Phytochemical characterization and evaluation of antioxidant and antimicrobial properties of Sesbania grandiflora leaf extracts

Abstract

Sesbania grandiflora (L.) Pers. is a medicinal plant widely used in traditional healthcare systems owing to its diverse therapeutic properties. The present study aimed to evaluate the phytochemical composition, antioxidant potential, and antibacterial activity of petroleum ether and methanolic leaf extracts of S. grandiflora. Preliminary phytochemical screening revealed the presence of alkaloids and coumarins in the petroleum ether extract, whereas the methanolic extract contained phenolics, tannins, flavonoids, cardiac glycosides, saponins, and coumarins, indicating a richer phytochemical profile. Antioxidant activity was assessed using the Ferric Reducing Antioxidant Power (FRAP) assay at concentrations ranging from 20-100 µg mL⁻¹. The methanolic extract exhibited superior antioxidant activity, with inhibition increasing from 32.57% to 78.11%, compared with 13.50% to 60.40% for the petroleum ether extract, approaching the activity of the standard ascorbic acid (49.09-80.34%). Antibacterial activity was evaluated against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the disc diffusion method. The methanolic extract showed stronger antibacterial activity, producing maximum inhibition zones of 17, 13, and 18 mm against E. coli, P. aeruginosa, and S. aureus, respectively, at 10 mg disc⁻¹, whereas the petroleum ether extract exhibited corresponding inhibition zones of 11, 9, and 10 mm. The enhanced antioxidant and antibacterial activities of the methanolic extract were attributed to its higher content of phenolic and flavonoid compounds. The findings demonstrate that S. grandiflora leaves are a promising source of natural bioactive compounds with significant antioxidant and antimicrobial potential, supporting their traditional medicinal use and warranting further phytochemical characterization and pharmacological investigations.