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DNA cleavage by Maillard reaction product of an amino acid and glucose
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A spin trapping agent, PBN, produced a spin adduct with AN = 1.61 mT and A H = 0.472 mT from o-diazoquinone, and a spin adduct with A N = 1.60 mT and An=0.421 mT from p-diazoquinone. The coupling constants were similar to those reported for other phenyl radicals. The results indicate that diazoquinones generated hydroxyphenyl radicals, which induced DNA chain breaking and formed 8-(0- and p-hydroxyphenyl)purine adducts and thus induced mutagenicity in Salmonella. 27 Hiramoto, K., T. Yosihida, T. Kato and K. Kikugawa, Tokyo College of Pharmacy, 1432-1 Horinouchi, Hachioji, Tokyo 192-03 (Japan) DNA cleavage by Maillard reaction product of an amino acid and glucose
The DNA cleaving activity of the Maillard reaction product of tyrosine and glucose which emitted chemiluminescence was investigated. Maillard reaction of tyrosine and glucose was carried out on a hot plate at 2000C for 5 rain after tyrosine and glucose were mixed well at a ratio of 1:1 (w/w). The reaction product was dissolved into water and mixed with pBR322 DNA solution. The mixture was incubated at pH 7 and 37°C overnight. DNA cleavage was detected by agarose gel eleetrophoresis. The product showed a significant activity to cleave DNA. However, heated samples of tyrosine alone, glucose alone and their mixture did not reveal the activity. This result indicates that the Maiila~d reaction is essential tbr DNA cleaving activity. Scavengers for OH radical and superoxide anion exerted no influence on DNA cleavage, but singlet oxygen quenchers, i.e., azide and DABCO, slightly inhibited DNA cleavage. Singlet oxygen was detected by ESR spectroscopy after the Maillard reaction product was incubated with 2,2,6,6tetramethyipiperidine in ethanol. An ESR signal due to singlet oxygen appeared, and the signal disappeared by addition of azide or DABCO into the incubation mixture. These results indicate that the Maillard reaction product is responsible for DNA cleavage,
which may be due to singlet oxygen and also other active species. 28 Hirayama, T., K. lguchi and T. Watanabe, Department of Food Chemistry and Environmental Toxicology, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607 (Japan) Structural determination of directly mutagenic compounds as the $9 metabolites of 2,4-dinitrobiphenyi derivatives
In a previous paper, we made a preliminary investigation of the effect of the quantity of $9 under 20-rain preincubation on the mutagenicity of typical nitroarenes in Salmonella typhimurium TA98. The mutagenicity of 2,4-dinitro-biphenyl derivatives, e.g., 2,4,6-, 2,4,2'-, 2,4,3'- and 2,4,4'tri- (TNBp) and 2,4,2',4'-tetra-nitrobiphenyl (TNBp*), was enhanced by the treatment with $9 mix. In order to elucidate the ;nechanisms of mutagenic activation of the above aitrobiphenyls by use of a mammalian activation system, 2,4,6TNBp (0.09 rev./nmole +S9) and 2,4,2',4'TNBp* (457 rev./nr.~,~ +$9) were incubated with S9 mix for 48 h, s~pa,'ately, and their mutagenie metaboUtes were separated by SiP z column chromatography. In 2,4,6-TNBp, 2,4-diamino.6nitroBp (0.5 rev,/nmole -$9) was isolated as a metabolite. In 2,4,2 ',4'-TNBp *, 2,4'-diamino2',4-dinitroBp (25460 rev./nmole -$9) and 2,2'dinitrobenzidine (34 rev./nmole - $ 9 ) w e r e isolated and their structures were determined by their physico-chemical characteristics and the GC/MS data of their deamination products. From the HPLC analysis of these metabolites, the mutagenicity of 2,4'-diamino-2',4-dinitroBp ( - $ 9 ) contributed 100% of the mutagenicity of 2,4,2',4'-TNBp* ( + $9), whereas the mutagenicity of 2,4-diamino-6-nitroBp ( - $ 9 ) contributed only 0.4% of that of 2,4,6-TNBp (+$9). The mutagenicity of 2,2'-dinitrobenzidine was reduced to half by the treatment with $9 mix, whereas the mutagenicity was expected to be enhanced by a mammalian metabolic activation system.
A spin trapping agent, PBN, produced a spin adduct with AN = 1.61 mT and A H = 0.472 mT from o-diazoquinone, and a spin adduct with A N = 1.60 mT and An=0.421 mT from p-diazoquinone. The coupling constants were similar to those reported for other phenyl radicals. The results indicate that diazoquinones generated hydroxyphenyl radicals, which induced DNA chain breaking and formed 8-(0- and p-hydroxyphenyl)purine adducts and thus induced mutagenicity in Salmonella. 27 Hiramoto, K., T. Yosihida, T. Kato and K. Kikugawa, Tokyo College of Pharmacy, 1432-1 Horinouchi, Hachioji, Tokyo 192-03 (Japan) DNA cleavage by Maillard reaction product of an amino acid and glucose
The DNA cleaving activity of the Maillard reaction product of tyrosine and glucose which emitted chemiluminescence was investigated. Maillard reaction of tyrosine and glucose was carried out on a hot plate at 2000C for 5 rain after tyrosine and glucose were mixed well at a ratio of 1:1 (w/w). The reaction product was dissolved into water and mixed with pBR322 DNA solution. The mixture was incubated at pH 7 and 37°C overnight. DNA cleavage was detected by agarose gel eleetrophoresis. The product showed a significant activity to cleave DNA. However, heated samples of tyrosine alone, glucose alone and their mixture did not reveal the activity. This result indicates that the Maiila~d reaction is essential tbr DNA cleaving activity. Scavengers for OH radical and superoxide anion exerted no influence on DNA cleavage, but singlet oxygen quenchers, i.e., azide and DABCO, slightly inhibited DNA cleavage. Singlet oxygen was detected by ESR spectroscopy after the Maillard reaction product was incubated with 2,2,6,6tetramethyipiperidine in ethanol. An ESR signal due to singlet oxygen appeared, and the signal disappeared by addition of azide or DABCO into the incubation mixture. These results indicate that the Maillard reaction product is responsible for DNA cleavage,
which may be due to singlet oxygen and also other active species. 28 Hirayama, T., K. lguchi and T. Watanabe, Department of Food Chemistry and Environmental Toxicology, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607 (Japan) Structural determination of directly mutagenic compounds as the $9 metabolites of 2,4-dinitrobiphenyi derivatives
In a previous paper, we made a preliminary investigation of the effect of the quantity of $9 under 20-rain preincubation on the mutagenicity of typical nitroarenes in Salmonella typhimurium TA98. The mutagenicity of 2,4-dinitro-biphenyl derivatives, e.g., 2,4,6-, 2,4,2'-, 2,4,3'- and 2,4,4'tri- (TNBp) and 2,4,2',4'-tetra-nitrobiphenyl (TNBp*), was enhanced by the treatment with $9 mix. In order to elucidate the ;nechanisms of mutagenic activation of the above aitrobiphenyls by use of a mammalian activation system, 2,4,6TNBp (0.09 rev./nmole +S9) and 2,4,2',4'TNBp* (457 rev./nr.~,~ +$9) were incubated with S9 mix for 48 h, s~pa,'ately, and their mutagenie metaboUtes were separated by SiP z column chromatography. In 2,4,6-TNBp, 2,4-diamino.6nitroBp (0.5 rev,/nmole -$9) was isolated as a metabolite. In 2,4,2 ',4'-TNBp *, 2,4'-diamino2',4-dinitroBp (25460 rev./nmole -$9) and 2,2'dinitrobenzidine (34 rev./nmole - $ 9 ) w e r e isolated and their structures were determined by their physico-chemical characteristics and the GC/MS data of their deamination products. From the HPLC analysis of these metabolites, the mutagenicity of 2,4'-diamino-2',4-dinitroBp ( - $ 9 ) contributed 100% of the mutagenicity of 2,4,2',4'-TNBp* ( + $9), whereas the mutagenicity of 2,4-diamino-6-nitroBp ( - $ 9 ) contributed only 0.4% of that of 2,4,6-TNBp (+$9). The mutagenicity of 2,2'-dinitrobenzidine was reduced to half by the treatment with $9 mix, whereas the mutagenicity was expected to be enhanced by a mammalian metabolic activation system.