(W1030-01-02) Potential Biomedical Applications of Silver Nanoparticles Synthesized Using Anisotes trisulcus Extract from Saudi Arabia: Antioxidant, Antibacterial, and Anti-Proliferative Properties

Purpose: This study aims to highlight the green synthesis of silver nanoparticles (AgNPs) using Anisotes trisulcus leaf extract and investigate their antioxidant, antimicrobial, and antiproliferative properties.

Methods: The study employed a green synthesis approach to produce AgNPs utilizing the aqueous leaf extract of Anisotes trisulcus for the bioreduction of silver nitrate (AgnO₃). Optimization of synthesis parameters was conducted, involving the systematic variation of the volume ratio of aqueous leaf extract to AgNO₃, the concentration of AgNO₃, reaction temperature, and reaction time. The resulting formulation was thoroughly characterized using UV-visible spectroscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD). Furthermore, the study evaluated the antioxidant activity of the optimized formulation through the DPPH method and ABTS assay. The antibacterial properties of the green-synthesized AgNPs were investigated, encompassing Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and biofilm inhibition rate assessments against Escherichia coli and Staphylococcus aureus. Additionally, an in vitro cytotoxicity study was conducted to assess the anticancer activity of biosynthesized AgNPs.

Results: The synthesis of silver nanoparticles (AgNPs) from the aqueous leaf extract of Anisotes trisulcus was optimized under specific conditions, revealing that the optimal parameters include 6 mM of AgNO3 in a 1:9 ratio, a reaction temperature of 40°C, and a reaction time of 4 hours, resulting in AgNPs with a band energy of 3.63 eV. Characterization of the green-synthesized AgNPs using Dynamic Light Scattering (DLS) indicated a mean particle size of 70.89 ± 0.56 nm and a PDI of 0.122 ± 0.02 in the optimized formulation. Morphological analysis displayed predominantly spherical particles with uniform distribution, as confirmed by EDX, which revealed a prominent silver (Ag) peak constituting 68.3% by weight. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) analyses identified the presence of functional groups facilitating biosynthesis and confirmed the face-centered cubic (FCC) crystalline structure, respectively. The green-synthesized AgNPs exhibited exceptional antioxidant activity, surpassing the efficacy of the aqueous leaf extract, as demonstrated by IC50 values of 25.35 μg/mL for DPPH and 29.79 μg/mL for ABTS. Moreover, the AgNPs displayed potent antibacterial activity with a MIC against Escherichia coli (6.25 µg/mL) and Staphylococcus aureus (12.5 µg/mL), and a remarkable biofilm inhibitory rate. Also. In the presence of AgNPs, E. coli and S. aureus strains displayed MBC values of 12.5 and 25 µg/mL, respectively. At a sub-MIC concentration of MIC/4, AgNPs exhibited a biofilm inhibitory rate of 38.98±0.45% on E. coli and 30.65±0.35% on S. aureus. As the concentration increased to MIC/2, the biofilm inhibitory rates increased to 54.27±1.23% for E. coli and 51.49±1.04% for S. aureus. At the MIC concentration, AgNPs demonstrated even greater biofilm inhibition, with rates of 74.31±0.88% for E. coli and 69.94±0.30% for S. aureus. The highest biofilm inhibitory rates were observed at 2MIC concentration, reaching 88.44±0.54% for E. coli and 80.19±0.90% for S. aureus. However, cytotoxicity assessments on A549 cells revealed a dose-dependent effect, with an IC50 of 107.9 μg/mL at 24 hours and 119 μg/mL at 48 hours, indicating concentration-dependent compromise of cell viability.

Conclusion: The green synthesis of silver nanoparticles (AgNPs) from Anisotes trisulcus leaf extract proved successful under optimized conditions. The characterized AgNPs exhibited a well-defined spherical morphology, crystalline structure, and significant antioxidant potential, surpassing the efficacy of the leaf extract. Moreover, the AgNPs displayed potent antibacterial activity against Escherichia coli and Staphylococcus aureus, with notable biofilm inhibition. However, cytotoxicity assessments on A549 cells indicated a dose-dependent effect, highlighting the need for careful consideration of concentration in potential biomedical applications. Overall, the study emphasizes the multifaceted bioactivities of green-synthesized AgNPs, providing valuable insights for future therapeutic and biomedical research.

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Acknowledgements: The authors are thankful to the Deanship of Scientific Research at Najran University for funding this work under the Research Priorities and Najran Research funding program. grant code (NU/NRP/MRC/12/33).