Synthesis and Antimicrobial Studies of New Antibacterial Azo-Compounds Active against Staphylococcus aureus and Listeria monocytogenes
Stefano Piotto,
Simona Concilio,
Lucia Sessa,
Rosita Diana,
Gabriel Torrens,
Carlos Juan,
Ugo Caruso,
Pio Iannelli
Affiliations
Stefano Piotto
Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
Simona Concilio
Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
Lucia Sessa
Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
Rosita Diana
Department of Chemical Science, University of Napoli “Federico II”, Cupa Nuova Cintia, Napoli 21-80126 , Italy
Gabriel Torrens
Servicio de Microbiología, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain
Carlos Juan
Servicio de Microbiología, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain
Ugo Caruso
Department of Chemical Science, University of Napoli “Federico II”, Cupa Nuova Cintia, Napoli 21-80126 , Italy
Pio Iannelli
Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
Some novel (phenyl-diazenyl)phenols (4a–m) were designed and synthesized to be evaluated for their antibacterial activity. Starting from an active previously-synthesized azobenzene chosen as lead compound, we introduced some modifications and optimization of the structure, in order to improve solubility and drug conveyance. Structures of all newly-synthesized compounds were confirmed by 1H nuclear magnetic resonance (NMR), mass spectrometry, and UV-Vis spectroscopy. Antibacterial activity of the new compounds was tested with the dilution method against the bacteria strains Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa PAO1. All the compounds were selectively active against Gram-positive bacteria. In particular, compounds 4d, 4h, and 4i showed the highest activity against S. aureus and Listeria monocytogenes, reaching remarkable MIC100 values of 4 μg/mL and 8 μg/mL. The relationship between antimicrobial activity and compound structure has suggested that the presence of hydroxyl groups seems to be essential for antimicrobial activity of phenolic compounds.
