Abstract

Aim: the chemical profile and biological activities of alcoholic extracts of the arial parts of three Saudi Astragalus species have been comparatively investigated in this research. Materials and methods: Three Saudi Astragalus species (A. spinosus Vahl, A. armatus Willd and A. sieberi DC.) were collected from the wild area of Rafhaa city, Northern border region in Saudi Arabia. phytochemical screening was carried out using the general standard procedure, Total Flavonoid (TFC) and total polyphenolic (TPC) contents were determined by AlCl3 Colorimetric Method and Folin–Ciocalteu reagent method, respectively. Flavonoid markers (kaempferol, apigenin, rutin, luteolin and quercetin) and phenolic compounds (gallic, caffeic, coumaric, ferulic, cinnamic, syringic and chlorogenic acids) were quantitatively traced for the first time in these Saudi Astragalus species using HPLC method. The antibacterial and antifungal studies were carried out by well diffusion method. Cytotoxic activities studies were carried out against Hep G-2, HCT-116 and A-549 cancer cell lines using MTT assay procedure. Antioxidant activities were measured using DPPH method. Immunostimulant Activity were examined using lymphocyte proliferation method. Results: The chemical screening confirmed the presence of triterpenes, flavonoids, sterols, glycosides, saponins and polyphenolic compounds and absence of anthraquinones in all species, while A. spinosus shows the highest percentages of TFC and TPC. ethyl acetate fractions of A. spinosus and A. sieberi showed potent cytotoxic activities IC50 = 50.2, 22.6 and 29.1 µg/ml for A. spinosus and 39.8,28.8 and 47.2 µg/ml for A. sieberi against tumor cell lines, HepG-2, HCT-116 and A-549 respectively. A. spinosus showed a DPPH radical scavenging effect (IC50) = 69 μg/ml, compared with other two species (IC50) = 161, and 313 μg/ml for A. armatus and A. sieberi respectively. The Astragalus samples showed mild antimicrobial activities, and imunomodulating activities. Conclusion: The present research shows the quality control testing, for the first time, of three Saudi Astragalus species and Astragalus-containing recipes. The present work provides valuable information for new drug or food supplement research and development.

Key words: Astragalus spinosus, Astragalus armatus, Astragalus sieberi, phytochemical screening, cytotoxic activities, antioxidant activities.