Evaluation of antioxidant and antimicrobial properties of silver nanoparticles biosynthesized using weed (Dactyloctenium aegyptium) extracts for sustainable environment, agriculture and ethnomedicine

Abstract

In order to maintain a sustainable environment, one of the strategies available for weed management is their conversion for use in pharmacological applications. Aqueous and ethanol extracts of Dactyloctenium aegyptium was utilized for silver nanoparticles (AgNPs) synthesis following established protocol. Techniques including Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), UV–visible (UV–vis) spectroscopy, and Fourier Transform Infrared (FTIR) spectroscopy were used to analyze the synthesized AgNPs. The antioxidant as well as antibacterial activities of activity of aqueous (AE), ethanol (EE) extracts of Dactyloctenium aegyptium and the biosynthesized silver nanoparticles (AgNPs-AE and AgNPs-EE) were evaluated using standard methods.The first indication of successful AgNPs synthesis were the color changes observed after the addition of AgNO3 solution to the aqueous and ethanol extracts of Dactyloctenium aegyptium respectively. The UV spectrum of AgNPs-AE and AgNPs-EE were both observed to be 550 nm which is characteristic of silver nanoparticles.The reduction of silver ions (Ag+) to silver nanoparticles was revealed by the FT-IR analysis to involve biomolecules including flavonoids and phenolic acid. The SEM analysis revealed that the biosynthesized silver nanoparticles were irregularly spherical with diameters ranging from 14.35 μm-20 μm. The formation of silver nanoparticles were further confirmed by the EDX spectrum which revealed signals from Ag (0.3 and 3 keV).The result of the antioxidant activity of the samples (AE, EE, AgNPs-AE, and AgNP-EE) showed that AgNPs-EE had the highest total phenol and flavonoid content, as well as total antioxidant power followed by AgNPs-AE and ethanol extract and then the aqueous extracts. The antibacterial activity also revealed that for all the test pathogens,AgNPs-EE showed the greatest inhibitory capacity, followed by AgNPs-AE and then Levofloxacin. All the test pathogens used were however resistant to AE and EE. Silver nanoparticles biosynthesized using Dactyloctenium aegyptium can therefore be explored as an antioxidant and antibacterial agent after proper pharmacological evaluations.