Discovery and druggability evaluation of pyrrolamide-type GyrB/ParE inhibitor against drug-resistant bacterial infection

The bacterial ATP-competitive GyrB/ParE subunits of type II topoisomerase are important anti-bacterial targets to treat super drug-resistant bacterial infections. Herein we discovered novel pyrrolamide-type GyrB/ParE inhibitors based on the structural modifications of the candidate AZD5099 that was withdrawn from the clinical trials due to safety liabilities such as mitochondrial toxicity. The hydroxyisopropyl pyridazine compound 28 had a significant inhibitory effect on Gyrase (GyrB, IC50 = 49 nmol/L) and a modest inhibitory effect on Topo IV (ParE, IC50 = 1.513 μmol/L) of Staphylococcus aureus. It also had significant antibacterial activities on susceptible and resistant Gram-positive bacteria with a minimum inhibitory concentration (MIC) of less than 0.03 μg/mL, which showed a time-dependent bactericidal effect and low frequencies of spontaneous resistance against S. aureus. Compound 28 had better protective effects than the positive control drugs such as DS-2969 ( 5) and AZD5099 ( 6) in mouse models of sepsis induced by methicillin-resistant Staphylococcus aureus (MRSA) infection. It also showed better bactericidal activities than clinically used vancomycin in the mouse thigh MRSA infection models. Moreover, compound 28 has much lower mitochondrial toxicity than AZD5099 ( 6) as well as excellent therapeutic indexes and pharmacokinetic properties. At present, compound 28 has been evaluated as a pre-clinical drug candidate for the treatment of drug-resistant Gram-positive bacterial infection. On the other hand, compound 28 also has good inhibitory activities against stubborn Gram-negative bacteria such as Escherichia coli (MIC = 1 μg/mL), which is comparable with the most potent pyrrolamide-type GyrB/ParE inhibitors reported recently. In addition, the structure-activity relationships of the compounds were also studied.

Determination of plasma protein binding of peptide drug candidates by dextran-coated charcoal / 中国药科大学学报

@#The conventional equilibrium dialysis and ultrafiltration methods cannot be used to determine the protein binding of some peptides because of their non-specific adsorption on the semipermeable membrane or poor stability in the plasma. The method of dextran-coated charcoal adsorption combined with LC-MS/MS were used. Based on the kinetic principle of initial rate of candidate drugs absorbed to dextran-coated charcoal, seven phosphorylated peptides with the same amino acid sequence and different configurations in rat plasma were selected as the study model using; the protein binding in rat plasma were determined; the amino acid distribution rules affecting the changes in protein binding rates of peptide candidate drugs were summarized. The results suggest that the dextran charcoal adsorption method, as a supplementary method for the determination of plasma protein binding, is suitable for peptides or organic drug candidates that cannot be determined by traditional techniques.

Study on Pharmacological Key Problems of Druggability Evaluation for Novel Chinese Materia Medica / 世界科学技术-中医药现代化

The research and development (R & D) of novel Chinese materia medica (CMM) have made a great progress in recent years.But problems still exist in druggability evaluation of novel CMM,such as uncertain evaluation content and lack of key technology.Druggability evaluation is the key to the success or failure for R & D of novel CMM.Observation on the effect and safety of novel CMM is the core of druggability evaluation.The important pharmacological problems include the choice of evaluation indicator,clinical indication,analysis of material basis,investigation of mechanism,research on pharmacokinetics and safety evaluation.Modem technologies should be used in druggability evaluation.We should have a correct understanding of the concept of novel CMM.The grasp of the meaning of novel drugs and the essence of CMM theory will be helpful for R & D of novel CMM.