Evaluation of saponin-rich/poor leaf extract-mediated silver nanoparticles and their antifungal capacity

Abstract

One-pot green synthesis of silver nanoparticles (AgNPs) has attracted much attention due to its simplicity, high feasibility in scaling up production, abundantly renewable sources, and environmental friendliness. Herein, Ocimum tenuiflorum and Phyllanthus urinaria leaf extracts (OT-ext and P.uri.ext, respectively) were chosen as reacting agents with rich and poor saponins to fabricate two biogenic AgNPs and characterize them. OT-AgNPs were simply and successfully generated by OT-ext. Ultraviolet-visible spectra showed the peak centered at 434 nm, which confirmed the presence of AgNPs after an 8-h reaction. FT-IR showed the organic functional groups (OH, C═O, C═C, CH, and COC) capping the surface of OT-AgNPs, which agreed with energy-dispersive X-ray spectroscopy analysis exhibiting the composition containing C, O, and Ag. Transmission electron microscopy micrographs revealed that OT-AgNPs possess spherical morphology, with a size range of 5–61 nm, and the majority having a small size within that range. In comparison, P.uri.AgNPs formed by P.uri.ext had a size distribution in a similar range, but the P.uri.AgNP diameter shifted toward larger sizes. Further, OT-AgNPs and P.uri.AgNPs showed an effective antifungal ability against Fusarium oxysporum, Aspergillus niger, and Aspergillus flavus. Overall, it was found that the rich saponins in the extracts lead to the formation of smaller AgNPs, but all extract-mediated AgNPs with a size less than 100 nm can act as a fungicide for various applications.

Keywords

• silver nanoparticles
• plant extract
• antifungi
• saponins
• phytoconstituent screening