Charles Tanielian

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Hematoporphyrin derivative (HpD) is a complex mixture of monoporphyrinic compounds, including hematoporphyrin, and oligomers containing up to eight porphyrin units. In methanol a sensitizer concentration-independent quantum yield of 0.64 is measured for the HpD-induced production of singlet molecular oxygen O2 (1Delta(g)). This finding is consistent with(More)
Determining whether the first step of photooxygenation is Type I or Type II is a necessary prerequisite in order to establish the mechanism of photodynamic action. But this distinction is not sufficient, because other processes, both consecutive and competitive, commonly participate in the overall mechanism. Thus, in both Type I and Type II reactions, the(More)
Plasmid DNA is efficiently photocleaved by sodium pheophorbides (Na-Phdes) a and b in the absence of oxygen as well as in the presence of oxygen. Fluorescence microscopic observation shows a rapid incorporation of Na-Phde a into nuclei, mitochondria, and lysosome of human oral mucosa cells. In contrast Na-Phde b is incorporated only into the plasma(More)
The objective of this work is to reexamine the competitive degradation of deoxyribose by hydroxyl radicals (.OH) produced by the reaction between H2O2 and Fe(2+)-EDTA. The .OH radicals produced attack deoxyribose (D, rate constant kD) and eventually an .OH scavenger (S, rate constant kS). First, we examined the effect of [D], [H2O2], [Fe(2+)-EDTA],(More)
The rate constants for the reactive (kR) and unreactive (kQ) interaction of singlet molecular oxygen with three esters of polyunsaturated fatty acids (PUFA: cis-methyl oleate, MO; cis-methyl linoleate, MLA and cis-ethyl linolenate, ELN) are determined. The values of the ratio kQ/kR are 0.51, 0.26 and 0.20 for MO, MLA and ELN, respectively. This variation(More)
The photosensitized oxygenation of organic molecules plays a key role in numerous processes of biological and industrial significance, such as, for example, photodynamic action and photodegradation of polymers. These reactions proceed either via quenching by the substrate of photophysically generated singlet oxygen, O2(1deltag), or via addition of ground(More)
The selectivity and efficacy of photodynamic therapy (PDT) may be improved by the combined use of photosensitizers in a similar manner to the combined use of drugs in cancer chemotherapy. Two photosensitizers (haematoporphyrin derivative (HPD) and rhodamine 123 (Rh-123) were analysed which can be irradiated at the same wavelength (514 nm), are(More)
This paper discusses the mechanism of photooxygenation reactions sensitized by dyes, such as: rose bengal, methylene blue, tetraphenylporphin and chlorophyll a. First it is shown more particularly that: the quantum yields of singlet oxygen O2(1 delta g) production gamma delta, and of intersystem crossing singlet S1-triplet T1, gamma is, are not always equal(More)