- ANTIMICROBIAL COMPOUNDS
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Provided herein is technology relating to antimicrobial compounds and particularly, but not exclusively, to analogs of rifalazil having increased inhibition of RNA polymerase and decreased induction of human cy-tochrome P450. The compounds have an increased affinity for a bacterial RNA polymerase (e.g., a MTB RNA polymerase) and a decreased affinity for a human pregnane X receptor. Thus, in some embodiments, the steric clash of A or R with residues in the binding pocket of the human pregnane X receptor reduces an affinity of the compound for the human pregnane X receptor. Consequently, in some embodiments the steric clash thus reduces the induction (e.g., an activity) of a cytochrome P450 and/or other related proteins.
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- Structure-based design of novel benzoxazinorifamycins with potent binding affinity to wild-type and rifampin-resistant mutant Mycobacterium tuberculosis RNA polymerases
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By utilization of three-dimensional structure information of rifamycins bound to RNA polymerase (RNAP) and the human pregnane X receptor (hPXR), representative examples (2b-d) of a novel subclass of benzoxazinorifamycins have been synthesized. Relative to rifalazil (2a), these analogues generally display superior affinity toward wild-type and Rif-resistant mutants of the Mycobacterium tuberculosis RNAP but lowered antitubercular activity in cell culture under both aerobic and anaerobic conditions. Lowered affinity toward hPXR for some of the analogues is also observed, suggesting a potential for reduced Cyp450 induction activity. Mouse and human microsomal studies of analogue 2b show it to have excellent metabolic stability. Mouse pharmacokinetics in plasma and lung show accumulation of 2b but with a half-life suggesting nonoptimal pharmacokinetics. These studies demonstrate proof of principle for this subclass of rifamycins and support further expansion of structure-activity relationships (SARs) toward uncovering analogues with development potential.
- Gill, Sumandeep K.,Xu, Hao,Kirchhoff, Paul D.,Cierpicki, Tomasz,Turbiak, Anjanette J.,Wan, Baojie,Zhang, Nan,Peng, Kuan-Wei,Franzblau, Scott G.,Garcia, George A.,Showalter, H. D. Hollis
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p. 3814 - 3826
(2012/07/30)
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