Antioxidant and Antimicrobial Activities of Green‐Synthesized Silver Nanoparticles Using a Cocktail Aqueous Extract of <i>Capparis sepiaria</i> Root and <i>Tabernaemontana elegans</i> Bark

Abstract The increasing incidence of antimicrobial resistance (AMR) poses a serious threat to public health, which necessitates the development of alternative countermeasures to combat it. Green nanotechnology, in particular the use of silver nanoparticles (AgNPs), shows promise in combating AMR. Although the synthesis of AgNPs using medicinal plant extracts has been explored, combining extracts from two medicinal plants to synthesize AgNPs with enhanced properties has received less attention. Therefore, this study addresses this gap by presenting the green synthesis of AgNPs using a cocktail of Capparis sepiaria – Tabernaemontana elegans (CsTe) aqueous extract as reducing, stabilizing, and capping agents. The focus is on assessing the antioxidant and antimicrobial activities of the synthesized CsTe‐AgNPs. Various parameters, such as pH, temperature, extract and silver concentrations, reaction ratio, and synthesis time, were optimized to enhance the efficiency of CsTe‐AgNPs synthesis. The CsTe‐AgNPs were monodispersed and spherical, with an average core size of 14 ± 2.953 and 7 ± 3.849 nm, and hydrodynamic size of 23 ± 12.260 and 138 ± 2.086 nm for pH = 6 and pH = 11, respectively. The FTIR analysis revealed a shift in peaks of biomolecules present in the CsTe extracts that could be responsible for the reduction of Ag salt to form CsTe‐AgNPs. Notably, CsTe‐AgNPs_pH11 had potent antimicrobial activity, with a minimum inhibitory concentration (MIC) of 12.5 ± 0 µg/mL against K. pneumoniae and P. aeruginosa , and a slightly higher MIC for C. albicans of 25 ± 5.449 µg/mL. This study demonstrated the effectiveness of using a mixture of two extracts to synthesize AgNPs with enhanced antioxidant and antimicrobial activities, and therefore, could serve as a promising reagent to combat AMR.