Phytochemical Analysis, Antioxidant, and Antimicrobial Activities of Nicotiana glauca graham Leaves Extracts and Leaf Extract Mediated Synthesized Silver Nanoparticles

Abstract

The Nicotiana glauca belongs to the genus Nicotiana and it is traditionally used for the treatment of many diseases. This study aims to screen the phytochemicals present in the leaf extracts, to evaluate the antioxidant and antimicrobial activities of leaf extracts and leaf extract-mediated synthesized silver nanoparticles. The leaves of Nicotiana glauca were collected from Eteya town and the plant material was identified at National Herbarium, Addis Ababa University. The powder of the leaves was macerated with distilled water, methanol, n-hexane, and chloroform. Silver nanoparticle synthesis was prepared by mixing using 3mM silver nitrate solution and leaf water extract and it was characterized by X-ray diffraction and scanning electron microscopy. The phytochemical analysis was done using standard methods. The antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl scavenging assay and the in vitro antimicrobial activities evaluation were done by using the agar disk diffusion method against selected bacterial and fungal strain. The result of phytochemical analysis implied the presence of alkaloids, saponins, flavonoids, terpenoids, tannins, Phenolics, Steroids, and glycosides. The antioxidant activity of silver nanoparticles methanol, chloroform, and n-hexane was (94.22%, 86.11%, 70.67%, 61.62%, and 58.34%). In the 2,2-diphenyl-1-picrylhydrazyl assay, green synthesis silver nanoparticles have an Ic50 value of 78 µg/ml, and methanol extract gave an Ic50 value of 170 µg/ml. The results of the antimicrobial activities evaluation showed that the leaf extract and the synthesized silver nanoparticles have antimicrobial activities. The highest zone of inhibition observed was that of 16.33±1.16mm for synthesized silver nanoparticles and 15.33±1.16mm for leaf extract. The lowest zone of inhibition observed was 9.67±0.58mm for synthesized silver nanoparticles and 7.33±0.58mm for leaf extract. In conclusion, the leaf extracts Nicotiana glauca and leaf extract mediated synthesized silver nanoparticles have good antioxidant and antimicrobial activities. Further study should be done on the phytochemical constituents, antioxidant, and antimicrobial activities of this plant.