Antimicrobial, antibiofilm, and virulence gene modulatory effects of supercritical CO₂ extracts of Thymbra spicata against clinical MRSA isolates
Folia Microbiologica, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1007/s12223-026-01572-5
- Dergi Adı: Folia Microbiologica
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, EMBASE, MEDLINE, Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Biomedical Reference Collection: Corporate Edition (EBSCO), Health Research Premium Collection (ProQuest), Pharma Collection (ProQuest)
- Anahtar Kelimeler: Biofilm, Gene expression, MRSA, Supercritical CO₂, Thymbra spicata
- Çukurova Üniversitesi Adresli: Evet
Özet
In this study, extracts of Thymbra spicata were obtained using supercritical carbon dioxide (scCO₂) extraction under two different pressure conditions, namely 120 atm (T1) and 300 atm (T2), while maintaining a constant temperature of 40 °C. GC–MS analysis demonstrated that increasing the extraction pressure from 120 to 300 atm enhanced the recovery of the major bioactive constituents, with thymol and carvacrol increasing from 22.65% to 14.05% in T1 to 28.04% and 18.48% in T2, respectively. The antibacterial activities of the obtained extracts were evaluated against 16 methicillin-resistant Staphylococcus aureus (MRSA) isolates using agar well diffusion and minimum inhibitory concentration (MIC) assays. In addition, the antibiofilm activity of the extracts against MRSA was investigated. Morphological alterations in bacterial cells following treatment were examined using scanning electron microscopy (SEM). Furthermore, the effects of the extracts on the expression levels of the icaA, dltB, and vraR genes were assessed. The T2 extract exhibited stronger antibacterial activity than the T1 extract, as evidenced by its lower MIC values. Notably, the MIC value of T2 was determined to be 64 µg/mL for 15 of the tested MRSA isolates. The agar well diffusion results further supported these findings, with T2 producing significantly larger inhibition zones than T1 (p < 0.05). At a concentration of 2×MIC, the T2 extract inhibited more than 66% of biofilm formation. Morphological evaluation revealed pronounced damage to the integrity of bacterial cells. Gene expression analysis demonstrated that T2 significantly downregulated the expression of the icaA, dltB, and vraR genes, suggesting its potential to attenuate biofilm formation, cell wall-associated functions, and stress response mechanisms in MRSA. Biocompatibility assessment demonstrated that both extracts exhibited low cytotoxicity toward L929 fibroblast cells, with cell viabilities of 89% for T1 and 87% for T2 at 1000 µg/mL. Overall, the superior antibacterial and antibiofilm activities of the T2 extract may be attributed to its higher thymol and carvacrol contents, highlighting the influence of extraction pressure on the recovery of bioactive compounds and its potential as a safe natural antimicrobial agent against MRSA.