THE HISTOCHEMICAL REACTION OF ARYL AMINES WITH TISSUE ALDEHYDES PRODUCED BY PERIODIC AND CHROMIC ACIDS

Abstract

The polyaldehydes produced in tissue by periodic or chromic acid oxidation are demonstrable with Schiff reagent. The Schiff reaction is prevented by prior condensation with arylamines, best in glacial acetic acid. The Schiff s base thus formed with m-amlnophenol is readily demonstrated by alkaline azo coupling, best with fast black K, also with other stable diazotates. Methyl iodide methylation followed by hot hydroalcoholic hydrolysis reliberates aldehyde and forms secondary amines in the case of azomethines of the structure RCH=NA. The Schiff''s bases formed in the present instance do not liberate aldehyde appreciably when subjected to this reaction sequence. They do undergo azo coupling in glacial acetic acid and in 1 N HC1, 10% acetic acid, also when such arylamines as m-toluidine, N-methyl-m-toluidine, aniline and o-anisidine, but not N,N-dimethylaniline are substituted for m-amlnophenol. The alkaline azo coupling reaction of the m-aminophenol aldehyde condensation product is much retarded by nitrosation, and largely though not completely restored by azide reduction of the nitrosamine. The nitrosamines formed by nitrosation of the condensation product with several arylamines yield colored products with arylamines such as p-nitroaniline and o-aminoazotoluene, which is essentially the Feigl reaction for nitrosamines. The tertiary amine formed by glacial acetic acid condensation of aldehyde with N-methyl-m-toluidine shows acid azo coupling which is prevented by presumably C -nitrosation in the para position, and when this nitrosation is done at 3[degree]C in strict darkness, diazotization occurs and is demonstrable by alkaline coupling with S acid to form a blue compound at polysaccharide sites, constrastlng with the red simultaneously formed at known tyrosine sites, which latter occur without N-methyl-m-toluidine condensation. It is concluded that the primary arylamlne aldehyde condensation product formed in tissues in aldehyde blockade reactions is a secondary amine, probably of Eibner''s diphenamine type, and that the product similarly formed when N-methyl-m-toluidine is used as the arylamlne is a tertiary amine.