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ABT-072 is a non-nucleoside HCV NS5B polymerase inhibitor that was discovered as part of a program to identify new direct-acting antivirals (DAAs) for the treatment of HCV infection. This compound was identified during a medicinal chemistry effort to improve on an original lead, inhibitor 1, which we described in a previous publication. Replacement of the amide linkage in 1 with a trans-olefin resulted in improved compound permeability and solubility and provided much better pharmacokinetic properties in preclinical species. Replacement of the dihydrouracil in 1 with an N-linked uracil provided better potency in the genotype 1 replicon assay. Results from phase 1 clinical studies supported once-daily oral dosing with ABT-072 in HCV infected patients. A phase 2 clinical study that combined ABT-072 with the HCV protease inhibitor ABT-450 provided a sustained virologic response at 24 weeks after dosing (SVR24) in 10 of 11 patients who received treatment.

Research toward a next-generation HCV NS5A inhibitor has identified fluorobenzimidazole analogs that demonstrate potent, broad-genotype in vitro activity against HCV genotypes 1-6 replicons as well as HCV NS5A variants that are orders of magnitude less susceptible to inhibition by first-generation NS5A inhibitors in comparison to wild-type replicons. The fluorobenzimidazole inhibitors have improved pharmacokinetic properties in comparison to non-fluorinated benzimidazole analogs. Discovery of these inhibitors was facilitated by exploring SAR in a structurally simplified inhibitor series.

Curative interferon and ribavirin sparing treatments for hepatitis C virus (HCV)-infected patients require a combination of mechanistically orthogonal direct acting antivirals. A shared component of these treatments is usually an HCV NS5A inhibitor. First generation FDA approved treatments, including the component NS5A inhibitors, do not exhibit equivalent efficacy against HCV virus genotypes 1-6. In particular, these first generation NS5A inhibitors tend to select for viral drug resistance. Ombitasvir is a first generation HCV NS5A inhibitor included as a key component of Viekira Pak for the treatment of patients with HCV genotype 1 infection. Since the launch of next generation HCV treatments, functional cure for genotype 1-6 HCV infections has been achieved, as well as shortened treatment duration across a wider spectrum of genotypes. In this paper, we show how we have modified the anchor, linker, and end-cap architecture of our NS5A inhibitor design template to discover a next generation NS5A inhibitor pibrentasvir (ABT-530), which exhibits potent inhibition of the replication of wild-type genotype 1-6 HCV replicons, as well as improved activity against replicon variants demonstrating resistance against first generation NS5A inhibitors.

Leucine is an essential branched-chain amino acid that acts as a substrate for protein synthesis and as a signaling molecule. Leucine not incorporated into muscle protein is ultimately oxidized through intermediates such as β-hydroxy-β-methylbutyrate (HMB) which itself is reported to enhance muscle mass and function in rats and humans. HMB has been reported in the plasma following oral leucine administration in sheep and pigs but not in Sprague-Dawley rats, the standard preclinical model. Therefore, we conducted radiolabeled absorption, distribution, metabolism and excretion (ADME) studies in rats using a low (3 mg/kg) or high dose (1,000 mg/kg) of (14)C-leucine. Blood, tissue, and urine samples were analyzed for (14)C-leucine and its metabolites by HPLC-MS. Our results show for the first time that (14)C-HMB appears in plasma and urine of rats following an oral dose of (14)C-leucine. (14)C-leucine appears in plasma as (14)C-α-ketoisocaproic acid (KIC) with a slower time course than (14)C-HMB, a putative product of KIC. Further, two novel metabolites of leucine were detected in urine, N-acetyl leucine and glycyl leucine. Mass balance studies demonstrate that excretory routes accounted for no more than 0.9 % of the radiolabel and approximately 61 % of the dose was recovered in the carcass. Approximately 65 % of the dose was recovered in total, suggesting that approximately one-third of the leucine dose is oxidized to CO2. In conclusion, this study demonstrates endogenous production of HMB from leucine in adult rats, a standard preclinical model used to guide design of clinical trials in nutrition.

The synthesis and structure–activity relationships of a novel aryl uracil series which contains a fused 5,6-bicyclic ring unit for HCV NS5B inhibition is described. Several analogs display replicon cell culture potencies in the low nanomolar range along with excellent rat pharmacokinetic values.

Benzothiadiazine inhibitors of the HCV NS5B RNA-dependent RNA polymerase are an important class of non-nucleoside inhibitors that have received considerable attention in the search for novel HCV therapeutics. Research in our laboratories has identified a novel series of tetracyclic benzothiadiazine inhibitors of HCV polymerase bearing a benzylamino substituent on the B-ring. Compounds in this series exhibit low-nanomolar activities in both genotypes 1a and 1b polymerase inhibition assays and subgenomic replicon assays. Optimization of pharmacokinetic properties in rat led to compound 30, which has good oral bioavailability (F = 56%) and a favorable tissue distribution drug profile, with high liver to plasma ratios. Compound 30 is a potent inhibitor in replicon assays, with EC(50) values of 10 and 6 nM against genotypes 1a and 1b, respectively.

Stearoyl-CoA desaturase 1 (SCD1) catalyzes the committed step in the biosynthesis of monounsaturated fatty acids from saturated, long-chain fatty acids. Studies with SCD1 knockout mice have established that these animals are lean and protected from leptin deficiency-induced and diet-induced obesity, with greater whole body insulin sensitivity than wild-type animals. In this work, we have discovered a series of potent, selective, orally bioavailable SCD1 inhibitors based on a known pyridazine carboxamide template. The representative lead inhibitor 28c also demonstrates excellent cellular activity in blocking the conversion of saturated long-chain fatty acid-CoAs (LCFA-CoAs) to monounsaturated LCFA-CoAs in HepG2 cells.

The hemodynamic effects of a series of potent and selective 4-aminopyridine carboxamide-based pan-JNK inhibitors were assessed in an anesthetized rat model. The effects of these agents on mean arterial pressure, heart rate, cardiac contractility, and peripheral vascular resistance are described, and the implication for targeting protein kinases in metabolic diseases is discussed.

Starting from a rapidly metabolized adamantane 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitor 22a, a series of E-5-hydroxy-2-adamantamine inhibitors, exemplified by 22d and (+/-)-22f, was discovered. Many of these compounds are potent inhibitors of 11beta-HSD1 and are selective over 11beta-HSD2 for multiple species (human, mouse, and rat), unlike other reported species-selective series. These compounds have good cellular potency and improved microsomal stability. Pharmacokinetic profiling in rodents indicated moderate to large volumes of distribution, short half-lives, and a pharmacokinetic species difference with the greatest exposure measured in rat with 22d. One hour postdose liver, adipose, and brain tissue 11beta-HSD1 inhibition was confirmed with (+/-)-22f in a murine ex vivo assay. Although 5,7-disubstitued-2-adamantamines provided greater stability, a single, E-5-position, polar functional group afforded inhibitors with the best combination of stability, potency, and selectivity. These results indicate that adamantane metabolic stabilization sufficient to obtain short-acting, potent, and selective 11beta-HSD1 inhibitors has been discovered.

A series of metabolically stable adamantane amide 11beta-HSD1 inhibitors have been synthesized and biologically evaluated. These compounds exhibit excellent HSD1 potency and HSD2 selectivity and good pharmacokinetic and pharmacodynamic profiles.

Ghrelin, a gut-derived orexigenic hormone, is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Centrally administered ghrelin has been shown to cause hunger and increase food intake in rodents. Inhibition of ghrelin actions with ghrelin antibody, peptidyl GHS-R antagonists, and antisense oligonucleosides resulted in weight loss and food intake decrease in rodents. Here we report the effects of GHS-R antagonists, some of which were potent, selective, and orally bioavailable. A structure-activity relationship study led to the discovery of 8a, which was effective in decreasing food intake and body weight in several acute rat studies.

Described herein is the development of a potent non-nucleoside, small molecule inhibitor of genotype 1 HCV NS5B Polymerase. A 23 μM inhibitor that was active against HCV polymerase was further elaborated into a potent single-digit nanomolar inhibitor of HCV NS5B polymerase by additional manipulation of the R and R1 substituents. Subsequent modifications to improve physical properties were made in an attempt to achieve an acceptable pharmacokinetic profile.

The purpose of this investigation was to examine the effects of surgery and anesthesia on in vivo CYP3A activity and portal venous blood flow. Midazolam, a CYP3A probe for both rats and humans, was administered orally (2.7 mg), intravenously (0.57 mg), or via the portal vein (0.57 mg) to rats 4 h after anesthesia with ketamine/xylazine and surgery for placement of indwelling vascular and duodenal catheters and 3 days after surgery (chronic). The systemic clearance of midazolam was 51 +/- 4 ml/min/kg in the chronic animals, and this was significantly decreased (29 +/- 1 ml/min/kg, P = 0.024) in acute rats studied 4 to 6 h after anesthesia and surgery. The hepatic availability (FH), directly determined from the aortic and hepatic venous concentration gradient, was significantly higher in the acute animals (0.57 +/- 0.05) compared with the chronic animals (0.33 +/- 0.07, P = 0.001). Hepatic availability was determined using a classical approach in which FH was calculated from the area under the plasma concentration versus time curve ratio after portal venous or intravenous administration. FH was higher in the acute rats (0.48) compared with the chronic animals (0.27 +/- 0.03). Portal venous blood flow was significantly lower in the acute animals (5.0 +/- 0.4 ml/min/100 g body weight) compared with the chronic animals (9.1 +/- 0.9 ml/min/100 g body weight, P = 0.015). The effect of surgery and anesthesia was confirmed using the indicator dye dilution method after infusion of [14C]polyethylene glycol 4000 into the superior mesenteric artery. Our data suggest that anesthesia and surgery decreases both hepatic CYP3A activity and hepatic blood flow in rats. Studies performed in rats within 3 days of surgery and anesthesia are conducted under nonphysiologic conditions and therefore provide inaccurate assessment of drug disposition, in particular, clearance and bioavailability.

Objective To determine the effect of chronic exposure to endotoxin (lipopolysaccharide) and Staphylococcal enterotoxin B on hepatic injury and function. Design Prospective, controlled trial. Setting Research laboratory in a university hospital. Subjects Male Sprague-Dawley rats weighing 325-350 g with chronic vascular and bile catheters. Interventions Chronically catheterized rats were treated daily with saline, 50 microg/kg Staphylococcal enterotoxin B alone, 1000 microg/kg lipopolysaccharide alone, 1000 microg/kg lipopolysaccharide with 50 microg/kg Staphylococcal enterotoxin B, or 100 microg/kg lipopolysaccharide with 50 microg/kg Staphylococcal enterotoxin B for 10 days. Serum and biliary measures of hepatic injury and dysfunction were measured before and then 6 hrs and 1, 2, 3, 7, and 10 days after the start of treatment. The animals were killed at 10 days and the livers examined histologically. Measurements and main results Mean rates of bile flow, biliary indocyanine green excretion, and bile acid flux were significantly decreased immediately after treatment (6 hr, 1 and 2 days) and then at 10 days. Increases in biliary and serum gamma-glutamyltransferase and serum bile acids also occurred in a similar bimodal pattern. Animals treated with lipopolysaccharide or Staphylococcal enterotoxin B alone became tolerant and did not develop the bimodal pattern of hepatic dysfunction. Histologic examination of the liver at 10 days revealed periportal inflammation and fibrosis. Conclusions The combination of lipopolysaccharide and Staphylococcal enterotoxin B leads to late liver injury, whereas either toxin alone does not. These data may explain the frequent development of liver dysfunction in patients exposed to multiple bacterial toxins such as in sepsis, multiple-system organ failure, and other diseases with altered intestinal permeability.

To determine whether endotoxin-induced hyperlactatemia in hemodynamically stable animals is due to increased lactate production or decreased lactate clearance by measuring lactate turnover rate in the vascular compartment (LTRvc).Prospective, controlled trial.Research laboratory in a university hospital.Male Sprague-Dawley rats weighing 275-425 g with chronic vascular catheters.Chronically catheterized rats were treated with 6 microg/kg endotoxin or saline. LTRvc was determined from the specific activity of carbon-14 [14C]lactate in aortic blood during a constant infusion of [14C]lactate into the inferior vena cava. The role of the splanchnic organs in lipopolysaccharide-induced alterations in LTRvc was determined from the splanchnic first-pass clearance of [14C]lactate infused into the superior mesenteric artery and direct measurements of blood lactate concentration gradients across the splanchnic organs.Despite a 260% increase in lactate concentrations after lipopolysaccharide treatment, the specific activity of [14C]lactate and the LTRvc did not change, indicating that lipopolysaccharide-induced hyperlactatemia is caused by decreased lactate clearance from the vascular compartment rather than increased lactate flux into the vascular compartment. In contrast, lactate clearance by the splanchnic system was increased. The specific activity of [14C]lactate in aortic blood decreased 33% after lipopolysaccharide treatment when the [14C]lactate was infused into the superior mesenteric artery, indicating increased first-pass clearance of [14C]lactate by the splanchnic organs. Furthermore, the hepatic venous-aortic concentration gradient of lactate became increasingly negative after lipopolysaccharide treatment, indicating increased vascular extraction of lactate by the splanchnic system (0.07 +/- 0.07 micromol/mL vs. -0.34 +/- 0.14 micromol/mL).Lipopolysaccharide-induced hyperlactatemia in hemodynamically stable rats is caused by a net decrease in lactate clearance from the vascular compartment despite the fact that the clearance of lactate by the splanchnic system remains intact.

The mechanism of liver injury in endotoxemia is unclear. Previous studies have shown that splenectomy protects the liver from endotoxin-induced injury. The purpose of this study was to determine the relationship of TNFalpha and IFNgamma release and endotoxin-induced liver injury in splenectomized and nonsplenectomized rats. Splenectomized and nonsplenectomized (Sham) rats with chronic catheters in the aorta and inferior vena cava (IVC) were parenterally infused with 10 to 5000 microg/kg endotoxin. TNFalpha, IFNgamma, and alanine aminotransferase (ALT), a marker of hepatocellular damage, were measured in aortic blood. Compared to sham controls, splenectomized animals demonstrated significantly reduced endotoxin-induced ALT concentrations at endotoxin doses10 microg/kg. Peak endotoxin-induced TNFalpha concentrations were not significantly different between the splenectomized and sham groups. In contrast, peak endotoxin-induced IFNgamma concentrations were significantly decreased in the splenectomized group. These data suggest a relationship between endotoxin-induced IFNgamma and liver injury. We speculate that the spleen contributes to the endotoxin-induced liver injury by modulating release of IFNgamma.

We describe here N-phenylpyrrolidine-based inhibitors of HCV NS5A with excellent potency, metabolic stability, and pharmacokinetics. Compounds with 2S,5S stereochemistry at the pyrrolidine ring provided improved genotype 1 (GT1) potency compared to the 2R,5R analogues. Furthermore, the attachment of substituents at the 4-position of the central N-phenyl group resulted in compounds with improved potency. Substitution with tert-butyl, as in compound 38 (ABT-267), provided compounds with low-picomolar EC50 values and superior pharmacokinetics. It was discovered that compound 38 was a pan-genotypic HCV inhibitor, with an EC50 range of 1.7-19.3 pM against GT1a, -1b, -2a, -2b, -3a, -4a, and -5a and 366 pM against GT6a. Compound 38 decreased HCV RNA up to 3.10 log10 IU/mL during 3-day monotherapy in treatment-naive HCV GT1-infected subjects and is currently in phase 3 clinical trials in combination with an NS3 protease inhibitor with ritonavir (r) (ABT-450/r) and an NS5B non-nucleoside polymerase inhibitor (ABT-333), with and without ribavirin.

Most models of liver dysfunction in sepsis use endotoxin (lipopolysaccharide; LPS) to induce a pathophysiological response. In our study published in this issue (Beno DWA, Uhing MR, Goto M, Chen Y, Jiyamapa-Serna VA, and Kimura RE. Am J Physiol Gastrointest Liver Physiol 280: G858–G865, 2001), the adverse effect of LPS on hepatic function in vivo was only significant at relatively high LPS doses despite high tumor necrosis factor-α concentrations. However, many patients with sepsis are exposed to multiple bacterial toxins that may augment the immune response, resulting in increased hepatic dysfunction. We have developed a model of polymicrobial sepsis by parentally administering a combination of staphylococcal enterotoxin B (SEB) and LPS. Using this model, we demonstrate that SEB (50 μg/kg) potentiates the effect of LPS-induced hepatic dysfunction as measured by decreased rates of biliary indocyanine green clearance and bile flow. These increases were most pronounced with doses of 10 and 100 μg/kg LPS, doses that by themselves do not induce hepatic dysfunction. This may explain the seemingly increased incidence and severity of liver dysfunction in sepsis, and it suggests that the exclusive use of LPS for replicating septic shock may not be relevant for studies of hepatic dysfunction.

Most animal studies of cytokine release during sepsis or endotoxemia have used models in which studies are performed during or immediately after surgical stress. In a previous study, we showed that surgical stress as measured by elevated endogenous corticosterone concentrations attenuated the endotoxin-induced tumor necrosis factor alpha (TNFalpha) response. To determine whether surgical stress attenuates the endotoxin-induced interferon-gamma (IFN-gamma) response, chronically catheterized male Sprague-Dawley rats were treated with endotoxin 10 microg/kg immediately after surgery for catheter placement (surgical stress group, SS group) or at least 4 days postoperative (nonstressed group, NS group). We found that peak endotoxin-induced IFN-gamma responses were similar in the SS and NS groups (2094 +/- 315 pg/mL vs. 1863 +/- 307 pg/mL). Baseline corticosterone concentrations were significantly elevated in the SS group compared to the NS group (273.8 +/- 15.2 ng/mL vs. 30.0 +/- 8.5 ng/mL, P < 0.001). Peak TNFalpha concentrations were significantly reduced in the SS group compared to the NS group (5.2 +/- 1.9 ng/mL vs. 69.9 +/- 10.3 ng/mL, P = 0.0002). While peak serum TNFalpha concentrations were inversely related to baseline corticosterone concentrations, there was no correlation between peak IFN-gamma concentrations and baseline corticosterone concentrations or between TNFalpha and IFN-gamma concentrations. We conclude that surgical stress associated with elevated concentrations of endogenous corticosterone does not attenuate the endotoxin-induced IFN-gamma response despite an attenuation of the endotoxin-induced TNFalpha response. Because the effect of stress on different cytokines is varied, studies of sepsis and endotoxemia must account for the effects of experimentally-induced stress on cytokine responses.

Recent studies have demonstrated that 1,25-dihydroxyvitamin D3 (D3) can activate Raf kinase and induce Egr expression in cultured rat hepatic Ito cells (Lissoos, T. W., Beno, D. W. A., and Davis, B. H. (1993) J. Biol. Chem. 268, 25132-25138). Since Raf is an upstream activator of mitogen-activated protein kinase (MAPK), the current study evaluated the ability of D3 to activate MAPK. D3-activated MAPK and induced its cytoplasmic to perinuclear translocation in Ito cells. MAPK activation was found to be protein kinase C-dependent, which was analogous to previous studies of D3 and Raf activation. To further explore the D3 cascade, a series of transient transfections were performed using dominant negative raf and MAPK mutant plasmids which effectively block Ras-induced Raf and MAPK activity, respectively. D3 induced a marked increase in the expression of a chloramphenicol acetyltransferase reporter gene linked to the Egr promoter (egr-CAT). When the dominant negative Raf plasmid was co-transfected, there was no significant reduction in egr-CAT. In contrast, when the dominant negative MAPK plasmid was co-transfected, egr-CAT induction was completely abolished. These results suggest that 1) D3 stimulates MAPK via a protein kinase C-dependent pathway, 2) D3-induced Egr expression can occur via a pathway independent of Ras-induced Raf, and 3) D3 absolutely requires MAPK activity for Egr expression.

A high-throughput screen against human DGAT-1 led to the identification of a core structure that was subsequently optimized to afford the potent, selective, and orally bioavailable compound 14. Oral administration at doses ≥0.03 mg/kg significantly reduced postprandial triglycerides in mice following an oral lipid challenge. Further assessment in both acute and chronic safety pharmacology and toxicology studies demonstrated a clean profile up to high plasma levels, thus culminating in the nomination of 14 as clinical candidate ABT-046.

1,25-Dihydroxyvitamin D3's (D3) potential mitogenic mechanism of action was pursued in cultured rat hepatic Ito cells, a fibrogenic effector cell which proliferates in vivo during liver injury and fibrogenesis. D3 stimulated Ito cell DNA synthesis and potentiated platelet-derived growth factor-induced mitogenesis. D3's enhancement of [3H]thymidine incorporation was associated with nuclear Egr expression. Recent studies have causally linked the activated proto-oncogene c-Raf with downstream Egr induction. The serine-threonine kinase Raf protein is phosphorylation-activated by a large array of agonists including plasma membrane and cytoplasmic tyrosine kinases but has not previously been associated with the steroid superfamily of mediators. To consider potential prenuclear acute pathways of D3-induced stimulation, the activation of Raf was examined following D3 exposure. D3 induced Raf activation as assessed via (a) enhanced Raf phosphorylation following in vivo 32P labeling, (b) enhanced kinase function utilizing exogenous histone 1 protein as substrate, and (c) the shift in Raf physical localization changing from a diffuse cytoplasmic distribution to a perinuclear domain. A similar activation of Raf kinase was found in 3T3 cells exposed to D3 with enhanced histone phosphorylation detectable within 1 min following stimulation. The proximal cascade leading to Raf kinase activation may involve a protein kinase activity was severely attenuated by stimulated kinase activity was severely attenuated by previous phorbol ester treatment for 20 h or staurosporine pretreatment.

A series of quinoline derivatives was synthesized as potential bioisosteric replacements for the benzothiadiazine moiety of earlier Hepatitis C NS5B polymerase inhibitors. Several of these compounds exhibited potent activity in enzymatic and replicon assays.

The hepatitis C virus (HCV) NS5B polymerase is essential for viral replication and has been a prime target for drug discovery research. Our efforts directed toward the discovery of HCV polymerase inhibitors resulted in the identification of unsymmetrical dialkyl-hydroxynaphthalenoyl-benzothiadiazines 2 and 3. The most active compound displayed activity in genotypes 1a and 1b polymerase and replicon cell culture inhibition assays at subnanomolar and low nanomolar concentrations, respectively. It also displayed an excellent pharmacokinetic profile in rats, with a plasma elimination half-life after intravenous dosing of 4.5 h, oral bioavailability of 77%, and a peak liver concentration of 21.8 microg/mL.

4,4-Dialkyl-1-hydroxy-3-oxo-3.4-dihydronaphthalene-3-yl benzothiadiazine derivatives were synthesized and evaluated as inhibitors of genotypes 1a and 1b HCV NS5B polymerase. A number of these compounds exhibited potent activity against genotypes 1a and 1b HCV polymerase in both enzymatic and cell culture activities. A representative compound also showed favorable pharmacokinetics in the rat.

A highly potent and selective DGAT-1 inhibitor was identified and used in rodent models of obesity and postprandial chylomicron excursion to validate DGAT-1 inhibition as a novel approach for the treatment of metabolic diseases. Specifically, compound 4a conferred weight loss and a reduction in liver triglycerides when dosed chronically in DIO mice and depleted serum triglycerides following a lipid challenge in a dose-dependent manner, thus, reproducing major phenotypical characteristics of DGAT-1(-/-) mice.

Dipeptidyl peptidase IV (DPP4) inhibitors are emerging as a new class of therapeutic agents for the treatment of type 2 diabetes. They exert their beneficial effects by increasing the levels of active glucagon-like peptide-1 and glucose-dependent insulinotropic peptide, which are two important incretins for glucose homeostasis. Starting from a high-throughput screening hit, we were able to identify a series of piperidinone- and piperidine-constrained phenethylamines as novel DPP4 inhibitors. Optimized compounds are potent, selective, and have good pharmacokinetic profiles.

A preliminary safety evaluation of ACC2 inhibitor 1-(S) revealed serious neurological and cardiovascular liabilities of this chemotype. A systematic structure-toxicity relationship study identified the alkyne linker as the key motif responsible for these adverse effects. Toxicogenomic studies in rats showed that 1-(R) and 1-(S) induced gene expression patterns similar to that seen with several known cardiotoxic agents such as doxorubicin. Replacement of the alkyne with alternative linker groups led to a new series of ACC inhibitors with drastically improved cardiovascular and neurological profiles.

A novel series of pyrrolidine-constrained phenethylamines were developed as dipeptidyl peptidase IV (DPP4) inhibitors for the treatment of type 2 diabetes. The cyclohexene ring of lead-like screening hit 5 was replaced with a pyrrolidine to enable parallel chemistry, and protein co-crystal structural data guided the optimization of N-substituents. Employing this strategy, a >400x improvement in potency over the initial hit was realized in rapid fashion. Optimized compounds are potent and selective inhibitors with excellent pharmacokinetic profiles. Compound 30 was efficacious in vivo, lowering blood glucose in ZDF rats that were allowed to feed freely on a mixed meal.

Dipeptidyl peptidase IV (DPP4) deactivates glucose-regulating hormones such as GLP-1 and GIP, thus, DPP4 inhibition has become a useful therapy for type 2 diabetes. Optimization of the high-throughput screening lead 6 led to the discovery of 25 (ABT-341), a highly potent, selective, and orally bioavailable DPP4 inhibitor. When dosed orally, 25 dose-dependently reduced glucose excursion in ZDF rats. Amide 25 is safe in a battery of in vitro and in vivo tests and may represent a new therapeutic agent for the treatment of type 2 diabetes.

The incorporation of constrained tertiary amines into an existing class of N-benzyl-4-aminopiperidinyl chromone-based MCHr1 antagonists led to the identification of a series of chiral racemic compounds that displayed good to excellent functional potency, binding affinity, and selectivity over the hERG channel. Further separation of two distinct chiral racemic compounds into their corresponding pairs of enantiomers revealed a considerable selectivity for MCHr1 for one configuration, in addition to a striking difference in oral exposure between one pair of enantiomers in diet-induced obese mice. Oral administration of the most potent compound in this class in the same animal model led to significant reduction of fat mass in a semi-chronic model for weight loss.

Dipeptidyl peptidase-IV (DPP-IV) inhibitors are poised to be the next major drug class for the treatment of type 2 diabetes. Structure-activity studies of substitutions at the C5 position of the 2-cyanopyrrolidide warhead led to the discovery of potent inhibitors of DPP-IV that lack activity against DPP8 and DPP9. Further modification led to an extremely potent (Ki(DPP)(-)(IV) = 1.0 nM) and selective (Ki(DPP8) > 30 microM; Ki(DPP9) > 30 microM) clinical candidate, ABT-279, that is orally available, efficacious, and remarkably safe in preclinical safety studies.

A novel class of adamantane ethers 11beta-hydroxysteroid hydrogenase type I inhibitors has been discovered. These compounds have excellent HSD-1 potency and selectivity against HSD-2. The structure-activity relationships, selectivity, metabolism, PK, ex vivo pharmacodynamic data, and an X-ray crystal structure of one of these inhibitors bound to h-HSD-1 are discussed.

The discovery and pharmacological evaluation of potent, selective, and orally bioavailable growth hormone secretagogue receptor (GHS-R) antagonists are reported. Previously, 2,4-diaminopyrimidine-based GHS-R antagonists reported from our laboratories have been shown to be dihydrofolate reductase (DHFR) inhibitors. By comparing the X-ray crystal structure of DHFR docked with our GHS-R antagonists and GHS-R modeling, we designed and synthesized a series of potent and DHFR selective GHS-R antagonists with good pharmacokinetic (PK) profiles. An amide derivative 13d (Ca2+ flux IC50 = 188 nM, [brain]/[plasma] = 0.97 @ 8 h in rat) showed a 10% decrease in 24 h food intake in rats, and over 5% body weight reduction after 14-day oral treatment in diet-induced obese (DIO) mice. In comparison, a urea derivative 14c (Ca2+ flux IC50 = 7 nM, [brain]/[plasma] = 0.0 in DIO) failed to show significant effect on food intake in the acute feeding DIO model. These observations demonstrated for the first time that peripheral GHS-R blockage with small molecule GHS-R antagonists might not be sufficient for suppressing appetite and inducing body weight reduction.

A liver-selective glucocorticoid (GC) receptor antagonist (A-348441) was used to determine the effect of reduced hepatic GC signaling on hepatic glucose production. Fasted conscious dogs were studied in the presence (GRA, n = 6) or absence (CON, n = 6) of the intraduodenally administered GC receptor antagonist (100 mg/kg). All dogs were maintained on a pancreatic clamp and in a euglycemic state for 7 hours to ensure that any changes in glucose metabolism were the direct result of the effects of A-348441, which was given at the start of a 5-hour experimental period. In the GRA group, the arterial plasma insulin level was 4.6 +/- 0.7 and 4.8 +/- 0.6 microU/mL during the basal and the last 30 minutes of the experimental periods, respectively. In the CON group, it was 4.0 +/- 0.3 and 4.5 +/- 0.5 microU/mL in the 2 periods, respectively. The arterial plasma glucagon level was 49 +/- 4 and 46 +/- 3 pg/mL in the 2 periods in the GRA group, and 45 +/- 3 and 42 +/- 3 pg/mL in the CON group. Net hepatic glucose balance progressively decreased in the GRA group from 1.31 +/- 0.18 to 0.49 +/- 0.30 mg/kg per minute, whereas in the CON group, net hepatic glucose balance was 1.17 +/- 0.09 and 1.43 +/- 0.18 mg/kg per minute during the basal and last 30 minutes of the experimental periods, respectively. No significant change in net renal or gut glucose balance or nonhepatic glucose uptake was observed in either group. This study demonstrates that the GC receptor plays an important role in the regulation of basal hepatic glucose production and represents a significant potential therapeutic target.

A series of non-nucleoside HCV NS5B polymerase inhibitors based on the N-1-benzyl or N-1-[3-methylbutyl]-4-hydroxy-1,8-naphthyridon-3-yl benzothiadiazine core substituted in the D-ring aromatic moiety have been prepared and evaluated. Aromatic substituents extending from position 7 of the D-ring exhibited excellent potency against both genotypes 1a and 1b.

Glucocorticoids amplify endogenous glucose production in type 2 diabetes by increasing hepatic glucose output. Systemic glucocorticoid blockade lowers glucose levels in type 2 diabetes, but with several adverse consequences. It has been proposed, but never demonstrated, that a liver-selective glucocorticoid receptor antagonist (LSGRA) would be sufficient to reduce hepatic glucose output (HGO) and restore glucose control to type 2 diabetic patients with minimal systemic side effects. A-348441 [(3b,5b,7a,12a)-7,12-dihydroxy-3-{2-[{4-[(11b,17b)-17-hydroxy-3-oxo-17-prop-1-ynylestra-4,9-dien-11-yl] phenyl}(methyl)amino]ethoxy}cholan-24-oic acid] represents the first LSGRA with significant antidiabetic activity. A-348441 antagonizes glucocorticoid-up-regulated hepatic genes, normalizes postprandial glucose in diabetic mice, and demonstrates synergistic effects on blood glucose in these animals when coadministered with an insulin sensitizer. In insulin-resistant Zucker fa/fa rats and fasted conscious normal dogs, A-348441 reduces HGO with no acute effect on peripheral glucose uptake. A-348441 has no effect on the hypothalamic pituitary adrenal axis or on other measured glucocorticoid-induced extrahepatic responses. Overall, A-348441 demonstrates that an LSGRA is sufficient to reduce elevated HGO and normalize blood glucose and may provide a new therapeutic approach for the treatment of type 2 diabetes.

We have previously shown that systemic infusion of the bacterial toxins Staphylococcal enterotoxin B (SEB) and endotoxin (LPS) induces hepatic dysfunction as measured by decreased biliary indocyanine green (ICG) excretion. In this study, we compare the effects of these bacterial toxins after infusion into the portal and systemic circulation and directly measure biliary bile acid excretion as a measure of cholestasis. We hypothesized that bacterial toxins infused into the portal vein would induce greater hepatic dysfunction than toxins infused into the systemic circulation. Using a chronically catheterized rat model, biliary bile acid excretion was directly measured after infusion of LPS at 10 and 100 microg/kg with and without 50 microg/kg SEB into the portal vein (IPV) or inferior vena cava (IV) at baseline, and at 6 and 24 h. We found that when LPS was infused alone, only IPV administration caused a significant decrease in bile acid excretion at 6 h. There was no change in bile acid excretion after IV administration of LPS. In contrast, when the combination of LPS and SEB was infused, both IV and IPV administration significantly decreased bile acid excretion at 6 and 24 h. At 6 h post-LPS and -SEB administration, the decrease in bile acid excretion was significantly greater after IPV than IV administration. There was no site-specific difference in IFN-gamma release after infusion of toxins. However, peak TNFalpha release was decreased in IPV-infused rats [10 microg/kg (P < 0.05) or 100 microg/kg (P = ns) LPS with SEB] compared with the same doses in IV-infused rats. These data question the role of systemic TNF-alpha and IFN-gamma in regulating hepatic dysfunction and suggest a differential functional response of the liver to systemic and gut-derived septic events. This study also further explains the frequent development of liver dysfunction in patients with sepsis, multisystem organ failure, and other diseases with altered intestinal permeability.

Patients with severe trauma injury are transiently exposed to increased serum concentrations of tumor necrosis factor-alpha (TNF-alpha). These patients are susceptible to the development of multisystem organ failure (MSOF) triggered by subsequent exposure to bacterial toxins either via infection or increased intestinal permeability. We simulated the cytokine response of trauma by infusing 0.8 or 8.0 microg/kg of TNF-alpha (priming dose) into chronically catheterized rats. After 48 h, rats were challenged with endotoxin [lipopolysaccharide (LPS); 10 or 1,000 microg/kg]. Animals primed with either dose of TNF-alpha and then challenged with 1,000 microg/kg of LPS demonstrated significantly increased mortality, mean peak serum concentrations of interferon-gamma (IFN-gamma), and blood lactate concentrations (P0.05) compared with nonprimed animals. Mean peak serum concentrations of IFN-gamma and blood lactate concentrations were increased after challenge with 10 microg/kg of LPS only in animals primed with 8.0 microg/kg of TNF-alpha. Priming with TNF-alpha did not increase mortality after challenge with 10 microg/kg of LPS. These data suggest that both TNF-alpha release and the subsequent exposure to bacterial toxins mediate the pathophysiological progression from trauma to subsequent MSOF.

The objective of the study was to determine whether ursodeoxycholic acid (Ursodiol) is protective against ibuprofen (IBU)-induced enteropathy.Using the chronically catheterized rat model, IBU (60 mg/kg body weight per day) was infused via the gastric catheter twice daily. Pancreatic enzyme (PE; 10,000 U lipase/kg body weight per day) and Ursodiol (10 mg/kg body weight per day) in two doses were infused via the duodenal catheter. Rats were assigned to one of six treatment groups and were administered treatment for 20 days: control, IBU, PE, IBU + PE, IBU + Ursodiol, and IBU + PE + Ursodiol. The entire jejunum, ileum, cecum, and colon were available for histologic analysis using previously described techniques.Addition of Ursodiol to high-dose IBU and normal doses of PE showed a significant reduction in the percentage of rats with ulcers (P0.05), total number of serositis events (P0.01), total number of severe ulcers (P0.001), and an absence of ulcers in the large intestine.Ursodiol, the drug of choice for the treatment of cystic fibrosis liver disease, may offer a safe method of using high-dose IBU in these patients by ameliorating the enteropathy.

Using a nonstressed chronically catheterized rat model in which the common bile duct was cannulated, we studied endotoxin-induced alterations in hepatic function by measuring changes in the maximal steady-state biliary excretion rate of the anionic dye indocyanine green (ICG). Biliary excretion of ICG was calculated from direct measurements of biliary ICG concentrations and the bile flow rate during a continuous vascular infusion of ICG. Despite significant elevations in mean peak serum tumor necrosis factor-alpha (TNF-alpha) concentrations (90.9 +/- 16.2 ng/ml), there was no effect on mean rates of bile flow or biliary ICG clearance after administration of 100 microg/kg endotoxin at 6 or 24 h. Significant differences from mean baseline rates of bile flow and biliary ICG excretion did occur after administration of 1,000 microg/kg endotoxin (mean peak TNF-alpha 129.6 +/- 24.4 ng/ml). Furthermore, when rats were treated with up to 16 microg/kg of recombinant TNF-alpha, there was no change in mean rates of bile flow or ICG biliary clearance compared with baseline values. These data suggest that the complex regulation of biliary excretion is not mediated solely by TNF-alpha.

An epidemic of fibrosing colonopathy, a new disease caused by the prolonged administration of excessive doses of pancreatic enzymes, was first reported in 1994. More than 60 cases were known to occur worldwide before dosage guidelines were enforced. Predisposing factors were young age, previous intestinal surgery, meconium ileus equivalent, and use of H2 blockers, corticosteroids, and DNase. Abnormal features included foreshortened colon, strictures, marked submucosal fibrosis, ascites, and nodular hyperplasia of the liver. Histologic examination showed eosinophilia, mild cryptitis, epithelial regeneration, and widespread interruption of the muscularis mucosa. These findings are distinct from, but share many of the features of, those of Crohn’s’s disease and ischemic bowel disease. The pathogenic mechanisms remain unknown.

Background High-dose ibuprofen therapy limits the progression of lung disease in patients with cystic fibrosis. However, ibuprofen increases intestinal permeability, which potentiates intestinal damage caused by high-dose pancreatic enzyme treatment, as was shown in a previous study by this group. In the present study, the combined effects of ibuprofen and pancreatic enzyme treatment on the intestine and liver were examined. Methods Using a chronically catheterized rat model, high-dose ibuprofen (60 mg/kg x day in two doses), with or without pancreatic enzyme treatment was infused into gastric and duodenal catheters, respectively, for 20 days. Six groups were studied: control group; ibuprofen treatment alone; pancreatic enzyme treatment alone (two groups: normal dose, 10,000 U lipase/kg x day and high dose, 40,000 U lipase/kg x day); and ibuprofen combined with pancreatic enzyme (two groups: ibuprofen with high-dose pancreatic enzyme and ibuprofen and low-dose pancreatic enzyme). After treatment, rats were autopsied, and complete histologic analyses of the entire intestine and liver were performed. Results Ibuprofen caused mild ulceration of the small intestine in 50% of rats. Pancreatic enzyme treatment alone did not induce ulceration of the intestine. The combination of pancreatic enzyme and ibuprofen treatment increased the severity of the ulcers in the small intestine but not the number of ulcers or the percentage of rats affected. Ibuprofen treatment alone did not cause ulcers in the large intestine, but with the addition of pancreatic enzymes, ulceration and fibrosis were present. Conclusions Ibuprofen at doses used to limit progression of cystic fibrosis lung disease caused enteropathy in 50% of rats. There was synergism between ibuprofen and pancreatic enzyme treatment in the production of severe ulcers. Ulcers in the cecum and colon were increased with combined ibuprofen and pancreatic enzyme treatment compared with incidence in control animals.

Previous investigators have demonstrated that the tumor necrosis factor-alpha (TNF-alpha) response to endotoxin is inhibited by exogenous corticosterone or catecholamines both in vitro and in vivo, whereas others have reported that surgical and nonsurgical stress increase the endogenous concentrations of these stress-induced hormones. We hypothesized that elevated endogenous stress hormones resultant from experimental protocols attenuated the endotoxin-induced TNF-alpha response. We used a chronically catheterized rat model to demonstrate that the endotoxin-induced TNF-alpha response is 10- to 50-fold greater in nonstressed (NS) rats compared with either surgical-stressed (SS, laparotomy) or nonsurgical-stressed (NSS, tail vein injection) models. Compared with the NS group, the SS and NSS groups demonstrated significantly lower mean peak TNF-alpha responses at 2 mg/kg and 6 micrograms/kg endotoxin [NS 111.8 +/- 6.5 ng/ml and 64.3 +/- 5.9 ng/ml, respectively, vs. SS 3.9 +/- 1.1 ng/ml (P < 0.01) and 1.3 +/- 0.5 ng/ml (P < 0.01) or NSS 5.2 +/- 3.2 ng/ml (P < 0.01) at 6 micrograms/kg]. Similarly, baseline concentrations of corticosterone and catecholamines were significantly lower in the NSS group [84.5 +/- 16.5 ng/ml and 199.8 +/- 26.2 pg/ml, respectively, vs. SS group 257. 2 +/- 35.7 ng/ml (P < 0.01) and 467.5 +/- 52.2 pg/ml (P < 0.01) or NS group 168.6 +/- 14.4 ng/ml (P < 0.01) and 1,109.9 +/- 140.7 pg/ml (P < 0.01)]. These findings suggest that the surgical and nonsurgical stress inherent in experimental protocols increases baseline stress hormones, masking the endotoxin-induced TNF-alpha response. Subsequent studies of endotoxic shock should control for the effects of protocol-induced stress and should measure and report baseline concentrations of corticosterone and catecholamines.

The reactive oxygen intermediate H2O2 can function as a signaling molecule to activate gene expression. In this study, we demonstrate that oxidant stress induced by tumor necrosis factor alpha (TNFalpha) or H2O2 differentially regulates intercellular adhesion molecule-1 (ICAM-1) and interleukin-8 (IL-8) gene expression in endothelial and epithelial cells. Northern blot analysis revealed that TNFalpha induced both ICAM-1 and IL-8 expression in either the A549 lung epithelial cell line or the human microvessel endothelial cell line (HMEC-1). In contrast, H2O2 selectively induced only ICAM-1 in HMEC-1 and only IL-8 in A549. This cell type-specific pattern of IL-8 expression was also observed in several other endothelial and epithelial cells. TNFalpha induced greater IL-8 gene expression as compared with H2O2, but the kinetics of induction were similar. The induction of epithelial IL-8 message was accompanied by a corresponding increase in functional IL-8 protein secretion as determined by a neutrophil motility assay. The increased neutrophil motility stimulated by conditioned media from H2O2- or TNFalpha-exposed A549 cells was completely inhibited by an anti-IL-8 antibody. TNFalpha and H2O2 also induced a differential pattern of CC chemokine expression in A549. While TNFalpha induced both RANTES and MCP-1, H2O2 induced only MCP-1. These data suggest that epithelial cells under oxidant stress contribute to the inflammatory cytokine network by selective production of IL-8, MCP-1, and RANTES, which may critically influence the site-specific recruitment of leukocyte subsets.

Increased Ito cell collagen production occurs during in vivo liver fibrogenesis. Regulation of the overproduction of collagen was studied in cultured rat hepatic Ito cells, which resemble the myofibroblast associated with liver fibrosis. Previous studies suggest that the steroid hormones, retinoic acid, and glucocorticoids may have antifibrogenic properties in vitro and in vivo when used at pharmacological doses. Their potential roles at physiological levels are not well understood. The current study examined the potential regulation of the overproduction of type I collagen in cultured rat hepatic Ito cells by another steroid hormone, 3,5,3'-triiodo-L-thyronine (T3). T3 induced a 3.4-fold reduction in type I collagen production. The effect was dose dependent and was maximal with physiological levels of T3 (10(-9) M). The effect of T3 was independent of any suppression in total protein synthesis. The mechanism of the suppressive effect of T3 on collagen production was explored and was found to be at a posttranslational level. This study suggests that the inhibitory effects of T3 on type I collagen production are likely caused by enhanced intracellular turnover of type I collagen.

A series of (5-substituted pyrrolidinyl-2-carbonyl)-2-cyanopyrrolidine (C5-Pro-Pro) analogues was discovered as dipeptidyl peptidase IV (DPPIV) inhibitors as a potential treatment of diabetes and obesity. X-ray crystallography data show that these inhibitors bind to the catalytic site of DPPIV with the cyano group forming a covalent bond with the serine residue of DPPIV. The C5-substituents make various interactions with the enzyme and affect potency, chemical stability, selectivity, and PK properties of the inhibitors. Optimized analogues are extremely potent with subnanomolar K(i)'s, are chemically stable, show very little potency decrease in the presence of plasma, and exhibit more than 1,000-fold selectivity against related peptidases. The best compounds also possess good PK and are efficacious in lowering blood glucose in an oral glucose tolerance test in ZDF rats.