Photophysical and Redox Properties of a Series of Phthalocyanines: Relation with Their Photodynamic Activities on TF-1 and Daudi Leukemic Cells

Abstract— The photodynamic therapy (PDT) efficiency of five phthalocyanines, chloroaluminum phthalocyanine (AlPc), dichlorosilicon phthalocyanine (SiPc), bis (tri- n -hexylsi-loxy)silicon phthalocyanine (PcHEX), bis (triphenyl-siloxy)silicon phthalocyanine (PcPHE) and nickel phthalocyanine (NiPc), was assessed on two leukemic cell lines TF-1 and erythroieukemic and B lymphoblastic cell lines, Daudi, respectively. AlPc showed the best photocytotox-icity leading to 0.008 surviving fraction at 2 × 10⁻⁹ M for TF-1 and 4 × 10⁻⁹ M for Daudi. At 5 × 10⁻⁷ M , SiPc and PcHEX induced a significant photokilling, whereas NiPc and PcPHE were inactive. Laser flash photolysis and photoredox properties of the phthalocyanines were investigated to try to relate these parameters with the biological effects. AlPc showed the longest triplet lifetime: 484 fis in dimethyl sulfoxide/H₂O. This value was increased up to 820 u.s when AlPc was complexed with human serum albumin used as a membrane model. Such an enhancement was not observed with the silicon phthalocyanines. Upon irradiation, all the phthalocyanines generated singlet oxygen with 0.29–0.37 quantum yield values. The reduction potentials of the excited states obtained from measurement in the ground state and energy of the excited triplets show that AlPc is the best electron acceptor. The in vitro photocytotoxicity observed and the measured parameters are in agreement with a key role of electron transfer in PDT assays involving these phthalocyanines.     

Electronic Absorption and Emission Spectra of 1, 3-Diaryltriazenes

The Pariser-Parr-Pople (PPP) type LCI-SCF-MO calculations were used to study the models of 1, 3-diphenyltriazene (1) , 1, 3-bis(3-pyridyl)triazene (2) , 1, 3-bis (2, 4-dichlorophenyl)triazene (3) , and 1, 3-bis (4-ethoxycarbonyl)triazene (4) . The results of the calculations were compared with the experimental electronic absorption and emission (fluorescence, phosphorescence) spectra of these compounds.     

EFFICIENT PHOTODYNAMIC ACTION OF VICTORIA BLUE BO AGAINST THE HUMAN LEUKEMIC CELL LINES K-562 AND TF-1

Abstract— Photodynamic induced cytotoxicity by Victoria blue BO (VB-BO), merocyanine 540 (MC540), Nile blue A (NB) and 4-tetrasulfonatophenyl-porphyrin (4-TSPP) has been studied on two human leukemic cell lines: K-562 and TF-1. Cells were incubated with dyes and irradiated with different doses of white light. Cell survival was assessed by propidium iodide (PI) staining using flow cytometry analysis. Concentrations of 5 x 10 ⁸ M VB-BO were found to kill 75% of cells, and a concentration of 1 × 10⁻⁷ M induced more than 99% of cell killing. To obtain the same cytotoxic level, the presence of 2.6 × 10⁻⁵ M of MCS40 during irradiation was needed. Under the conditions used, NB was ineflective as a photosensitizer, although uptake studies showed that this dye was taken by the cells in much greater amounts than any other studied dye. Cell cycle distribution of TF-1 cells, surviving MC540 or VB-BO photoscnsitization has bccn studied by flow cytometry analysis after staining with Hoechst 33342 and PI. It was found that cells in G₁ phase were slightly more resistant toward MCS40– and VB-BO-mediated photosensitization than cells in other phascs of the ccll cycle     

REGENERATION OF NAD+ AND NADP+ COFACTORS BY PHOTOSENSITIZED ELECTRON TRANSFER

Abstract The irradiation with visible light of photosensitizer dyes like methylene blue or N-methyl phenazonium methyl sulfate leads to the oxidation of reduced coenzymes such as pyridine nucleotides (NADH or NADPH). This photoredox reaction can be used to regenerate the oxidized form of these coenzymes in enzymatic reactions and total consumption of a substrate with catalytic amounts of enzyme, coenzyme and photosensitizer can be performed. The process has been studied on two common enzymatic reactions: ethanol oxidation by alcohol-NAD ⁺ -oxidoreductase and gluconate-6-phosphate oxidation by 6-phospho-D-gluconate-NADP⁺-2-oxidoreductase. In the first case, a turnover number of 1125 has been obtained for the photoregeneration of NAD ⁺ from NADH.     

Etude du Comportement Photochimique de quelques Diaryl-1,3-triazènes

Study of the Photochemical Behaviour of Some Diaryl-1,3-triazenes The photolysis of Diaryl-1,3-triazenes gives products whose structures are consistent with a cage recombination process of homolytically formed radicals and subsequent abstraction of hydrogen from the solvent molecules by arylamino radicals. In aromatic solvents, a free-radical chain process leads to the formation of products resulting from the homolytic substitution on the solvent. Quenching experiments show that singlet and triplet excited states are reactive but that intersystem crossing efficiency is low.     

Synthesis of Aluminum Phthalocyanines Bearing Bulky Lipophilic Substituents

The axial binding of alkyl chains or cholesterol moiety on one side of aluminum phthalocyanine was performed by reacting hydroxyaluminumphthalocyanine with the corresponding chloroalkylsilanes ot the chlorodiphenylcholesteryloxysilane.     

DIFFÉRENCE DE COMPORTEMENT ENTRE LES RÉACTIFS ELECTROPHILES DIÉTHYLTRICHLOROMÉTHYLPHOS- PHONATE ET TÉTRACHLORURE DE CARBONE OPPOSÉS AU TRIÉTHYLPHOSPHITE

Abstract

The reaction of triethylphosphite 1 with diethyltrichloromethylphosphonate 2b in the absence of solvents and catalysts yields mainly diethyl(1,1-dichloropropyl)phosphonate 4 and diethyldichloromethylphosphonate 7. These main products are accompanied by a variety of by-products which differ considerably from those obtained in the reaction between triethyl phosphite and CCl₄. Both reactions would begin by a halophilic substitution of triethylphosphite on the positive halogen. For diethyltrichloromethylphosphonate 2b the formed carbanion would then attack preferentially the carbon β to P⁺ and the hydrogen γ to P⁺ on heterophosphonium cation. In contrast, the less sterically hindered trichloromethyl carbanion formed by the halophilic attack of triethylphosphite on carbon tetrachloride would rather attack mainly the positive P⁺ of this cation. The tetraethyl(dichloromethylene)bisphosphonate 8 previously reported by Kukhar and Sagina to be the main product formed in the thermal reaction between triethylphosphite and diethyltrichloromethylphosphonate was not found under our conditions. We observed its formation only under photochemical irradiation.     

Phototoxicity of some novel porphyrin hybrids against the human leukemic cell line TF-1

Photodynamic induced cytotoxicity by porphyrin-DNA cross linker/intercalator hybrid diads and triads has been studied on the human leukemic cell line TF-1. Cells were incubated for 1 to 4 h with these new photosensitizers and irradiated with white light. Cell survival was assessed by the propidium iodide staining, using flow cytometry analysis. A comparison of the dark and light cell survival factor values suggests that irradiation has a significant effect on the toxicity at low concentrations for the porphyrin-chlorambucil diad and to a lesser extent at high concentrations for the porphyrin-acridone diad, the porphyrin-acridine diad and the porphyrin-cholic acid-chlorambucil triad. While the intrinsic antileukemic (via DNA cross-linking) activity of the chlorambucil moiety and the structural details may be responsible for the photoenhancement of the toxicity, the presence of acridine or acridone which are avid intercalators of DNA, is responsible for a similar effect seen for diads.     

Synthèse de N-Alkyl-arylamines par Thermolyse ou Photolyse d'Alkyl-3-diaryl-1,3-triazènes

Synthesis of N-Alkyl-arylamines by Thermolysis or Photolysis of 3-Alkyl-1,3-bis(p-chlorophenyl)triazenes The thermolysis of 3-alkyl-1,3-bis(p-chlorophenyl)triazenes in benzene or methanol leads to the formation of N-alkyl-p-chloroanilines ( 2 ) in 19–50% yield, N-alkyl-bis(p-chlorophenyl)amines ( 3 ) in 7.5–15.5% yield and 4,4′-dichlorobiphenyle ( 4 ) in 1–7% yield; besides with benzene as the substrate, 4-chlorobiphenyle ( 5 ) (12–20% yield) was also formed. The photolysis in methanol gives only the N-alkyl-p-chloroanilines ( 2 ) in 32–40% yield. In these two cases the results are consistent with a radical pair formation in a solvent cage, recombination (thermolysis) and/or diffusion (thermolysis and photolysis) with intermolecular abstraction of hydrogen. A free radical chain mechanism is involved in the photolytic process and the quantum yield is high.