Synthesis and characterization of new acid-functionalized porphyrins displaying antimicrobial activity against gram positive bacteria, yeasts and filamentous fungi with or without ultra-high irradiance

• New porphyrins with carboxylic acid functions have been synthesized and characterized. • The antimicrobial activity against two strains of S. aureus and against the yeast C. albicans and the filamentous fungi A. fumigatus was evaluated under photodynamic inactivation. • The minimum inhibition concentration value of the best compound was only 0.048 μg/mL with S. aureus , which is sixteen times more effective than the vancomycin reference used in the clinic. The antimicrobial activity of new acid-functionalized porphyrins, with or without ultra-high irradiance, was investigated. Antibacterial efficacy was evaluated against Staphylococcus aureus (methicillin-resistant or methicillin-sensitive strains) and antifungal efficacy was evaluated against the yeast Candida albicans and the filamentous fungi Aspergillus fumigatus . Overall, the porphyrins tested are more effective against S. aureus . The best results were obtained with zinc diacid porphyrins 4 and 5 after only 3 min of ultra-high irradiation (500 mW/cm 2 , 405 nm), demonstrating that acid-functionalized porphyrins are promising as novel antimicrobial drugs for surface disinfection.