Comparative photodynamic inactivation of bioluminescent E. coli by pyridinium and inverted pyridinium chlorins

Photodynamic inactivation (PDI) is a therapeutic approach in study due to the ability to reduce or completely eliminate the bacterial strains without the development of resistance mechanisms. In this therapeutic methodology the cationic chlorins (Chls) with pyridinium or inverted pyridinium moieties are one of the photosensitizers exploited in our biological approaches. In this context, we synthesized and characterized new free-base and zinc(II) complexes of pyridinium or inverted pyridinium Chl derivatives (1b, 2, 2a and 2b, respectively) for the inactivation of Escherichia coli (E. coli). The PDI assay was performed with white light irradiation delivered at a fluence rate of 25 mW cm−2. The obtained results of this study demonstrate high PDI efficiency of the zinc(II) metallated Chl 1b, reaching the detection limit of the bioluminescent method (5.2 log reduction) in 45 min of irradiation.publishe

Photodynamic inactivation of a RNA-virus model using water-soluble β-octa-Substituted pyridinium-pyrazolyl phthalocyanines

Among the various groups of microorganisms, viruses have generally a greater capacity for mutation, especially RNA viruses, as was demonstrated by SARS-CoV2 virus mutations. This high mutation rate promotes the development of their resistance to traditional antivirals and establishes the resistance behaviour in virus populations, decreasing their susceptibility to these drugs. In this context, the photodynamic treatment appears as a potentially effective method against microorganisms and, considering its mode of action is not likely to lead to the development of resistance. In this work, two newly zinc(II) phthalocyanines (ZnPcs) bearing pyridinium-pyrazolyl groups (2a and 3a) were synthesized, characterized, and applied in photodynamic inactivation (PDI) of bacteriophage Φ6 (or Phage Phi6) as a RNA-virus model. These quaternized dyes were applied at different concentrations (from 5.0 to 20 μM, and under white light irradiation in the irradiance range between 50 and 150 mW/cm2) to test their efficiency for possible clinical or environmental applications. The results showed that the new cationic ZnPcs 2a and 3a efficiently inactivate the RNA-virus model (bacteriophage Φ6), even at the lowest tested irradiance. These compounds are thus promising photosensitizers to be used in various contexts.info:eu-repo/semantics/publishedVersio

Diels-Alder reactions of Ni(II) β-vinyl-meso-tetraarylporphyrins

The cycloaddition reactions of nickel(II) β-vinyl-meso-tetraphenylporphyrins with tetracyanoethylene (TCNE) in chloroform, afford [2+2] adducts containing a cyclobutane ring and [4+2] adducts. The [2+2] adducts can also be produced by rearrangement of the [4+2] chlorins

Meso-Tetraphenylporphyrin Dimer Derivative as a Potential Photosensitizer in Photodynamic Therapy

Studies on the synthesis, preliminary in vivo biological activity, singlet oxygen and fluorescence yields of a climeric porphyrin (D1) are described. The pharmacokinetic behavior and photodynamic properties of the dimer D1 were examined in Balb/c mice bearing an MS-2 fibrosarcoma. Compound D1 shows a high selectivity for tumor localization (tumor/peritumoral tissue ratios of dye concentration ranging between ca 100 and 140 at 24 h after drug administration of 5.0-1.0 mg kg-1 into DL-α-dipalmitoylphosphatidylcholine liposomes). The phototherapeutic efficiency of dimer D1 was evaluated by following the growth curves of fibrosarcoma irradiated with red light (600-700 nm) with a total dose of 400 J cm-2, at 24 h after intravenous injection. Photodynamic therapy-treated tumors showed a significant delay in growth as compared to untreated control mice. The results obtained suggest that the porphyrin dimer D1 may be a promising candidate for further use in PDT experiments

A facile and effective synthesis of 4-imino-3-(arylidene)- azetidine-2-thiones via phosphorus pentasulfide

<div><p>A new and an efficient synthesis of 4-imino-3-(arylidene)-azetidine-2-thiones is reported. The reaction of arylidenemalononitriles with phosphorus pentasulfide and ethanol affords the title products in good yields. Elemental analysis, infrared, ¹H NMR, ¹³C NMR and mass spectral data elucidated structure of newly synthesized compounds.</p></div

Evaluation of meso-substituted cationic corroles as potential antibacterial agents

ABSTRACT Cationic derivatives of 5,10,15-tris[4-(pyridin-4-ylsulphanyl)-2,3,5,6-tetrafluorophenyl]-corrolategallium(III)pyridine and 5,10,15-tris[4-(pyridin-2-ylsulfanyl)-2,3,5,6-tetrafluorophenyl]-correlategallium(III)pyridine were synthesized and their photosensitizing properties against the naturally bioluminescent Gram-negative bacterium Allivibrio fischeri were evaluated. The cationic corrole derivatives exhibited antibacterial activity at micromolar concentrations against this Gram-negative bacterium strain

Evaluation of meso-substituted cationic corroles as potential antibacterial agents

<div><p>ABSTRACT Cationic derivatives of 5,10,15-tris[4-(pyridin-4-ylsulphanyl)-2,3,5,6-tetrafluorophenyl]-corrolategallium(III)pyridine and 5,10,15-tris[4-(pyridin-2-ylsulfanyl)-2,3,5,6-tetrafluorophenyl]-correlategallium(III)pyridine were synthesized and their photosensitizing properties against the naturally bioluminescent Gram-negative bacterium Allivibrio fischeri were evaluated. The cationic corrole derivatives exhibited antibacterial activity at micromolar concentrations against this Gram-negative bacterium strain.</p></div

Characterization of Isomeric Cationic Porphyrins with β-Pyrrolic Substituents by Electrospray Mass Spectrometry: The Singular Behavior of a Potential Virus Photoinactivator

Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) have been used to differentiate the 2- and 4-methylpyridyl isomers of free-base and metallated cationic β-vinylpyridylporphyrins. The analysis by ESI-MS/MS of the deuterated analogs and semiempirical calculations of structural and electronic parameters were also undertaken. The two free-base isomers are easily differentiated by ESI-MS/MS but the presence of a metallic center renders differentiation of the metallated isomers less effective. The data acquired show that of all the studied compounds, the free-base 2-methylpyridyl isomer, which was operative in the in vitro photoinactivation of Herpes simples virus, has a different gas-phase behavior. Local distortion of the macrocycle due to the presence of the β-vinylpyridyl substituent occurs for all the compounds, but a different electron density distribution can account for the observed gas-phase behavior of this potential virus photoinactivator