Green Synthesis of Nerium oleander leaves extract Silver Nanoparticles and Evaluation of its Antibacterial and Antioxidant Activities

Nerium oleander (Apocynaceae) has been used traditionally for the treatment of inflammation, bacterial infection, pain and heart diseases. The purpose of this research was to synthesize silver nanoparticles (AgNPs) of Nerium oleander leaves extract using an eco-friendly technique. The AgNPs were evaluated using scanning electron microscope (SEM), X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). Examination of the powdered leaves using a microscope revealed the presence of paracytic stomata. Phytochemical screening confirmed the presence of cardiac glycosides, saponins, flavonoids, and tannins. The free radical scavenging assay results indicated that the leaves extract and synthesized AgNPs possessed antioxidant activity when compared to ascorbic acid (standard) with half-maximal inhibitory concentrations (IC50) of 3.70, 2.36 and 1.94mg/mL for the extract, silver nanoparticles and ascorbic acid respectively. The results of the antimicrobial studies showed zones of inhibition ranging from 3.26-7.49mm and 2.48-6.72mm for the synthesized AgNPs and the leaves extract respectively which indicated significant antibacterial activity against both gram positive and negative bacteria used in the research. However, the activity against the gram-positive bacteria was significantly higher than that of the gram-negative bacteria (P<0.05). Silver nanoparticles were successfully synthesized in the study using Nerium oleander leaves extract and they could have potential pharmaceutical applications as antimicrobial and antioxidant agents due to their relatively small particle sizes and large surface area.