Recherche et détermination structurale des métabolites secondaires de deux espèces appartenant à la famille Fabaceae

Abstract

This work is devoted to the phytochemical study of two species, Lotus roudairei Bonnet and Genista ferox Poiret belonging to Lotus and Genista genus respectively of the Fabaceae family. Lotus roudairei specie has never been subject of a phytochemical or a biological study. The aim of the present work is isolation and structural determination of the isolated products from different extracts belonging to the mentioned species, as well as the in-vitro evaluation of the antioxidant activity and the antiproliferative activity against Human cancer cells (HeLa) of extracts from both species. The chemical investigation of CH1, AE1 et BU1 extracts of the aerial parts of Lotus roudairei led to the isolation and characterization of 15 compounds of various skeletons: steroids, acids, flavonoids and isoflavonoids. The n-butanol extract of Genista ferox gave 3 compounds. The isolation and purification of isolated compounds were carried out by combining different chromatographic methods. Their structural determination was achieved through the use of spectroscopic techniques, such as UV spectroscopy, 1D NMR (1H, 13C), 2D NMR (COSY, HSQC and HMBC), HPLC/TOF-MS and GC/MS and by comparison with literature data. The quantification of phenolic acids and flavonoids in extracts of both species was performed by HPLC-TOF/MS. The results revealed the presence of 13 phenolic acids and 10 flavonoids in Lotus roudairei and 44 compounds comprising 17 organic and phenolic acids and 27 flavonoids and phenolic compounds in Genista ferox. The antioxidant activity of CH1 and AE1 extracts of Lotus roudairei was estimated by the DPPH test and β-Carotene bleaching assay. The AE1 extract exhibited the most important antioxidant activity compared to BHA used as standard. The antioxidant activity of CHT, AET, BUT and MET extracts from stems and CHF, AEF, BUF and MEF extracts from leaves of Genista ferox was evaluated by the DPPH test. The AET and AEF extracts showed significant antioxidant activity compared with ascorbic acid used as standard. Concerning the antiproliferative activity, the results showed that the BU1 extract of Lotus roudairei and the two extracts BUT and BUF of Genista ferox showed the lowest activity against HeLa cells (carcinoma of the human uterine cervix), while the ME1 extract of L.roudairei and the AET extract of G.ferox showed the highest activity against HeLa cells.