Determination of Photosensitizing Potential of Lapachol for Photodynamic Inactivation of Bacteria

Antimicrobial photodynamic inactivation (aPDI) offers a promising alternative to combat drug-resistant bacteria. This study explores the potential of lapachol, a natural naphthoquinone derived from <i>Tabebuia avellanedae</i>, as a photosensitizer (PS) for aPDI. Lapachol's photosensitizing properties were evaluated using <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> strains under blue LED light (450 nm). UV-vis spectroscopy confirmed lapachol's absorption peak at 482 nm, aligning with effective excitation wavelengths for phototherapy. Photoinactivation assays demonstrated significant bacterial growth inhibition, achieving complete eradication of <i>S. aureus</i> at 25 µg·mL^-1 under light exposure. Scanning electron microscopy (SEM) revealed morphological damage in irradiated bacterial cells, confirming lapachol's bactericidal effect. This research underscores lapachol's potential as a novel photosensitizer in antimicrobial photodynamic therapy, addressing a critical need in combating antibiotic resistance.