Etudes phytochimique et pharmacologique d’une plante saharienne et d’espèces de la région des Aurès.

Abstract

Our goal in this work was to search the secondary metabolites of flavonoids type from two species from Asteraceae and Cistaceae families in order to search new natural compounds of biological interest. Thirteen (13) extracts from different species including twelve (12) from the Aures regions were subjected to a phytochemical screening. On the basis of these preliminary results, the phytochemical investigation of the aerial parts two species, Pulicaria inuloides and Cistus albidus from the Bechar and the Aures regions respectively was carried out. This approach allowed the isolation of twelve natural compounds, among which eleven flavonoids, one phenolic compound as well as two acetyl derivatives of one of the isolated compounds were characterized using spectroscopic methods such as UV-Visible, IR and NMR. The biological activities in vitro (antioxidant and antibacterial activity) as well as the total phenolic and flavonoids compounds of the various extracts were discussed. We also reported the evaluation of the in vitro antiprotozoal activity of the two species Pulicaria inuloides and Cistus albidus against Leishmania amazonensis, Trypanosoma cruzi and Acanthamoeba castellanii str. Neff. The bioguided fractionation of the CHCl3 extract from the aerial part of P. inuloides leads to the isolation and characterization of quercetagetin-3,5,7,3'-tetramethylether as the active ingredient. Two acetylated derivatives were prepared from this natural compound and these three compounds were evaluated for their activities against the promastigote form of L. amazonensis. All these compounds exhibited moderate leishmanicidal activity with IC50 values ranging from 0.234 to 0.484 mM and low toxicity to macrophage cells (CC50 ranging from 0.365 to 0.664 mM). This study reported the antiprotozoal evaluation of Pulicaria inuloides for the first time and the results show that this species can be considered as a source of anti-leishmanicidal agents. The bioguided fractionation of the active extract of CHCl3 from C. albidus against T. cruzi led to the isolation of two fractions F6,4 and F6,5 which showed also a potent activity up to 100 μg/ml. The bioguided fractionation of the active extract of AcOEt from the aerial part of C. albidus against A. castellanii led to the isolation of a fraction F14A which showed a significant activity up to 100 μg / ml. Fractions F6,4 ; F6,5 and F14A consists of product mixtures, which have not been separated. We have also described the chemical compositions of the essential oils of Pulicaria inuloides and Cistus albidus. The major compounds of the species C. albidus are manool and 15,16-dinorlabd-8(20)- en-13-one whose skeleton of type labdane is a specific marker in this genus, these compounds are not described in samples from other regions and in particular in the Mediterranean regions (Spain and France) that appeared in the literature. The major compounds of the species Pulicaria inuloides are: δ- cadinene, α-muurolene, γ-cadinene, α-epi-cadinol and α-cadinol are not present in the other samples of Pulicaria inuloides from other areas published in the literature. In this study, the mineral content (inorganic elements) of 21 isolated extracts of various aromatic species of the Sahara (P. inuloides) and the Aures region (Euphorbia helioscopia L., Peganum harmala L., Daphne gnidium L., Calendula algeriensis L., Bunium incrassatum L., Echinops ritro L. Marrubium deserti de Noè., Juniperus oxycedrus L., Juniperus phoenicea L., Marrubium vulgare L., Cedrus atlantica (Endl.) Manetti and Thymus algeriensis L.) were also determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS) . The results obtained showed higher concentrations of Ca, K, Mg, Na and S (mg/kg) in the different plant extracts.