The Collaborative International Dictionary of English v.0.48:
Isatogen \I*sat"o*gen\, n. [Isatin + -gen.] (Chem.) A complex nitrogenous radical, C8H4NO2, regarded as the essential residue of a series of compounds, related to isatin, which easily pass by reduction to indigo blue. -- I*sat`o*gen"ic, a. [1913 Webster]