The invention relates to new 3′-, 7-substituted-indirubins of formula (I) wherein R represents N—OH, N—O-alkyl or N—O—CO-alkyl, NO—(Ra)n1-Het, N—O—(Y)n1—N Ra Rb, N—O—CO—N(Rb Rc), radical with Het representing an aliphatic nitrogeneous heterocycle, Y being an optionally substituted —CH2— radical, n1 being 1 to 3, and X is an halogen atom selected in the group comprising F, Cl, Br, I, and Z is H or CH3 and the salts thereof.