title: Inhibition of poly(ADP-ribose)polymerase activity by nucleoside analogs of thymidine.
abstract: The poly ADP-ribosylation of proteins catalyzed by poly(ADP-ribose)polymerase (PARP) is involved in a number of important cellular metabolic activities. We evaluated various analogs of deoxythymidine and deoxyuridine as inhibitors of PARP. Most of these compounds have antiviral and/or anticancer activities. The structural requirements for these nucleoside analogs to be inhibitors of PARP were determined. The compounds evaluated had various substitutions on the 2-, 4- and/or 5-position of the pyrimidine ring, as well as on the 2'-, 3'- and/or 5'-position of the pentose moiety. Inhibition of PARP was strongly dependent on the size of the alkyl or halogen substituent on the 5-position of the pyrimidine ring. Whereas the 5-position of the pyrimidine ring could be varied, alteration of the 2- or 4-position drastically decreased the inhibition of PARP. Kinetic analysis was performed with concentrations of 1-10 microM NAD+. The Ki values for many compounds were five to seven times lower than the Ki for 3-aminobenzamide, a previously described potent inhibitor of PARP. Compounds with combined substituents at both the 5-position of the pyrimidine ring and the 3'- or 5'-position of deoxyribose generally were potent inhibitors of PARP, as for example 3'-amino-2', 3'-dideoxy-(E)-5-(2-bromovinyl)uridine (Ki = 0.7 microM), or 5'-azido-2',5'-dideoxy-5-ethyluridine (Ki = 0.8 microM). The 5-halogenated analogs had Ki values of 18, 35, 110 and greater than 1000 microM for 5-iodo-2'-deoxyuridine, 5-bromo-2'-deoxyuridine, 5-chloro-2'-deoxyuridine, and 5-fluoro-2'-deoxyuridine, respectively, and the 5-alkyl analogs had Ki values of 45, 2.2, 7, 16 and 180 microM for 5-methyl-2'-deoxyuridine, 5-ethyl-2'-deoxyuridine, 5-propyl-2'-deoxyuridine, 5-butyl-2'-deoxyuridine and 5-pentyl-2'-deoxyuridine, respectively. Two other compounds with substituents in the 5-position of the pyrimidine moiety also had potent activities: (E)-5-(2-bromovinyl)-2'-deoxyuridine (Ki = 6 microM) and 5-trifluoromethyl-2'-deoxyuridine (Ki = 1.6 microM). Compounds substituted in the 2'-, 3'- and/or 5'-position of the deoxyribose moiety were investigated and 5'-azido-5'-deoxythymidine, 5'-amino-5'-deoxythymidine, 3'-azido-3'-deoxythymidine and 3'-deoxythymidine (d2T) and Ki values of 12, 16, 18 and 30 microM, respectively.
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06510.
authors.forename: A D
authors.initials: AD
authors.lastname: Pivazyan
authors.forename: E M
authors.initials: EM
authors.lastname: Birks
authors.forename: T G
authors.initials: TG
authors.lastname: Wood
authors.forename: T S
authors.initials: TS
authors.lastname: Lin
authors.forename: W H
authors.initials: WH
authors.lastname: Prusoff
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D003857:Deoxyuridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015224:Dideoxynucleosides / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000302:isolation & purification; D013936:Thymidine / Q000031:analogs & derivatives*; D014407:Tumor Cells, Cultured / Q000201:enzymology
chemical_list: D001549:Benzamides; D015224:Dideoxynucleosides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C024082:5'-amino-5'-deoxythymidine; C012244:5-chloro-2'-deoxyuridine; C025160:3-aminobenzamide; D011065:Poly(ADP-ribose) Polymerases; D013936:Thymidine; D003857:Deoxyuridine