Contribution à l’étude phytochimique et biologique de deux plantes médicinales Thapsia garganica L. et Prunus persica L.

Abstract

Plants natural extracts contain a variety of biologically active molecules. In this regard, as a part of the valuation of two medicinal plants Prunus persica L. (leaves) and Thapsia garganica L. (leaves and roots), the focus of the present study is set on investigating the phytochemical composition and biological activity of different extracts from these two plants. On the one hand, selective extraction of flavonoids (butanol fraction, ethyl acetate and ether), tannins, saponosides and alkaloids gave acceptable yields varying between 0.33% and 3.62% for both plants. However, the best yield was obtained in the essential oils of T. garganica leaves (18.10%). On the other hand, total phenolic contents of methanol and aqueous extracts of P. persica leaves were respectively (2.5; 1.14 mg EAG / 100 mg DM) while those of methanolic extracts of T. garganica leaves and roots were respectively 2.21 and 1.63 mg EAG / 100 mg DM. The GC/MS analysis of essential oils from T.garganica leaves revealed several compounds such as: (+) - 3-Carene, 10- (acetylmethyl) (25.69%), furfuryl alcohol (10.96%), Furfural (7.69%), Ethanone, 1- (1H-pyrrol-2-yl) (6.49%), Heptanoic acid (6.17%), Eugenol (4.24%) and Butyrovanillone (2.57%). Separation by column chromatography allowed us to obtain 06 compounds belonging to flavonoids’ family, which were subsequently identified by NMR 1H and NMR 13C. The evaluation of the DPPH• free radical scavenging power showed remarkable antioxidant potential of all tested extracts. In Frap assay, a strong antioxidant capacity was noted in all extracts compared to that of ascorbic acid. The antibacterial activity of the different extracts was evaluated against seven bacterial strains. All extracts exhibited significant inhibition against Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus cereus and Staphylococcus aureus. Regarding the antifungal activity, the method of radial growth on solid medium against two fungal strains, methanolic extract of the roots of T.garganica showed a significant inhibition against Aspargillus flavus by limiting fungal growth over a diameter of 46 mm. The in vivo antibacterial activity of T. garganica leaves extracts was assessed against Pseudomonas aeruginosa on local rabbits. The obtained results indicated that diethyl ether extract inhibited the strain’s growth for a period of seven days, with a remarkable decrease in wound sizes and temperature degrees.