Antibacterial, hemoglobin/albumin-interaction, and molecular docking properties of phytogenic AgNPs functionalized by three antibiotics of penicillin, amoxicillin, and tetracycline

Abstract

Phyto-derived silver nanoparticles (AgNPs) were modified by three antibiotics including penicillin, amoxicillin, and tetracycline to measure antibacterial activity against Gram-positive and Gram-negative bacteria. According to disc diffusion assay, Staphylococcus aureus exhibited a higher sensitivity compared to Escherichia coli and Pseudomonas aeruginosa under AgNPs/tetracycline stress. Damage of the cell envelops of S. aureus and E. coli as sensitive bacteria under MIC concentrations of Ag NPs/tetracycline was observed by SEM images. AFM technique showed a smaller size of albumin protein (8–13 nm) with a higher level of roughness equals to 74.87 nm relative to hemoglubin (5–6.9 nm) by roughness value of 47.04 nm. Interaction of main secondary metabolites includes nootkatone, nootkatin, daphnauranol C, α-Cyperone, (E)-Nerolidol, and (Z)-α-Bisabolene epoxide surrounding phyto-derived AgNPs with the binding cavities of exfoliative toxin A and exfoliative toxin B as virulence factors of S. aureus was evaluated by molecular docking study. Among these natural compounds, daphnauranol C had the suitable binding affinity as value of ˗ 6.4 kcal/mol compared with other metabolites. Based on the results of this study, tetracycline and daphanuranol C can be considered to further evaluations to obtain novel formulation of AgNPs as an efficient weapon against bacterial infections.