Isolation, structural determination of secondary metabolites and biological activities of asphodelus tenuifolius (Liliaceae).

Abstract

The works presented in this manuscript is a continuation of the phytochemical research carried out by our phytochemistry group affiliated to the VARENBIOMOL research unit from many years on medicinal and aromatic plants growing in different regions of the country, including the vaste Sahara. The first aim of this research is to value the biological resources related to the plant biodiversity of the Algerian flora and the knowledge associated with this flora in terms of traditional use in medicine, and the second one is the separation and identification of new bioactive compounds with interesting biological activities. The choice of Asphodelus tenuifolius specie for a phytochemical and a biological study in this thesis was based mainly on the fact that this specie belongs to the Liliaceae family known for its richness in various secondary metabolites with a good biological and pharmacogical interest, as well as for the good reputation of using this plant in local traditional medicine. For this purpose, the organic extracts of A. tenuifolius specie were studied chemically using various chromatographic methods (TLC, CC, preparative plates, HPLC…) to lead the isolation and the identification of seventeen pure compounds using various spectroscopic analysis, 1D and 2D NMR (1H, 13C, COSY, HSQC, HMBC ...), ECD analysis, HRESI-MS and ESI-MS spectroscopy, UV-Visible, IR and also with comparison with the literature data. All These data allowed us especially to characterize two new structures of anthraquinones isolated from the Chloroform extract with ten other known compounds dividing into two flavonoids, one sterol, one nitrogen phenolic compound, an anthraquinone and two glycoside anthraquinones with three more compounds in the process of identification, most of these classes are known with their therapeutic benefit and interesting biological activities. Phytochemical study of Ethyl Acetate extract of this specie allowed also the isolation of six known compounds: two phenolic acids, three flavonoids and one anthraquinone. Quantitative estimation of total polyphenols and flavonoids contents (TPC and TFC) showed that the Chloroform extract has a high content of polyphenols and flavonoids compared to Ethyl acetate and Butanol extracts. The biological activities assays like: antioxidant, antibacterial, antifungal, cytotoxic and antiviral performed for the different organic extracts, as well as a cytotoxic activity in A375 (human melanoma) cancer cell line carried out on the two new isolated compounds, confirm the pharmacological and the therapeutic properties of this specie and give an explication of their traditional uses.