Abstract

      Background and Objectives: Antibiotic resistance in bacteria has actuated researchers toward evaluating many new antibacterial compounds of which are the thiazoles. In this research the inhibitory effects of novel thiazole derivatives were unraveled on Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa and Klebsiella pneumoniae and oxothiazole liver toxicity effects were assessed on mice.

       Methods: The antibacterial effect of thiazole derivatives was evaluated by measuring the halo zone with disk diffusion method and dilution procedure in microplate in order to discriminate the minimum inhibitory concentration (MIC) and the liver toxicity of oxothiazole, also, was discerned by injecting 160 mg/kg, 265 mg/ kg and 350 mg/kg doses to mice as well as scrutinizing the liver histopathology.

      Results: Derivatives utilized in experiment had no inhibitory effect on Pseudomonas aeruginosa and Klebsiella pneumoniae, though their inhibitory effect was observed on Staphylococcus aureus and Streptococcus agalactiae. For Staphylococcus aureus and Streptococcus agalactiae the diameters of growth inhibition zone were 8.9-22.3 mm and 16.1-25.6 mm, respectively and MIC of 50-200 and 25-100 µg/ml by order. Additionally, by increasing the injection dose of oxothiazole with 160 mg/ml, 265 mg/ml and 350 mg/ml doses, the hepatitis lesions and liver necrosis were observed in experimental mice.

       Discussion: The thiazole derivatives possessed more inhibitory trace on gram positive bacteria than gram negative ones. Furthermore, the likely presence of oxygen link to thiazole ring in tested compounds results in the enhancement of inhibitory potency of these substances. Besides, our results suggest that high doses of oxothiazole cause severe liver damage and rapid death less than 24 hours.

       Keywords: Thiazole derivatives, Antibacterial effects, Oxothiazole, Liver toxicity.

ABSTRACT
       Background and Objective: Anaerobic bacteria are the main cause of periodontitis. It has been shown that green tea and black tea have antibacterial effect. The aim of this study was to determine he antibacterial effect of Iranian green tea and black tea against Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia.
        Methods: Aqueous and methanolic extracts of Iranian green tea and black tea at concentrations ranging from 10 to 500 mg/ml were tested against standard strains of A. actinomycetemcomitans  (ATCC 33384), P. gingivalis (ATCC 33227) and P. intermedia (ATCC 25671) using agar disk diffusion, broth microdilution and determination of minimum inhibitory concentration.
         Results: P. gingivalis, A. actinomycetemcomitans and P. intermedia were sensitive to the methanolic extract of Iranian green tea at concentrations of 100-500 mg/ml, 10-500 mg/ml and 50-500mg/ml, respectively. P. gingivalis, A. actinomycetemcomitans and P. intermedia were sensitive to the methanolic extract of Iranian black tea at concentrations of 200-500 mg/ml, 20-500 mg/ml and 200-500 mg/ml, respectively. In addition, P. gingivalis, A. actinomycetemcomitans and P. intermedia were sensitive to the aquatic extract of Iranian green tea at concentrations of 200-500mg/ml, 100-500 mg/ml and 200-500 mg/ml, respectively.
        Conclusion: The aquatic and alcoholic extracts of Iranian green tea and black tea have antibacterial activity against A. actinomycetemcomitans, P. intermedia and P. gingivalis. Therefore, incorporation of Iranian black tea as an effective native herb could be beneficial for prevention of oral cavity diseases.
          Keywords: Tea, Green Tea, Antibacterial Agents, Anaerobic Bacteria.