Estimation of β-3,4-dimethoxyphenethylamine and related compounds in urine extracts by radioimmunoassay

Antibodies to β-3,4-dimethoxyphenethylamine (DMPEA) were produced by immunizing rabbits with conjugates of N -succinyl-DMPEA coupled to poly l -lysine. N -(3′,4′-dimethoxyphenethyl)-4-hydroxyphenylacetamide was synthesized, iodinated to high specific activity, and used to develop a sensitive and specific radioimmunoassay (RIA) capable of measuring 100 pg DMPEA. While most of the binding energy of the antisera is directed toward the 3,4-dimethoxyphenyl nucleus, structural changes in the ethylamine side chain are also recognized. High pressure liquid chromatography was used in conjunction with RIA to identify the immunologically active material. In the chloroform extracts of six urine samples, all of this material cochromatographed with [ 3 H]DMPEA. In four other samples, the immunologically active component(s) did not correspond to DMPEA or to the metabolites that were tested. It is evident that normal individuals excrete different amounts of DMPEA.