Comparative chemical and biological investigations of three Saudi Astragalus species

ABSTRACT

Aim: The chemical profile and biological activities of alcoholic extracts of the aerial parts of three SaudiAstragalus species have been comparatively investigated in this research.Materials and Methods: Three Saudi Astragalus species (A. spinosus Vahl, A. armatus Willd, and A. sieberiDC.) were collected from the wild area of Rafhaa city, Northern border region in Saudi Arabia. Phytochemicalscreening was carried out using the general standard procedure, total flavonoid content (TFC) and totalpolyphenolic content (TPC) were determined by AlCl3 colorimetric method and Folin–Ciocalteu reagentmethod, respectively. Flavonoid markers (kaempferol, apigenin, rutin, luteolin, and quercetin) and phenoliccompounds (gallic, caffeic, coumaric, ferulic, cinnamic, syringic, and chlorogenic acids) were quantitativelytraced for the first time in these Saudi Astragalus species using high performance liquid chromatography (HPLC)method. The antibacterial and antifungal studies were carried out by well diffusion method. Cytotoxic activitiesstudies were carried out against Hep G-2, HCT-116, and A-549 cancer cell lines using 3-(4,5-dimethylthiazol2-yl)-2-5-diphenyltetrazolium bromide (MTT) assay procedure. Antioxidant activities were measured using2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Immunostimulant activity was examined using lymphocyteproliferation 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 highestpercentages of TFC and TPC. Ethyl acetate fractions of A. spinosus and A. sieberi showed potent cytotoxicactivities, expressed as 50% inhibitory concentration (IC50) = 50.2, 22.6, and 29.1 µg/ml for A. spinosus and39.8, 28.8, and 47.2 µg/ml for A. sieberi against tumor cell lines, HepG-2, HCT-116, and A-549, respectively.Astragalus spinosus showed a DPPH radical scavenging effect (IC50) = 69 μg/ml, compared with other twospecies (IC50) = 161 and 313 μg/ml for A. armatus and A. sieberi, respectively. The Astragalus samples showedmild antimicrobial activities and immunomodulating activities.Conclusion: The present research shows the quality control testing, for the first time, of three Saudi Astragalusspecies and Astragalus-containing recipes. The present work provides valuable information for new drug orfood supplement research and development.