UNNATURAL ENANTIOMERS OF 5-AZACYTIDINE ANALOGUES: SYNTHESES AND ENZYMATIC PROPERTIES

2′-Deoxy-β-L-5-azacytidine (L-Decitabine), β-L-5-azacytidine, and derivatives were stereospecifically prepared starting from L-ribose or L-xylose. D- and L-enantiomers of 2′-deoxy-β-5-azacytidine were weak substrates of human recombinant deoxycytidine kinase (dCK), whereas both enantiomers of β-5-azacytidine or the L-xylo-analogues were not substrates of the enzyme. None of the reported derivatives of β-L-5-azacytidine was a substrate of human recombinant cytidine deaminase (CDA).