Comparative characterization and anti Helicobacter pylori activity of green synthesized silver nanoparticles from red and yellow fruited Ficus carica L. leaf extracts

BACKGROUND: Green synthesis of silver nanoparticles (AgNPs) using plant extracts offers an eco-friendly and sustainable approach for developing novel antimicrobial agents. Ficus carica L. leaf extract (FcLE), rich in bioactive phytochemicals, has potential as a natural reducing and stabilizing agent. This study aimed to comparatively evaluate AgNPs synthesized from yellow- and red-fruited F. carica L. leaf extracts and assess their antibacterial activity against Helicobacter pylori. RESULTS: FcLE exhibited strong bioreduction capability, likely mediated by the transformation of phytochemicals (catechin, myricetin, and epigallocatechin gallate) into oxidized derivatives acting as reducing and capping agents. Optimal synthesis conditions were identified at 1% (v/v), 50 °C, and neutral pH, ensuring nanoparticle stability and preventing agglomeration. Morphological characterization revealed distinct differences, with yellow-fruited FcLE producing monodisperse, spherical AgNPs (average diameter 3.87 nm) with a narrow size distribution, whereas red-fruited FcLE generated larger, clustered particles (~ 40-50 nm). X-ray diffraction confirmed a crystalline biphasic silver/silver oxide structure, with higher metallic silver phase purity (60%) in yellow-fruited FcLE-AgNPs. Zeta potential values (up to - 50 mV) indicated strong colloidal stability due to electrostatic repulsion. Antibacterial assays demonstrated moderate inhibition against Escherichia coli and Staphylococcus aureus (11 ± 0.6 mm and 10 ± 0.5 mm, respectively). Against H. pylori, yellow- and red-fruited FcLE-AgNPs produced mean inhibition zones of 20.00 ± 0.00 mm and 18.33 ± 0.58 mm, respectively, whereas the crude leaf extract showed no antibacterial activity under the tested conditions. Tetracycline produced a larger inhibition zone (49 mm) and served as the positive control. In silico docking further suggested that FcLE-derived compounds may interact with the urease enzyme. CONCLUSIONS: These findings demonstrate that FcLE phytochemicals enable efficient synthesis of stable AgNPs at low concentrations and contribute to enhanced antibacterial activity. The synthesized nanoparticles exhibit promising In vitro antibacterial activity against H. pylori and warrant further investigation as plant-mediated nanomaterials for the management of H. pylori-associated gastric infections.