Formation and excretion of pyrrole 2 carboxylate in man

Abstract

A detailed investigation of the purification of pyrrole 2 carboxylate (PCA) from human and rat urine indicates that previously reported mean values overestimate the correct quantity of free PCA by a factor of approximately 3 for rat urine and approximately 5 for human urine. Although several criteria of purity were satisfied by a previous method, pyrrole reactive impurities were still present in the final fractions. These impurities are separated from PCA by chromatography through an amino acid analyzer ion exchange resin. With the corrected method, normal human values for endogenous urinary PCA in 16 individuals averaged 0.51 μmol/day, with a range of 0.20 to 1.3 μmol. AND A SD of 0.31 μmol and a The probable source of human PCA is free hydroxy L proline, as inferred from the high value for PCA in the urine of a subject with hereditary hydroxyprolinemia, and from the 3 to 8 fold elevation in PCA excretion by 2 normal subjects after a large oral load of hydroxy L proline. Subcutaneous administration of [2 14C1)PCA to a single human subject indicated almost complete conversion of the exogenous compound to derivatives, which are largely excreted in the urine. Data are discussed suggesting that much or all of the PCA in human urine may be formed in urine from a labile precursor, presumably Δ1 pyrroline 4 hydroxy 2 carboxylate.