Background Essential oils are of great interest for their analgesic and anti-inflammatory properties. We aimed to study the content of the essential oil of the Origanum vulgare of the Armenian highlands (OVA) in different periods of vegetation and to investigate its antinociceptive and anti-inflammatory effects in mice ( in vivo ) and cytotoxic action in cultured cells ( in vitro ). OVA essential oil was extracted from fresh plant material by hydro-distillation. Methods For OVA essential oil contents determination the gas chromatography-mass spectrometry method was used. Formalin and hot plate tests and analysis of cell viability using the methyl-thiazolyl-tetrazolium (MTT) assay were used. Results The maximal content of β-caryophyllene and β-caryophyllene oxide in OVA essential oil was revealed in the period of blossoming (8.18% and 13.36%, correspondently). In the formalin test, 4% OVA essential oil solution (3.5 mg/mouse) exerts significant antinociceptive and anti-inflammatory effects ( P = 0.003). MTT assay shows approximately 60% cytotoxicity in HeLa and Vero cells for 2.0 μL/mL OVA essential oil in media. Conclusions The wild oregano herb of Armenian highlands, harvested in the blossoming period, may be considered as a valuable source for developing pain-relieving preparations.

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Every day, a lot of people suffer from different types and intensity pain. Pain is probably the most common symptomatic reason to seek medical consultation. Unfortunately, despite improved knowledge of underlying mechanisms and better treatments, many people who have any type of pain receive inadequate care and non-effective drugs. Although the pain transmission channels are intensively studied, and the drug market is constantly replenished with new analgesics, it is well known that existing medications for the treatment of pain are often associated with serious side effects and rapid development of tolerance (moderate efficiency, physical dependence, respiratory arrest, suffocation, cardiac arrest, etc.). Thus, there is a need for new, more effective remedies. For this reason, despite the presence of a large number of anti-pain drugs, research and development of more effective and safe means for anaesthesia continue. Natural resources, particularly venoms, are a perspective supplier of antinociceptive and anti-inflammatory medicines. Venoms are complex mixtures of bioactive substances with high selectivity for physiological processes, including modulation of different ion channels, receptors function, and metabolic pathways. Thus, venoms represent an extensive source of molecules for the development of therapeutic agents. The goal of this study was the comparison of antinociceptive effects of five different cobras' venom antinociceptive action of cobras’ venoms was carried out under the same experimental conditions, at the same doses, during acute and inflammatory pain in mice in “formalin test”. To avoid toxic effects, the sublethal dose of each cobra venom (approximately 1/10 LD 50 ) was selected. The behavioural study showed that all tested venoms had a slight sensitizing effect in the acute phase during the first 5 min. In the second, inflammatory phase (16*25min), all tested cobra’s venoms (3μg/0.1ml, intraperitoneal) showed significant antinociceptive action, particularly the Naja naja oxiana venom decreased pain sensitivity by 48.4%, the Naja naja pallida venom by 75.4%, the Naja naja nigricincta venom by 38.5%, the Naja naja kaouthia venom by 33.2%, and the Ophiophagus Hannah venom by 78.3%, (p<0.05). The analgesic capacity of Analgin and Diclofenac under the same conditions were 77.9% and 88.7%, respectively. Thus, the Naja n. pallida and Ophiophagus Hannah venoms have shown the most expressed antinociceptive action, and they have competitive effectiveness compared to classic analgesics. They may be chosen as the most effective from tested venoms for further development of pain relief remedies.