Phytosynthesized Silver Nanoparticles from Waste <i>Kigelia africana</i> Flowers: Characterization and Functional Applications

Plant extracts provide a rapid, cost-effective, and sustainable route for synthesizing metallic nanoparticles, and various extracts have been used to produce silver nanoparticles. The ethanolic extract of waste Kigelia africana flowers exhibited both reduction and stabilization effects. The formation of silver nanoparticles (Ka-AgNPs) was confirmed by visual color change and further validated using spectroscopic and microscopic techniques. Ultraviolet-Visible spectroscopy of the synthesized nanoparticles showed a characteristic absorption peak at 421.36 nm. Fourier Transform Infrared Spectroscopy (FT-IR) revealed absorption bands corresponding to phytoconstituents acting as capping agents. Field Emission Scanning Electron Microscopy (FESEM) provided insights into the morphology, while X-ray Diffraction (XRD) indicated an average crystalline size of 41.56 nm. Antioxidant activity, assessed via 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays, yielded IC₅₀ values of 27.88 and 17.18μg/mL, respectively. The nanoparticles also exhibited significant antimicrobial activity. Moreover, α-amylase and α-glucosidase inhibition studies demonstrated promising antidiabetic potential, with IC₅₀ values of 98.26μg/mL and 125.34μg/mL, respectively. Overall, this study highlights the multifunctionality of silver nanoparticles synthesized using waste K. africana flowers, underscoring their potential medicinal applications.