Activators of the CFTR Cl- channel may be useful for therapy of cystic fibrosis. Short-circuit current ( Isc) measurements were done on human bronchial epithelial cells to characterize the best flavone and benzimidazolone CFTR activators identified by lead-based combinatorial synthesis and high-throughput screening. The 7,8-benzoflavone UCcf-029 was a potent activator of Cl- transport, with activating potency (<1 μM) being much better than other flavones, such as apigenin. The benzimidazolone UCcf-853 gave similar Isc but with lower potency (5–20 μM). In combination, the effect induced by maximal UCcf-029 and UCcf-029, UCcf-853, and apigenin increased strongly with increasing basal CFTR activity: for example, Kd for activation by UCcf-029 decreased from >5 to <0.4 μM with increasing basal Isc from ∼4 μA/cm2 to ∼12 μA/cm2. This dependence was confirmed in permeabilized Fischer rat thyroid cells stably expressing CFTR. Our results demonstrate efficacy of novel CFTR activators in bronchial epithelia and provide evidence that activating potency depends on basal CFTR activity.

Ethiprole differs from fipronil, the major phenylpyrazole insecticide, only in an ethylsulfinyl substituent replacing the trifluoromethylsulfinyl moiety. This study compares their photochemistry, metabolism, action at the gamma-aminobutyric acid (GABA) receptor, and insecticidal potency. On exposure to sunlight as a thin film, ethiprole undergoes oxidation (major), reduction, and desethylsulfinylation but not desulfinylation whereas the major photoreaction for fipronil is desulfinylation. Metabolic sulfone formation is more rapid with ethiprole than fipronil in human expressed CYP3A4 in vitro and mouse brain and liver in vivo. High biological activity is observed for the sulfide, sulfoxide, sulfone, and desulfinyl derivatives in both the ethiprole and the fipronil series in GABA receptor assays (human recombinant beta3 homomer and house fly head membranes) with [(3)H]EBOB and in topical toxicity to house flies with and without the P450-inhibiting synergist piperonyl butoxide. On an overall basis, the ethiprole series is very similar in potency to the fipronil series.

3-[4-[1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazolo]]-3-(trifluoromethyl)diazirine is a fipronil-based (i.e. fiprole), high-affinity probe for the GABA receptor. For synthesis of the tritium-labeled version of this trifluoromethyldiazirinylfiprole ([(3)H]TDF) the required intermediate, 3-[4-[1-(2,6-dichloro-3-iodo-4-trifluoromethylphenyl)-5-iodopyrazolo]]-3-(trifluoromethyl)diazirine, was prepared in 10 steps from pyrazole and 3,5-dichloro-4-fluorobenzotrifluoride. One of the key transformations was lithiation and subsequent iodination of the 4-(2,2,2-trifluoro-1-hydroxyethyl)pyrazole intermediate. The last step involved reduction of the diiodofiprole with tritium, Pd/C, and triethylamine in ethyl acetate and afforded [(3)H]TDF with a specific activity of 15 Ci/mmol and 99% radiopurity.

No abstract

Staphylococcus aureus is a leading causative agent in sepsis, endocarditis, and pneumonia. An emerging concept is that prognosis worsens when the infecting S. aureus strain has the capacity to not only colonize tissue as an extracellular pathogen, but to invade host cells and establish intracellular bacterial populations. In previous work, we identified host CDC42 as a central regulator of endothelial cell invasion by S. aureus. In the current work, we report that ML 141, a first-in-class CDC42 inhibitor, decreases invasion and resultant pathogenesis in a dose-dependent and reversible manner. Inhibition was found to be due in part to decreased remodeling of actin that potentially drives endocytic uptake of bacteria/fibronectin/integrin complexes. ML 141 decreased binding to fibronectin at these complexes, thereby limiting a key pathogenic mechanism used by S. aureus to invade. Structural analogs of ML 141 were synthesized (designated as the RSM series) and a subset identified that inhibit invasion through non-cytotoxic and non-bactericidal mechanisms. Our results support the development of adjunctive therapeutics targeting host CDC42 for mitigating invasive infection at the level of the host.