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.