Étude phytochimique et évaluation des activités antioxydante, antibactérienne et cytotoxique de deux plantes du genre Phagnalon (Asteraceae)

Abstract

Our phytochemical and biological works concerned the aerial parts of two species belonging to Asteraeae family : Phagnalon saxatile (L) Cass. and Phagnalon sordidum L. Several chromatographic methods allowed us to isolate ten products from the n-butanol and ethyl acetate extracts of Phagnalon saxatile from which one is new, and twenty one products from Phagnalon sordidum. Structures were determined by different spectral methods: nuclear magnetic resonance with different applications (NMR 1H, NMR 13C, COSY, HSQC and HMBC), the mass spectrometry, UV, acid hydrolysis as well as comparison with literature data. 4 methods were used to evaluate the antioxidant activity of Phagnalon sordidum and Phagnalon saxatile. The latter showed a good activity by the use of 4 methods: DPPH, ABTS, CUPRAC and superoxide radical scavenging activity by alkaline DMSO whereas Phagnalon sordidum exhibited a moderate activity with DPPH and CUPRAC tests. Furthermore, petroleum ether and chloroform extracts from Phagnalon saxatile showed moderate antibacterial activity against the tested strains. The isolated products (1-O- β-D-glucopyranosyl-1,4-dihydroxy-2-((E) 2-oxo-3-butenyl) benzene, 1-O-β-glucopyranosyl- 2(3’,3’-diméthylallyl) hydroquinone and Potassium 4-hydroxy-3-methoxybenzoique acide methyl ester-5-sulfate) from Phagnalon saxatile showed a moderate cytotoxic activity by the use of MTT method.