ECO FRIENDLY SYNTHESIS OF ZINC OXIDE NANO PARTICLES USING Causonis trifolia EXTRACT: CHARACTERIZATION AND EVALUATION OF ANTIMICROBIAL and ANTIOXIDANT ACTIVITY

The synthesis of nanoparticles using plants provides an environmentally friendly and sustainable alternative for developing multifunctional materials with applications in biomedicine, agriculture, and environmental remediation. Antibiotic resistance remains a global challenge, affecting healthcare in both developed and developing nations. The rise of multidrug-resistant infections has significantly impacted current antibacterial therapies, necessitating alternative strategies such as plant-mediated nanomaterials, which possess bioactive compounds with therapeutic potential. Zinc oxide nanoparticles (ZnO NPs), known for their semiconducting and antimicrobial activities, are particularly promising due to their Generally Recognized as Safe (GRAS) status and potent ability to disrupt microbial membranes via reactive oxygen species (ROS) generation. The present study was intended to synthesize ZnO NPs derived from leaf, stem, and fruit extracts of Causonis trifolia, an ethnomedicinal plant, and evaluate their structural, antimicrobial, and antioxidant activities. ZnO NPs were synthesized through a green synthesis route using aqueous plant extracts as stabilizing and reducing agents. Characterization was carried out by employing UVVisible, XRD, SEM, EDX, and FTIR spectroscopic techniques. Antibacterial and antifungal efficacy was assessed via agar well diffusion against a range of pathogenic Gram-positive and Gram-negative bacteria and fungal strains. Antioxidant potential was assessed by employing DPPH radical scavenging and Ferric Reducing Antioxidant Power (FRAP) assays. Spectral and morphological analysis confirmed the successful formation of crystalline ZnO NPs, with the largest and most crystalline particles obtained from leaf extract (60.91 nm), followed by fruit (45.73 nm) and stem extracts (11.45 nm). Antibacterial studies revealed that stem-extract ZnO NPs exhibited the strongest inhibition, particularly against gram-positiveClostridium perfringens (30.0 mm), Staphylococcus aureus (28.0 mm), and gram-negative Vibrio cholerae, Escherichia coli (28.0 mm each),followed by Pseudomonas aeruoginosa (25.0 mm). Antifungal assays similarly showed maximum activity from stem-derived NPs against Candida albicans (24.0 mm) and Saccharomyces cerevisiae (14.0 mm). Antioxidant evaluation revealed that stem-derived NPs had the highest DPPH scavenging activity (IC₅₀ = 195.28 µg/mL), while fruit-derived NPs showed superior FRAP activity (IC₅₀ = 198.96 µg/mL), highlighting phytochemical influence on bioactivity. In conclusion, Causonis trifolia extracts effectively mediate the green synthesis of ZnO NPs with promising antimicrobial and antioxidant potential. These findings support their relevance as alternative therapeutic agents in combating antibiotic-resistant infections and advancing biomedical nanotechnology.