-transparent.png){kind=logo}
The mechanism of the generation and the quantitative analysis of singlet oxygen (1O2) formed by the exposure of a hematoporphyrin derivative (HpD) to light was re-evaluated by electron spin resonance (ESR) combined with 2,2,6,6,-tetramethyl-4-piperidine (TMPD). The change from TMPD to 2,2,6,6,-tetramethyl-4-piperidine-N-oxide (TAN) has been reported to depend on singlet oxygen. However, we confirmed that this reagent also react with superoxide anion (O2-) and hydroxyl radicals (OH). Therefore, the reactions between TMPD and 1O2, O2- and OH were re-examined using a kinetic approach. We found that the generation of TAN was proportional to the concentration of TMPD and HpD, as well as to the duration and strength of the illumination. The generation of TAN was not inhibited by dimethyl-sulfoxide (DMSO) or superoxide dismutase (SOD). The reaction rate between TMPD and 1O2 was determined to be 5.0 x 10(-7) M min-1. The generation of 1O2 from HpD was 2.7 x 10(-7) M min-1 under our conditions. The competitive reaction observed between 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and TMPD for O2- or OH shows that TMPD reacts with both forms of active oxygen, but gave no ESR signal. The second-order reaction rate constant of TMPD between O2- and OH was calculated as 73 M-1 s-1 and 1.5 x 10(9) M-1 s-1, respectively. The photochemical generation of 1O2 from methylene blue, another sensitizer, was also demonstrated by this method. These results show that ESR signal of TAN can be used for the highly selective monitoring of 1O2.
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
November 1987,
Scientia Sinica. Series B, Chemical, biological, agricultural, medical & earth sciences,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
October 1989,
Biulleten' eksperimental'noi biologii i meditsiny,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
May 1999,
Free radical biology & medicine,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
April 2022,
JACS Au,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
January 2001,
Free radical biology & medicine,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
June 1987,
Cancer letters,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
December 1988,
Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
March 1987,
Biochimica et biophysica acta,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
July 2000,
Biological trace element research,
T Ando, and
T Yoshikawa, and
T Tanigawa, and
M Kohno, and
N Yoshida, and
M Kondo
January 1985,
Photochemistry and photobiology,
