The Collaborative International Dictionary
Murexan
Murexan \Mu*rex"an\, n. [From Murexide.] (Chem.) A complex nitrogenous substance obtained from murexide, alloxantin, and other ureids, as a white, or yellowish, crystalline which turns red on exposure to the air; -- called also uramil, dialuramide, and formerly purpuric acid.
Wiktionary
murexan
n. (context obsolete chemistry English) A poorly-characterized nitrogenous material formed from several ureids