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Chapter 5,886

Metabolism of riboflavin tetra butyrate in the liver

Miyata, K.

Journal of the Nagoya Medical Association 105(3-4): 140-146

1981


Accession: 005885166

Riboflavin 2', 3', 4', 5'-tetrabutyrate (R-BUT), which is a deposit form of riboflavin, has been recognized as an agent used in suppressing lipid peroxidation in the body because of its accessibility to the lipids involved in peroxidation. The migration of R-BUT and its hydrolysates into the liver, hepatic vein outflow and bile was investigated by perfusing isolated rat liver with R-BUT. Perfusion was carried out by both recycling and single-pass. The recycling was performed by the method of Miller, and the single-pass by collecting the perfusate of the hepatic vein outflow without recycling. In the recycling system, .apprx. 95% of R-BUT disappeared from the perfusate within 10 min after perfusion was started, indicating that the incorporation of R-BUT into the liver markedly occurred in a short period of perfusion. Most of the flavins increased in the liver were fat-soluble in both perfusion systems. Analysis of the flavins in the liver perfused with R-BUT indicated that R-BUT was hydrolyzed to riboflavin through riboflavin-tri, -di and -monobutyrate during perfusion in both systems and that these partial hydrolyzates remained in the liver for a rather long time. In the bile, the concentration of flavin remarkably increased and most of the flavins were also fat-soluble in both systems, while R-BUT was not detectable. As for hepatic vein outflow in the single-pass system 78.3% of flavins were fat-soluble during 20 min-perfusion with R-BUT. R-BUT is incorporated into the liver from the blood stream through the portal vein to be deposited in the form of its intact or partially hydrolyzed forms for a certain period, and deposited flavins migrate either into the blood stream through the hepatic vein or into the bile in the form of fat-soluble flavins. The excretion into the bile indicates the occurrence of enterohepatic circulation of fat-soluble flavins.

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