EXPLORATION OF DYE CHEMISTRY IN TAENZER UNNA ORCEIN TYPE ELASTIN STAINING

Musso's demonstration of the amino- and hydroxyphenoxazone structure of synthetic orcein suggested trial of simpler mixtures and isolated pure dyes of the phenoxazine phenoxazone series. It was further thought that explorations of this sort might reveal which of the hitherto demonstrated 14 chromatographic components of orcein might take part in or even be chiefly responsible for the elective staining of elastin. Accordingly trials were made in a hydrochloric acid (0.12 N) 70% alcohol technic based on Taenzer's original method of a number of commercially available dyestuffs and indicators and a number of products were synthesized by variants of Musso's technic for resorcin blue: air oxidation of resorcinol in the presence of ammonia. Those tested are the following: Azolitmin, Lacmoid, Resorufin, Resorcin Blue (MLB), C.I. No. 51020, Gallocyanin C.I. 51030, Brilliant Cresyl Blue C.I. 51010, Nile Blue C.I. 51180, a Nile red preparation, Bernthsen's Methylene Violet; Azure A, Toluidine Blue C.I. 52040, several laboratory synthetic lots of Musso's Resorcin Blue in which oxidation was done with H2O2 and varying amounts of ammoni were used, and 2 batches in which resorcinol was partly or completely replaced by m-aminophenol. Successful to excellent elastin stains were achieved with Lacmoid, Resorcin Blue MLB, part of the Musso Resorcin Blue products and the two m-aminophenol oxilation products Elastin purple FP and Elastin Videt PR. From the failure of azolitmin and resorufin, both 7-hydroxy-2-phenoxazones and the success of resorcin blue (MLB) 7-N,N-dimethylamino-2-phenoxazone, it appears suggested that the aminophenoxazone structure may be a determining characteristic. The success with m-aminophenol substitution in the Musso air oxidation NH3 synthesis tends to support this view. While I have had some success with the Victoria blues first used by Lustgarten, using other technics, these dyes and some other triphenylmethanes do not successfully take the place of orcein in acid alcohol staining methods. Rosanilin and pararosanilin do stain rodent elastica from acid aqueous and alcoholic solutions but adult human elastica does not so stain. We suspect a diphenamine Schiff base condensation with the known free aldehyde of rodent elastica. This is confirmed by more or less complete blockade of pararosanilin acid alcohol staining with p-toluidine in glacial acetic acid, 1 hr, hydroxylamine: sodium acetate: H2O 10:20:40 3 hr and 5% phenylhydrazine HCl 3 hr on dog, rat and guinea pig arteries. The hydroxylamine gave complete blocking, the other two reagents partial. Altogether about 50 dye samples were tested. © 1969 Springer-Verlag.