli O157:H7","volume":"89","author":"Abdulabbas","year":"2022","journal-title":"Egypt J. Hosp. Med."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1016\/j.ijantimicag.2016.11.031","article-title":"Synergy against extensively drug-resistant Acinetobacter baumannii in vitro by two old antibiotics: Colistin and chloramphenicol","volume":"49","author":"Wei","year":"2017","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1139\/m73-216","article-title":"Antibacterial activity of beta-thujaplicin","volume":"19","author":"Trust","year":"1973","journal-title":"Can. J. Microbiol."},{"key":"ref_33","first-page":"129","article-title":"Antimicrobial action of natural substances on oral bacteria","volume":"30","author":"Saeki","year":"1989","journal-title":"Bull. Tokyo Dent. Coll."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Houdkova, M., Chaure, A., Doskocil, I., Havlik, J., and Kokoska, L. (2021). New broth macrodilution volatilization method for antibacterial susceptibility testing of volatile agents and evaluation of their toxicity using modified MTT assay in vitro. Molecules, 26.","DOI":"10.3390\/molecules26144179"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Wang, T.H., Hsia, S.M., Wu, C.H., Ko, S.Y., Chen, M.Y., Shih, Y.H., Shieh, T.M., Chuang, L.C., and Wu, C.Y. (2016). Evaluation of the antibacterial potential of liquid and vapor phase phenolic essential oil compounds against oral microorganisms. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0163147"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1111\/j.1740-0929.2011.00915.x","article-title":"Effects of a combination of hinokitiol (\u03b2-thujaplicin) and an organic acid mixture on ruminal fermentation in heifers fed a high-grain diet","volume":"83","author":"Ishii","year":"2012","journal-title":"Anim. Sci. J."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"7424","DOI":"10.1128\/AAC.01374-16","article-title":"Changing epidemiology of group B Streptococcus susceptibility to fluoroquinolones and aminoglycosides in France","volume":"60","author":"Hays","year":"2016","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2704","DOI":"10.1093\/jac\/dkx207","article-title":"Genomic sequences of Streptococcus agalactiae with high-level gentamicin resistance, collected in the BSAC bacteraemia surveillance","volume":"72","author":"Doumith","year":"2017","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"e222","DOI":"10.5001\/omj.2020.79","article-title":"Group A Streptococcus antibiotic resistance in Iranian children: A meta-analysis","volume":"36","author":"Khademi","year":"2021","journal-title":"Oman Med. J."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Wohlfarth, E., Kresken, M., and Deuchert, F. (2024). Antimicrobial ausceptibility of bacterial pathogens from patients with ocular surface infections in Germany, 2020\u20132021: A comparison with the data from three previous national studies. Antibiotics, 13.","DOI":"10.3390\/antibiotics13060471"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Marks, L.R., Clementi, E.A., and Hakansson, A.P. (2012). The human milk protein-lipid complex HAMLET sensitizes bacterial pathogens to traditional antimicrobial agents. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0043514"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"e03205-22","DOI":"10.1128\/spectrum.03205-22","article-title":"Hinokitiol selectively enhances the antibacterial activity of tetracyclines against Staphylococcus aureus","volume":"11","author":"Le","year":"2023","journal-title":"Microbiol. Spectr."},{"key":"ref_43","first-page":"1621","article-title":"Synergistic effect of \u03b2-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli in vitro Sheng Wu Gong","volume":"39","author":"Zhang","year":"2023","journal-title":"Cheng Xue Bao"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1080\/14787210.2020.1705155","article-title":"Antibiotic combination therapy against resistant bacterial infections: Synergy, rejuvenation and resistance reduction","volume":"18","author":"Coates","year":"2020","journal-title":"Expert Rev. Anti Infect. Ther."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Le\u00f3n-Buitimea, A., Garza-C\u00e1rdenas, C.R., Garza-Cervantes, J.A., Lerma-Escalera, J.A., and Morones-Ram\u00edrez, J.R. (2020). The demand for new antibiotics: Antimicrobial peptides, nanoparticles, and combinatorial therapies as future strategies in antibacterial agent design. Front Microbiol., 11.","DOI":"10.3389\/fmicb.2020.01669"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Alves-Barroco, C., Rivas-Garc\u00eda, L., Fernandes, A.R., and Baptista, P.V. (2020). Tackling multidrug resistance in streptococci\u2014From novel biotherapeutic strategies to nanomedicines. Front Microbiol., 11.","DOI":"10.3389\/fmicb.2020.579916"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1829","DOI":"10.1039\/D4MD00860J","article-title":"Hinokitiol potentiates antimicrobial activity of bismuth drugs: A combination therapy for overcoming antimicrobial resistance","volume":"16","author":"Ip","year":"2025","journal-title":"RSC Med. Chem."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Xue, B., Li, H., Gao, S., Quan, Y., Wang, Y., Yi, L., and Wang, Y. (2025). Andrographolide reverses the susceptibility of Streptococcus suis to aminoglycoside antibiotics by proton motive force. BMC Vet. Res., 21.","DOI":"10.1186\/s12917-024-04430-z"},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Takada, K., Yoshioka, Y., Morikawa, K., Ariyoshi, W., and Yamasaki, R. (2025). Glucose supplementation enhances the bactericidal effect of penicillin and gentamicin on Streptococcus sanguinis persisters. Antibiotics, 14.","DOI":"10.3390\/antibiotics14010036"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"129","DOI":"10.2115\/fiber.58.129","article-title":"Photolysis and antimicrobial activity of hinokitiol in antimicrobial\/deodorant processed textiles","volume":"58","author":"Nakashima","year":"2002","journal-title":"Sen\u2019i Gakkaishi"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"110333","DOI":"10.1016\/j.mehy.2020.110333","article-title":"A possible application of hinokitiol as a natural zinc ionophore and anti-infective agent for the prevention and treatment of COVID-19 and viral infections","volume":"145","author":"Hoang","year":"2020","journal-title":"Med. Hypotheses"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1186\/1743-422X-8-348","article-title":"Effect of oral care gel on the quality of life for oral lichen planus in patients with chronic HCV infection","volume":"12","author":"Nagao","year":"2011","journal-title":"Virol. J."},{"key":"ref_53","first-page":"3039269","article-title":"Effect of oral care in a patient with depression and burning mouth syndrome during the COVID-19 pandemic","volume":"2021","author":"Nagao","year":"2021","journal-title":"Case Rep. Dent."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"100410","DOI":"10.1016\/j.prmcm.2024.100410","article-title":"Hinokitiol attenuates gentamicin-induced nephrotoxicity by reversing oxidative stress and inflammation","volume":"10","author":"Karunakar","year":"2024","journal-title":"Pharmacol. Res. Mod. Chin. 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