Journal of ethnopharmacology · 2026
Rapid bactericidal and anti-virulence effects of Quercus infectoria gall extract against the pharyngitis causing pathogen Streptococcus pyogenes.
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Tanabat Tananya, Lethongkam Sakkarin, Voravuthikunchai Supayang Piyawan, Yingkajorn Mingkwan, Paosen Supakit
Аннотация
ETHNOPHARMACOLOGICAL RELEVANCE: Streptococcus pyogenes is a common cause of acute bacterial pharyngitis in children and adults. The global emergence of antibiotic resistance and increasing treatment failures have become serious clinical problems. Quercus infectoria galls have traditionally been used in Asian medicinal traditions as an astringent remedy for oral and pharyngeal conditions, including sore throat and related inflammations.
AIM OF THE STUDY: This study investigated the antibacterial activity and anti-virulence properties of Q. infectoria gall extract against S. pyogenes.
MATERIALS AND METHODS: The phytochemical composition of the extract was characterized using Liquid Chromatography-Mass Spectrometry (LC-MS). Antibacterial activity was assessed using minimum inhibitory (MIC) and bactericidal (MBC) concentration assays and time-kill studies. Anti-virulence effects were evaluated by hemolysis assays, biofilm inhibition was investigated by confocal laser scanning microscopy (CLSM), and structural changes in bacterial cells by scanning and transmission electron microscopy (SEM and TEM). Quorum sensing inhibition was examined using Chromobacterium violaceum, and expressions of virulence-related genes were analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).
RESULTS: LC-MS analysis indicated that the ethanolic gall extract of Quercus infectoria is rich in hydrolyzable tannins, especially gallotannins, along with phenolic acids and flavonoids. The extract exhibited potent antibacterial activity against Streptococcus pyogenes. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the reference strain S. pyogenes ATCC 19615 were 256 μg/mL and 512 μg/mL, respectively, while the clinical isolates (n = 9) exhibited MIC and MBC values ranging from 64 to 128 μg/mL. Time-kill assays demonstrated a 99.99 % reduction in bacterial viability within 6 h at 2 MIC. Significant reductions in hemolytic activity and biofilm integrity were observed (p < 0.05). CLSM revealed decreased viable bacteria and increased dead cells within biofilms, while SEM and TEM revealed structural damage to bacterial surfaces and cytoplasmic contents. Quorum sensing was inhibited, reducing violacein production. RT-qPCR indicated downregulation of virulence genes involved in protease secretion, capsule formation, and quorum sensing.
CONCLUSIONS: Q. infectoria gall extract effectively inhibited the growth and virulence of S. pyogenes, supporting the potential of the extract as a natural therapeutic agent against antibiotic-resistant streptococcal infections.
AIM OF THE STUDY: This study investigated the antibacterial activity and anti-virulence properties of Q. infectoria gall extract against S. pyogenes.
MATERIALS AND METHODS: The phytochemical composition of the extract was characterized using Liquid Chromatography-Mass Spectrometry (LC-MS). Antibacterial activity was assessed using minimum inhibitory (MIC) and bactericidal (MBC) concentration assays and time-kill studies. Anti-virulence effects were evaluated by hemolysis assays, biofilm inhibition was investigated by confocal laser scanning microscopy (CLSM), and structural changes in bacterial cells by scanning and transmission electron microscopy (SEM and TEM). Quorum sensing inhibition was examined using Chromobacterium violaceum, and expressions of virulence-related genes were analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).
RESULTS: LC-MS analysis indicated that the ethanolic gall extract of Quercus infectoria is rich in hydrolyzable tannins, especially gallotannins, along with phenolic acids and flavonoids. The extract exhibited potent antibacterial activity against Streptococcus pyogenes. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the reference strain S. pyogenes ATCC 19615 were 256 μg/mL and 512 μg/mL, respectively, while the clinical isolates (n = 9) exhibited MIC and MBC values ranging from 64 to 128 μg/mL. Time-kill assays demonstrated a 99.99 % reduction in bacterial viability within 6 h at 2 MIC. Significant reductions in hemolytic activity and biofilm integrity were observed (p < 0.05). CLSM revealed decreased viable bacteria and increased dead cells within biofilms, while SEM and TEM revealed structural damage to bacterial surfaces and cytoplasmic contents. Quorum sensing was inhibited, reducing violacein production. RT-qPCR indicated downregulation of virulence genes involved in protease secretion, capsule formation, and quorum sensing.
CONCLUSIONS: Q. infectoria gall extract effectively inhibited the growth and virulence of S. pyogenes, supporting the potential of the extract as a natural therapeutic agent against antibiotic-resistant streptococcal infections.