2-Thio derivatives of dUrd and 5-fluoro-dUrd and their 5'-monophosphates: synthesis, interaction with tumor thymidylate synthase, and in vitro antitumor activity.
A convenient synthesis of 5-fluoro-2-thiouracil (11) is based on hydrolytic deamination of 5-fluoro-2-thiocytosine (9). Lewis acid-catalyzed condensation of di-TMS-5-fluoro-2-thiouracil (13) or di-TMS-2-thiouracil (14) with 2-deoxy-3,5-di-O-p-toluyl-D-ribofuranosyl chloride (15) led to mixtures of the beta- and alpha-anomers of 3',5'-toluylated 2'-deoxy-5-fluoro-2-thiouridine (16 and 18) or 2'-deoxy-2-thiouridine (17 and 19), each of which was deblocked with MeOH-NH3 to give the desired free anomeric nucleoside pairs 1, 5 and 3, 7, respectively. These were selectively converted to the corresponding 5'-monophosphates 2, 6 and 4, 8, with the aid of the wheat shoot phosphotransferase system. Conformations of the nucleosides 1, 3, 5, 7 are deduced from 1H NMR spectra, and circular dichroism spectra for nucleotide anomeric pairs 2, 6 and 4, 8 are reported. Whereas beta-2-thio-dUMP (4) was a good substrate (Km approximately 10(-5) M), beta-5-fluoro-2-thio-dUMP (2) proved to be a potent competitive, slow-binding inhibitor (Ki approximately 10(-8) M) of the purified enzymes from Ehrlich ascites carcinoma and L1210 cells. The alpha-anomer 6 was a weak inhibitor, with Ki in the mM range, and its congener 8 hardly interacted with the enzyme. The beta-anomer 1 exhibited antitumor activity in a mouse leukemic cell line L5178Y (IC50 approximately 10(-6) M), hence 40-100-fold weaker than 5-fluoro-dUrd. Its alpha-anomer 5 was 10-fold less active, but exhibited at least 10-fold higher selectivity with respect to the tumor cells than the beta-anomer 1.
Bretner
M
M
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa.
Kulikowski
T
T
Dzik
J M
JM
Balińska
M
M
Rode
W
W
Shugar
D
D
D016475:3T3 Cells; D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D001667:Binding, Competitive; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D002455:Cell Division / Q000187:drug effects; D003856:Deoxyuracil Nucleotides / Q000138:chemical synthesis / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D005467:Floxuridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D007700:Kinetics; D007939:Leukemia L1210 / Q000201:enzymology; D051379:Mice; D013053:Spectrophotometry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013891:Thiouridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D003856:Deoxyuracil Nucleotides; D005467:Floxuridine; D013891:Thiouridine; D013940:Thymidylate Synthase