Discovery of Potent Isoindolinone Inhibitors that Target an Active Conformation of PARP1 Using DNA-Encoded Libraries.

Inhibition of poly (ADP-ribose) polymerase-1 (PARP1), a DNA repair enzyme, has proven to be a successful strategy for the treatment of various cancers. With the appropriate selection conditions and protein design, DNA-encoded library (DEL) technology provides a powerful avenue to identify small molecules with the desired mechanism of action towards a target of interest. However, DNA-binding proteins, such as PARP1, can be challenging targets for DEL screening due to non-specific protein-DNA interactions. To overcome this, we designed and screened a PARP1 catalytic domain construct without the autoinhibitory helical domain. This allowed us to interrogate an active, functionally-relevant form of the protein resulting in the discovery of novel isoindolinone PARP1 inhibitors with single-digit nanomolar potency. These inhibitors also demonstrated little to no PARP1-DNA trapping, a property that could be advantageous in the clinic.

A novel class of 3-(phenoxy-phenyl-methyl)-pyrrolidines as potent and balanced norepinephrine and serotonin reuptake inhibitors: synthesis and structure-activity relationships.

A series of 3-(phenoxy-phenyl-methyl)-pyrrolidine analogues were discovered to be potent and balanced norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitors. Several of these compounds were identified to have suitable in vitro pharmacokinetic properties for an orally dosed and CNS-targeted drug. Compound 39b, in particular, was identified as a potent NET and SERT reuptake inhibitor (NSRI) with minimal off-target activity and demonstrated robust efficacy in the spinal nerve ligation model of pain behavior.

Preclinical efficacy of THRX-200495, a dual pharmacology muscarinic receptor antagonist and ß(2)-adrenoceptor agonist (MABA).

Combinations of a muscarinic receptor antagonist (MA) and a ß(2)-adrenoceptor agonist (BA) improve bronchodilation in COPD patients to a greater extent than drugs with either mechanism alone. Here, using an in vivo model of bronchoprotection in guinea pigs, we characterize a single agent with dual-acting MA and BA activity, THRX-200495 (MABA). THRX-200495 was compared to a fixed-dose combination of a short-acting muscarinic receptor antagonist (SAMA) and a ß(2)-adrenoceptor agonist (SABA). The SAMA/SABA combination consisted of a 1:5.7 ratio of ipratropium and albuterol (the components of Combivent®). Conscious guinea pigs received aqueous nebulized solutions of vehicle or test compound by aerosol exposure. Bronchoprotective potency was estimated in anesthetized, tracheotomized and ventilated guinea pigs at predetermined time points after aerosol exposure by measuring changes in ventilation pressure. The individual (MA, BA) and composite (MABA) pharmacologies were assessed by determining protection against bronchoconstrictor responses induced by methacholine in the presence of propranolol (for MA activity), histamine (for BA activity) or methacholine (MABA activity). Bronchoprotection was calculated as percent inhibition of methacholine or histamine response relative to the vehicle group. THRX-200495 exhibited matched MA (ID(50) = 11.4 µg/mL) and BA (ID(50) = 11.2 µg/mL) potency and potent dual pharmacology (MABA ID(50) = 3.5 µg/mL) that persisted for over 24 h. The combination of ipratropium/albuterol exhibited bronchoprotective activity that was 2.6-fold more potent as a BA (ID(50) = 5.7 µg/mL) than as an MA (ID(50) = 14.6 µg/mL) at 0.5 h post-dose and 37-fold more potent as an MA (ID(50) = 4.3 µg/mL) than a BA (ID(50) = 159 µg/mL) at 1.5 h post aerosol exposure. Under MABA pharmacological conditions, ipratropium/albuterol produced potent bronchoprotective activity (ID(50) = 2.0/11.4 µg/mL) and an apparent additive effect of the two pharmacologies. In conclusion, a dual-acting prototypical MABA, THRX-200495, demonstrated potent, balanced and long-lasting bronchodilation in a guinea pig model of bronchoprotection that was greater than either the MA or BA mechanisms alone.

Muscarinic receptor subtypes and signalling involved in the attenuation of isoprenaline-induced rat urinary bladder relaxation.

ß-Adrenoceptors are important mediators of smooth muscle relaxation in the urinary bladder, but the concomitant presence of a muscarinic agonist, e.g., carbachol, can attenuate relaxation responses by reducing potency and/or efficacy of ß-adrenoceptor agonists such as isoprenaline. Therefore, the present study was designed to explore the subtypes and signalling pathways of muscarinic receptors involved in the attenuation of isoprenaline-induced isolated rat detrusor preparations using novel subtype-selective receptor ligands. In radioligand binding studies, we characterized BZI to be a M(3)-sparing muscarinic agonist, providing selective M(2) stimulation in rat bladder, and THRX-182087 as a highly M(2)-selective antagonist. The use of BZI and of THRX-182087 in the presence of carbachol enabled experimental conditions with a selective stimulation of only M(2) or M(3) receptors, respectively. Confirming previous findings, carbachol attenuated isoprenaline-induced detrusor relaxation. M(2)-selective stimulation partly mimicked this attenuation, indicating that both M(2) and M(3) receptors are involved. During M(3)-selective stimulation, the attenuation of isoprenaline responses was reduced by the phospholipase C inhibitor U 73,122 but not by the protein kinase C inhibitor chelerythrine. We conclude that both M(2) and M(3) receptors contribute to attenuation of ß-adrenoceptor-mediated relaxation of rat urinary bladder; the signal transduction pathway involved in the M(3) component of this attenuation differs from that mediating direct contractile effects of M(3) receptors.

Use of thiazoles in the halogen dance reaction: application to the total synthesis of WS75624 B.

The total synthesis of the pyridine-thiazole-containing natural product WS75624 B (1) is described. This synthesis proceeds via the Stille coupling of appropriately functionalized pyridine and thiazole components, and this paper details our studies on the use of the halogen dance reaction to prepare the desired thiazole. Various halogen dance reactions on thizoles are described, including a novel one-pot multistep reaction in which 2-bromothiazole is treated with LDA in the presence of a silyl chloride at -78 degrees C and quenched with an electrophile to provide the highly functionalized thiazole derivatives 27.

Total synthesis of caerulomycin C via the halogen dance reaction.

[reaction: see text] The total synthesis of caerulomycin C is described. Key steps in this synthesis utilize 1,2-, 1,3-, and 1,4-halogen dance reactions for the functionalization of the pyridine ring.