Formation mechanisms of melanoidins and fluorescent pyridinium compounds as advanced glycation end products.
The formation mechanisms of melanoidins as advanced glycation end products (AGEs) have not been resolved. Blue and red pigments generated in the D-xylose-glycine reaction system are postulated to be intermediate oligomers in the generation of melanoidins. A novel blue pigment, designated blue-M5, was identified as a similar structure to blue-M1 except for the side chain of two dihydroxypropyl groups. Blue pigments were also generated in the D-glucose-glycine and D-xylose-beta-alanine reaction systems as well as in the D-xylose-glycine reaction system. Blue pigments by the Maillard reaction might be formed by the decarboxylation of two molecules of pyrrolopyrrole-2-carbaldehydes (PPA). PPA, composed of a side chain of a dihydroxypropyl group, was identified as a precursor of blue pigments. In fact, blue-M5 was generated by the incubation of PPA alone. Blue pigments, which involved pyrrolopyrrole structures, were readily changed to brown polymers. Glyceraldehyde-derived pyridinium (GLAP) compound, a glyceraldehyde-derived fluorescent AGE, and lysyl-pyrropyridine, a 3-deoxyglucosone-derived fluorescent AGE, were detected at higher levels in the plasma proteins and the tail tendon collagen of streptozotocin-induced diabetic rats compared to normal rats. GLAP and lysyl-pyrropyridine, therefore, might be related to the progression of diabetic complications.
Hayase
Fumitaka
F
Department of Agricultural Chemistry, Meiji University, Kanagawa 214-8571, Japan. fumi@isc.meiji.ac.jp
Usui
Teruyuki
T
Ono
Yoriyuki
Y
Shirahashi
Yoshinobu
Y
Machida
Tomomi
T
Ito
Takashi
T
Nishitani
Nozomu
N
Shimohira
Kazuhito
K
Watanabe
Hirohito
H
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000737:chemistry / Q000378:metabolism*; D005985:Glyceraldehyde / Q000032:analysis / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D015416:Maillard Reaction; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000737:chemistry / Q000378:metabolism*; D051381:Rats
D017127:Glycation End Products, Advanced; D011108:Polymers; D011726:Pyridinium Compounds; C011908:melanoidin polymers; D005985:Glyceraldehyde