Enhanced Antimicrobial and Synergistic Antifungal Activity of Centratherum anthelminticum Seed Extract-Derived Silver Nanoparticles

Abstract

With the increasing concern over antibiotic resistance and the side effects of synthetic drugs, there is a need for the development of novel and potent alternative bactericidal agents. Metallic nanoparticles, a promising alternative to antibiotics, target multiple biomolecules concurrently, making it difficult for bacteria to develop resistance against them. The present work reports the enhanced antimicrobial and synergistic antifungal activity of Centratherum anthelminticum (CA) seed-ethyl acetate (EA) extract-derived silver nanoparticles (AgNPs)—(CA-EA-AgNPs)—via biogenic synthesis. The CA-EA-AgNPs exhibited significantly enhanced antimicrobial activity against Staphylococcus epidermidis, Staphylococcus aureus (Gram-positive), Proteus mirabilis, and Pseudomonas aeruginosa (Gram-negative) bacteria compared to the crude CA-EA extract. CA-EA-AgNPs also demonstrated potent antifungal activity against the dandruff-causing fungus Malassezia furfur and displayed a synergistic effect when combined with ketoconazole, increasing the zone of inhibition from 15 mm (ketoconazole alone) and 11 mm (AgNPs alone) to 19 mm (combination). The synthesis of CA-EA-AgNPs was optimized by systematically varying parameters such as pH, temperature, reaction time, CA-EA extract concentration, and AgNO₃ concentration. The AgNPs were extensively characterized using UV-visible spectroscopy, dynamic light scattering, zeta potential, fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis . To our knowledge, this research is the first to report the antifungal activity of C. anthelminticum-derived AgNPs against Malassezia furfur. The results highlight the potential of C. anthelminticum seed extract as a green resource for synthesizing AgNPs with promising applications in combating microbial infections, particularly skin and soft tissue infections.