FIELD: chemistry.SUBSTANCE: invention relates to compounds of formula I in which: X8 denotes N, and X5 and X6 denote CH R7 denotes phenyl or C5-6-heteroaryl group which is optionally substituted with one or more groups selected from halogen, hydroxy group, nitro group, cyano group, carboxy group and thiol, or phenyl or a methoxy group -C(=O)CH3, -C(=O)OCH3, -C(=O)OCH2CH3, -C(=O)OC(CH3)3, -C(=O)NH2, -C(=O)NHCH3, -C(=O)N(CH3)2, -C(=O)NHCH2CH3, -C(=O)N(CH2CH3)2, -NH2, -NHCH3, -N(CH3)2, -NHCH(CH3)2, -N(CH2CH3)2 or C1-4-alkyl, optionally substituted with a hydroxy group RN3 and RN4, together with the nitrogen atom with which they are bonded, form a heterocyclic ring selected from morpholine, thiomorpholine, piperidinyl, piperazinyl, homopiperazinyl and a pyrrolidinyl ring, optionally substituted at the carbon atom with one or two C1-4-alkyl groups R2 denotes NRN5RN6, where RN5 and RN6, together with the nitrogen atom with which they are bonded, form a heterocyclic ring selected from morpholine, thiomorpholine, piperdinyl, piperazinyl, homopiperazinyl and a pyrrolidinyl ring, optionally substituted at the carbon atom with one or two C1-4-alkyl groups or a pharmaceutically acceptable salt thereof, and where "C5-6-heteroaryl" denotes a heteroaryl group selected from furan, thiophene, pyrrole, imidazole, pyrazole, triazole, oxazole, isoxazole, thiazole, isothiazole, oxadiazole, tetrazole, octatriazole, isoxazine, pyridine, pyridazine, pyrimidine, pyrazine and triazine and where "C3-5-heterocyclyl", as used here, relates to a univalent structure obtained by removing a hydrogen atom from the ring of the heterocyclic compound, where that structure contains 5 or 6 ring atoms, 1-4 of which are ring heteroatoms selected from oxygen, nitrogen and sulphur and under the condition that when R2 denotes an unsubstituted morpholine group, RN3 and RN4, together with the nitrogen atom with which they are bonded, form a morpholine group, R7 does not denote an unsubstituted phenyl, and when
