Fluence-rate-dependent photosensitized oxidation of NADH.

The photosensitizing activity of dimethoxyhaematoporphyrin, excited by a laser pulse at 532 nm (YAG-Nd3+), was investigated using reduced nicotinamide adenine dinucleotide (NADH) as a substrate. The photo-oxidative modification of NADH was monitored by measuring the absorbance at 340 nm. The use of nanosecond pulses (15 and 0.5 ns) resulted in photosensitized NADH oxidation which depended on the fluence but not on the fluence rate up to a peak fluence rate of 10(7) W cm-2. At higher fluence rates a decrease in NADH photo-oxidation was observed, as well as on irradiation with picosecond pulses (35 ps). Stern-Volmer assay of the quenching by sodium azide revealed a decrease in quenching efficiency with increasing peak fluence rate. Oxidation of NADH was not suppressed by the addition of 20 mM sodium azide at peak fluence rates above 6 x 10(9) W cm-2. This observation, as well as the significant bleaching of dye absorption, indicates excitation of the photosensitizer into higher lying excited singlet states and the involvement of processes other than photodynamic action.

[1]  T. Gantchev,et al.  Photoproducts generated from hematoporphyrin under high-intensity picosecond flash photolysis , 1990, Radiation and environmental biophysics.

[2]  T. Hasan,et al.  Mechanistic investigation of doxycycline photosensitization by picosecond-pulsed and continuous wave laser irradiation of cells in culture. , 1990, The Journal of biological chemistry.

[3]  M. Shopova,et al.  HYDRATED ELECTRON FORMATION IN NANOSECOND and PICOSECOND LASER FLASH PHOTOLYSIS OF HEMATOPORPHYRIN IN AQUEOUS SOLUTION , 1991, Photochemistry and photobiology.

[4]  Ricardas Rotomskis,et al.  Singlet-singlet and triplet-triplet absorption of hematoporphyrin diacetate , 1986 .

[5]  Rinaldo Cubeddu,et al.  Hematoporphyrin derivative: experimental evidence for aggregated species , 1982 .

[6]  C. Foote.  CHAPTER 3 – Photosensitized Oxidation and Singlet Oxygen: Consequences in Biological Systems , 1976 .

[7]  M. Yamashita,et al.  Picosecond time-resolved fluorescence spectroscopy of hematoporphyrin derivative , 1984 .

[8]  E. Reddi,et al.  FLASH PHOTOLYSIS STUDIES OF HEMATO‐AND COPRO‐PORPHYRINS IN HOMOGENEOUS AND MICROHETEROGENEOUS AQUEOUS DISPERSIONS , 1983 .

[9]  J. Martín,et al.  The role of oxygen radicals in dye-mediated photodynamic effects in Escherichia coli B. , 1987, The Journal of biological chemistry.

[10]  I. Kochevar,et al.  Laser intensity and wavelength dependence of Rose-Bengal-photosensitized inhibition of red blood cell acetylcholinesterase. , 1989, Biochimica et biophysica acta.

[11]  R. Pottier,et al.  The photochemistry of haematoporphyrin and related systems. , 1986, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[12]  T J Dougherty,et al.  Identification of singlet oxygen as the cytotoxic agent in photoinactivation of a murine tumor. , 1976, Cancer research.

[13]  C. Gomer,et al.  In vitro and in vivo light dose rate effects related to hematoporphyrin derivative photodynamic therapy. , 1985, Cancer research.

[14]  N. Warne,et al.  Photodynamic inactivation of selected intracellular enzymes by hematoporphyrin derivative and their relationship to tumor cell viability in vitro. , 1984, Cancer letters.

[15]  V. Letokhov,et al.  High quantum yield of photochemical reactions of protoporphyrin-IX induced by powerful ultrashort laser pulses , 1981 .

[16]  P Jones,et al.  Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution. , 1976, The Biochemical journal.

[17]  J. Cadet,et al.  Photochemistry of nucleic acids in cells. , 1992, Journal of photochemistry and photobiology. B, Biology.

[18]  W. Koppenol.  Reactions involving singlet oxygen and the superoxide anion , 1976, Nature.

[19]  H. Schneckenburger,et al.  Time-resolved fluorescence in photobiology. , 1988, Journal of photochemistry and photobiology. B, Biology.

[20]  A. Andreoni,et al.  Two-step photoactivation of hematoporphyrin by excimer-pumped dye-laser pulses. , 1987, Journal of photochemistry and photobiology. B, Biology.

[21]  James Dillon,et al.  IN VITRO STUDIES ON THE PHOTOSENSITIZED OXIDATION OF LENS PROTEINS BY PORPHYRINS , 1987, Photochemistry and photobiology.

[22]  H. Mukhtar,et al.  Photoenhancement of lipid peroxidation associated with the generation of reactive oxygen species in hepatic microsomes of hematoporphyrin derivative-treated rats. , 1985, Cancer research.

[23]  P. C. Chan,et al.  Singlet oxygen as a mediator in the hematoporphyrin-catalyzed photooxidation of NADPH to NADP+ in deuterium oxide. , 1977, The Journal of biological chemistry.

[24]  Rinaldo Cubeddu,et al.  Two-step laser activation of hematoporphyrin derivative , 1982 .

[25]  C J Gomer,et al.  Properties and applications of photodynamic therapy. , 1989, Radiation research.

[26]  J. Moan,et al.  Photodynamic effects of haematoporphyrin derivative on synchronized and asynchronous cells of different origin. , 1981, British Journal of Cancer.

[27]  A. Girotti,et al.  Photooxidation of cell membranes in the presence of hematoporphyrin derivative: reactivity of phospholipid and cholesterol hydroperoxides with glutathione peroxidase. , 1988, Biochimica et biophysica acta.