title: Nucleosides. 116. 1-(beta-D-Xylofuranosyl)-5-fluorocytosines with a leaving group on the 3' position. Potential double-barreled masked precursors of anticancer nucleosides.
abstract: Syntheses of five pairs of cytosine and 5-fluorocytosinexylofuranosyl nucleosides in which the 3'-hydroxyl group is replaced by Cl, Br, OMs, or OTs are described. Those xylosyl nucleosides with a good leaving group at the 3' position exhibit good inhibitory activity against L5178Y and P815 mouse leukemic cells in vitro at rather low concentrations, and like that of ara-C this cytotoxicity is reversed by 2'-deoxycytidine but not by thymidine. Xylosylcytosines are not active against ara-C resistant lines of L5178Y and P815 cells; however, the corresponding 5-fluorocytosine analogues exhibit significant cytotoxicity against these ara-C resistant leukemic cell lines, and this activity is reversed by thmidine but not by deoxycytidine. These data support the "double-barreled" masked precursor hypothesis in that xylosyl-5-fluorocytosines substituted at the 3' position by a good leaving group exhibit activity akin to that of ara-C in the ara-C sensitive lines, while these nucleosides act as 5-fluoropyrimidines in the ara-C resistant lines.
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis*; D002460:Cell Line; D003597:Cytosine Nucleotides / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D007942:Leukemia, Experimental / Q000188:drug therapy; D051379:Mice; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents; D003597:Cytosine Nucleotides