Carvacrol (2-methyl-5-(1-methylethyl)-phenol) is a predominant monoterpenic phenol which occurs in many essential oils of the family Labiatae including Origanum, Satureja, Thymbra, Thymus, and Corydothymus species. This study was designed to investigate the hepatoprotective and antioxidant properties of carvacrol on D-galactosamine (D-GalN)-induced hepatotoxicity and oxidative damage in male albino Wistar rats. D-GalN hepatotoxic rats exhibited elevation in the activities of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase, and lipidperoxidative markers such as thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides. Activities of enzymatic antioxidants (superoxide dismutase, catalase, and glutathione peroxidase) and the levels of non-enzymatic antioxidants (vitamin C, vitamin E, and reduced glutathione) in the plasma, erythrocytes, liver, and kidney decreased in the hepatotoxic rats. Oral administration of carvacrol for 21 days brought these parameters towards normal. The biochemical observations were supported by histological studies of rat liver and kidney tissues. These results suggest that carvacrol could afford a significant hepatoprotective and antioxidant effect against D-GalN-induced rats.
Aim/Background:Medicinal plants have ability to resist microorganisms by synthesizing secondary metabolites such as phenols. Rosmarinic acid (RA) is a phenylpropanoid widely distributed in plants and well known as therapeutic and cosmetic agent. Methicillin-resistant Staphylococcus aureus (MRSA) which is resistant to all kinds of β-lactams, threatens even most potent antibiotics. To improve the efficiency of antibiotics against multi-drug resistant bacteria and to reduce the antibiotic dose, the antibacterial activity and the synergistic effect of RA with standard antibiotics against S. aureus and MRSA was investigated.Materials and Methods:Antibacterial activity of RA against S. aureus and a clinical isolate of MRSA was evaluated by agar well diffusion method. Minimum inhibitory concentration (MIC) of RA was determined by broth dilution method. Synergism of RA with various antibiotics against S. aureus and MRSA was studied by broth checkerboard method and time-kill kinetic assay. Effect of RA on microbial surface components recognizing adhesive matrix molecules (MSCRAMM’s) of S. aureus and MRSA was studied using sodium dodecyl sulfate - polyacrylamide gel electrophoresis.Results:MIC of RA was found to be 0.8 and 10 mg/ml against S. aureus and MRSA, respectively. RA was synergistic with vancomycin, ofloxacin, and amoxicillin against S. aureus and only with vancomycin against MRSA. The time-kill analysis revealed that synergistic combinations were a more effective than individual antibiotics. MSCRAMM’s protein expression of S. aureus and MRSA was markedly suppressed by RA + vancomycin combination rather than RA alone.Conclusion:The synergistic effects of RA with antibiotics were observed against S. aureus and MRSA. RA showed inhibitory effect on the surface proteins MSCRAMM’s. Even though RA was shown to exhibit a synergistic effect with antibiotics, the MIC was found to be higher. Thus, further studies on increasing the efficacy of RA can develop it as an adjuvant for antibiotics.
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