Indican

 A glucoside (C14H17NO6) obtained from woad (indigo plant, Isatis Tinctoria) and other plants (see indigo), as a yellow or light brown sirup. When purified it is obtained as spear-shaped crystals. It has a nauseous bitter taste. By the action of acids, enzymes, etc., it breaks down into sugar and indigo. It is the source of natural indigo. Chemically it is the 3-glucoside of indole, H-indol-3-yl-.  [1913 Webster]

 An indigo-forming substance, found in urine, and other animal fluids, and convertible into red and blue indigo (urrhodin and uroglaucin). Chemically, it is indoxyl sulphate of potash, C8H6NSO4K, and is derived from the indol formed in the alimentary canal. Called also uroxanthin.  [1913 Webster]