Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Chemistry, Medicinal, Pharmacology & Pharmacy, PURINE NUCLEOSIDES, LITHIATION, URIDINES, POSITION, ROUTE, ASSAY, AIDS, AZT, HIV, Antiviral Agents, Cell Line, Cell Survival, HIV-1, Humans, Indicators and Reagents, Molecular Structure, Structure-Activity Relationship, Thymine, 0304 Medicinal and Biomolecular Chemistry, 0305 Organic Chemistry, 1115 Pharmacology and Pharmaceutical Sciences, Medicinal & Biomolecular Chemistry, 3214 Pharmacology and pharmaceutical sciences, 3404 Medicinal and biomolecular chemistry, 3405 Organic chemistry

Abstract:

A series of novel acyclouridine derivatives substituted at both the C-5 and C-6 positions were synthesized for the purpose of improving the activity of a recently reported HIV-1-specific lead, 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT). Preparation of C-6 substituted derivatives was carried out based on the following three methods: (1) LDA (lithium diisopropylamide) lithiation of a thymine derivative (4) and subsequent reaction with electrophiles, (2) an addition-elimination reaction of HEPT or its 6-(phenylsulfinyl) derivative (10), or (3) palladium-catalyzed cross-coupling between a 6-iodo derivative (16) and terminal alkynes. Following the methods, 21 C-6 substituted analogues were synthesized. Among these, 6-(cyclohexylthio) (8), 6-phenoxy (13), and 6-benzyl (27) derivatives showed anti-HIV-1 (HTLV-IIIB) activity with EC50 values of 8.2, 85, and 23 microM, respectively. Preparation of C-5 substituted derivatives was based on either LTMP (lithium 2,2,6,6-tetramethylpiperidide) lithiation of 6-(phenylthio)uracil derivative 37 or the above mentioned palladium-catalyzed cross-coupling of a 5-iodo-6-(phenylthio)uracil derivative (38). Following these methods, 11 C-5 substituted analogues were synthesized. Some 5-substituted derivatives (5-I, 44; 5-CH = CPh2, 49; 5-CH = CHPh (Z), 54; and 5-CH = CH2, 55) were more active than HEPT, but their selectivity indices (SI = CC50/EC50) were lower than that of HEPT. Compound 8 was also evaluated against another HIV-1 strain (HTLV-IIIRF) and HIV-2 strains (LAV-2ROD and LAV-2EHO). Only HTLV-IIIRF was as sensitive as HTLV-IIIB.