چکیده (انگلیسی):

Objective: To investigate the chemical composition of a moderately polar extract
(CHCl3 soluble part of the MeOH–H2O extract) obtained from the aerial parts (leaves and
flowers) of Centaurea diluta Ait. subsp. algeriensis (Coss. & Dur.) Maire, a species
endemic to Algeria and Morocco on which no reports are available to date. To evaluate
in vitro the cytotoxic, antifungal and antimicrobial activities of this extract and the
cytotoxic and antimicrobial activities of its isolated secondary metabolites.
Methods: The cytotoxic effects of the extract were investigated on 3 human cancer cell
lines i.e. the A549 non-small-cell lung carcinoma (NSCLC), the MCF7 breast adenocarcinoma
and the U373 glioblastoma using a MTT colorimetric assay. Biological data
allowed to guide the fractionation of the extract by separation and purification on silica
gel 60 (CC and TLC). The isolated compounds which were characterized by spectral
analysis, mainly HR-ESIMS, HR-EIMS, UV and NMR experiments (1H, 13C, COSY,
ROESY, HSQC and HMBC) and comparison of their spectroscopic data with those reported
in the literature, were evaluated for cytotoxic activities on six cancer cell lines
(A549, MCF7, U373, Hs683 human glioma, PC3 human prostate and B16-F10 murine
melanoma). The direct and indirect antibacterial and antifungal activities were determined
using microdilution methods for the raw extract and TLC-bioautography and microdilution
methods against standard and clinical strains for the isolated compounds.
Results: The raw extract reduced cell viability with IC50s of 27, 25 and 21 mg/mL on
A549, MCF7 and U373, respectively. Five secondary metabolites: two phenolic compounds
(vanillin 1, paridol 3), a lignan [(−)-arctigenin 2] and two flavonoid aglycones
(eupatilin 4 and jaceosidin 5), were then isolated from this extract. Moderate cytotoxic
effects were observed for (−)-arctigenin 2 (IC50s: 28 and 33 mM on Hs683 and B16-F10,
respectively), eupatilin 4 (IC50s: 33 and 47 mM on B16-F10 and PC3, respectively) and
jaceosidin 5 (IC50s: 32 and 40 mM on PC3 and B16-F10, respectively).
Conclusions: All the isolated compounds were described for the first time from this
species. Although inactive against 7 tested microorganisms (fungi, bacteria and yeast,
human or plant pathogens), the raw extract was able to potentiate the effect of beta-lactam