Etude écophysiologique, développement et importance des plantes médicinales du genre Mentha dans le Parc National d’El-Kala (Nord-Est Algérie)

Abstract

Mentha species are widely used by native habitants of El-Tarf region, as condiment, flavor or herb in culinary preparations but also used for therapeutic properties as carminative, sedative, antispasmodic and well known to treat stomach pain. The aim of this work was first to inventory and geolocalisate Mentha species of the National Park of El-Kala and then to investigate the total phenolics, flavonoids and tannins content and the in-vitro antioxidant activities of methanolic extracts and essential oils, then to evaluate the chemical composition of essential oils obtained from aerial parts of six wildMentha species: M. aquatica, M. arvensis, M x piperita, M. pulegium, M. rotundifolia and M x villosa. Chemical composition was analyzed by GC-MS method and biological activities investigated by DPPH, B-carotene bleaching and ion chelating assays for the antioxidant activity, as well as the inhibition of acetycholinesterase. The methanol extracts of mints were rich in phenolic compounds and exhibited a powerful antioxidant activity ranged from7.5µg/mlto44.66 µg/ml,which varied significantly among species. M. aquatica stands out with an efficient antioxidant ability which is correlated to the high total phenolics contents, followed by M. arvensis and M. piperita with very close values, comparing to M. pulegium, M. rotundifolia and M. villosa with lowest values. Qualitative and quantitative variations were observed among species. The highest yield of oils, obtained by hydrodistillation, was recorded for M. pulegium with 1.8%. A total of 27 compounds were identified with the predominance of oxygenated monoterpenes such as menthofurane (73.38%), rotundifolone (65.99%), pulegone (59.12%), menthol (49.89%), menthone (20.84%), neomenthol (20.76%), 1.8-cineol (18.16%) and β-caryophyllene (12.55%). In general, M. aquatica exhibited the strongest antioxidant level with IC50 of 0.69±0.06 mg/ml assessed by DPPH assay, 0.16±0.02 mg/ml by β-Carotene bleaching and 1.73±0.17 mg/ml by ferrous ion chelating method. Whereas M. arvensisstood out with IC50 of 27.5mg/ml for acetylcholinesterase inhibitory.These results show that Mentha species from NPEK have a great potential of polyphenols which can be used as a natural food preservative and antioxidant source. Moreover, mints could be exploited for their pharmacological application in order to prevent induced diseases relied to oxidative stress.