Iodine catalysed synthesis and antibacterial evaluation of thieno-[2,3-d]pyrimidine derivatives

Scaffold hopping and optimisation of 3',4'-dihydroxyphenyl- containing thienopyrimidinones: synthesis of quinazolinone derivatives as novel allosteric inhibitors of HIV-1 reverse transcriptase-associated ribonuclease H

Bioisosteric replacement and scaffold hopping are powerful strategies in drug design useful for rationally modifying a hit compound towards novel lead therapeutic agents. Recently, we reported a series of thienopyrimidinones that compromise dynamics at the p66/p51 HIV-1 reverse transcriptase (RT)-associated Ribonuclease H (RNase H) dimer interface, thereby allosterically interrupting catalysis by altering the active site geometry. Although they exhibited good submicromolar activity, the isosteric replacement of the thiophene ring, a potential toxicophore, is warranted. Thus, in this article, the most active 2-(3,4-dihydroxyphenyl)-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-one 1 was selected as the hit scaffold and several isosteric substitutions of the thiophene ring were performed. A novel series of highly active RNase H allosteric quinazolinone inhibitors was thus obtained. To determine their target selectivity, they were tested against RT-associated RNA-dependent DNA polymerase (RDDP) and integrase (IN). Interestingly, none of the compounds were particularly active on (RDDP) but many displayed micromolar to submicromolar activity against IN.

Synthesis of Dihydrobenzo[b]pyrimido[4,5-e][1,4]Thiazepines; Derivatives of a Novel Ring System

Several derivatives of the novel dihydrobenzo[b]pyrimido[4,5-e][1,4]thiazepine ring system have been synthesised through the initial heterocyclisation of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine with o-aminothiophenol followed by treatment with various secondary amines in boiling ethanol.

Exploiting drug-resistant enzymes as tools to identify thienopyrimidinone inhibitors of human immunodeficiency virus reverse transcriptase-associated ribonuclease H

The thienopyrimidinone 5,6-dimethyl-2-(4-nitrophenyl)thieno[2,3-d]pyrimidin-4(3H)-one (DNTP) occupies the interface between the p66 ribonuclease H (RNase H) domain and p51 thumb of human immunodeficiency virus reverse transcriptase (HIV RT), thereby inducing a conformational change incompatible with catalysis. Here, we combined biochemical characterization of 39 DNTP derivatives with antiviral testing of selected compounds. In addition to wild-type HIV-1 RT, derivatives were evaluated with rationally designed, p66/p51 heterodimers exhibiting high-level DNTP sensitivity or resistance. This strategy identified 3',4'-dihydroxyphenyl (catechol) substituted thienopyrimidinones with submicromolar in vitro activity against both wild type HIV-1 RT and drug-resistant variants. Thermal shift analysis indicates that, in contrast to active site RNase H inhibitors, these thienopyrimidinones destabilize the enzyme, in some instances reducing the Tm by 5 °C. Importantly, catechol-containing thienopyrimidinones also inhibit HIV-1 replication in cells. Our data strengthen the case for allosteric inhibition of HIV RNase H activity, providing a platform for designing improved antagonists for use in combination antiviral therapy.

Synthesis and Anticancer Evaluation of New Derivatives of 3-Phenyl-1,5-Dimethyl-1H-[1,2,4]Triazolo[4′,3′:1,2]Pyrimido[4,5-e][1,3,4]Oxadiazine

The synthesis of new derivatives of 3-phenyl-1,5-dimethyl-1H-[1,2,4]triazolo[4′,3′:1,2]pyrimido[4,5-e][1,3,4]oxadiazines 5a–e and 7a–e is described through heterocyclisation of hydrazino derivative (3) with aromatic aldehydes or carbon disulfide and alkyl halides. [(1,5-Dimethyl-3-phenyl-1H-[1,2,4]triazolo[4′,3′:1,2]pyrimido[4,5-e][1,3,4]oxadiazin-7-yl) sulfanyl]methyl cyanide was singled out to be tested on different cancer cell lines including HeLa, MCF-7, and HepG2. Malignant cells were cultured in DMEM medium and incubated with different concentrations of the titled compounds. Cell viability was quantified by MTT assay.