The present invention provides a medicament comprising a chemical compound according to formula A: wherein R1 is hydrogen, fluorine, chlorine, bromine, hydroxy, mercapto, methoxy, ethoxy, acetoxy, methyl, ethyl, propyl, isopropyl, t-butyl, nitro, amin, N,N-dimethylaminoyl, N,N-diethyl-aminoyl; R2 is hydrogen, a C1-8-alkyl e.g. methyl, ethyl, propyl, isopropyl, butyl, t-butyl; an C1-8-acyl e.g. acetyl, propionyl; R3 is a C5-12-heterocyclic ring, e.g. furanyl, pyranyl, pyrrolyl, pyridinyl, pyrazolyl, thienyl, thiazolyl, indolyl or -0R4 ; R4 is a C5-C12-aromatic ring e.g. phenyl; unsubstituted or substituted in any position with fluorine, chlorine, bromine, methoxy, ethoxy, C1-8-carboxy; Z is OH or 0; and n is 0, 1, 2 or 3, and m is 0, 1, 2 or 3, and its use for the activation of the aryl hydro carbon receptor.