Jeremy John Edmunds

Discovery of a Series of Imidazo[4,5-b]pyridines with Dual Activity at Angiotensin II Type 1 Receptor and Peroxisome Proliferator-Activated Receptor-gamma.

Mining of an in-house collection of angiotensin II type 1 receptor antagonists to identify compounds with activity at the peroxisome proliferator-activated receptor-γ (PPARγ) revealed a new series of imidazo[4,5-b]pyridines 2 possessing activity at these two receptors. Early availability of the crystal structure of the lead compound 2a bound to the ligand binding domain of human PPARγ confirmed the mode of interaction of this scaffold to the nuclear receptor and assisted in the optimization of PPARγ activity. Among the new compounds, (S)-3-(5-(2-(1H-tetrazol-5-yl)phenyl)-2,3-dihydro-1H-inden-1-yl)-2-ethyl-5-isobutyl-7-methyl-3H-imidazo[4,5-b]pyridine (2l) was identified as a potent angiotensin II type I receptor blocker (IC(50) = 1.6 nM) with partial PPARγ agonism (EC(50) = 212 nM, 31% max) and oral bioavailability in rat. The dual pharmacology of 2l was demonstrated in animal models of hypertension (SHR) and insulin resistance (ZDF rat). In the SHR, 2l was highly efficacious in lowering blood pressure, while robust lowering of glucose and triglycerides was observed in the male ZDF rat.

Discovery of selective and orally bioavailable protein kinase Cθ (PKCθ) inhibitors from a fragment hit.

Protein kinase Cθ (PKCθ) regulates a key step in the activation of T cells. On the basis of its mechanism of action, inhibition of this kinase is hypothesized to serve as an effective therapy for autoimmune diseases such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriasis. Herein, the discovery of a small molecule PKCθ inhibitor is described, starting from a fragment hit 1 and advancing to compound 41 through the use of structure-based drug design. Compound 41 demonstrates excellent in vitro activity, good oral pharmacokinetics, and efficacy in both an acute in vivo mechanistic model and a chronic in vivo disease model but suffers from tolerability issues upon chronic dosing.

Stereocontrolled synthesis of calyculin A: construction of the C(1)–C(14) tetraene nitrile unit

An enantioselective and geometrically selective synthesis of the C(1)–C(14) tetraene nitrile unit of calyculin A, using aldol chemistry with (+)-(E)-diisopinocampheylborane and Stille coupling, is described.

Stereocontrolled synthesis of calyculin A: construction of the C(26)–C(37) amide-oxazole unit

(–)-B-[3-(Diisopropylaminodimethylsilyl)allyl]diisopinocampheylborane and Cornforth–Meyers chemistry, and Evans alkylation were employed to construct the C(26)–C(37) amide–oxazole unit of calyculin A.

Stereocontrolled synthesis of calyculin A: Construction of the C(15)-C(25) spiroketal unit

Two concise enantioselective syntheses of the C(15)–C(25) spiroketal unit of calyculin A, using derivatives of allyldiisopinocampheylborane efficieintly to control 1,2- and 1,3-diol stereochemistries, are reported.

Optimized protein kinase Cθ (PKCθ) inhibitors reveal only modest anti-inflammatory efficacy in a rodent model of arthritis.

We previously demonstrated that selective inhibition of protein kinase Cθ (PKCθ) with triazinone 1 resulted in dose-dependent reduction of paw swelling in a mouse model of arthritis.1,2 However, a high concentration was required for efficacy, thus providing only a minimal safety window. Herein we describe a strategy to deliver safer compounds based on the hypothesis that optimization of potency in concert with good oral pharmacokinetic (PK) properties would enable in vivo efficacy at reduced exposures, resulting in an improved safety window. Ultimately, transformation of 1 yielded analogues that demonstrated excellent potency and PK properties and fully inhibited IL-2 production in an acute model. In spite of good exposure, twice-a-day treatment with 17l in the glucose-6-phosphate isomerase chronic in vivo mouse model of arthritis yielded only moderate efficacy. On the basis of the exposure achieved, we conclude that PKCθ inhibition alone is insufficient for complete efficacy in this rodent arthritis model.

In vitro and in vivo antithrombotic activity of PD-198961, a novel synthetic factor Xa inhibitor.

PD-198961, 3-(4-5-[(2R,6S)-2,6-dimethyltetrahydro-1(2H)-pyridinyl]pentyl-3-oxo-3,4-dihydro-2-quinoxalinyl)-4-hydroxybenzenecarboximidamide, is a novel, synthetic factor Xa inhibitor with a Ki of 2.7 nM against human factor Xa. The aim of the present study was to evaluate the pharmacokinetic profile and antithrombotic efficacy of PD-198961 in rabbits. When tested in vitro, PD-198961 doubled prothrombin time (PT) and activated partial thromboplastin time (aPTT) at concentrations of 0.13 and 0.32 μM in human plasma, 0.2 and 0.09 μM in rabbit plasma, 0.3 and 0.4 μM in dog plasma, respectively. Intravenous administration of PD-198961 at 1 mg/kg over 30 minutes resulted in a maximal prolongation in PT and aPTT of 4.9 ± 0.4 and 4.1 ± 0.9-fold of baseline, respectively. The peak plasma concentration of PD-198961 was 977 ± 96 ng/ml. The anticoagulant effect of PD-198961 was readily reversible; coagulation parameters and plasma concentration returned to near baseline 15 minutes after cessation of infusion. There was a good correlation between PT prolongation and plasma concentration of PD-198961 (r = 0.93). In an FeCl3–induced model of arterial thrombosis in rabbits, the antithrombotic effects of PD-198961 were compared with that of LB-30057, a direct thrombin inhibitor, and enoxaparin, a low molecular weight heparin (LMWH). PD-198961 dose dependently increased the time to occlusion (TTO), reduced thrombus weight (TW), and decreased the incidence of occlusion. When administered at 3.0 μg/kg/min IV, PD-198961 prolonged TTO from 28 ± 5 minutes (control) to 120 ± 0 minutes (P < 0.001) and reduced TW from 9.9 ± 1.5 mg (control) to 2.8 ± 0.9 mg (P < 0.01). PD-198961 also dose dependently inhibited ex vivo plasma FXa activity. At the highest dose tested, PD-198961 increased aPTT to 1.4 ± 0.1-fold of baseline (compared with 1.5 ± 0.1 and 2.8 ± 0.3-fold of baseline for LB-30057 [CI-1028] and enoxaparin, respectively), and had modest effects on bleeding time (≤ 2-fold). These results indicate that PD-198961 is a potent FXa inhibitor and an effective antithrombotic agent at doses that produce only modest changes in normal hemostasis.

Synthesis of benzocycloheptenones by 1,3-dipolar additions of 2-(1,3-benzodioxol-5-ylmethyl)-4-hydroxy-3-methoxy-carbonylisoquinolin-2-ium chloride with dipolarophiles

The addition of thionyl chloride to dihydroisoquinolines affords isoquinolinium chlorides which are readily converted to the corresponding ylides upon treatment with sodium hydrogen carbonate. These ylides undergo facile 1,3-dipolar additions with dimethyl acetylenedicarboxylate, maleic anhydride and acrylonitrile to afford the corresponding benzocycloheptenone cycloadduct.

Observations on the reaction of cephalosporin V esters with hypervalent lodoarene dihalides

Reaction of cephalosporin V esters with 4-t-butyl iodobenzene difluoride is solvent dependent yielding the oxazoline (5) in acetonitrile and the fluorazetidinone (6) in dichloromethane; in contrast, the iodoarene dichloride gives the rearranged isothiazole (9).

Prodrugs for colon-restricted delivery: Design, synthesis, and in vivo evaluation of colony stimulating factor 1 receptor (CSF1R) inhibitors

The ability to restrict low molecular weight compounds to the gastrointestinal (GI) tract may enable an enhanced therapeutic index for molecular targets known to be associated with systemic toxicity. Using a triazolopyrazine CSF1R inhibitor scaffold, a broad range of prodrugs were synthesized and evaluated for enhanced delivery to the colon in mice. Subsequently, the preferred cyclodextrin prodrug moiety was appended to a number of CSF1R inhibitory active parent molecules, enabling GI-restricted delivery. Evaluation of a cyclodextrin prodrug in a dextran sodium sulfate (DSS)-induced mouse colitis model resulted in enhanced GI tissue levels of active parent. At a dose where no significant depletion of systemic monocytes were detected, the degree of pharmacodynamic effect–measured as reduction in macrophages in the colon–was inferior to that observed with a systemically available positive control. This suggests that a suitable therapeutic index cannot be achieved with CSF1R inhibition by using GI-restricted delivery in mice. However, these efforts provide a comprehensive frame-work in which to pursue additional gut-restricted delivery strategies for future GI targets.