Comparative analysis of phytochemical properties of extracts obtained from flowers and leaves of Astragalus angustifolius collected from different locations

Abstract

Plants containing phenolic secondary metabolites such as tannins and flavonoids are of great interest due to their antioxidant and antimicrobial effects on health. Many species belonging to the Astragalus genus possess promising bioactive phyto-compounds and are used in folk medicine worldwide. In this study, extracts were obtained using two different solvents (ethanol and methanol) from the flowers and leaves of Astragalus angustifolius collected from two different locations in Kahramanmaraş. The antioxidant and antimicrobial activities of these extracts were compared, along with their total phenolic and flavonoid contents. Additionally, the fixed oil content of the extracts was examined using GC-MS analysis, revealing 8 different fatty acid components. The main fatty acid components of the plant extracts were found to be linoleic, oleic, and gamma-linolenic acids in high abundance at both locations. In the methanol extracts of A. angustifolius, total phenolic content ranged from 14.82 to 15.47 mg GAE/g dw in leaves and from 4.38 to 5.30 mg GAE/g dw in flowers. Similarly, flavonoid content ranged from 8.14 to 9.26 mg QE/g dw in leaves and from 5.08 to 5.20 mg QE/g dw in flowers. Leaves exhibited higher phenol and flavonoid content and antioxidant activity compared to flowers. Moreover, methanol was observed to be more successful than ethanol in retrieving the bioactive content of the plant material. This conclusion was confirmed by both antioxidant capacity tests such as FRAP and IC50 values, and the difference in phenol and flavonoid levels between leaves and flowers. Antimicrobial activity determination using the well-diffusion method showed that A. angustifolius leaf extracts had a broad spectrum of effects on test microorganisms.