Synergistic Antibacterial Efficacy of Biogenic Synthesized Silver Nanoparticles using Ajuga bractosa with Standard Antibiotics: A Study Against Bacterial Pathogens

Abstract

Background: Multi-drug resistance in bacterial pathogens is a major concern of today. Green synthesis technology is being used to cure infectious diseases.

Objectives: The aim of the current research was to analyze the antibacterial, antioxidant, and phytochemical screening of green synthesized silver nanoparticles using Ajuga bracteosa.

Methods: Extract of A. bracteosa was prepared by maceration technique. Silver nanoparticles were synthesized using A. bracteosa extract and were confirmed by UV-Vis spectrophotometer, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The antibacterial, anti-biofilm, cell proliferation inhibition, TLC-Bioautography, TLC-Spot screening, antioxidant, and phytochemical screening were also investigated.

Results: UV-Vis spectrum and Scanning electron microscopy confirmed the synthesis of green nanoparticles at 400 nm with tube-like structures. FTIR spectrum showed that functional groups of nanoparticles have a role in capping and stability of AgNP. Agar well diffusion assay represented the maximum antibacterial effect of ABAgNPs against Escherichia coli, Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, and Pseudomonas aeruginosa at 0.10 g/mL concentration compared to ABaqu. Two types of interactions among nanoparticles, aqueous extract, and antibiotics (Synergistic and additive) were recorded against tested pathogens. Crystal violet, MTT, TLC-bio-autography, and spot screening supported the findings of the antibacterial assay. Highest antioxidant potential effect in ABaqu was 14.62% (DPPH) and 13.64% (ABTS) while 4.85% (DPPH) and 4.86% (ABTS) was recorded in ABAgNPs. Presence of phytochemical constituents showed pharmacological importance.

Conclusion: It was concluded that green synthesis is an innovative technology in which natural products are conjugated with metallic particles and are used against infectious pathogens. The current research showed the significant use of green nanoparticles against etiological agents.

Keywords: Ajuga bracteosa; TLC-Bioautography; TLC-Spot screening; antibacterial effect; crystal violet assay; minimum inhibitory concentration; nanoparticles; nanotechnology; phytochemical screening; synergistic effect..