Green synthesis of hypericin from <i>Hypericum perforatum</i> (St. John’s Wort) for photodynamic Antibacterial treatment against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>

Hypericin, also known as naphthodianthrone, is a naturally occurring photosensitiser derived from anthraquinone. It has gained attention owing to its prospective use in photodynamic therapy (PDT) for cancer treatment. PDT is a minimally invasive treatment that utilises light, a photosensitiser, and oxygen to kill the target cells. However, conventional synthesis methods of hypericin harm the environment and human health. Therefore, researchers focused on developing green extraction methods for hypericin to overcome these limitations. In this study, hypericin was extracted from <i>Hypericum perforatum</i> using a green ­synthesis method and characterised using Fourier-transform infra-red spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV), high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC). Hypericin generates reactive oxygen species (ROS) upon light activation, which disrupts bacterial cell walls and inhibits vital metabolic processes. This mechanism ensures potent antibacterial effects against both gram-positive <i>S. aureus</i> and gram-negative <i>E. coli,</i> making hypericin a prominent photosensitiser for photodynamic antibacterial therapy.