Antibacterial activity and spectroscopic characteristics of silver nanoparticles synthesized via plant and in vitro leaf-derived callus extracts of Mucuna pruriens (L.) DC.

Abstract

In this paper, we describe the green synthesis of silver nanoparticles (AgNPs) using plant extracts, as well as their structural, optical, and antibacterial activities against Escherichia coli and Bacillus velezensis bacteria. For the study, several sections (root, leaves, and seed) of Mucuna pruriens, an immense medicinal herbal used to treat Parkinson's disease, were evaluated. Also, the seeds were grown in-vitro in the modified Murashige and Skoog's medium and the leaf derived callus supplemented by different phytohormones like picloram (pic), thidiazuron (TDZ), 6-benzylaminopurine (BAP) and 2-isopentenyl adenine (2-iP) were selected for this study. This is the first report of distinct callus obtained from M. pruriens and used for green nanoparticle synthesis. The prepared materials were thoroughly evaluated for structural and optical properties using XRD, FTIR, and UV-Visible spectroscopy. During synthesis, the colour changes from colourless to reddish brown, and the existence of an SPR peak in the absorption spectra confirms the formation of AgNPs. The FTIR spectra reveals the presence of phenolic group and alkyl ether groups, which were responsible for the reduction of silver ions during the green synthesis. The aqueous extracts of plant parts and callus obtained from different hormones showed very poor antibacterial activity. However, the green synthesized nanoparticles fabricated by different plant extracts showed good antimicrobial activity towards E. coli and B. velezensis bacteria. amongst the investigated results, highest antimicrobial activity against E. coli (84.8%) and B. velezensis (78.1%) was shown by AgNPs mediated by leaf extracts respectively followed by 0.5 mg/L pic and 2.0 mg/L BAP callus mediated silver nanoparticle solution. According to the findings, green produced AgNPs are promising candidates for antibacterial applications against E. coli and B. velezensis.