In vitro Antimicrobial Photodynamic Activity of Tecoma stans Yellow Flowers Extract Loaded in Nano-Emulsion

Antimicrobial photodynamic therapy (aPDT) is an approach that was recently used to combat the resistance developed by pathogens toward antimicrobial drugs. Tecoma stans (L.) Jus., a prevalent tree in Egypt, was reported to be a promising photosensitizer in PDT. This study investigates the antimicrobial photodynamic activity of the methanolic crude extract of Tecoma stans (L.) Juss. ex Kunth (T. stans) loaded in a nano-emulsion as a natural photosensitizer. Molecular docking and molecular dynamics studies were conducted to investigate the binding between delphinidin as a promising lead and DNA's active site and to assess its stability through simulation The nano-emulsion formulation (TSFE-NE) was prepared, characterized, and evaluated for its antimicrobial photodynamic activities against three types of microorganisms: Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and the pathogenic yeast Candida albicans. The percentage of microbial eradication was calculated after irradiation at 90 Mw/cm2. The microbial eradication of TSFE-NE was enhanced after light exposure. Eradication percentages of 97.43%, 90.56%, and 87.77% were obtained for Escherichia coli, Staphylococcus aureus, and Candida albicans, respectively. These results confirmed the efficacy of natural photosensitizer and nanotechnology combination for improving antimicrobial photodynamic activities