CHEMICAL COMPOSITION OF THE ESSENTIAL OIL OF MENTHA SPICATA L. FROM TUNISIA AND ITS BIOLOGICAL ACTIVITIES

ABSTRACT In the present investigation, essential oil (EO) and methanolic extract of Tunisian Mentha spicata leaves were tested for their chemical composition and biological activities. Results showed that EO was characterized by the predominance of oxygenated monoterpenes (92.18%), followed by monoterpene hydrocarbons and sesquiterpenes whose respective amounts were 2.74 and 3.1% of the whole EO. The main volatile compound of M. spicata EO was L‐menthone, accounting for 32.74% of the total volatiles, followed by pulegone (26.67%). The phenolic composition of methanolic extracts was determined by reversed‐phase high‐performance liquid chromatography. The major flavonoid component was apigenin with a mean concentration of 38.4 mg/100 g dry weight. M. spicata leave extract tested for their antioxidant and antibacterial activities showed a significant antiradical and superoxide anion scavenging capacity in addition to the great potential for antimicrobial activities against the bacteria tested. PRACTICAL APPLICATIONS Spearmint (Mentha spicata L.) is an aromatic plant belonging to the Lamiaceae family. M. spicata L. is commercially cultivated in many regions of the world. Spearmint oil has economical importance and is used in perfumery, confectionary and pharmaceutical preparations. Tunisia is blessed with a rich source of aromatic plants, many of which have not been previously investigated for their chemical constituents and biological potentials. Among these plants, we can mention M. spicata L. (Lamiaceae), which is largely distributed from the humid to the upper arid regions. This work was carried out as a first step for a chemical and biological activity of Tunisian M. spicata through phenolic and essential oil composition. A further isolation and purification of M. spicata phenolics and volatiles will be associated with an application in food industry as antioxidants, additives for food preservation and for enhancing their nutritional value and organoleptic quality. Furthermore, a pharmacological study could be established through in vivo assays in order to discover new anticarcenogenic, anti‐inflammatory, antimutagenic and other activities of M. spicata. Such results could be used in pharmaceutical formulations, leading to new human drugs from this medicinal plant.