A constituent of urine which darkens on oxidation, perhaps potassium indoxylsulphate (‘indican of urine’). Cf. melanic acid n. at melanic, adj. 1.

A whitish substance occasionally found as a cloud in or pellicle upon urine; erroneously supposed by Nauche to be diagnostic of pregnancy.

(a) The natural glucoside (C26H31NO17) formed in plants which yield indigo, by the decomposition of which indigo-blue is produced; it forms a…

7-methylxanthine, C6H6O2N4, a purine sometimes found in human urine.

a crystalline compound, C8H8O4, which oxidizes to a black compound in air, is an intermediate in the metabolism of aromatic amino-acids, and is…

Any of a group of colourless tetrapyrrole compounds produced by the reduction of bilirubin, esp. by bacterial action in the gut, and forming…

Any of a group of porphyrins, occurring esp. in the urine during certain types of porphyria, in which each of the pyrrole rings has one acetate and…

Any porphyrinogen in which the pyrrole rings have side chains as in a uroporphyrin.

(more fully 4-pyridoxic acid) a biologically inactive compound which is the form in which excess vitamin B6 (see pyridoxine, n.) is usually excreted.