Cytoprotective and Antioxidant Effects of Silver Nanoparticles Synthesised from the <i>Pisonia grandis</i> L. Extracts Against Hydrogen Peroxide-induced Toxicity in Human Cardiomyocytes

Background: Myocardial Infarction (MI) is a major cause of global mortality, with oxidative stress being a central mechanism underlying cardiomyocyte injury. Hydrogen peroxide (H₂O₂) induced oxidative damage is widely used as an in vitro model to mimic myocardial stress. Plant-mediated nanomaterials have emerged as promising cardioprotective agents due to their antioxidant potential. Aim: This study evaluates the protective effect of Polyvinyl Alcohol (PVA)-encapsulated silver nanoparticles synthesised using the ethanolic extract of Pisonia grandis leaves (PVA AgNPs Pg) against H₂O₂-induced oxidative stress in Human Cardiomyocytes (HCM). Methods: The synthesised nanoparticles were characterised using Ultraviolet (UV)–visible spectroscopy, Transmission Electron Microscopy (TEM), X-ray Powder Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Energy-Dispersive X-ray (EDX) analysis, and Scanning Electron Microscopy (SEM). HCM cells were pretreated with PVA AgNPs Pg followed by H₂O₂ exposure. Cell viability, intracellular Reactive Oxygen Species (ROS), antioxidant enzyme levels (SOD, CAT, GSH, and GPX), and mitochondrial integrity using Mitotracker Green (MTG) staining were evaluated. Digoxin was used as the reference drug. Results: H₂O₂ exposure significantly decreased cell viability and induced morphological alterations. Pretreatment with PVA AgNPs Pg markedly improved cell survival and significantly enhanced antioxidant enzyme levels. ROS generation was effectively suppressed, demonstrating protection comparable to digoxin. Confocal microscopy revealed modulation of mitochondrial function, indicated by altered MTG expression in treated cells. Conclusion: PVA-encapsulated silver nanoparticles derived from P. grandis exert significant cardioprotective effects against oxidative stress by enhancing antioxidant defence, reducing ROS, and preserving mitochondrial integrity, suggesting their potential in myocardial infarction management. Major Findings: PVA-encapsulated silver nanoparticles from P. grandis leaves showed cardioprotective effects against H₂O₂-induced oxidative stress by enhancing antioxidant enzymes, reducing ROS generation, preserving mitochondrial function, and demonstrating efficacy comparable to digoxin.