Clove-mediated green synthesis of silver nanoparticles and in vitro investigation of their antimicrobial, antioxidant, and anticancer potential.

INTRODUCTION: Green synthesis of silver nanoparticles (AgNPs) using plant extracts offers an eco-friendly and sustainable strategy for developing multifunctional nanomaterials with biomedical applications. This study aimed to biosynthesize AgNPs using Syzygium aromaticum (clove) extract and evaluate their physicochemical characteristics and antioxidant, anti-inflammatory, antiviral, anticancer, and antibacterial activities. METHODS: AgNPs were biosynthesized using clove extract and characterized by Ultraviolet-Visible Spectroscopy (UV-Vis), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy-Dispersive X-ray Spectroscopy (EDX). Antioxidant activity was determined by IC₅₀ analysis, while anti-inflammatory potential was assessed using hemolysis protection and human red blood cell (HRBC) membrane stabilization assays. Antiviral activity was evaluated against hepatitis A virus (HAV), Coxsackievirus B4 (COXB4), and herpes simplex virus type 1 (HSV-1). Cytotoxicity was assessed in human colorectal carcinoma (CaCO₂) and normal lung fibroblast (Wi-38) cells. Antibacterial activity was tested against multidrug-resistant (MDR) bacterial strains, and quantitative molecular analyses were performed to determine the expression of bacterial virulence genes and cancer-related genes. All reported values represent the mean of three independent experiments. RESULTS: The synthesized AgNPs were predominantly spherical, well dispersed, and had an average particle size of approximately 9.5 nm. XRD confirmed a crystalline face-centered cubic (fcc) structure, while UV-Vis analysis showed a characteristic surface plasmon resonance peak at 437 nm, confirming successful nanoparticle formation. The AgNPs exhibited strong antioxidant activity with an IC₅₀ of approximately 13.5 μg/mL and demonstrated significant anti-inflammatory activity through membrane stabilization and hemolysis protection. Antiviral assays showed marked inhibition of HAV, COXB4, and HSV-1 at 250 μg/mL, with the highest inhibition observed against HAV (74%). Cytotoxicity studies revealed selective anticancer activity, with an IC₅₀ of approximately 137 μg/mL against CaCO₂ cells compared with 387 μg/mL for Wi-38 cells. Broad-spectrum antibacterial activity was observed against MDR Staphylococcus aureus (ATCC 27217), Staphylococcus haemolyticus (ATCC 29970), Escherichia coli (BAA-197), and Klebsiella pneumoniae (BAA-1705). Molecular analyses demonstrated significant suppression of bacterial virulence genes, including luxS in E. coli (70%), fnbA-a and cna in S. aureus (74%), fnbA-h in S. haemolyticus (77%), and rmpA in K. pneumoniae (81%) at AgNP concentrations of 10 μg/mL for Gram-positive and 12.5 μg/mL for Gram-negative strains. In CaCO₂ cells, AgNP treatment significantly downregulated c-MYC (0.49-fold), K-RAS (0.67-fold), and BCL2 (0.78-fold; p < 0.01), while significantly upregulating BAX (1.74-fold). DISCUSSION: Clove-mediated AgNPs demonstrated potent multifunctional biological activities, including antioxidant, anti-inflammatory, antiviral, selective anticancer, and antibacterial effects, accompanied by modulation of cancer-associated and bacterial virulence genes. These findings highlight the therapeutic potential of biosynthesized AgNPs as promising candidates for the development of novel antimicrobial and anticancer nanomedicines.