isatogen

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]

n. [ Pref. di- + isatine + -gen. ] (Chem.) A red crystalline nitrogenous substance of artificial production, which by reduction passes directly to indigo. [ 1913 Webster ]