The discovery of benzoxazine sulfonamide inhibitors of NaV1.7: Tools that bridge efficacy and target engagement.

The voltage-gated sodium channel NaV1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of NaV1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat NaV1.7 versus human NaV1.7 was observed, rendering in vivo rat pharmacology studies challenging. Herein, we report the discovery and optimization of novel benzoxazine sulfonamide inhibitors of human, rat and mouse NaV1.7 which enabled pharmacological assessment in traditional behavioral rodent models of pain and in turn, established a connection between formalin-induced pain and histamine-induced pruritus in mice. The latter represents a simple and efficient means of measuring target engagement.

Discovery and optimization of a potent and selective triazolopyridinone series of c-Met inhibitors.

Deregulation of the receptor tyrosine kinase c-Met has been implicated in several human cancers and is an attractive target for small molecule drug discovery. Herein, we report the discovery of a structurally diverse series of carbon-linked quinoline triazolopyridinones, which demonstrates nanomolar inhibition of c-Met kinase activity. This novel series of inhibitors exhibits favorable pharmacokinetics as well as potent inhibition of HGF-mediated c-Met phosphorylation in a mouse liver pharmacodynamic model.

Probiotic yogurt in the elderly with intestinal bacterial overgrowth: endotoxaemia and innate immune functions.

A study was conducted in healthy elderly living independently in senior housing to assess the impact of a probiotic yoghurt supplement on small intestinal bacterial overgrowth. Twenty-three participants with positive and thirteen participants with negative hydrogen breath test were studied before and after a period of 4 weeks of probiotic yoghurt administration. Intestinal permeability, plasma endotoxin levels, phagocytic activity of leucocytes, cytokine production by monocytes and free radical response of neutrophils were determined. Intestinal permeability was similar for the two groups and was unaffected by probiotic treatment. Both plasma endotoxin levels and the basal phagocytic activity of leucocytes decreased after yoghurt intake in the two groups. Exposure of monocytes and neutrophils ex vivo led to an increased cytokine response and free radical response, respectively. The normalisation of the various cytokine responses was more apparent in the group with positive breath test. In addition, the plasma levels of lipoplysaccharide binding protein and soluble CD14, lipoplysaccharide pattern recognition receptors and surrogate markers of lipoplysaccharide permeability were diminished by the end of the study. In conclusion, probiotic administration in the elderly normalises the response to endotoxin, and modulates activation markers in blood phagocytes, and therefore may help reduce low-grade chronic inflammation.

Discovery and optimization of potent and selective triazolopyridazine series of c-Met inhibitors.

Deregulation of the receptor tyrosine kinase c-Met has been implicated in several human cancers and is an attractive target for small molecule drug discovery. We previously showed that O-linked triazolopyridazines can be potent inhibitors of c-Met. Herein, we report the discovery of a related series of N-linked triazolopyridazines which demonstrate nanomolar inhibition of c-Met kinase activity and display improved pharmacodynamic profiles. Specifically, the potent time-dependent inhibition of cytochrome P450 associated with the O-linked triazolopyridazines has been eliminated within this novel series of inhibitors. N-linked triazolopyridazine 24 exhibited favorable pharmacokinetics and displayed potent inhibition of HGF-mediated c-Met phosphorylation in a mouse liver PD model. Once-daily oral administration of 24 for 22days showed significant tumor growth inhibition in an NIH-3T3/TPR-Met xenograft mouse efficacy model.

Discovery and optimization of triazolopyridazines as potent and selective inhibitors of the c-Met kinase.

Tumorigenesis is a multistep process in which oncogenes play a key role in tumor formation, growth, and maintenance. MET was discovered as an oncogene that is activated by its ligand, hepatocyte growth factor. Deregulated signaling in the c-Met pathway has been observed in multiple tumor types. Herein we report the discovery of potent and selective triazolopyridazine small molecules that inhibit c-Met activity.

Is nutrient intake a gender-specific cause for enhanced susceptibility to alcohol-induced liver disease in women?

AIM: Women have a higher susceptibility to alcohol-induced liver disease (ALD) than men. Gender-related differences in food preference were described in previous studies for several populations, but not in alcohol abusers. As certain micronutrients are reported to take influence on the development of ALD in animal experiments, the hypothesis of the present retrospective cross-sectional study was that gender-dependent (micro-) nutrient intake in patients with ALD may cause the higher susceptibility of women to this disease. METHODS: In 210 patients (male: 158, female: 52) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and in 336 controls (male: 208, female: 128), nutrient intake was determined by a computer-guided diet history, and related to the severity of ALD in dependence on the sex of the patients. RESULTS: No significant differences between males and females with ALD were calculated for the intake (per kg body weight/day) of protein, carbohydrates, fat, and the intake (per kg body weight/day) of most micronutrients. In females with ALD, higher intake was found for vitamin C (ALD3), calcium (ALD2), iron (ALD1 and ALD2), and zinc (ALD1), but the consumption of none of these micronutrients seems to contribute to a higher susceptibility to ALD in females. CONCLUSION: Though the present study confirms the higher susceptibility to ALD in women, the data of calculated daily macro- and micronutrient intake do not suggest any explicit influence of gender-specific nutrition in the development of ALD.

Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: summary of a symposium.

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram-negative bacteria in the intestine, which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram-negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan, which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram-negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, l-glutamine, oats supplementation, or zinc, thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram-negative bacteria and preserving intestinal permeability to endotoxin may attenuate alcoholic liver and other organ injuries.

Correction to "Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement".

[This corrects the article DOI: 10.1021/acsmedchemlett.6b00243.].

Saturation of retinol-binding protein correlates closely to the severity of alcohol-induced liver disease.

Impaired metabolism of retinol has been shown to occur in alcohol-induced liver disease (ALD). The purpose of the present study was to investigate the saturation of retinol-binding protein (RBP) in 6 patients with different stages of ALD. Hospitalized alcohol consumers (n=118) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and 45 healthy control subjects were nutritionally assessed, and retinol and RBP content was measured in plasma by high-performance liquid chromatography and enzyme-linked immunosorbent assay methods, respectively. No differences were noted in daily retinol intake, but subjects with ALD had significantly lower concentrations of retinol in plasma (ALD1: 1.81+/-0.17 micromol/l [mean+/-S.E.M.]; ALD2: 1.95+/-0.24 micromol/l; ALD3: 0.67+/-0.13 micromol/l) compared to controls (2.76+/-0.19 micromol/l). Subjects of group ALD2 had significantly higher plasma RBP levels than controls (P<.05) and patients with ALD1 (P<.05) and ALD3 (P<.001). The relative saturation of RBP with retinol decreased with severity of ALD (controls: 76.8+/-5.0%; ALD1: 55.8+/-6.5%; ALD2: 43.5+/-6.2%; ALD3: 29.0+/-5.1%). The present study indicates that plasma concentrations of retinol and RBP per se do not correlate to severity of ALD, but rather that the retinol/RBP ratio links to the severity of alcohol-induced liver damage. From these results, a reduced availability of retinol in the periphery due to an altered saturation of RBP can be concluded.

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement.

Human genetic evidence has identified the voltage-gated sodium channel NaV1.7 as an attractive target for the treatment of pain. We initially identified naphthalene sulfonamide 3 as a potent and selective inhibitor of NaV1.7. Optimization to reduce biliary clearance by balancing hydrophilicity and hydrophobicity (Log D) while maintaining NaV1.7 potency led to the identification of quinazoline 16 (AM-2099). Compound 16 demonstrated a favorable pharmacokinetic profile in rat and dog and demonstrated dose-dependent reduction of histamine-induced scratching bouts in a mouse behavioral model following oral dosing.

Decreased expression of cytochrome P450 protein in non-malignant colonic tissue of patients with colonic adenoma.

BACKGROUND: Cytochrome P450 (CYP) enzymes in epithelial cells lining the alimentary tract play an important role in both the elimination and activation of (pro-)carcinogens. To estimate the role of cytochrome P450 in carcinogenesis of the colon, expression patterns and protein levels of four representative CYPs (CYP2C, CYP2E1, CYP3A4 and CYP3A5) were determined in colon mucosa of normal and adenomatous colonic tissue of patients with adenomas and disease-free controls. METHODS: Expression of CYP2C, CYP2E1, CYP3A4, and CYP3A5 in colon mucosa of normal and adenomatous colonic tissue of patients with adenoma and disease-free controls was determined by RT-PCR. Protein concentration of CYPs was determined using Western blot. RESULTS: With the exception of CYP3A5, expression of CYP mRNA was similar among groups and tissues (e.g. normal colon mucosa and adenoma). CYP3A5 mRNA expression was significantly higher in adenoma in comparison to normal tissue of patients with adenoma (approximately 48%). When comparing protein concentrations of CYPs measured in adenomas with neighboring normal colonic mucosa no differences were found. However, in normal tissue of patients with adenomas, protein levels of CYP2C8, CYP3A4 and CYP3A5, but not that of CYP2E1, were significantly lower than in biopsies obtained from disease-free controls. Specifically, in normal colonic mucosa of patients protein concentrations of CYP2C8, CYP3A4, and CYP3A5 were approximately 86%, approximately 69%, and approximately 54%, respectively, lower than in disease-free controls. CONCLUSION: In conclusion, among other factors, the altered protein levels of certain CYPs (e.g. CYP2C8, CYP3A4 and CYP3A5) in colon mucosa might contribute to the development of neoplasia in the colon.

Acute but not chronic ethanol exposure impairs retinol oxidation in the small and large intestine of the rat.

BACKGROUND AND AIM: Ethanol has been shown to inhibit retinol oxidation at the level of alcohol dehydrogenase in liver and colon but not previously in the small intestine. In the present study we investigated how chronic alcohol feeding and acute ethanol exposure affects retinol dehydrogenase activity in the colon and small intestine of the rat. METHODS: Rats were fed ethanol in a liquid diet for six weeks. Control rats received a similar diet but with ethanol isocalorically replaced by carbohydrates. Retinol dehydrogenase was analyzed from cell cytosol samples from the small and the large intestine with respect to maximum activity (V(max)), Michaelis-Menten constant (K(m)), and inhibition by ethanol (2-43 mM) in vitro. RESULTS: Both the V(max) and the catalytic efficiency (V(max)/K(m)) were found to be significantly higher in the colon than in the small intestine (2.9-3.6 and 54-70 times higher, respectively). While chronic alcohol feeding did not affect these parameters, acute ethanol exposure reduced V(max) and V(max)/K(m) dose-dependently (p < 0.001) in both intestinal segments. CONCLUSION: The present data demonstrate that ethanol markedly inhibits in vitro cytosolic retinol oxidation in the small intestinal mucosa, which is considerably lower than that found in the colon. Considering the vital importance of retinol on intestinal integrity, our finding suggests that this might contribute to the ethanol-induced increase in intestinal permeability.

Distribution of cytochrome P450 2C, 2E1, 3A4, and 3A5 in human colon mucosa.

BACKGROUND: Despite the fact that the alimentary tract is part of the body's first line of defense against orally ingested xenobiotica, little is known about the distribution and expression of cytochrome P450 (CYP) enzymes in human colon. Therefore, expression and protein levels of four representative CYPs (CYP2C(8), CYP2E1, CYP3A4, and CYP3A5) were determined in human colon mucosa biopsies obtained from ascending, descending and sigmoid colon. METHODS: Expression of CYP2C, CYP2E1, CYP3A4, and CYP3A5 mRNA in colon mucosa was determined by RT-PCR. Protein concentration of CYPs was determined using Western blot methods. RESULTS: Extensive interindividual variability was found for the expression of most of the genes. However, expression of CYP2C mRNA levels were significantly higher in the ascending colon than in the sigmoid colon. In contrast, mRNA levels of CYP2E1 and CYP3A5 were significantly lower in the ascending colon in comparison to the descending and sigmoid colon. In sigmoid colon protein levels of CYP2C8 were significantly higher by ~73% than in the descending colon. In contrast, protein concentration of CYP2E1 was significantly lower by ~81% in the sigmoid colon in comparison to the descending colon. CONCLUSION: The current data suggest that the expression of CYP2C, CYP2E1, and CYP3A5 varies in different parts of the colon.

Lycopene, beta-carotene, and colorectal adenomas.

BACKGROUND: Epidemiologic studies found that high tomato intakes reduce the risk of colorectal cancers. This beneficial effect is assumed to be caused by high intakes of lycopene, a carotenoid with strong antioxidant activity that is present predominantly in tomatoes. OBJECTIVE: We assessed the relation between plasma lycopene concentrations and colorectal adenomas, the precursors for most colorectal cancers. In addition, the concentrations of 2 other antioxidants, beta-carotene and alpha-tocopherol, were measured. DESIGN: White subjects undergoing a complete colonoscopy were included in the study (73 with adenomas, 63 without any polyps, and 29 with hyperplastic polyps). A detailed dietary history and information on alcohol consumption and smoking habits were collected from all subjects. Plasma lycopene, beta-carotene, and alpha-tocopherol concentrations were measured by using HPLC. RESULTS: Patients with adenomas and control subjects without polyps did not differ significantly in body mass index; intakes of energy, fat, protein, carbohydrates, fiber, beta-carotene, and alcohol; or prevalence of smoking, but patients with adenomas were slightly older. The median plasma lycopene concentration was significantly lower in the adenoma group than in the control group (-35%; P = 0.016). The median plasma beta-carotene concentration also tended to be lower in the adenoma group (-25.5%), but the difference was not significant. In the multiple logistic regression, only smoking (odds ratio: 3.02; 95% CI: 1.46, 6.25; P = 0.003) and a plasma lycopene concentration < 70 microg/L (odds ratio: 2.31; 1.12, 4.77; P = 0.023) were risk factors for adenomatous polyps. Patients with hyperplastic polyps did not differ significantly from control subjects in any variable. CONCLUSION: Our findings support the hypothesis that lycopene contributes to the protective effect of high tomato intakes against the risk of colorectal adenomas.

Prevalence of small bowel bacterial overgrowth and its association with nutrition intake in nonhospitalized older adults.

OBJECTIVES: To determine the prevalence of small bowel bacterial overgrowth (SBBO) in older adults and to assess whether SBBO is associated with abdominal complaints and nutrient intake. DESIGN: Cross-sectional survey. SETTING: Eight senior residence sites in Stuttgart, Germany. PARTICIPANTS: Older adults living independently in senior residence houses. MEASUREMENTS: The prevalence of SBBO was measured in 328 subjects, of whom 294 were aged 61 and older, by measuring hydrogen concentration (parts per million; ppm) in exhaled air after ingestion of 50 g glucose. Anthropometric data were obtained and nutritional status was recorded with a computer-aided diet history. RESULTS: The prevalence of a positive hydrogen breath test (>10 ppm increase) was 15.6% in older adults, compared with 5.9% in subjects aged 24 to 59. The intake of inhibitors of gastric acid production contributed significantly to the high prevalence of a positive breath test in older adults, which was associated with lower body weight, lower body mass index, lower plasma albumin concentration, and higher prevalence of diarrhea. Subjects with a positive hydrogen breath test consumed significantly less fiber, folic acid, and vitamins B2 and B6 than those without. No difference was observed in the intake of energy, protein, fat, or carbohydrates. CONCLUSION: Prevalence of SBBO is associated with reduced body weight, which is paralleled by reduced intake of several micronutrients. Malabsorption resulting from diarrhea might be an aggravating factor contributing to weight loss in these subjects.

Effect of alcohol consumption on the gut.

Consumption of large quantities of alcoholic beverages leads to disturbances in the intestinal absorption of nutrients including several vitamins. The inhibition of the absorption of sodium and water caused by alcohol contributes to the tendency in alcoholics to develop diarrhoea. Excessive alcohol consumption (even a single episode) can result in duodenal erosions and bleeding and mucosal injury in the upper jejunum. An increased prevalence for bacterial overgrowth in the small intestine may contribute to functional and/or morphological abnormalities of this part of the gut and also to non-specific abdominal complaints in alcoholics. The mucosal damage caused by alcohol increases the permeability of the gut to macromolecules. This facilitates the translocation of endotoxin and other bacterial toxins from the gut lumen to the portal blood, thereby increasing the liver's exposure to these toxins and, consequently, the risk of liver injury. The results of recent experimental studies support the assumption that alcohol significantly modulates the mucosal immune system of the gut.

First-pass metabolism of ethanol in human beings: effect of intravenous infusion of fructose.

Intravenous infusion of fructose has been shown to enhance reduced form of nicotinamide adenine dinucleotide reoxidation and, thereby, to enhance the metabolism of ethanol. In the current study, the effect of fructose infusion on first-pass metabolism of ethanol was studied in human volunteers. A significantly higher first-pass metabolism of ethanol was obtained after administration of fructose in comparison with findings for control experiments with an equimolar dose of glucose. Because fructose is metabolized predominantly in the liver and can be presumed to have virtually no effects in the stomach, results of the current study support the assumption that only a negligible part of first-pass metabolism of ethanol occurs in the stomach.

Water metabolism in rats subjected to chronic alcohol administration.

AIM: While the diuretic action of acute ingestion of alcohol has been studied extensively, the effect of chronic alcohol consumption has received less attention. The aim of the present study was to investigate the effect of chronic alcohol consumption on the balance of water intake and excretion and certain renal functions in rats during a period of 12 months. ANIMALS AND STUDY DESIGN: Male Wistar rats received either alcohol (15% v/v; group A, n = 65) or tap water (group C, n = 35) as drinking fluid. Urine and faeces were collected from 6 rats of each group during 7 days, at monthly intervals. In further experiments, the animals received a low-protein/high-fat diet with and without alcohol. RESULTS: When the rats were fed the standard diet, 24-hour urine excretion was significantly reduced in group A compared with group C. This difference was even more pronounced when the animals were fed the low-protein/high-fat diet. The reduced urine excretion was not due to lower liquid consumption and the pattern of daily excretion of faeces was comparable with that observed for urine excretion. Both sodium and potassium excretion and the diuretic response to an acute water load were significantly reduced in group A compared with group C. The changes in water balance induced by chronic alcohol consumption were reversible within a few days when the rats received water instead of 15% alcohol. CONCLUSIONS: Chronic alcohol consumption has an antidiuretic effect in rats. The percentage of total ingested fluid leaving the body as hidden water loss increases after alcohol consumption by up to 25-26% over control values.

The discovery and optimization of a novel class of potent, selective, and orally bioavailable anaplastic lymphoma kinase (ALK) inhibitors with potential utility for the treatment of cancer.

A class of 2-acyliminobenzimidazoles has been developed as potent and selective inhibitors of anaplastic lymphoma kinase (ALK). Structure based design facilitated the rapid development of structure-activity relationships (SAR) and the optimization of kinase selectivity. Introduction of an optimally placed polar substituent was key to solving issues of metabolic stability and led to the development of potent, selective, orally bioavailable ALK inhibitors. Compound 49 achieved substantial tumor regression in an NPM-ALK driven murine tumor xenograft model when dosed qd. Compounds 36 and 49 show favorable potency and PK characteristics in preclinical species indicative of suitability for further development.

Arginine does not exacerbate markers of inflammation in cocultures of human enterocytes and leukocytes.

Enteral arginine supplementation in the critically ill has become a matter of controversy. In this study, we investigated effects of the addition of 0.4 and 1.2 mmol/L arginine in a coculture model on markers of inflammation, enterocyte layer integrity, and amino acid transport. In this model, a monolayer of intestinal epithelial cells (Caco-2) separated compartments with nonpathogenic Escherichia coli and mononuclear leukocytes. Activation of enterocytes and leukocytes was assessed by the measurement of nitric oxide, TNF-alpha, IL-6, IL-8, IL-10, and IFN-gamma. Further outcomes were the transepithelial flux of 22 amino acids, their catabolism, and the integrity of the enterocyte layer assessed as permeability of fluorescein dextran (M(r) 4400). Bacterial stimulation of intestinal epithelial cells enhanced the basolateral concentration of nitric oxide and all cytokines measured. Supplementation with arginine did not affect epithelial integrity, production of any of the cytokines investigated, or the amount of nitric oxide. The amino acid used primarily by nonstimulated intestinal epithelial cells cocultured with leukocytes was glutamine. Activation of IEC with bacteria significantly enhanced the catabolism of serine, asparagine, and lysine, and reduced glutamine catabolism. Addition of arginine increased ornithine formation and moderately reduced transepithelial transport of methionine and other amino acids. Hence, arginine supplementation does not interfere with inflammation-associated cross-talk between human enterocytes and leukocytes. Because it also does not seem to affect the integrity of enterocyte layers, a detrimental role of arginine during septic-like conditions seems unlikely.