Characterization and Biological Activities of Silver Nanoparticles Synthesized from Stems of Sarcocephalus latifolius (Sm) E.A. Bruce and Massularia acuminata (G. Don) Bullock ex Hoyl. (Rubiaceae)

Emmanuel Olusegun Ajayi*, Samuel Wale Odeyemi, Gloria Aderonke Otunola and Anthony Jide Afolayan*

Medicinal Plants and Economic Development (MPED) Research Center, Department of Botany, University of Fort Hare, Alice 5700, South Africa

*Corresponding authors: E-mail: EAjayi@ufh.ac.za; Aafolayan@ufh.ac.za

Abstract

Silver nanoparticles (AgNPs) have been synthesized from the stems of Sarcocephalus latifolius (SL) and Massularia acuminata (MA) and characterized for their sizes and shapes using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Complete formations of the AgNPs were observed with colour change from colourless to brownish-black. Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDS/EDX) were conducted to detrmine the various functional groups and the concentration of metal ions of the molecules. The data analysis showed sizes of 3-41 nm and 3-37 nm, spherical shaped nanoparticles for Sarcocephalus latifolius and Massularia acuminata, respectively as revealed by TEM, complementing the results for SEM. FT-IR identifies ethylene groups as the reducing and capping agents for the formation of the nanoparticles. The X-ray diffraction pattern confirmed the presence of silver crystallites and as well as their sizes, confirming the TEM results. Silver nanoparticles exhibited not too good potentials as free radical scavengers when compared to the standard drugs. The synthesized AgNPs in suspension showed activity against Gram-positive and Gram-negative bacteria with minimum inhibitory concentrations (MICs) to be in the range from 62.5 to 250 μg/mL. In summary, the synthesized AgNPs showed acceptable sizes and shapes of nanoparticles.

Keywords

Silver nanoparticles, Sarcocephalus latifolius, Massularia acuminata.

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