RESUMO
This paper reports the synthesis and antiviral properties of new difluoromethylbenzoxazole (DFMB) pyrimidine thioether derivatives as non-nucleoside HIV-1 reverse transcriptase inhibitors. By use of a combination of structural biology study and traditional medicinal chemistry, several members of this novel class were synthesized using a single electron transfer chain process (radical nucleophilic substitution, S(RN)1) and were found to be potent against wild-type HIV-1 reverse transcriptase, with low cytotoxicity but with moderate activity against drug-resistant strains. The most promising compound 24 showed a significant EC(50) value close to 6.4 nM against HIV-1 IIIB, a moderate EC(50) value close to 54 µM against an NNRTI resistant double mutant (K103N + Y181C), but an excellent selectivity index >15477 (CC(50) > 100 µM).
Assuntos
Fármacos Anti-HIV/síntese química , Benzoxazóis/síntese química , Transcriptase Reversa do HIV/metabolismo , Pirimidinas/síntese química , Inibidores da Transcriptase Reversa/síntese química , Sulfetos/síntese química , Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacologia , Benzoxazóis/química , Benzoxazóis/farmacologia , Linhagem Celular Tumoral , Transcriptase Reversa do HIV/genética , HIV-1/efeitos dos fármacos , HIV-1/genética , Humanos , Mutação , Pirimidinas/química , Pirimidinas/farmacologia , Inibidores da Transcriptase Reversa/química , Inibidores da Transcriptase Reversa/farmacologia , Relação Estrutura-Atividade , Sulfetos/química , Sulfetos/farmacologiaRESUMO
A series of 66 new indolone-N-oxide derivatives was synthesized with three different methods. Compounds were evaluated for in vitro activity against CQ-sensitive (3D7), CQ-resistant (FcB1), and CQ and pyrimethamine cross-resistant (K1) strains of Plasmodium falciparum (P.f.), as well as for cytotoxic concentration (CC(50)) on MCF7 and KB human tumor cell lines. Compound 26 (5-methoxy-indolone-N-oxide analogue) had the most potent antiplasmodial activity in vitro (<3 nM on FcB1 and = 1.7 nM on 3D7) with a very satisfactory selectivity index (CC(50) MCF7/IC(50) FcB1: 14623; CC(50) KB/IC(50) 3D7: 198823). In in vivo experiments, compound 1 (dioxymethylene derivatives of the indolone-N-oxide) showed the best antiplasmodial activity against Plasmodium berghei, 62% inhibition of the parasitaemia at 30 mg/kg/day.
Assuntos
Antimaláricos/síntese química , Indóis/síntese química , Animais , Antimaláricos/farmacologia , Linhagem Celular Tumoral , Resistência a Medicamentos , Humanos , Indóis/farmacologia , Óxidos/síntese química , Óxidos/farmacologia , Parasitemia/tratamento farmacológico , Testes de Sensibilidade Parasitária , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
The ability of ten imidazolyl nitrones to directly scavenge free radicals (R(*)) generated in polar ((*)OH, O(*)(2)(-), SO(*)(3)(-) cysteinyl, (*)CH(3)) or in apolar (CH(3)-(*)CH-CH(3)) media has been studied. When oxygen or sulfur-centered radicals are generated in polar media, EPR spectra are not or weakly observed with simple spectral features. Strong line intensities and more complicated spectra are observed with the isopropyl radical generated in an apolar medium. Intermediate results are obtained with (*)CH(3) generated in a polar medium. EPR demonstrates the ability of these nitrones to trap radicals to the nitrone C(alpha) atom (alpha radical adduct) and to the imidazol C(5) atom (5-radical adduct). Beside the nucleophilic addition of the radical to the C(alpha) atom, the EPR studies suggest a two-step mechanism for the overall reaction of R(*) attacking the imidazol core. The two steps seem to occur very fast with the (*)OH radical obtained in a polar medium and slower with the isopropyl radical prepared in benzene. In conclusion, imidazolyl nitrones present a high capacity to trap and stabilize carbon-centered radicals.