Maillard pentosidine

Several markers for the Maillard reaction have been described in the literature. For example, the product initially formed between glucose and lysine is partly transformed into furosine (Heyns et ah, 1968) on acid hydrolysis. Conversely, the fluorescent amino acid pentosidine (Sell and Monnier, 1989) is an advanced glycation endproduct (AGE) and may form covalent bonds between proteins (cross-linking). Furthermore, the Maillard reaction leads to an increase in characteristic fluorescence (excitation 370 nm, emission 440 nm) (Monnier et ah, 1984 Pongor et ah, 1984). 

HPLC. Furosine and pentosidine, indicators of the initial and advanced stages of fhe Maillard reaction, respectively, increased in glucose-exposed slices (figs. 3,4 fable 3). Hydroxylysylpyridinoline apparenfly did nof form in fhe demineralized dentin at 37°C, as it did not increase in dentin exposed at 37°C (table 3). 

Monnier VM and Sell DR (1994) The advanced Maillard reaction in aging and age-related diseases probed with pentosidine. Spec Publ - R Soc Chem 151, 235-243. 

The 328/378- and 370/440 fluorescences are characteristic for pentosidine and Maillard products, respectively (Dyer et al., 1991b) while the 317/407 fluorescence indicates dityrosine formation (Huggins et al., 1993). 

The increase of carboxymethyllysine (batch 1) and pentosidine (batches 1 and 11) thus observed provided additional proof for fhe Maillard reaction in caries (fable 3, figs. 2, 3). The pentosidine level ranged from abouf equal fo a manifold of the level in sound dentin. The formation of pentosidine can only account for a fraction of the increase in 328/378 fluorescence, which is in accordance with a major contribution from a different fluorophore as stated above. Unfortunately, an increase of dify-rosine as expected from fhe gain in 317/407 fluorescence (fable 2) could not be substantiated unequivocally by HPLC analysis because dityrosine co-eluted with lysylpyridinoline. Even if we would consider dityrosine to originate the lysylpyridinoline peaks observed in HPLC of carious dentin, but not of sound dentin, only one quarter of the increase in 317/407 fluorescence would derive from difyrosine. 

Interestingly, sound human dentin contained a more or less constant level of the advanced Maillard products, pentosidine and car-boxymethyllysine, irrespective of age (fable 3). Alfhough human denfin collagen is not turned over and the advanced products should thus increase during life, we suggesf fhaf fhe Maillard reacfion occurs in pre-denfin collagen, but is halted upon mineralization. ... 

The level of pentosidine of nondiabetic pulmonary cancer patients in treatment with the antineoplastic drug, cisplatin, has been found to be higher than in healthy subjects,443 when the protein from urine, plasma, and erythrocyte membranes was examined by HPLC. Urine pyrraline was unaffected. This work implies a whole field of study of the interactions of medication with the Maillard reaction. 

G20. Grandhee, S. K., and Monnier, V. M., Mechanism of formation of the Maillard protein cross-link pentosidine. Glucose, fructose, and ascorbate as pentosidine precursors. J. Biol. Chem. 266, 11649-11653 (1991). 

K. M. Biemel, O. Reihl, J. Conrad, and M. O. Lederer, Formation pathways for lysine-arginine cross-Unks derived fi om hexoses and pentoses by Maillard processes. Unraveling the structure of a pentosidine precursor, /. Biol. Chem., 276 (2001) 23405-23412. 

Takahashi, M., Ohishi, T., Aoshima, H., Kawana, K., Kushida, K., Inoue, T., and Horiuchi, K., 1993, The Maillard protein cross-link pentosidine in urine from diabetic patients, Diabetologia 36 664-667. 

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