RESUMEN
In this work, we describe an improved series of N-phenylpyrrolamide inhibitors that exhibit potent activity against DNA gyrase and are highly effective against high-priority gram-positive bacteria. The most potent compounds show low nanomolar IC50 values against Escherichia coli DNA gyrase, and in addition, compound 7c also inhibits E. coli topoisomerase IV in the nanomolar concentration range, making it a promising candidate for the development of potent dual inhibitors for these enzymes. All tested compounds show high selectivity towards the human isoform DNA topoisomerase IIα. Compounds 6a, 6d, 6e and 6f show MIC values between 0.031 and 0.0625 µg/mL against vancomycin-intermediate S. aureus (VISA) and Enterococcus faecalis strains. Compound 6g shows an inhibitory effect against the methicillin-resistant S. aureus strain (MRSA) with a MIC of 0.0625 µg/mL and against the E. faecalis strain with a MIC of 0.125 µg/mL. In a time-kill assay, compound 6d showed a dose-dependent bactericidal effect on the MRSA strain and achieved bactericidal activity at 8 × MIC after 8 h. The duration of the post-antibiotic effect (PAE) on the MRSA strain for compound 6d was 2 h, which corresponds to the PAE duration for ciprofloxacin. The compounds were not cytotoxic at effective concentrations, as determined in an MTS assay on the MCF-7 breast cancer cell line.
Asunto(s)
Antibacterianos , Girasa de ADN , Relación Dosis-Respuesta a Droga , Pruebas de Sensibilidad Microbiana , Inhibidores de Topoisomerasa II , Antibacterianos/farmacología , Antibacterianos/química , Antibacterianos/síntesis química , Humanos , Inhibidores de Topoisomerasa II/farmacología , Inhibidores de Topoisomerasa II/química , Inhibidores de Topoisomerasa II/síntesis química , Girasa de ADN/metabolismo , Relación Estructura-Actividad , Estructura Molecular , Enterococcus faecalis/efectos de los fármacos , Pirroles/farmacología , Pirroles/química , Pirroles/síntesis química , Amidas/farmacología , Amidas/química , Amidas/síntesis química , Escherichia coli/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacosRESUMEN
Human DNA topoisomerase II is one of the major targets in anticancer therapy, however ATP-competitive inhibitors of this target have not yet reached their full potential. ATPase domain of human DNA topoisomerase II belongs to the GHKL ATPase superfamily and shares a very high 3D structural similarity with other superfamily members, including bacterial topoisomerases. In this work we report the discovery of a new chemotype of ATP-competitive inhibitors of human DNA topoisomerase IIα that were discovered through screening of in-house library of ATP-competitive inhibitors of bacterial DNA gyrase and topoisomerase IV. Systematic screening of this library provided us with 20 hit compounds. 1,2,4-Substituted N-phenylpyrrolamides were selected for a further exploration which resulted in 13 new analogues, including 52 with potent activity in relaxation assay (IC50 = 3.2 µM) and ATPase assay (IC50 = 0.43 µM). Cytotoxic activity of all hits was determined in MCF-7 cancer cell line and the most potent compounds, 16 and 20, showed an IC50 value of 8.7 and 8.2 µM, respectively.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Antineoplásicos/uso terapéutico , ADN-Topoisomerasas de Tipo II/química , Inhibidores de Topoisomerasa II/uso terapéutico , Antineoplásicos/farmacología , Humanos , Simulación del Acoplamiento Molecular , Inhibidores de Topoisomerasa II/farmacologíaRESUMEN
ATP competitive inhibitors of DNA gyrase and topoisomerase IV have great therapeutic potential, but none of the described synthetic compounds has so far reached the market. To optimise the activities and physicochemical properties of our previously reported N-phenylpyrrolamide inhibitors, we have synthesized an improved, chemically variegated selection of compounds and evaluated them against DNA gyrase and topoisomerase IV enzymes, and against selected Gram-positive and Gram-negative bacteria. The most potent compound displayed IC50 values of 6.9â¯nM against Escherichia coli DNA gyrase and 960â¯nM against Staphylococcus aureus topoisomerase IV. Several compounds displayed minimum inhibitory concentrations (MICs) against Gram-positive strains in the 1-50⯵M range, one of which inhibited the growth of Enterococcus faecalis, Enterococcus faecium, S. aureus and Streptococcus pyogenes with MIC values of 1.56⯵M, 1.56⯵M, 0.78⯵M and 0.72⯵M, respectively. This compound has been investigated further on methicillin-resistant S. aureus (MRSA) and on ciprofloxacin non-susceptible and extremely drug resistant strain of S. aureus (MRSA VISA). It exhibited the MIC value of 2.5⯵M on both strains, and MIC value of 32⯵M against MRSA in the presence of inactivated human blood serum. Further studies are needed to confirm its mode of action.
Asunto(s)
Antibacterianos/química , Topoisomerasa de ADN IV/antagonistas & inhibidores , Pirrolidinas/química , Inhibidores de Topoisomerasa II/farmacología , Amidas/química , Antibacterianos/farmacología , Girasa de ADN/efectos de los fármacos , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Humanos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Inhibidores de Topoisomerasa II/químicaRESUMEN
The ATP binding site located on the subunit B of DNA gyrase is an attractive target for the development of new antibacterial agents. In recent decades, several small-molecule inhibitor classes have been discovered but none has so far reached the market. We present here the discovery of a promising new series of N-phenylpyrrolamides with low nanomolar IC50 values against DNA gyrase, and submicromolar IC50 values against topoisomerase IV from Escherichia coli and Staphylococcus aureus. The most potent compound in the series has an IC50 value of 13â¯nM against E. coli gyrase. Minimum inhibitory concentrations (MICs) against Gram-positive bacteria are in the low micromolar range. The oxadiazolone derivative 11a, with an IC50 value of 85â¯nM against E. coli DNA gyrase displays the most potent antibacterial activity, with MIC values of 1.56⯵M against Enterococcus faecalis, and 3.13⯵M against wild type S. aureus, methicillin-resistant S. aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). The activity against wild type E. coli in the presence of efflux pump inhibitor phenylalanine-arginine ß-naphthylamide (PAßN) is 4.6⯵M.