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Biomedical subjects

Y H Pang

Publications and source records attributed to Y H Pang.

9 recordsLinked to original sources

[The kinetics of ascorbic acid oxidation catalyzed by Cu(II)/H2DCA in the presence of DNA].

In phosphate buffer (pH 7.40), at 20.00 +/- 0.05 degrees C, the visible spectra of Cu(II) and Cu(II) complexes and the kinetics of ascorbic acid oxidation catalyzed by Cu(II)/H2DCA in the presence of DNA were studied. Measurements were reported on rate of .OH formation by the oxidation of ascorbic acid in the presence of Cu(II)/H2DCA. It showed that ternary complex Cu(II)/H2DCA/DNA may exist in the system in which DNA strand was broken by ascorbic acid in the presence of Cu(II)/H2DCA, and it was assumed that the DNA-breaking action of ascorbic acid in the presence of Cu(II)/H2DCA conformed to site-specific Fenton reaction mechanism. All the result of DNA-breaking action can be explained in terms of this site-specific Fenton reaction mechanism.

Ascorbic Acid↗

[DNA-breaking action of ascorbic acid in the presence of Cu(II)/demethylcantharic acid complex].

Effects of various factors on the DNA-breaking action of ascorbic acid in the presence of Cu(II)/demethylcantharic acid complex were studied in phosphate buffer (pH 7.40), at 37.0 +/- 0.1 degrees C. It was shown that .OH produced from Fenton reaction of H2O2 which can be formed from the oxidation of ascorbic acid was responsible for the DNA-breaking action of ascorbic acid and the simple Fenton reaction cannot explain all the results.

Ascorbic Acid↗

[Effect of diglycylhistidine on the oxidation of ascorbate catalyzed by Cu(II)].

Glycylglycylhistidine (GGH) was synthesized using mixed anhydride method, and Cu(II): GGH = 1:1 complex was identified using UV, ESR, CD, ORD and FAB/MS technique. The oxidation of ascorbate catalyzed by cupric ion in RPMI 1640 medium (pH 7.40) was studied. The activation energy E = 39.2 kJ/mol. The addition of GGH inhibited the oxidation of ascorbate catalyzed by cupric ion. The investigations with ESR and fluorimetry indicate that there are Cu(I), ascorbate radical (AH), O2-., H2O2 and .OH during the oxidation.

Animals↗