Eco-friendly synthesis of Ag/CeO₂ and CuO/CeO₂ nanocomposites using <i>Curcuma longa</i> extract and assessment of their antioxidant, antifungal, and cytotoxic activities

This work focused on the biosynthesis of Ag/CeO₂ and CuO/CeO₂ nanocomposites (NCs) using <i>Curcuma longa</i> extract. The nanocomposites were efficiently characterized using different techniques such as FTIR, UV-visible spectroscopy, zeta potential, DLS, TEM, SEM, EDX, and XRD analyses. The <i>C. longa</i> extract provided high phenolic and flavonoid contents, while demonstrating strong antioxidant action at IC₅₀ = 0.042 mg mL^-1. In particular, both nanocomposites exhibited privileged antifungal activity against <i>Macrophomina phaseolina</i> with superiority to CuO/CeO₂ (MIC = 29 µg mL^-1) over Ag/CeO₂ (MIC = 49 µg mL^-1). TEM analyses confirmed the adverse effect of nanocomposites on the fungal cell wall. The CuO/CeO₂ structure led to mitochondrial and cytoplasmic damage in MCF-7 cells (IC₅₀ = 0.5071 µg mL^-1) according to cytotoxicity tests; however, the Ag/CeO₂ NC resulted in significant nuclear damage and an increased occurrence of autophagy events. The nanocomposites showed cytotoxic properties by causing oxidative stress, leading to damage of the genomic material and defects in cell structure, suggesting potential therapeutic applications.