Separation and characterization of urinary indoles resembling 5-hydroxytryptamine and tryptamine.

The occurrence of 5-hydroxytryptamine (serotonin) in normal human urine is suggested by the experiments of Page and his co-workers. Twarog & Page (1953) examined acetone extracts of urine by a pharmacological method (isolated heart of Venus mercenaria) and reported a 'serotonin-like activity' equivalent to 0'1-10yeg. of 5-hydroxytryptamine/ ml. ofurine. Later, Bumpus&Page (1955) described indoles with Rp values similar to 5-hydroxytryptamine, N-methyl-5-hydroxytryptamine and NNdimethyl 5 hydroxytryptamine (bufotenin) in similar extracts. In neither of these studies was the identity of the indoles confirmed by more than one test. In the present work, a preliminary report of which has already been given (Rodnight, 1955), the ion-exchange resin Zeo-Karb 226 has been used to examine human urine for the presence of 5-hydroxytryptamine and related indoles. Zeo-Karb 226 is a carboxylic acid-type resin with similar properties to the resin Amberlite IRC 50, recently used to determine histamine in rat urine (Wilson, 1954). Weakly acidic resins of this type have several features which render them suitable for extracting amines from body fluids under mild conditions. In particular, they can be buffered, enabling columns to be operated at a neutral pH. Bases such as 5hydroxytryptamine are then retained by the resin, whereas neutral ampholytes like tryptophan are not. Moreover, the absorbed bases can be readily displaced by weakly acidic solutions, in which they may be more stable than in the alkaline solutions often used with strongly acidic cation exchangers.