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Background and purpose: Dental caries is a pathological infectious disease. It begins with the formation of dental plaques which is a structurally and functionally organized biofilm. Streptococcus mutans is the most important bacterium in the formation of dental plaque and dental caries. This study aimed at evaluating the antibacterial and antibiofilm activity of Quercus infectoria galls against Streptococcus mutans. Materials and methods: The bacterial strain used in this study was Streptococcus mutans (ATCC: 25923). Extracts were prepared by Soxehlet apparatus and maceration. They were then dissolved in sterile distilled water to a final concentration of 0.16 to 10.00 mg/ml. The antimicrobial activities of the extracts were determined using well diffusion method. The antibiofilm activities of the extracts were examined in a microdilution assay using TTC. Statistical analysis was performed in SPSS V.18. Results: The methanol, ethanol, and acetone extracts of Quercus infectoria galls showed strong inhibitory effects against Streptococcus mutans. The MIC values of extracts were similar and ranged from 160µg/ml to 320µg/ml, whereas the MBC values ranged from 320µg/ml to 640µg/ml. Aqueous extracts of oak galls did not show antimicrobial activity. The extracts of Quercus infectoria galls strongly inhibited the formation of Streptococcus mutans biofilms at concentrations higher than 19.5µg/ml. Conclusion: The extracts of Quercus infectoria galls displayed similarities in their antibacterial activity against Streptococcus mutans. Also, they were found effective in preventing biofilm formation of Streptococcus mutans. The galls of Quercus infectoria are considered potentially good sources of antimicrobial agent

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Background and purpose: Due to the increasing importance of protecting human health and preserving the environment, drug resistance and water pollution have drawn significant attention. Nanoparticles have emerged as one of the most promising solutions, with cobalt nanoparticles being particularly interesting due to their unique properties. This study focuses on the green synthesis of cobalt nanoparticles using Mentha pulegium and investigates their potential antimicrobial and photocatalytic activities.
Materials and methods: n this experimenal study, cobalt nanoparticles were synthesized through green methods using M. pulegium aqueous extract. The synthesized nanoparticles were characterized using various analytical techniques, including UV-visible spectroscopy, SEM, EDX, FTIR, and XRD. Furthermore, the antibacterial effects of these nanoparticles were investigated against ATCC strains and ciprofloxacin-resistant strains. Their photocatalytic activity was evaluated for the degradation of methylene blue (MB) in the presence of NaBH4.
Results: XRD analysis revealed that the synthesized nanoparticles were amorphous, while SEM images showed irregularly shaped particles with an average diameter of 53.91 nm. The cobalt nanoparticles demonstrated excellent antibacterial activity. The maximum antibacterial effects were observed against ATCC strains, specifically K. pneumoniae (MIC and MBC values of 0.859 and 13.75 μg/mL, respectively) and S. aureus (MIC and MBC values of 1.72 and 27.5 μg/mL, respectively). For ciprofloxacin-resistant strains, the maximum effects were observed against E. coli (MIC and MBC values of 0.859 and 6.87 μg/mL, respectively) and P. mirabilis (MIC and MBC values of 0.859 and 1.72 μg/mL, respectively). These nanoparticles efficiently degraded methylene blue in the presence of NaBH4 within 30 minutes, following first-order kinetics with a rate constant of 0.0567 min^-¹.
Conclusion: The results showed that M. pulegium effectively contributed to the formation of nanoparticles, acting as a reducing, stabilizing, and capping agent. In this study, the synthesized cobalt nanoparticles exhibited significant antibacterial activity and effective dye degradation properties. These findings suggest the potential application of cobalt nanoparticles in various biological fields.