Alexandra Bukovská, Štefan Čikoš, Štefan Juhás, Gabriela Il’ková, Pavol Rehák, and Juraj Koppel*Author informationArticle notesCopyright and License informationDisclaimer
Abstract
We examined the anti-inflammatory effects of the combination of thyme and oregano essential oil dietary administered at three concentrations (0.4% thyme and 0.2% oregano oils; 0.2% thyme and 0.1% oregano oils; 0.1% thyme and 0.05% oregano oils) on mice with TNBS-induced colitis. Treatment of colitic animals with the essential oils decreased the mRNA levels of pro-inflammatory cytokines IL-1β, IL-6, GM-CSF, and TNFα, especially after application of the medium dose. The medium dose of the essential oils significantly lowered the amount of IL-1β and IL-6 proteins too. Moreover, administration of the medium dose decreased the mortality rate, accelerated the body weight gain recovery, and reduced the macroscopic damage of the colonic tissue. Our results indicate that combined treatment with appropriate concentrations of thyme and oregano essential oils can reduce the production of proinflammatory cytokines, and thereby attenuate TNBS-induced colitis in mice.Go to:
1. INTRODUCTION
Intestinal inflammatory diseases are a serious problem in human as well as veterinary medicine. The etiology of these diseases is often multifactorial and the underlying molecular mechanisms are poorly understood [1]. The current medicinal therapies for inflammatory gut diseases involve treatment with nonsteroidal anti-inflammatory drugs, antibiotics, corticosteroids, and immunosuppressant, but the application of these drugs is limited due to their toxicity and side effects [2]. Therefore, there is an increased interest in finding an alternative treatment with fewer side effects.
There is evidence supporting the therapeutic usefulness of oral administration of various plant extracts in inflammatory diseases of the gut. Experimental data obtained in mouse and rat models of colitis suggest that the beneficial effects of the plant extracts could be mediated by their effects on mucosal cytokines production or/and action [3–9]. Increased levels of proinflammatory cytokines [IL-1, IL-6, IL-8, TNFα, IL-12, and IFNγ] were found in inflamed intestinal mucosa in various animal models and humans [10–13], as well as in farm animals [14, 15].
Thyme (Thymus vulgaris L.) and oregano (Origanum vulgare L.) are aromatic plants of the Mediterranean flora commonly used as spices and for medicinal purposes. Like other various Thymus species, thyme is traditionally used for its antiseptic, antispasmodic, and antitussive effects. Furthermore, thyme possesses antimicrobial, antifungal, antioxidative, and antiviral properties [16–19]. The essential oil derived from thyme (T. vulgaris L.) is a mixture of monoterpenes and one of the main compounds of this oil is a natural terpenoid thymol [20]. Thymol exhibits multiple biological activities including anti-inflammatory [21], immunomodulating [22], antioxidant [23], antibacterial [24, 25], antifungal [26], and free radical scavenging properties [27]. Oregano is recognized for its potential therapeutic role because of its diaphoretic, carminative, antispasmodic, antiseptic, and tonic properties. Oregano, (Origanum syriacum L.) similar to thyme, evinces antioxidant and antimicrobial activities [28] and some reports deal with its antimutagenic and anticarcinogenic effects [29]. Origanum essential oil is obtained by steam distillation of O. vulgare and its major compounds are carvacrol and thymol [30]. Origanum essential oil is known to possess antimicrobial, antifungal, and antioxidant activities [31, 32].
The aim of our study was to examine possible beneficial effects of thyme and oregano essential oils on intestinal inflammation. The results of our preliminary experiment suggested that the administration of thyme oil in combination with oregano oil could be more effective in improvement of trinitrobenzene sulphonic acid (TNBS)-induced colitis than the separate administration of these essential oils. In the present study, we evaluated further the effect of administration of three different doses of thyme and oregano oil combination on TNBS-induced colitis in mice.Go to:
2. MATERIALS AND METHODS
2.1. Animals and treatment
Male 7-week-old Balb/c mice weighing 18–25 g were purchased from Velaz (Prague, Czech Republic). The animals were maintained under standard conditions of temperature (21 ± 1°C), relative humidity (55 ± 10%), and 12 hours/12 hours light/dark cycle. All mice were housed in specific pathogen-free conditions. All animal experimentations were reviewed and approved by the Ethical Committee of the Institute of Animal Physiology.
After a period of adaptation, weight-matched animals were randomized into five groups: group A (20.2 ± 0.971 g), group B (20.6 ± 0.75 g), and group C (20.71 ± 0.844 g), mice with TNBS-induced colitis treated with three different doses (see Table 1) of thyme and oregano oil combination; group D (21.03 ± 1.025 g), mice with TNBS-induced colitis; group E (18.74 ± 1.189 g), sham-treated mice.
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