ABSTRACT
PKCθ plays an important role in T cell biology and is a validated target for a number of disease states. A series of potent and selective PKCθ inhibitors were designed and synthesized starting from a HTS hit compound. Cell activity, while initially a challenge to achieve, was built into the series by transforming the nitrile unit of the scaffold into a primary amine, the latter predicted to form a new hydrogen bond to Asp508 near the entrance of the ATP binding site of PKCθ. Significant improvements in physiochemical parameters were observed on introduction of an oxetane group proximal to a primary amine leading to compound 22, which demonstrated a reduction of symptoms in a mouse model of multiple sclerosis.
ABSTRACT
Indoleamine-2,3 dioxygenaseâ 1 (IDO1) has emerged as a central regulator of immune responses in both normal and disease biology. Due to its established role in promoting tumour immune escape, IDO1 has become an attractive target for cancer treatment. A novel series of highly cell potent IDO1 inhibitors based on a 4-amino-1,2,3-triazole core have been identified. Comprehensive kinetic, biochemical and structural studies demonstrate that compounds from this series have a noncompetitive kinetic mechanism of action with respect to the tryptophan substrate. In co-complex crystal structures, the compounds bind in the tryptophan pocket and make a direct ligand interaction with the haem iron of the porphyrin cofactor. It is proposed that these data can be rationalised by an ordered-binding mechanism, in which the inhibitor binds an apo form of the enzyme that is not competent to bind tryptophan. These inhibitors also form a very tight, long-lived complex with the enzyme, which partially explains their exquisite cellular potency. This novel series represents an attractive starting point for the future development of potent IDO1-targeted drugs.
Subject(s)
Enzyme Inhibitors/pharmacology , Indoleamine-Pyrrole 2,3,-Dioxygenase/antagonists & inhibitors , Triazoles/pharmacology , Crystallography, X-Ray , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , HeLa Cells , Humans , Indoleamine-Pyrrole 2,3,-Dioxygenase/metabolism , Models, Molecular , Molecular Structure , Structure-Activity Relationship , Triazoles/chemical synthesis , Triazoles/chemistryABSTRACT
Protein kinase C θ (PKCθ) has a central role in T cell activation and survival; however, the dependency of T cell responses to the inhibition of this enzyme appears to be dictated by the nature of the antigen and by the inflammatory environment. Studies in PKCθ-deficient mice have demonstrated that while antiviral responses are PKCθ-independent, T cell responses associated with autoimmune diseases are PKCθ-dependent. Thus, potent and selective inhibition of PKCθ is expected to block autoimmune T cell responses without compromising antiviral immunity. Herein, we describe the development of potent and selective PKCθ inhibitors, which show exceptional potency in cells and in vivo. By use of a structure based rational design approach, a 1000-fold improvement in potency and 76-fold improvement in selectivity over closely related PKC isoforms such as PKCδ were obtained from the initial HTS hit, together with a big improvement in lipophilic efficiency (LiPE).
Subject(s)
Autoimmune Diseases/drug therapy , Isoenzymes/antagonists & inhibitors , Piperazines/chemical synthesis , Protein Kinase C/antagonists & inhibitors , Protein Kinase Inhibitors/chemical synthesis , Pyridines/chemical synthesis , Animals , Drug Design , Humans , Inhibitory Concentration 50 , Interleukin-2/antagonists & inhibitors , Lymphocyte Activation/drug effects , Mice , Piperazines/pharmacokinetics , Protein Kinase C-theta , Pyridines/pharmacokinetics , T-Lymphocytes/immunologyABSTRACT
The identification of a novel series of PKCθ inhibitors and subsequent optimization using docking based on a crystal structure of PKCθ is described. SAR was rapidly generated around an amino pyridine-ketone hit; (6-aminopyridin-2-yl)(2-aminopyridin-3-yl)methanone 2 leading to compound 21 which significantly inhibits production of IL-2 in a mouse SEB-IL2 model.
Subject(s)
Aminopyridines/chemistry , Protein Kinase C/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Aminopyridines/pharmacology , Animals , Mice , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
[reaction: see text] The conjugate addition of in situ generated zinc alkynylides is reported. The use of chiral, ephedrine derived acceptors provides access to enantiomerically enriched beta-alkynyl acids in good yields.
ABSTRACT
[reaction: see text] The enantioselective addition reaction of terminal acetylenes and aldehydes mediated by Zn(OTf)2 and N-methyl ephedrine can be conducted with reagent grade solvent containing 84-1000 ppm H2O. The products can be isolated in high yield and useful enantioselectivities (up to 99% ee).