Etude phytochimique et biologique de deux plantes médicinales Algériennes

Abstract

This work concerned the phytochemical and biological study of two Algerian medicinal plants Thymus ciliatus (Desf) and Asteriscus graveolens (Forsk.) dc. belonging to the families Lamiaceae and Asteraceae ,respectively. This study led to the isolation of twenty seven products from which seventeen were identified including. Among the isolated compounds, 5 sesquiterpenes from which 3 were new, 6 flavonoids which 1 is new, 4 phenolic compounds and 2 monoterpenes. The structures of the isolated products were elucidated mainly by the combination of spectroscopic methods mainly: NMR techniques (1H, 13C, COSY, HSQC and HMBC), UV spectrophotometry, we also used high resolution mass spectrometry methods and comparison with literature data. The quantification of total phenols and total flavonoids contents of the EtOAc, nBuOH extracts of the aerial parts of Thymus ciliatus (Desf) were determined, EtOAc extract had the highest phenolic and flavonoid contents followed by n-butanol extract. This extracts showed an excellent antioxidant activity by DPPH test. The antioxidant activity of AcOEt and n-BuOH extracts of Asteriscus graveolens was estimated by the DPPH test and β-Carotene bleaching assay. The best result was obtained for the ethyl acetate extract, especially in the DPPH method, where its effect is greater than BHT and α-tocopherol used as standards. Both extracts and some isolated compounds of Asteriscus graveolens were tested for their cytotoxic effect in human cancer cell lines (HCT-116, DLD1 and HDFa). The results indicate that EtOAc extract and isolated compounds 9 α-hydroxyparthenolide, 9β-hydroxyparthenolide et 7,12-dihydroxy-6,7- dihydro-5,(6) E-dehydronerolidol showed significant activity compared to the n-BuOH extract and and the two new compounds. The chemical composition of the essential oil of aerial parts of Thymus ciliatus (Desf) Benth studied by GC-FID and GC-MS showed that this oil is mainly composed of elemol (6.80%), carvacrol (5.86%), γ-muurolene (5.18%), β-sesquiphellandrene (5.09%), bicyclogermacrene (5.04%), β-Pinene (4.49%) and curcumene (4.20%).