Illuminating New Frontiers: Exploring the Photosensitizing Potential of <i>Passiflora</i> Species in Combating Methicillin‐Resistant <i>Staphylococcus aureus</i> (MRSA) and Their Infection in Senescent Mice

Antimicrobial Photodynamic Therapy (aPDT) has become a potential alternative for treating multidrug-resistant bacterial skin infections, such as those caused by methicillin-resistant Staphylococcus aureus (MRSA), which are at high risk in aging individuals. One of the main components of aPDT is an agent known as a photosensitizer (PS). Some plants with high flavonoid content are reported as PS. In the genus Passiflora, flavonoids are predominant, but their photosensitizing activity has yet to be described. This study investigates the photosensitizing potential of extracts from Passiflora edulis, Passiflora alata, and Passiflora cincinnata. The butanolic fraction of P. cincinnata undergoes in vivo evaluation against intradermal MRSA infection in a senescent murine model (C57BL/6). In vitro assays determine the photoactivatable concentrations and their cytotoxicity. In vivo, MRSA-infected mice are divided into control, P. cincinnata-treated, and aPDT-treated groups. Subsequent assessments include cytokine levels, bacterial load, and cellular infiltrate in the ear. The P. cincinnata-treated group exhibits improved bacterial control, reduced leukocyte infiltration, and less weight loss. The aPDT group demonstrates a unique cytokine correlation profile, featuring more negative correlations among pro-inflammatory cytokines and interleukin-10. P. cincinnata emerges as an effective photosensitizer for aPDT in a senescent model and highlights the potential of underexplored plant-derived photosensitizers.