title: Synthesis of AZT 5'-triphosphate mimics and their inhibitory effects on HIV-1 reverse transcriptase.
abstract: In search of active nucleoside 5'-triphosphate mimics, we have synthesized a series of AZT triphosphate mimics (AZT P3Ms) and evaluated their inhibitory effects on HIV-1 reverse transcriptase as well as their stability in fetal calf serum and in CEM cell extracts. Reaction of AZT with 2-chloro-4H-1,3,2-benzodioxaphosphorin-4-one, followed by treatment of the phosphite intermediate 2 with pyrophosphate analogues, yielded the cyclic triphosphate intermediates 4b-4f, which were subjected to boronation and subsequent hydrolysis to give AZT 5'-alpha-borano-beta,gamma-bridge-modified triphosphates 6b-6f in moderate to good yields. Reaction of the cyclic intermediate 4d with iodine, followed by treatment with a series of nucleophiles, afforded the AZT 5'-beta,gamma-difluoromethylene-gamma-substituted triphosphates (7b-7i). Several different types of AZT P3Ms containing alpha-P-thio (or dithio) and beta,gamma-difluoromethylene (13,14), alpha,beta-difluoromethylene and gamma-P-methyl(or phenyl) (15,16), and alpha-borano-beta,gamma-difluoromethylene and gamma-O-methyl/phenyl (11,12) were also synthesized. The effectiveness of the compounds as inhibitors of HIV-1 reverse transcriptase was determined using a fluorometric assay and a poly(A) homopolymer as a template. A number of AZT P3Ms exhibited very potent inhibition of HIV-1 reverse transcriptase. Modifications at the beta,gamma-bridge of triphosphate rendered the AZT P3Ms 6b-6f with varied activities (K(i) from 9.5 to >>500 nM) while modification at the alpha,beta-bridge of triphosphate led to weak AZT P3M inhibitors. The results imply that the AZT P3Ms were substrate inhibitors, as is AZT triphosphate. The most active compound, AZT 5'-alpha-R(p)()-borano-beta,gamma-(difluoromethylene)triphosphate (AZT 5'-alphaB-betagammaCF(2)TP) (6d-I), is as potent as AZT triphosphate with a K(i)() value of 9.5 nM and at least 20-fold more stable than AZT triphosphate in the serum and cell extracts. Therefore, for the first time, a highly active and stable nucleoside triphosphate mimic has been identified, which is potentially useful as a new type of antiviral drug. The promising triphosphate mimic, 5'-alpha-borano-beta,gamma-(difluoromethylene)triphosphate, is expected to be valuable to the discovery of nucleotide mimic antiviral drugs.
authors.affiliation: Research Laboratories, Biota, Inc., 2232 Rutherford Road, Carlsbad, CA 92008, USA. g.wang@biota-inc.com
authors.forename: Guangyi
authors.initials: G
authors.lastname: Wang
authors.forename: Nicholas
authors.initials: N
authors.lastname: Boyle
authors.forename: Fu
authors.initials: F
authors.lastname: Chen
authors.forename: Vasanthakumar
authors.initials: V
authors.lastname: Rajappan
authors.forename: Patrick
authors.initials: P
authors.lastname: Fagan
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Brooks
authors.forename: Tiffany
authors.initials: T
authors.lastname: Hurd
authors.forename: Janet M
authors.initials: JM
authors.lastname: Leeds
authors.forename: Vivek K
authors.initials: VK
authors.lastname: Rajwanshi
authors.forename: Yi
authors.initials: Y
authors.lastname: Jin
authors.forename: Marija
authors.initials: M
authors.lastname: Prhavc
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Bruice
authors.forename: P Dan
authors.initials: PD
authors.lastname: Cook
mesh_terms: D004355:Drug Stability; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors*; D006801:Humans; D018894:Reverse Transcriptase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D015215:Zidovudine / Q000031:analogs & derivatives*
chemical_list: D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D054303:HIV Reverse Transcriptase