Introduction: Viola betonicifolia  is a rich source of numerous secondary metabolites, such as alkaloids, flavonoids, tannins, phenolic compounds, saponins, triterpenoids, and so on, that are biologically active towards different potential biomedical applications. To broaden the potential use of Viola betonicifolia  in the realm of bionanotechnology, we investigated the plant’s ability to synthesize gold nanoparticles (Au NPs) in a green and efficient manner for the very first time.
Methods: The gold nanoparticles (VB-Au NPs) were synthesized using the leaves extract of Viola betonicifolia , in which plant’s secondary metabolites function as both reducing and capping agents. The VB-Au NPs were successfully characterized with spectroscopic techniques. The antimicrobial properties of the VB-Au NPs were further explored against bacterial and mycological species. Additionally, their antioxidant, cytotoxic, and cytobiocompatibility properties were examined in vitro against linoleic acid peroxidation, MCF-7 cancer cells, and human mesenchymal stem cells (hMSCs), respectively.
Results: Results demonstrated that VB-Au NPs presented excellent antibacterial, antifungal, and biofilm inhibition performance against all the tested microbial species compared to plant leaves extract and commercially purchased chemically synthesized gold NPs (CH-Au NPs). Moreover, they also exhibited significant antioxidant potential, comparable to the external standard. The VB-Au NPs displayed good cytobiocompatibility with hMSCs and demonstrated excellent cytotoxic potential against MCF-7 cancer cells compared to CH-Au NPs. The current work presents a green method for synthesizing VB-Au NPs with enhanced antioxidant, antimicrobial, cytotoxic and biofilm inhibition efficacy compared to CH-Au NPs might be attributed to the synergistic effect of the nanoparticle’s physical properties and the adsorbed biologically active phytomolecules from the plant leaves extract on their surface.
Conclusion: Thus, our study establishes a novel ecologically acceptable route for nanomaterials’ fabrication with increased and/or extra medicinal functions derived from their herbal origins.
Keywords: Viola betonicifolia , gold NPs, antimicrobial, biofilm inhibition, antioxidant