4 research outputs found
Discovery of Efficacious Pseudomonas aeruginosa-Targeted Siderophore-Conjugated Monocarbams by Application of a Semi-mechanistic Pharmacokinetic/Pharmacodynamic Model
To identify new agents
for the treatment of multi-drug-resistant Pseudomonas
aeruginosa, we focused on siderophore-conjugated
monocarbams. This class of monocyclic β-lactams are stable to
metallo-β-lactamases and have excellent P. aeruginosa activities due to their ability to exploit the iron uptake machinery
of Gram-negative bacteria. Our medicinal chemistry plan focused on
identifying a molecule with optimal potency and physical properties
and activity for in vivo efficacy. Modifications to the monocarbam
linker, siderophore, and oxime portion of the molecules were examined.
Through these efforts, a series of pyrrolidinone-based monocarbams
with good P. aeruginosa cellular activity
(P. aeruginosa MIC<sub>90</sub> = 2
μg/mL), free fraction levels (>20% free), and hydrolytic
stability
(<i>t</i><sub>1/2</sub> ≥ 100 h) were identified.
To differentiate the lead compounds and enable prioritization for
in vivo studies, we applied a semi-mechanistic pharmacokinetic/pharmacodynamic
model to enable prediction of in vivo efficacy from in vitro data
Lead Optimization of 1,4-Azaindoles as Antimycobacterial Agents
In a previous
report, we described the discovery of 1,4-azaindoles, a chemical series
with excellent in vitro and in vivo antimycobacterial potency through
noncovalent inhibition of decaprenylphosphoryl-β-d-ribose-2′-epimerase
(DprE1). Nevertheless, high mouse metabolic turnover and phosphodiesterase
6 (PDE6) off-target activity limited its advancement. Herein, we report
lead optimization of this series, culminating in potent, metabolically
stable compounds that have a robust pharmacokinetic profile without
any PDE6 liability. Furthermore, we demonstrate efficacy for 1,4-azaindoles
in a rat chronic TB infection model. We believe that compounds from
the 1,4-azaindole series are suitable for in vivo combination and
safety studies
Thiazolopyridine Ureas as Novel Antitubercular Agents Acting through Inhibition of DNA Gyrase B
A pharmacophore-based search led
to the identification of thiazolopyridine
ureas as a novel scaffold with antitubercular activity acting through
inhibition of DNA Gyrase B (GyrB) ATPase. Evaluation of the binding
mode of thiazolopyridines in a Mycobacterium tuberculosis (Mtb) GyrB homology model prompted exploration of the side chains
at the thiazolopyridine ring C-5 position to access the ribose/solvent
pocket. Potent compounds with GyrB IC<sub>50</sub> ≤ 1 nM and
Mtb MIC ≤ 0.1 μM were obtained with certain combinations
of side chains at the C-5 position and heterocycles at the C-6 position
of the thiazolopyridine core. Substitutions at C-5 also enabled optimization
of the physicochemical properties. Representative compounds were cocrystallized
with Streptococcus pneumoniae (Spn)
ParE; these confirmed the binding modes predicted by the homology
model. The target link to GyrB was confirmed by genetic mapping of
the mutations conferring resistance to thiazolopyridine ureas. The
compounds are bactericidal in vitro and efficacious in vivo in an
acute murine model of tuberculosis
4‑Aminoquinolone Piperidine Amides: Noncovalent Inhibitors of DprE1 with Long Residence Time and Potent Antimycobacterial Activity
4-Aminoquinolone piperidine amides
(AQs) were identified as a novel
scaffold starting from a whole cell screen, with potent cidality on Mycobacterium tuberculosis (Mtb). Evaluation of the
minimum inhibitory concentrations, followed by whole genome sequencing
of mutants raised against AQs, identified decaprenylphosphoryl-β-d-ribose 2′-epimerase (DprE1) as the primary target responsible
for the antitubercular activity. Mass spectrometry and enzyme kinetic
studies indicated that AQs are noncovalent, reversible inhibitors
of DprE1 with slow on rates and long residence times of ∼100
min on the enzyme. In general, AQs have excellent leadlike properties
and good in vitro secondary pharmacology profile. Although the scaffold
started off as a single active compound with moderate potency from
the whole cell screen, structure–activity relationship optimization
of the scaffold led to compounds with potent DprE1 inhibition (IC<sub>50</sub> < 10 nM) along with potent cellular activity (MIC = 60
nM) against Mtb