DIKETOPIPERAZINE OF PROLYLHYDROXYPROLINE IN NORMAL HUMAN URINE

Identification of a urinary metabolite of perazine as a piperazine-2,5-dione derivative

A non-basic perazine metabolite has been isolated from the urine of schizophrenic patients ingesting perazine. Identification of this compound as 10-[3‘-(2“,5”-dioxo-4“-methyl-piperazinyl)-propyl]-phenothiazine sulphoxide was achieved using ultraviolet, infrared, nuclear magnetic resonance and mass spectroscopy.

The quantitative relationship of urinary peptide hydroxyproline excretion to collagen degradation

To determine the quantitative relationship of urinary hydroxyproline peptide excretion to collagen breakdown, known quantities of radioactive hydroxyproline peptides were administered to unlabeled animals and excertion of radioactivity in respiratory carbon dioxide, urine, and feces was measured. The major routes of excretion of collagen peptide metabolites were respiratory carbon dioxide (75%) and urine, as hydroxyproline-containing peptides (25%). Since the predominant urine hydroxyproline peptide linkage is proly-hydroxyproline, L-prolyl-L-hydroxyproline-(3)H was administered to unlabeled animals. Greater than 80% of the administered dipeptide was excreted in urine, suggesting that this peptide linkage is not hydrolyzed to a significant extent in vivo. These data suggest that urinary hydroxyproline excretion is a "fairly" sensitive indicator of collagen breakdown and can be used at the clinical level to quantitate changes in collagen breakdown.