Photosensitized Oxidation of Tryptophan and Hepatic Dysfunction in Neonatal Gerbils

Abstract

Hepatic dysfunction is a common metabolic complication of parenteral nutrition. Studies in animals have suggested that several amino acids, especially tryptophan, may play a role in the development of hepatic dysfunction. Further, photoirradiation of amino acids in the presence of photosensitizers, such as riboflavin, causes photooxidative changes in several amino acids. The present study was undertaken to determine the effect of tryptophan, after photoirradiation in the presence of riboflavin, on hepatic function in neonatal gerbils. Two-week-old suckling gerbils received approximately 4 mmol/kg/day of light-exposed or nonlight-exposed tryptophan or received saline intraperitoneally for 4 days. An increase in the activity of serum gamma-glutamyl transpeptidase was found in gerbils receiving both light-exposed and nonlight-exposed tryptophan compared to control. Concentrations of tryptophan were significantly higher in animals receiving saline than in the other two groups. There were no significant differences in the major tissue amino acids among the three groups of animals. Our data suggest the role of photosensitized oxidation of tryptophan in the pathogenesis of hepatic dysfunction in neonatal gerbils. It is possible that similar photooxidation occurring during infusion of parenteral amino acid solutions containing vitamins exposed to constant illumination in the newborn nursery is responsible for the observed hepatic dysfunction in parenterally fed neonates.

Photosensitized Oxidation of Tryptophan: Effect on Liver and Brain Tryptophan

“…In intact animals, we and others have previously demonstrated hepatotoxic effects of tryptophan photoproducts an viVO. 1,3,4 In the present study we extend the previous observations regarding tissue responses to tryptophan-riboflavin solutions. Of concern in the present report is the alteration in brain concentrations of tryptophan observed by us.…”

“…Results were compared with those of gerbils receiving similar injections of the parent solution, T + R + L. Data were analyzed by analysis of variance and the level of significance was set at p < 0.05; t-tests were carried out post-hoc if significance was achieved by ANOVA. 1 It was noted that the light-exposed riboflavin-containing solutions were pale compared with preexposure sotracings indicate fluorescent detectors and bottom tracings indicate UV detectors. lutions and that the light-protected riboflavin-containing solutions were slightly darker compared with preexposure solutions.…”

Photochemical‐like Behaviour of Riboflavin in the Dark Promoted by Enzyme‐generated Triplet Acetone

“…In this regard the formation of an adduct between riboflavin and tryptophan mediated by an enzymatic system in the absence of light might be very significant biologically in the clarification of the hepatic dysfunctions observed in animals when they are injected with mixtures containing riboflavin and tryptophan (Bhatia and Rassin, 1985). Ferrer, I. and E. Silva (1985) Study of a photo-induced lysozyme-riboflavin bond.…”

Recommendations for photoprotection of parenteral nutrition for premature infants: An ASPEN position paper

“…Administration of oxidized lipid can lead to cellular damage, and such effects can be magnified in the presence of trace elements. 4 When multivitamin preparations and other PN components (ie, ILEs) have been exposed to light and administered to animals, studies have shown adverse effects in the hepatobiliary system of gerbils 13 and in rats, 9,14,15 whereas pulmonary fibrosis has developed in guinea pigs. [16][17][18] These adverse findings could be reduced by protecting the PN admixtures and individual products from light.…”