Métabolites secondaires et principes actifs

Abstract

The present work focuses on a phytochemical and a biological study of two endemic Algerian species, Berberis hispanica from the family Berberidaceae and Stachys brachyclada from the family Lamiaceae. The phytochemical study of the ethyl acetate and n-butanol extracts of the aerial parts of the Berberis hispanica species has led to the isolation and identification of a phenolic acid, the first isolated caffeic acid in this species and two flavonoids:  Tamarixetin; Rutin.The structural identification has been performed using spectroscopic analysis techniques (MS,1H NMR, 13C NMR), supported by a comparison with literature data. As for the biological study of AcOEt extracts, n-BuOH and flavonoid tamarixetin of this species, it has given interesting results. The n-BuOH extract has shown a better richness in polyphenols and flavonoids compared to the AcOET extract. The two extracts; AcOEt and n-BuOH have demonstrated a very good antibacterial activity with respect to the Klebsiella pneumonia strain (15 mm to 100 mg/ml). As for the antioxidant activity of these two extracts, it has been evaluated by the free radical scavenging method (DPPH) and has shown that the AcOEt extract (IC50 = 79,8μg/mL) has a better activity compared with the n-BuOH extract (IC50 = 136, 2 μg/ml). In addition, the antiproliferative activity of the flavonoid tamarixetin indicates a good response against HeLa cells (carcinoma of the human uterine cervix). Concerning the phytochemical study of the MeOH extract of the aerial parts of the second Stachysbrachyclada species, it has led to the separation and purification of five flavonoids isolated for the first time in the species, namely: Stachysetin ; Lutéoline-7-O- -D-allopyranosyl-(1→2)-glucopyranoside ;  Isoscutellareine-7-O- -D-allopyranosyl-(1→2) glucopyranoside ; Apigénine ;  Lutéoline.Their identification has been carried out by combining our spectroscopic data (MS, 1D and 2D NMR) with those of the literature.