Porphyrin-Schiff Base Conjugates Bearing Basic Amino Groups as Antimicrobial Phototherapeutic Agents

PÉREZ, MARÍA EUGENIA; DURANTINI, JAVIER E.; REYNOSO, EUGENIA; ALVAREZ, MARÍA GABRIELA; MILANESIO, MARIA ELISA; DURANTINI, EDGARDO N.

MOLECULES

MOLECULAR DIVERSITY PRESERVATION INTERNATIONAL-MDPI

Lugar: Basel; Año: 2021 vol. 26

1420-3049

New porphyrin-Schiff base conjugates bearing one (6) and two (7) basic amino groupswere synthesized by condensation between tetrapyrrolic macrocycle-containing amine functionsand 4-(3-(N,N-dimethylamino)propoxy)benzaldehyde. This approach allowed us to easily obtainporphyrins substituted by positive charge precursor groups in aqueous media. These compoundsshowed the typical Soret and four Q absorption bands with red fluorescence emission (FF ~ 0.12) inN,N-dimethylformamide. Porphyrins 6 and 7 photosensitized the generation of O2(1Dg) (FD ~ 0.44)and the photo-oxidation of L-tryptophan. The decomposition of this amino acid was mainly mediatedby a type II photoprocess. Moreover, the addition of KI strongly quenched the photodynamic actionthrough a reaction with O2(1Dg) to produce iodine. The photodynamic inactivation capacity inducedby porphyrins 6 and 7 was evaluated in Staphylococcus aureus, Escherichia coli, and Candida albicans.Furthermore, the photoinactivation of these microorganisms was improved using potentiation withiodide anions. These porphyrins containing basic aliphatic amino groups can be protonated inbiological systems, which provides an amphiphilic character to the tetrapyrrolic macrocycle. Thiseffect allows one to increase the interaction with the cell wall, thus improving photocytotoxic activityagainst microorganisms.