الخلاصة:
The objective of our work is to carry out phytochemical and biological studies on the Algerian plants Inula conyza DC, Centaurea incana Desf belonging to the Asteraceae family, and Lathyrus latifolius L of the Fabaceae family. The phytochemical investigation of the two species: Inula conyza DC and Centaurea incana Desf allowed the separation of 10 products: two sesquiterpenes, six flavonoids and two phenolic compounds. The structural determination was based on the combination of 1D (1H NMR, 13C NMR) and 2D (COSY, HSQC, HMBC) NMR spectroscopic methods. Furthermore, a GC-MS analysis of the chloroform extract of Centaurea incana allowed the detection of 28 compounds, of which the lignan arctigenin was the main product with 33.97% of the total composition of the extract. The evaluation of the antioxidant potential of Inula conyza DC and Centaurea incana Desf was carried out by different methods: DPPH, ABTS, CUPRAC, GOR, reducing power, phenanthroline and β-Carotene. The results showed that the ethyl acetate extract of both species
was an excellent antioxidant agent, which was confirmed by the high levels of phenolic compounds. The detection and the quantization of flavonoids and phenolic acids present in the ethyl acetate and n-butanol extracts of the specie Lathyrus latifolius were carried out by LC-ESI/MS, which allowed the identification of 29 phytochemicals compounds: 11 phenolic acids, 16 flavonoids, 1 coumarin and a hydroxybenzaldehyde. The quantification of polyphenols and total flavonoids of Lathyrus latifolius L extracts was carried out, as well as the evaluation of antioxidant activities. The ethyl acetate and butanol extracts showed the best antioxidant activity.
