title: 5-Iodo-2'-deoxy-L-uridine and (E)-5-(2-bromovinyl)-2'-deoxy-L-uridine: selective phosphorylation by herpes simplex virus type 1 thymidine kinase, antiherpetic activity, and cytotoxicity studies.
abstract: 5-Iodo-2'-deoxy-L-uridine (L-IdU) and (E)-5-(2-bromovinyl)-2'-deoxy-L-uridine (L-BVdU) have been prepared and found to inhibit herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) with activities comparable to those of their analogs with the natural D-sugar configuration. The mechanism of inhibition is purely competitive for L-IdU (Ki = 0.24 microM) and mixed-type for L-BVdU (Ki = 0.13 microM). High performance liquid chromatographic analysis of the reaction products demonstrated that the viral enzyme phosphorylates both L-enantiomers to their corresponding monophosphates with efficiency comparable to that for D-enantiomers. Neither L-enantiomer inhibits the human cytosolic TK. In contrast to their D-enantiomers, L-IdU and L-BVdU have no effect on human thymidylate synthase, either in HeLa cells or in TK-deficient HeLa cells transformed with the HSV-1 TK gene. Both L-enantiomers (i) have no effect on HeLa cell growth, (ii) are 1000-fold less cytotoxic toward TK-deficient HeLa cells transformed with the HSV-1 TK gene than are their D-enantiomers, (iii) in contrast to their D-enantiomers, are fully resistant to hydrolysis by nucleoside phosphorylase, and, (iv) in spite of their much lower cytotoxicity, most probably due to the very low affinity of L-BVdU monophosphate and L-IdU monophosphate for thymidylate synthase, are only 1 or 2 orders of magnitude less potent than their D-enantiomers in inhibiting viral growth, with potency comparable to that of acyclovir.
authors.affiliation: Istituto di Genetica Biochimica ed Evoluzionistica, Consiglio Nazionale delle Ricerche, Pavia, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Spadari
authors.forename: G
authors.initials: G
authors.lastname: Ciarrocchi
authors.forename: F
authors.initials: F
authors.lastname: Focher
authors.forename: A
authors.initials: A
authors.lastname: Verri
authors.forename: G
authors.initials: G
authors.lastname: Maga
authors.forename: F
authors.initials: F
authors.lastname: Arcamone
authors.forename: E
authors.initials: E
authors.lastname: Iafrate
authors.forename: S
authors.initials: S
authors.lastname: Manzini
authors.forename: A
authors.initials: A
authors.lastname: Garbesi
authors.forename: L
authors.initials: L
authors.lastname: Tondelli
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D006367:HeLa Cells; D018259:Herpesvirus 1, Human / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D007065:Idoxuridine / Q000378:metabolism*; D010766:Phosphorylation; D013237:Stereoisomerism; D013937:Thymidine Kinase / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D000998:Antiviral Agents; C020235:brivudine; D013937:Thymidine Kinase; D001973:Bromodeoxyuridine; D007065:Idoxuridine