Urorosein

UROROSEIN, a red urinary pigment of protein origin, discovered by Nencki and Sieber and described by them in 1882. According to Salkowski's investigations, the chromogen of urorosein is indoleacetic acid; it is possible that a derivative of glycocoll-indolaceturic acid is also part of the chromogen. Under the influence of concentrated hydrochloric acid and a very dilute solution of potassium nitrite, the chromogen turns into urorosein. Urorosein is insoluble in ether and chloroform (distinguishing it from indirubin and skatolred). It dissolves well in water, ethyl alcohol, and amyl alcohol. A solution of urorosein in amyl alcohol yields a sharp absorption band in the green part of the spectrum between D and E (wavelength λ = 557 mµ). The color disappears upon the addition of alkalis and reappears upon acidification. The chromogen of urorosein is salted out by ammonium sulfate. The chromogen of urorosein has been found both in normal urine and in many pathological conditions, for example, in diabetes, typhoid fever, nephritis, cancer, etc. Regarding its detection in urine, see Urine. If nitrous acid has formed in standing urine under the influence of bacteria, the red coloration may appear after simple acidification with hydrochloric acid. To detect urorosein in blood, proteins are first removed with trichloroacetic acid. The appearance of urorosein in the blood indicates the presence of severe uremia, since urorosein is formed exclusively in cases of severe azotemia or hyperindicanemia.