Investigation of the phytochemicals and bioactivity potential of essential oil from Nepeta curvidens Boiss. & Balansa

Abstract

Nepeta curvidens is a plant of the mint family and an important species of the genus Nepeta. The main habitat of the N. curvidens in the Garin Mountains in Lorestan Province, Iran. Although locals have used N. curvidens as a food flavoring agent for years, few studies have been conducted on its phytochemical and biological properties. The chemical constituents of N. curvidens essential oil and then its biological properties were studied in detail in this investigation. N. curvidens essential oil was prepared from the aerial parts of the plant using the hydrodistillation method and its chemical composition was analyzed by the GC-MS method. Antimicrobial, antifungal, anti-Leishmania, and cytotoxic activities of the essential oil were investigated in vitro. In addition, antinociceptive and anti-inflammatory effects were evaluated in vivo. Most of N. curvidens essential oil compositions are composed of trans-caryophyllene (17.53%), allo-spathulenol (13.41%), germacrene D (10.12%), bicyclogermacrene (9.36%), α-pinene (9.12%), and β-phellandrene (6.87%). The highest antimicrobial and antifungal effects were observed against L. monocytogenes (MIC=156.25 μg/ml) and K. marxianus (MIC=625 µg/ml), respectively. Concentration-dependent effects were detected in the treatment of L. major, so that the number of macrophages infected with amastigote dropped significantly with higher concentrations. The essential oil showed the highest effect on the lung cancer cell line (A549) with the lowest IC50 (133.2μg/mL). The most resistant cell line to the essential oil was bladder cancer (C450) with an IC50 of 430.69 µg/mL. SI 19.49 index indicated high immunity of the essential oil on macrophage lines. Compared with morphine analgesic, the highest pain control effect of the essential oil was observed in primary and secondary phases at 100 mg/kg concentration in rats. At 100 mg/kg concentration, reduced swelling of the paw and ear was observed in mice compared to the dexamethasone anti-inflammatory drug. The essential oil presents remarkable therapeutic properties such as antifungal, antibacterial, anti-inflammatory properties that probably attributed to the presence of an important trans-caryophyllene compound. Outstandingly, the essential oil has low toxic effects on the normal line and high antitumor properties against cancer cells. Therefore, it is expected to be used in the preparation of less toxic drugs than chemical ones, although more studies are required.