Evaluation of Salophen-Based Immobilized Copper Nanoparticles Biosynthesized Using Curcuma Longa Extract: Physicochemical Characterization and Biological Study

چکیده مقاله

The treatment of infectious diseases has become more difficult today than in the past, as a result of the increasing resistance of pathogenic bacterial and fungal strains to antibiotics and antifungals. As a solution, it is necessary to design new antimicrobial agents to deal with these strains. Schiff bases and their metallic derivatives, especially silver and copper complexes, have a prominent place in the pharmaceutical industry due to their excellent inhibitory potential against microbial strains. In order to combine these inhibitory effects in a single compound, a novel Cu@Ag-salophen nanocomposite was prepared by immobilizing of biochemical synthesized copper nanoparticles from methanolic extract of Curcuma longa on an Ag(I) salophen Schiff base complex. The physicochemical characterization of prepared nanocomposite was attained by FTIR, UV/Vis, TEM, FESEM, EDAX, ICPAES, and XRD analyses. All the synthesized compounds, including Schiff base ligand, Ag complex, Cu nanoparticles, and the Cu@Ag-salophen nanocomposite, were assessed for their potential activities on DPPH free radicals and 8 different pathogenic microorganisms. The IC50 values in the range of 4.02–71.49 μg/ml were assessed in DPPH scavinging studies, indicating their potential to be utilized as potent antioxidant agents to treat oxidative stress-related diseases. Among the tested compounds, the Schiff base ligand exhibited excellent antioxidant effects. Regarding the antimicrobial activities, the Schiff base ligand showed a wide spectrum of antimicrobial effects, with MIC, MBC, and MFC values ranging from 256 to 4096 μg/ml. However, the Ag complex alone did not exhibit any inhibitory effect against the tested microbial strains. Interestingly, when the copper nanoparticles were combined with it in the form of the Cu@Ag-salophen nanocomposite, the resulting material was able to prevent the growth of 5 out of 8 tested strains. Synergistic effects were observed with nanocomposite against P. aeruginosa, S. epidermidis, and A. fumigatus strains. These findings suggest that the functionalization of the ligand and the incorporation of additional nanoparticles could further improve the antimicrobial efficacy of the Cu@Ag-salophen nanocomposite, converting it into a more efficient antimicrobial agent.