الفهرس 
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Abstract
Literature survey revealed that genus Astragalus has great reputation for its immunostimulant, anticancer, antiviral and hepatoprotective properties. These activities are attributed to the presence of biologically active secondary metabolites including cycloartane saponins, oleanane saponins, polysaccharides, polyphenols, aliphatic nitrocompounds and alkaloids. Because of many factors that harmfully affect the immune system nowadays, we focused our phytochemical study on the immune modulating activity of different fractions of some Egyptian Astragalus species and isolation of secondary metabolites of Astragalus asterias Steven, subspecies asterias. This thesis consists of three parts:
Part I: Immunostimulant activity screening of the alcoholic and aqueous extracts of some Egyptian Astragalus species.
Part II: Immunostimulant activity directed phytochemical investigation of Astragalus asterias Steven, subspecies asterias.
Part III: Determination of carbohydrate content in the alcoholic and aqueous extracts of some Egyptian Astragalus species by Phenol-sulfuric acid assay.
Part I
Immunostimulant activity screening of the alcoholic and aqueous extracts of some Egyptian Astragalus species
The ability of the aqueous and alcoholic extracts from different Egyptian Astragalus species to induce lymphoproliferative activity of human peripheral blood mononuclear cells (PBMC) was tested using neutral red uptake assay. The highest immunostimulant effect was given by the aqueous extract of the roots of Astragalus boeticus at a concentration of 0.781 µg/ml.
Part II
Immunostimulant activity directed phytochemical investigation of Astragalus asterias Steven, subspecies asterias
The ability of Astragalus asterias Steven, subspecies asterias extracts (chloroform, ethyl acetate and n-butanol extracts) to induce lymphoproliferative activity of resting human peripheral blood mononuclear cells (PBMC) was tested using neutral red uptake assay. The ethyl acetate extract showed significant immune stimulation activity at concentrations of 12.5, 25 and 50 µg/ml, and the n-butanol extract could weakly induce lymphorpoliferation at concentration of 6.25 µg/ml.
Therefore, our phytochemical investigation was focused on the ethyl acetate extract resulting in the isolation of two flavonoidal glycosides, and the n-butanol extract resulting in the isolation of two sugars. The identification, characterization and structure elucidation of the isolated compounds were based on their spectral characters.