title: Plasma and urine diketopiperazine concentrations in normal adults ingesting large quantities of aspartame.
abstract: In aqueous solution, aspartame can cyclicize to form its corresponding diketopiperazine (3-carboxymethyl-6-benzyl-2,5-diketopiperazine; DKP) and methanol. We measured plasma and urinary concentrations of DKP in samples obtained from six normal adult subjects ingesting 2.2 mg DKP/kg body weight. The DKP was administered as part of a dose of 200 mg aspartame/kg body weight. DKP concentrations in plasma were below the detection limit (less than 1 microgram/ml) of the high-pressure liquid chromatographic method at each time interval after ingestion at which they were measured. Mean (+/- SD) total urinary DKP excreted during the first 24-hr period after dosing was 6.68 +/- 1.30 mg (4.83 +/- 0.23% of the ingested DKP dose). Approximately 44% of the total DKP excreted was excreted in the first 4 hr after dosing.
mesh_terms: D000328:Adult; D001218:Aspartame / Q000378:metabolism*; D001557:Benzenesulfonates; D001711:Biotransformation; D001798:Blood Proteins; D002851:Chromatography, High Pressure Liquid; D004151:Dipeptides / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D010879:Piperazines / Q000097:blood / Q000378:metabolism* / Q000652:urine; D012459:Salicylates
chemical_list: D001557:Benzenesulfonates; D001798:Blood Proteins; D004151:Dipeptides; D010879:Piperazines; D012459:Salicylates; C053513:3-carboxymethyl-6-benzyl-2,5-diketopiperazine; C003366:sulfosalicylic acid; D001218:Aspartame