FIELD : medicine; pharmaceuticals.SUBSTANCE : invention relates to novel compounds of formula I or a pharmaceutically acceptable salt thereof, having cyclin-dependent kinase (CDK) inhibitor properties. In the compound of formula (I), X is nitrogen, Y and Z are CH; R1 is phenyl, pyridine or pyrimidine, substituted or unsubstituted by one or more substitutes selected from a group consisting of hydroxy, amino and halogen; R2 is hydrogen; and R3 is pyrimidine, substituted or unsubstituted by one or more substitutes selected from a group consisting of C1-C6 alkyl, tetrahydropyranyl, substituted or unsubstituted C1-C6 alkyl piperidinyl, morpholino, substituted or unsubstituted C1-C6 alkyl piperazinyl, amino, C1-C6 alkylamino and halogen.EFFECT : compounds can be used for treating or preventing neuroblastoma, glioblastoma, non-small-cell lung cancer, small-cell lung cancer or colon cancer, as well as degenerative brain disease, for example, Alzheimer' s disease.8 cl, 6 dwg, 9 tbl, 112 ex