Discovery of liver-targeted inhibitors of stearoyl-CoA desaturase (SCD1).

Inhibitors based on a benzo-fused spirocyclic oxazepine scaffold were discovered for stearoyl-coenzyme A (CoA) desaturase 1 (SCD1) and subsequently optimized to potent compounds with favorable pharmacokinetic profiles and in vivo efficacy in reducing the desaturation index in a mouse model. Initial optimization revealed potency preferences for the oxazepine core and benzylic positions, while substituents on the piperidine portions were more tolerant and allowed for tuning of potency and PK properties. After preparation and testing of a range of functional groups on the piperidine nitrogen, three classes of analogs were identified with single digit nanomolar potency: glycine amides, heterocycle-linked amides, and thiazoles. Responding to concerns about target localization and potential mechanism-based side effects, an initial effort was also made to improve liver concentration in an available rat PK model. An advanced compound 17m with a 5-carboxy-2-thiazole substructure appended to the spirocyclic piperidine scaffold was developed which satisfied the in vitro and in vivo requirements for more detailed studies.

Discovery of SCH 900271, a Potent Nicotinic Acid Receptor Agonist for the Treatment of Dyslipidemia.

Structure-guided optimization of a series of C-5 alkyl substituents led to the discovery of a potent nicotinic acid receptor agonist SCH 900271 (33) with an EC50 of 2 nM in the hu-GPR109a assay. Compound 33 demonstrated good oral bioavailability in all species. Compound 33 exhibited dose-dependent inhibition of plasma free fatty acid (FFA) with 50% FFA reduction at 1.0 mg/kg in fasted male beagle dogs. Compound 33 had no overt signs of flushing at doses up to 10 mg/kg with an improved therapeutic window to flushing as compared to nicotinic acid. Compound 33 was evaluated in human clinical trials.

Discovery of a potent nicotinic Acid receptor agonist for the treatment of dyslipidemia.

Nicotinic acid has been used clinically for decades to control serum lipoproteins. Nicotinic acid lowers very low-density lipoprotein (VLDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, and lipoprotein-a (LPa), and it is also effective in raising high-density lipoprotein (HDL)-cholesterol. However, nicotinic acid has several side effects in clinical use. The most notable is intense cutaneous vasodilation "flushing" on the upper body and face. We discovered a pyranopyrimidinedione series to be nicotinic acid receptor agonists. A potent nicotinic acid receptor agonist from this series {5-(3-cyclopropylpropyl)-2-(difluoromethyl)-3H-pyrano[2,3-d]pyrimidine-4,7-dione}with reduced flushing side effect in dogs was identified.

Discovery of novel orally active ureido NPY Y5 receptor antagonists.

We have derived a novel series of neuropeptide Y (NPY) Y5 receptor antagonists from the biphenylurea 3. Cyclohexylurea 21c, a member of the series, is a potent NPY Y5 receptor antagonist that exhibits excellent pharmacokinetic parameters in rats and dogs. On chronic oral administration to diet-induced obese rats, 21c displayed an anti-obesity profile, causing a modest reduction in food intake, a significant decrease in body weight gain, a decrease in adipose mass, and an increase in lean tissue mass.

Discovery of orally efficacious melanin-concentrating hormone receptor-1 antagonists as antiobesity agents. Synthesis, SAR, and biological evaluation of bicyclo[3.1.0]hexyl ureas.

Melanin-concentrating hormone (MCH) is a cyclic, nonadecapeptide expressed in the CNS of all vertebrates that regulates feeding behavior and energy homeostasis via interaction with the central melanocortin system. Regulation of this interaction results in modulation of food intake and body weight gain, demonstrating significant therapeutic potential for the treatment of obesity. The MCH-1 receptor (MCH-R1) has been identified as a key target in MCH regulation, as small molecule antagonists of MCH-R1 have demonstrated activity in vivo. Herein, we document our research in a bicyclo[3.1.0]hexyl urea series with particular emphasis on structure-activity relationships and optimization of receptor occupancy, measured both in vitro and via an ex vivo binding assay following an oral dosing regimen. Several compounds have been tested in vivo and exhibit oral efficacy in relevant acute rodent feeding models. In particular, 24u has proven efficacious in chronic rodent models of obesity, showing a statistically significant reduction in food intake and body weight over a 28 day study.

Effects of a selective melanin-concentrating hormone 1 receptor antagonist on food intake and energy homeostasis in diet-induced obese mice.

Melanin concentrating hormone (MCH) is a cyclic neuropeptide expressed in the lateral hypothalamus that plays an important role in energy homeostasis. To investigate the pharmacological consequences of inhibiting MCH signaling in murine obesity models, we examined the effect of acute and chronic administration of a selective MCH1 receptor antagonist (SCH-A) in diet-induced obese (DIO) and Lep(ob/ob) mice. Oral administration of SCH-A for 5 consecutive days (30 mg/kg q.d.) produced hypophagia, a loss of body weight and adiposity, and decreased plasma leptin levels in DIO mice, and hypophagia and reduced weight gain in Lep(ob/ob) mice. Chronic administration of SCH-A to DIO mice decreased food intake, body weight and adiposity, and plasma leptin and free fatty acids. These effects were accompanied by increases in several hypothalamic neuropeptides. Acute administration of SCH-A (30 mg/kg) prevented the decrease in energy expenditure associated with food restriction. These results indicate that MCH1 receptor antagonists may be effective in the treatment of obesity.

Biaryl ureas as potent and orally efficacious melanin concentrating hormone receptor 1 antagonists for the treatment of obesity.

Herein, we report a small molecule MCH-R1 antagonist which demonstrates oral efficacy in chronic rodent models. Substituted phenyl biaryl urea derivatives were synthesized and evaluated as MCH-R1 antagonists for the treatment of obesity. The structure-activity relationship studies in this series resulted in identification of urea 1 as a potent and selective MCH-R1 antagonist. Compound 1 exhibited oral efficacy in chronic (28 d) rodent models at 3-30 mpk showing significant reduction in food intake and weight gain relative to controls.

Melanin-concentrating hormone-1 receptor antagonism decreases feeding by reducing meal size.

Prior work has demonstrated that melanin-concentrating hormone-1 (MCH-1) receptor antagonism decreases food intake and body weight in obese rodents. The purpose of this study was to determine if the MCH-1 receptor antagonist-mediated hypophagia was due a decrease in meal size, meal frequency, or both. We performed a meal pattern analysis in free-feeding hyperphagic diet-induced obese (DIO) rats treated with 1, 3 or 10 mg/kg p.o. of the MCH-1 receptor antagonist T-226296 (a (-)enantiomer of N-[6-(dimethylamino)-methyl]-5,6,7,8-tetrahydro-2-naphthalenyl]-4'-fluoro[1,1'-biphenyl]-4 carboxamide). Food intake was continuously monitored for 24 h using a BioDAQ food intake monitoring system. A total of 10 mg/kg T-226296 significantly decreased body weight and 24-h food intake, and had no effect on locomotor activity. The decrease in food intake was due to a reduction in meal size, not meal frequency. We conclude that MCH-1 receptor antagonism with T-226296 decreases food intake in DIO rats by selectively reducing meal size, and that the reduced food intake is not due to a generalized behavioral malaise.

Meal pattern analysis of diet-induced obesity in susceptible and resistant rats.

OBJECTIVE: To characterize the meal patterns of free feeding Sprague-Dawley rats that become obese or resist obesity when chronically fed a high-fat diet. RESEARCH METHODS AND PROCEDURES: Male Sprague-Dawley rats (N = 120) were weaned onto a high-fat diet, and body weight was monitored for 19 weeks. Rats from the upper [diet-induced obese (DIO)] and lower [diet-resistant (DR)] deciles for body-weight gain were selected for study. A cohort of chow-fed (CF) rats weight-matched to the DR group was also studied. Food intake was continuously monitored for 7 consecutive days using a BioDAQ food intake monitoring system. RESULTS: DIO rats were obese, hyperphagic, hyperleptinemic, hyperinsulinemic, hyperglycemic, and hypertriglyceridemic relative to the DR and CF rats. The hyperphagia of DIOs was caused by an increase in meal size, not number. CF rats ate more calories than DR rats; however, this was because of an increase in meal number, not size. When expressed as a function of lean mass, CF and DR rats consumed the same amount of calories. The intermeal intervals of DIO and DR rats were similar; both were longer than CF rats. The nocturnal satiety ratio of DIO rats was significantly lower than DR and CF rats. The proportion of calories eaten during the nocturnal period did not differ among groups. DISCUSSION: The hyperphagia of a Sprague-Dawley rat model of chronic diet-induced obesity is caused by an increase in meal size, not number. These results are an important step toward understanding the mechanisms underlying differences in feeding behavior of DIO and DR rats.

Ezetimibe potently inhibits cholesterol absorption but does not affect acute hepatic or intestinal cholesterol synthesis in rats.

1. Ezetimibe (1-(4-fluorophenyl)-(3R)-[3-(4-fluorophenyl)-(3S)-hydroxypropyl]-(4S)-(4-hydroxyphenyl)-2-azetidinone) and its analog SCH48461 are potent and selective cholesterol absorption inhibitors that inhibit the transport of cholesterol across the intestinal wall, thereby lowering plasma cholesterol. 2. After a dose response for ezetimibe in rats was established, experiments were conducted to determine whether acute administration could alter hepatic or intestinal cholesterol synthesis. To determine whether this class of intestinal cholesterol absorption inhibitors could discriminate between newly synthesized cholesterol in the intestine versus exogenously administered cholesterol, rats were intraduodenally dosed with (14)C-cholesterol and (3)H-mevalonate, and mesenteric lymph was analyzed for radiolabeled cholesterol and cholesteryl ester content. 3. Ezetimibe attenuated diet-induced hypercholesterolemia 60-94% at doses of 0.1-3 mg x kg(-1) in rats. A single administration of ezetimibe did not have a direct effect on intestinal or hepatic cholesterol synthesis, while ketoconazole significantly inhibited cholesterol synthesis after a single dose. The ezetimibe analog, SCH48461, inhibited the movement of exogenously administered cholesterol into lymph, but did not affect the appearance of newly synthesized cholesterol into lymph. 4. These data suggest that this class of cholesterol absorption inhibitors does discriminate by blocking the movement of exogenous cholesterol in the enterocyte before it reaches the intracellular cholesterol pool to be incorporated into intestinal lipoproteins, without affecting the incorporation of newly synthesized cholesterol into intestinal lipoproteins.

Fat intake affects adiposity, comorbidity factors, and energy metabolism of sprague-dawley rats.

OBJECTIVE: Childhood obesity is an emerging health problem. This study assesses the effects of three levels of dietary fat (10%, 32%, and 45% measured by kilocalories) on weight gain, body composition, energy metabolism, and comorbidity factors in rats from weaning through maturation. RESEARCH METHODS AND PROCEDURES: The role of dietary fat on the susceptibility to obesity was assessed by feeding diets containing three levels of dietary fat to rats from weaning through 7 months of age. Body composition was analyzed by DXA after 6 and 12 weeks of dietary treatment. Energy metabolism was measured by indirect calorimetry. RESULTS: Energy intake, weight gain, fat mass, and plasma glucose, cholesterol, triglyceride, free fatty acid, leptin, and insulin levels increased dose-dependently with increased dietary fat. No difference in absolute lean mass among the three groups was observed. Therefore, the differences in weight gain are accounted for primarily by increased fat accretion. Compared with rats that were relatively resistant to obesity when on a 45% fat diet, diet-induced obesity-prone rats were in positive energy balance and had an elevated respiratory quotient, indicating a switch in energy substrate use from fat to carbohydrate, which promotes body-fat accretion. DISCUSSION: Our data support the hypothesis that administration of increasing amount of dietary fat to very young rats enhances susceptibility to diet-induced obesity and its comorbidities.