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Bound Malondialdehyde in Foods: Bioavailability of N,N‘-Di-(4-methyl-1,4-dihydropyridine-3,5-dicarbaldehyde)lysine

Girón-Calle, Julio, Alaiz, Manuel, Millán, Francisco, Ruiz-Gutierrez, Valentina, Vioque, Eduardo
Journal of agricultural and food chemistry 2003 v.51 no.16 pp. 4799-4803
bioavailability, essential amino acids, feces, foods, intraperitoneal injection, lipid peroxidation, lysine, malondialdehyde, microsomes, oral administration, proteins
Reactions between lipid peroxidation products and proteins in foods have detrimental nutritional effects, most importantly, losses of essential amino acids. One of the major products of the reaction of malondialdehyde and alkanals with amino groups are 4-substituted 1,4-dihydropyridine-3,5-dicarbaldehyde derivatives. The product of the reaction of lysine with malondialdehyde and acetaldehyde, N,N‘-di-(4-methyl-1,4-dihydropyridine-3,5-dicarbaldehyde)lysine (MDDL), has been synthesized and used for in vitro and in vivo bioavailability studies. Release of free lysine did not occur in incubations of MDDL with tissue homogenates. After oral administration of radioactively labeled MDDL, radioactivity was only recovered in feces. Radioactivity was not incorporated into hepatic microsomes after intraperitoneal administration, which would have indicated release of available lysine. These results show that MDDL is a form of unavailable lysine, because it is not metabolized to free lysine and cannot be absorbed from the gut. Thus, formation of this derivative in foods would result in loss of available lysine.