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Cyclin-dependent kinases (cdk) have recently raised considerable interest in view of their essential role in the regulation of the cell division cycle. The structure-activity relationships of edk inhibition showed that the 1, 3, and 7 positions of the purine ring must remain free, probably for a direct interaction, in which it behaves as a hydrogen bond acceptor. Olomoucine (6-(benzylamino)-2-[(2-hydroxyethyl)amino]-9-methylpurine, OC), roscovitine (6-(benzylamino)2(R)-[[1-(hydroxymethyl)propyl]amino]-9- isopropylpurine), and other N6,2,9-trisubstituted adenines were found to exert a strong inhibitory effect on the p34(cdc2)/cyclin B kinase. Removal or change of the side chain at position 2 or the hydrophobic group at position 9 dramatically decreased the inhibitory activity of olomoucine or roscovitine. Inhibition of cdk with OC and related compounds clearly arrests cell proliferation of many tumor cell lines at G1/S and G2/M transitions and also triggers apoptosis in the target tumor cells in vitro and in vivo. Thus, from a pharmacological point of view, OC may represent a model compound for a new class of antimitotic and antitumor drugs.

On treatment with boiling 1 N aqueous NaOH for 2 h, 3,7-dialkyladenine salts (7: R1, R2= Me, Et, or PhCH2; X= Br, I, or ClO4) gave 1-alkyl-4-(N-alkylamino)-1H-imidazole-5-carboxamides (8), 1-alkyl-4-amino-1H-imidazole-5-carboxamides (11), and N6,7-dialkyladenines (14) in 33-59 percent, 2-10 percent, and 2-5 percent yields, respectively.Under slightly milder reaction conditions, 3,7-dimethyladenine hydriodide (7a: X= I) afforded 1-methyl-4-(N-methylamino)-1H-imidazole-5-carboxamide (8a) together with 3,7-dimethylhypoxanthine (2a) as a by-product; 7-benzyl-3-methyladenine hydrobromide (7c: X= Br) furnished a small amount of 1-benzyl-4-(N-methylamino)-1H-imidazole-5-carboxamidine (5c) besides 1-benzyl-4-(N-methylamino)-1H-imidazole-5-carboxamide (8c), 1-benzyl-4-amino-1H-imidazole-5-carboxamide (11c), and 7-benzyl-N6-methyladenine (14c).These results are best interpreted in terms of pathways involving hydrolytic deamination, ring fission in the pyrimidine and imidazole moieties, cyclization, and Dimroth rearrangement.The instability of 7a (X= I) in aqueous alkali was compared with that of the four possible Nx,9-dimethyl isomers, and the relative ease with which the adenine ring underwent hydrolytic ring fission was found to decrease in the order 3,9- (17) >7,9- (18) >1,9- (19) >3,7- (7a) >>N6,9-dimethyl isomer (20).Keywords - 3,7-dialkyladenine alkaline hydrolysis; ring fission; deamination; rearrangement; 1-alkyl-4-(N-alkylamino)-1H-imidazole-5-carboxamide; 1-alkyl-4-amino-1H-imidazole-5-carboxamide; N6,7-dialkyladenine

The effect of various N6-substituents on the C(8)-hydrogen exchange of 9-substituted adenines has been estimated.The kinetic data clearly demonstrate that the N6-acyl groups significantly accelerate the C(8)-hydrogen exchange.This fa

An N6-acyl group in 9-substituted adenines shows the prominent substituent effect in the alkylation with alkyl halides; In a sharp contrast to 9-substituted adenines, alkylation of their N6-acyl derivatives occurred at N7-nitrogen rather then N1-nitrogen.The N6-acyl-7-alkyl-9-substituted adeninium halogenides thus prepared were converted into 7-substituted adenine and pteridine derivatives.