The condensation of indoxyl with isatin produces indirubin, which is a pinky-red pigment similar to indigo blue in structure . Indirubin has been isolated from the crude extract of B. cusia Brem. And from P. tinctorium. It is well known that plants contain. In addition to trans-indigo and trans-indirubin(isoindigotin,red), certain trace compounds such as cis-indigo (blue) , cis-indirubin. Indigo brown (isoindigo), indigo gluten ,indigo yellow and traces of flavonoids.