Abstract: Compounds of formula (I) or their pharmaceutically acceptable salts, or their stereoisomers or mixtures of stereoisomers, where: R1 is selected from the group consisting of: phenyl, and phenyl mono-, di-, or tri-substituted by a radical independently selected from the group consisting of F, Cl, Br, I, (C1-C6)-alkyl, COO—(C1-C6)-alkyl, and (C1-C6)-alkoxy; and R2 is a radical selected from the same group as R1, further including a phenyl substituted in 4-position by a radical independently selected from the group consisting of —O(CH2)CONH(CH2)3CH3 and OCH2COOC(CH3)3, a biphenyl-4-yl, thiazol-2-yl, and a thiazol-2-yl mono- or di-substituted by a radical selected from F and phenyl; inhibit cell proliferation of tumor cells independently of p53 protein and may also induce apoptosis in several tumor cells independently of p53 protein, being useful for the treatment of several types of cancer.