Antinociceptive activity of Thyme (Thymus vulgaris L. ) and interactions with neurotropics and analgesics

The plant world represents an important source of potential therapeutic agents, but concomitant administration of herbal and conventional medications may result in interactions with subsequent beneficial or adverse effects. This study was designed to examine the analgesic effect of thyme tincture and thyme syrup, two commonly used thyme formulations, and their interactions with codeine, paracetamol, pentobarbital and diazepam in mice. The identification and quantification of thymol and carvacrol were carried out by GC/MS and GC/FID. The analgesic activity was studied using a hot plate method. Effects of thyme syrup on diazepam-induced motor coordination impairment in rotarod test and on pentobarbital-induced sleeping time were also determined. Thymol (175.3 µg/mL and 9.73 µg/mL) and carvacrol (10.54 µg/mL and 0.55 µg/mL) concentrations were measured in tincture and syrup, respectively. Thyme syrup and tincture exhibited effective analgesic activity in the hot plate pain model. Pretreatment with thyme formulations reduced analgesic activity of codeine, and potentiated the analgesic activity of paracetamol. Co-administration of thyme formulations has led to potentiation of diazepam and pentobarbital depressive central nervous system effects. Thyme formulations interacted with tested conventional drugs, probably through interference with their metabolic pathways and succeeding altered concentrations and pharmacological effects.

Effects of pharmaceutical formulations containing thyme on carbon tetrachloride-induced liver injury in rats.

BACKGROUND: Herbal supplements are widely used in the treatment of various liver disases, but some of them may also induce liver injuries. Regarding the infuence of thyme and its constituents on the liver, conflicting results have been reported in the literature. The objective of this study was to examine the influence of two commonly used pharmaceutical formulations containing thyme (Thymus vulgaris L.), tincture and syrup, on carbon tetrachloride-induced acute liver injury in rats. METHODS: Chemical composition of investigated formulations of thyme was determined by gas chromatography and mass spectrometry. Activities of enzyme markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured using the kinetic spectrophotometric methods. Liver morphology was characterized by light microscopy using routine hematoxylin and eosin staining. RESULTS: Thymol was found to be predominant active constituent in both tincture and syrup. Investigated thyme preparations exerted antioxidant effects in liver by preventing carbon tetrachloride-induced increase of lipid peroxidation. Furthermore, co-treatment with thyme preparations reversed the activities of oxidative stress-related enzymes xanthine oxidase, catalase, peroxidase, glutathione peroxidase and glutathione reductase, towards normal values in the liver. Hepatotoxicity induced by carbon tetrachloride was reflected by a marked elevation of AST and ALT activities, and histopathologic alterations. Co-administration of thyme tincture resulted in unexpected exacerbation of AST and ALT values in serum, while thyme syrup managed to reduce activites of aminotransferases, in comparison to carbon tetrachloride-treated animals. CONCLUSIONS: Despite demonstrated antioxidant activity, mediated through both direct free radical scavenging and activation of antioxidant defense mechanisms, thyme preparations could not ameliorate liver injury in rats. Molecular mechanisms of diverse effects of thyme preparations on chemical-induced hepatotoxicity should be more in-depth investigated.