Phthalocyanine-sulfonamide conjugates: Synthesis and photodynamic inactivation of Gram-negative and Gram-positive bacteria

Phthalocyanines bearing four or eight sulfonamide units were synthesized and their efficiency in the photodynamic inactivation of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria was evaluated. Conjugates with simpler sulfonamide units (N,N-diethylbenzenesulfonamide, N-isopropylbenzenesulfonamide and N-(4-methoxyphenyl)benzenesulfonamide) caused stronger inactivation than those with heterocyclic groups (N-(thiazol-2-yl)benzenesulfonamide) or long alkyl chains (N-dodecylbenzenesulfonamide) in both bacteria. Furthermore, the encapsulation of the phthalocyanine sulfonamide conjugates within polyvinylpyrrolidone micelles, used as drug delivery vehicles, in general showed to enhance the inactivation efficiency. The results show that encapsulated phthalocyanine sulfonamide conjugates are a promising class of photosensitizers to be used in photodynamic antimicrobial therapy. (C) 2018 Elsevier Masson SAS. All rights reserved.