In vitro and in vivo evaluation of cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing properties of gold nanoparticles produced via a green chemistry synthesis using Gundelia tournefortii L. as a capping and reducing agent

The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology because it does not involve any harmful chemicals. The aim of the experiment was chemical characterization and evaluation of cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing activities of gold nanoparticles using aqueous extract of Gundelia tournefortii L. leaves (AuNPs@GT). These nanoparticles were characterized by fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and UV-visible spectroscopy. DPPH free radical scavenging test was done to assess the antioxidant properties, which indicated similar antioxidant potentials for AuNPs@GT and butylated hydroxytoluene. Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Fungicidal Concentration (MFC) were specified by macro-broth dilution assay. AuNPs@GT indicated higher antibacterial and antifungal effects than all standard antibiotics (p <= 0.01). Also, AuNPs@GT inhibited the growth of all bacteria and fungi and removed them at 2-4 mg/mL concentrations (p <= 0.01). In vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: untreated control, treatment with Eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% HAuCl4 ointment, treatment with 0.2% G. tournefortii ointment, and treatment with 0.2% AuNPs@GT ointment. These groups were treated for 10 days. For histopathological and biochemical analysis of the healing trend, a 3 x 3 cm section was prepared from all dermal thicknesses at day 10. Use of AuNPs@GT ointment in the treatment groups substantially reduced (p <= 0.01) the wound area, total cells, neutrophil, and lymphocyte and remarkably raised (p <= 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, fibroblast, and fibrocytes/fibroblast rate compared to other groups. The synthesized AuNPs@GT had great cell viability dose-dependently (Investigating the effect of the plant on HUVEC cell line) and revealed this method was nontoxic. The results showed that the leave aqueous extract of G. tournefortii is very good bioreductant in the synthesis of gold nanoparticles for treatment of bacterial, fungal, and skin diseases.