Asian Journal of Biotechnology and Bioresource Technology

Silver nanoparticles (AgNPs) were synthesised using an aqueous seed kernel extract of Entada rheedii Spreng. and evaluated for physicochemical characteristics and selected catalytic and biological activities. Nanoparticle formation was assessed by Fourier-transform infrared spectroscopy, X-ray diffraction, zeta-potential analysis, atomic force microscopy, and scanning electron microscopy. The UV-visible spectrum showed a sharp absorption peak at 408 nm, while Fourier-transform infrared spectroscopy indicated functional groups associated with nanoparticle reduction and capping. X-ray diffraction indicated a face-centred cubic crystalline structure with a crystallite size of 14.16 nm. The AgNPs had a zeta potential of −44.5 mV. Atomic force microscopy indicated spherical particles measuring 10–60 nm, whereas scanning electron microscopy showed spherical, aggregated particles measuring 80–170 nm. The AgNPs achieved 89.83% degradation of methyl orange in the presence of sodium borohydride. In the DPPH assay, the AgNPs showed an IC₅₀ value of 107.27 µg/mL, compared with 63.72 µg/mL for ascorbic acid; FRAP activity increased with concentration and was highest at 300 µg/mL. The largest antibacterial zones of inhibition were 24 mm against Pseudomonas aeruginosa and Enterococcus faecalis. In the α-amylase inhibition assay, the AgNPs showed an IC₅₀ of 82.82 µg/mL, compared with 151.13 µg/mL for the seed extract and 66.07 µg/mL for metformin. These findings support further investigation of E. rheedii-derived AgNPs.