Maillard Reaction in Vivo

In Chapter 13, six main ways of inhibiting the Maillard reaction in foods received attention refrigeration, the use of sulfur dioxide, lowering of pH, adjusting aw, and removing one or other of the reactants. Four of these are clearly not appropriate for in vivo systems, which normally cannot be refrigerated, have their pH or aw adjusted, or be exposed to sulfur dioxide. The reactants (and intermediate products derived from them) therefore become the main targets. 

According to Monnier et al.519 potential strategies against the Maillard reaction in vivo could thus focus on seven targets  

Monnier et al.519 had further comments on each. In this chapter, attention is paid especially to trapping agents and intervention through enzymes, ending up with mention of a recently demonstrated hypoglycaemic agent. 

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Dyer DG, Blackledge JA, Katz BM, Hull CJ, Adkisson HD, Thorpe SR, Lyons TJ and Baynes JW (1991a) The Maillard reaction in vivo. Z Ernahrungswiss 30, 29-45. 

The occurrence of Maillard reactions in vivo was observed for the first time only a few years ago. In 1975 we reported (3) the formation of deoxyfructoserotonin (Fig. 1) and deoxyfructolysine derivatives in the blood, in this second case poly-L-lysine being used as a model compound (Fig. 2). 

Nutrients can modify Maillard reactions in vivo by many different ways. 

Change of pH of Blood Plasma A slightly acid medium is usually needed for the Maillard reaction, but in some cases, e.g., with lysine-rich proteins, a slightly alkaline pH is also operating. Thus a small change in pH, due to the nature of food consumed or the pathologic metabolism of foodstuffs, can affect Maillard reactions in vivo. 

Food as Source of Starting Materials for Maillard Reaction in Vivo Nutrients are, of course, the origin of many different reducing sugars and amines or proteins, which are suspected to undergo a Maillard reaction in vivo. 

Availability of Starting Materials for Maillard Reaction in Vivo Not all starting materials present in the body are available for Maillard reaction. For example, trypotophan in blood, formed by digestion and absorption of tryptophan-rich proteins, is easily bound by plasma albumin, making it unavailable for further transformation. 

The efficient browning of proteins by 3-DG and MGO under anaerobic conditions emphasises that oxidation is not essential for Maillard reactions in vivo, although oxygen and oxidation appear to be rate-limiting for browning and crosslinking of proteins by aldo- and ketohexoses, as well as ascorbate. 

J. E. Litchfield, S. R. Thorpe, and J. W. Baynes, Oxygen is not required for the browning and crosslinking of protein by pentoses Relevance to Maillard reactions in vivo, Int. J. Biochem. Cell Biol, 1999, 31, 1297-1305. 

V. M. Monnier, Intervention against the Maillard reaction in vivo. Arch. Bio-... 

In conclusion, evidence has been gathered for a role of the Maillard reaction in caries. This reaction can cause inhibition of matrix degradation, which in turn inhibits lesion demineralization. Further research is needed to elucidate the pathways and the importance of this reaction in in vivo caries pathology. 

Mester, L. Szabados, L. Mester, K. Yadav, H. Maillard type carbonyl-amine reactions in vivo and their physiological effects. Prog. Food Nutr. Sci. 1981, 5 295-314. 

As already noted, the main interest of fructosamine derivatives in food and health sciences stems from their role as intermediates in tiie Maillard reaction in foods and in vivo. It is thought tiiat the vast majority of o-fructosamine transfoimation reactions, such as dehydration, oxidation, and fragmentation, are effected by acid/base and transition metal-ion catalysts. A relatively limited effort has been spent on proper documentation of proton- and metal-binding characteristics of D-fructosamine derivatives, however. Roper et a/. evaluated acidity constants for the P-pyranose tautomer of several D-fructose-amino acids using C-NMR. More precise p/iTa values were obtained from... 

Chuyen, N.V. Utsunomiya, N. Hidaka, A. Kato, H. 1990. Antioxidative effect of Maillard reaction products in vivo. In The Maillard Reaction in Food Processing, Human Nutrition and Physiology, Finot, P.A. Aesch-bacher, H.U. Hurrell, R.F. Liardon, R., Eds. Birkhauser Verlag Basel, 1990 pp 285-290. 

More recently, it has been shown that N-(l-deoxy-D-fructos-l-yl) derivatives of mammalian proteins are formed in vivo [44]. The process, which is called non-enzymatic glycation (formerly erroneously termed glycosylation), may be important in the pathology of diabetes [45] and of Alzheimer s disease [46], the formation of cataracts [47] as well as other aging processes [48]. The precise role of the Maillard reaction in the process of aging still remains a matter of specu-... 

The health impairing and toxic elfects of oxidation of lipids are due to loss of vitamins, polyenoic fatty acids, and other nutritionally essential components formation of radicals, hydroperoxides, aldehydes, epoxides, dimers, and polymers and participation of the secondary products in initiation of oxidation of proteins and in the Maillard reaction. Dilferent oxysterols have been shown in vitro and in vivo to have atherogenic, mutagenic, carcinogenic, angiotoxic, and cytotoxic properties, as well as the ability to inhibit cholesterol synthesis (Tai et ah, 1999 Wpsowicz, 2002). 

Unfortunately, the in vitro studies mentioned-above sometimes employed rather unnatural reactant concentrations and reaction conditions for simulation of the Maillard reaction. Little attention was paid to the likeliness of the reaction under the circumstances prevailing in the caries lesion in vivo. To provide a better understanding of the different... 

Being a biochemist, Maillard (20) studied the reaction of glycine with xylose or glucose at 40° and then at 34°C, in order to know the possibility of the change in vivo. 

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