Plant extracts contain sources of antimicrobial and antioxidant compounds that have been used as a reducing and stabilizing agents for biosynthesis of nanoparticles (NPs). Some studies suggest that plant extracts incorporating directed NPs, such as Ag, enhanced antioxidant activity, this study suggests the opposite. Red cabbage extract with silver NPs (Ag NPs) was prepared to study and how silver ions (Ag+) and Ag NPs influence antioxidant activity of red cabbage anthocyanin. Synthesized Ag NPs were characterized by UV–vis spectra, scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). We studied Ag NPs formation as a function of Ag+ and anthocyanin concentrations. Results show that Ag+ and Ag NPs decreased antioxidant activity of anthocyanin towards DPPH.