found: Work cat.: Work cat.: Indirubin, the red shade of indigo, 2006:foreword ("Indirubine" first used in 1855 to describe '"a red colouring matter present in indigo and indigo-bearing plants along with indigo-blue"; "indirubins" collectively refer to the bis-indole indirubin isometric to indigo and its derivatives)
found: McGraw-Hill dictionary of scientific and technical terms, c1989:p. 952 (Indigo red: a red isomer of indigo obtained in the manufacture of indigo; also known as indirubin)
found: OED online, Apr. 11, 2007(indirubin: a substance, isomeric with indigo-blue, obtained by decomposition of indican, crystallizing in long purple metallic-shining needles; also called indigo-purpurin and indigo-red)
