Antimicrobial and Antioxidant Potential of Astragalus psilocentros

Astragalus psilocentros Fisch. is a medicinal plant belongs to family Papilionaceae and is used to cure various diseases such as cancer, diabetes, liver diseases, hypertension, cardic ischemia, heart failure, nephiritis etc. The aim of this study was to identify the antimicrobial activity for controlling pathogens and antioxidant efficacy. The methanolic extract of A psilocentros was dissolved in water and partitioned with hexane, chloroform, ethyl acetate and n-butanol successively. Phytochemical screening revealed the presence of alkaloids, terpenoids, tannins, phenolics, sugars, saponins and flavonoids. Antimicrobial activity was carried out against four bacterial (Bacillus subtilis, Pasturell multicoda, Escherichia coli, Staphylococcus aureus) and two fungal (Aspergillus niger and Alternia fusarium) strains. The chloroform, ethyl acetate and methanol extracts were effective against these tested microbes. The antioxidant potential of all these fractions and remaining aqueous fraction was evaluated by seven methods i.e. DPPH free radical scavenging activity, total antioxidant activity, FRAP assay, TPC assay, inhibition of lipid peroxidation, ABTS assay and super anion radical scavenging activity. All the fractions exhibited significant antioxidant potential. The results revealed that ethyl acetate showed the highest % inhibition by DPPH radical (183.92 +/- 0.17), highest FRAP value of (56.86 +/- 0.39), highest TPC value (53.69 +/- 0.68) and highest inhibition by lipid peroxidation value (44.65 +/- 0.44). The chloroform soluble fraction showed the highest TAA of (0.7005 +/- 0.05). The GC-MS analysis of hexane soluble part of ethyl acetate fraction identified few potential markers responsible for the activity e.g., 1,3-bis-(trimethylsiloxy) benzene, diethyl benzoylmethylphosphonate, nonadecyl alcohol and 1,2-benzene dicarboxylic acid.