Etude phytochimique et valorisation des extraits bruts des feuilles de grenadier d’Ain Témouchent « Punica granatum» par l'étude de son activité antioxydante

Abstract

The pomegranate «Punica granatum" is a shrub of the family Punicacea, which can reach 6m in height. It is one of the oldest cultivated fruit species in the world. In recent decades, this tree has become more and more important and its culture has moved from the traditional character to develop into commercial orchards. It is considered a medicinal plant which has not yet revealed all of its secrets due to its bioactive components with therapeutic properties obtained in its extracts. The different parts of this plant and their extracts (juice, seed oil, bark and leaves) have shown strong biological activities. The present study is part of the development of the leaves of this medicinal plant "Punica granatum" from Ain Témouchent region, in order to identify its bioactive molecules with antioxidant properties. In this context, this investigation is based on a set of experiments carried out such as phytochemical tests, the determination of polyphenols and flavonoids, then the evaluation of the antioxidant power of the different crude extracts by two methods, namely the reducing power of iron. FRAP and the trapping of the DPPH radical. Phytochemical screening was carried out using simple and standard methods and the results obtained indicated that the three extracts are rich in: tannins, flavonoids, alkaloids, free quinones and reducing compounds. The determination of polyphenols and flavonoids reveals that the crude aqueous extract showed the best content of polyphenols and flavonoids with rates estimated at 38.8 mgEAG / gMS and 1.84 mgEC / gMS respectively. According to the DPPH free radical trapping method, the hydro-methanolic fraction exhibited excellent antioxidant activity compared to the two other extracts tested with an IC50 equal to 0.020 mg / ml. The same extract showed the best ability to reduce iron in the FRAP method. Finally, at the end of this work we deduce that the leaves of "Punica granatum" make it a precious medicinal plant with many medicinal properties. This reveals biological evidence that encourages its use as a natural antioxidant.