Inhibition of microbial growth by silver nanoparticles synthesized from Fraxinus xanthoxyloides leaf extract

Conventional antibiotics have been failed to treat infectious diseases due to emergence of multidrug resistance (MDR) in some common pathogens. The current study aimed to formulate new antimicrobials from greener sources. In the midst of these efforts, nanotechnology is a newly emerged field, in which the synthesis of new nanoparticles through novel and efficient means is on the rise.

The current work has been carried out to assess the potential of Fraxinus xanthoxyloides (FX) leaf extract in biosynthesis of silver nanoparticles (FX-AgNPs). This method is economical and simple one-step approach to synthesize AgNPs. Characterization of FX-AgNPs has been done by UV-Visible spectroscopy, scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electronic microscope (TEM) and Fourier transforms infrared spectroscopy (FT-IR). The formation of FX-AgNPs has confirmed through UV-Visible spectroscopy (at 430 nm) by change of colour owing to surface Plasmon resonance. Based on the XRD pattern, the crystalline property of FX-AgNPs has established. Functional groups existing in F. xanthoxyloides leaf extract are confirmed by FT-IR spectrum. SEM and TEM authenticated morphology of the AgNPs. The newly synthesized nanoparticles were evaluated for their antimicrobial potential. Minimum inhibitory concentration was determined against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA) strains, Pseudomonas aeruginosa and Candida albicans by microtiter plate assay. The lowest inhibition (69%) observed against MRSA was at a concentration of 50 ppm FX-AgNPs and maximum inhibition (81%) observed was against P. aeruginosa. The biosynthesized AgNPs triggered up to 68·6% reduction of the P. aeruginosa biofilm when compared to the control.

It can be concluded that nanoparticles could be a better alternative of antibiotics with greater efficacies and represent a valuable milestone to fight against infections caused by MDR pathogens.

This study imparts a useful insight into the development of a new antimicrobial agent from a novel source.