الخلاصة:
This work concerns the phytochemical study of Centaurea sempervirens synonym:
Cheirolophus sempervirens L. from Asteraceae family. This species was collected from
Constantine area. After extraction by maceration followed by chromatographic separations
and purifications on columns of grafted silica gel (diol), TLC and semi-preparative reverse
phase HPLC, 16 compounds were isolated from the chloroform and ethyl acetate extracts.
Among these compounds, 15 were identified. The structure elucidations of these compounds
were carried out by the combination of the results obtained from the analyses the high
resolution positive electrospray ionization mass spectra, 1D NMR (1H, 13C) and 2D NMR
(COSY, HSQC et HMBC) spectra as well as by comparing the results with the data of the
literature.
The chemical composition of the essential oil of aerial parts of C. sempervirens studied by
GC-FID and GC-MS, showed the presence of several chemical groups from which 6,10,14-
trimethylpentadeca-2-one (12,4%) and epi-torilenol (5,1%) were the major components. This
study was carried out for the first time.
The total phenolic and total flavonoid contents of the three extracts were determined, EtOAc
extract had the highest phenolic and flavonoid contents followed by n-butanol extract.
This step was followed by the evaluation of the in vitro antioxidant activity using two
methods: 1, 1- diphenyl-2-picrylhydrazyl radical scavenging (DPPH) and cupric ion reducing
antioxidant capacity (CUPRAC). The best result was obtained for the AcOEt with CUPRAC
method, where its effect is very closer to quercetin used as standard.
The result of the in vitro antibacterial activity of the three extracts by the disk-diffusion
method in an agar medium showed no significant activity.
