title: Effects of dietary di(2-ethylhexyl)phthalate, a putative endocrine disrupter, on enzyme activities involved in the metabolism of tryptophan to niacin in rats.
abstract: We have reported that the conversion ratio of tryptophan to niacin increased with increasing dietary concentration of di(2-ethylhexyl)phthalate (DEHP); the conversion ratio was about 2.0% in the control rat, which increased by about 30% in the rat fed with 3.0% DEHP diet. In this study, we investigated whether this abnormal increase in the conversion ratio by DEHP occurred through the alteration of the enzyme activities involved in the metabolism of tryptophan to niacin. Rats were fed with a diet containing 0%, 0.1%, 0.5%, or 1.0% DEHP for 21 days. The nine kinds of enzyme activities involved in the biosynthesis and catabolism in the liver and kidney were measured. Based on previous findings that the formation of quinolinic acid and its' metabolites significantly increased with DEHP administration, we proposed that the activity of 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase would be inhibited by DEHP intake. However, we found that the activities in the liver and kidney did not decrease in the rat fed with DEHP-containing diet. We discuss the discrepancy between the metabolite results and the enzyme activities.
authors.affiliation: Laboratories of Food Science and Nutrition, Department of Life Style Studies, School of Human Cultures, The University of Shiga Prefecture, 2500 Hassaka-cho, Hikone, Shiga, 522-8533, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fukuwatari
authors.forename: Mari
authors.initials: M
authors.lastname: Ohta
authors.forename: Etsuro
authors.initials: E
authors.lastname: Sugimoto
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Sasaki
authors.forename: Katsumi
authors.initials: K
authors.lastname: Shibata
mesh_terms: D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D002262:Carboxy-Lyases; D004051:Diethylhexyl Phthalate / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004702:Endocrine Glands / Q000187:drug effects*; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D009525:Niacin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D009525:Niacin; D014364:Tryptophan; D004051:Diethylhexyl Phthalate; D002262:Carboxy-Lyases; C024396:aminocarboxymuconate-semialdehyde decarboxylase