In vitro Antimicrobial and Antioxidant Activities of Methanol and Hexane Extract of Astragalus Species Growing in the Eastern Anatolia Region of Turkey

This study was conducted to evaluate the antimicrobial and antioxidant activities of the hexane and methanol extracts of the aboveground parts and roots of some Astragalus species grown in the vicinity of Erzurum, located in the eastern Anatolia, Turkey. The methanol extract, which was obtained from the aboveground parts of Astragalus species, exhibited mild free radical scavenging activity providing 50% inhibition at the concentrations between 68.8 and 400.4 μg/ml. The hexane/dichloromethane extracts of the aboveground parts of Astragalus species did not show any free radical scavenging activity. However, the linoleic acid oxidation inhibition ability of the non-polar extracts seems to be higher than that of the polar methanolic extracts. The methanol root extracts were mild antioxidants but the non-polar root extracts of A. microcephalus Willd., A. macrocephalus Willd., A. erinaceus Fisch. & Mey. ex Fischer, A. psoraloides Lam., and A. argyroides Becker ex Stapf. were extremely active in DPPH test. IC50 values were 35.2 μg/ml, 21.0 μg/ml, 22.0 μg/ml 20.3 μg/ml, and 38.0 μg/ml, respectively. In the case of β–carotene-linoleic acid system, the extract obtained from A. psoraloides Lam. exhibited strong inhibition among studied Astragalus species. Furthermore, the extracts, which were obtained from the tested Astragalus species, were evaluated for their possible in vitro antibacterial, anticandidal, and antifungal activities based on disk diffusion assay. The results suggested that none of the extracts has antimicrobial activity on the tested microorganisms.