Additionally, other significant phenolic compounds identified in the literature include gallic acid, caffeic acid, syringic acid, ferulic acid, p-coumaric acid, and rutin . Yerba mate is also rich in flavonoids, compounds known for their antioxidant properties, which protect cells against damage caused by free radicals, and for their role in promoting cardiovascular health by reducing inflammation and improving vascular function. Among the main flavonoids present in yerba mate are rutin, luteolin, and quercetin, the latter being one of the majority of flavonoids in the composition . In Figure , it can be seen that, in step II, the complex formed involves the sharing of electrons between the surface of the nanoparticles and the organic components of the extract, represented by "R" . Although "R" represents the majority of constituents of the yerba mate extract, other components may also be present . Subsequently, high-temperature calcination promotes the formation of CuO-NPs (step III).