Glycated Tryptophan in the Plasma of Chickens Fed Tryptophan-excess Diets

Abstract

When tryptophan is glycated with glucose, it results in forming two types of glycated tryptophan, glucose-tryptophan Amadori product and (1R, 3S)-1-(D- gluco-1,2,3,4,5-pentahydroxypentyl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (PHP-THβC). Hyperglycemia and high body temperature in avian species are supposed to elevate the concentration of glycated tryptophan in the plasma of chickens fed tryptophan-excess diets. However, plasma concentrations of both glucose-tryptophan Amadori product and PHP-THβC have not been determined so far. Young chickens were fed tryptophan-excess diets (1, 2 or 3% excess) for 14 or 21 days, and plasma concentrations of two types of glycated tryptophan were measured using liquid chromatograph mass spectrometer (LC/MS). In the present study, we successfully detected and quantified both glucose-tryptophan Amadori product and PHP-THβC in the plasma, which revealed that plasma concentrations of glucose-tryptophan Amadori product and PHP-THβC were approximately 1 and 2-4μM, respectively. Furthermore, plasma concentrations of glycated tryptophan compounds significantly correlated to that of plasma tryptophans, and total amount of both glycated tryptophan compounds was almost 10% of plasma tryptophan.