Generation of DNA-breaking activity in the Maillard reaction of glucose-amino acid mixtures in a solid system.

Maillard products of 1:1 solid mixtures of glucose-amino acid heated at 200 degrees C for 5 min induced single-strand breaks of DNA after incubation at 37 degrees C and pH 7.4 overnight. The products of Gly, His, Trp, Tyr, Phe and CySH transformed a plasmid supercoiled DNA (form I) into an open circular relaxed form (form II) and a linear form (form III). The breaking activity of the product of CySH was the highest. The product of Tyr caused fragmentation of single-stranded DNA, but did not cleave double-stranded linear DNA. The breaking activity of the product of Tyr was little or not at all inhibited by scavengers of singlet oxygen, hydroxyl radical, superoxide and hydrogen peroxide. Aqueous solutions of the products of all amino acids except CySH emitted chemiluminescence, which was partly due to singlet oxygen. High-performance liquid chromatography of the product of Tyr showed that the substances responsible for the DNA-breaking activity were eluted in a broad range, whereas those for chemiluminescence were eluted in an overlapped sharp peak. The Maillard reaction of glucose-amino acid in a solid state produced substances having DNA-breaking activity together with those generating single oxygen and emitting chemiluminescence.