Evaluation of thiazole containing biaryl analogs as diacylglycerol acyltransferase 1 (DGAT1) inhibitors.

Biphenyl carboxylic acids, exemplified by compound 5, are known potent inhibitors of diacylglycerol acyltransferase, DGAT1, an enzyme involved in the final committed step of triglyceride biosynthesis. We have synthesized and evaluated 2-phenylthiazole, 4-phenylthiazole, and 5-phenylthiazole analogs as DGAT1 inhibitors. The 5-phenylthiazole series exhibited potent DGAT1 inhibition when evaluated using an in vitro enzymatic assay and an in vivo fat tolerance test in mice. Compound 33 (IC50 = 23 nM) exhibiting promising oral pharmacokinetic parameters (AUCinf = 7058 ng h/ml, T1/2 = 0.83 h) coupled with 87 percent reduction of plasma triglycerides in vivo may serve as a lead for developing newer anti-obesity agents.

Synthesis and biological evaluation of isoxazole, oxazole, and oxadiazole containing heteroaryl analogs of biaryl ureas as DGAT1 inhibitors.

Diacylglycerol acyltransferase, DGAT1, is a promising target enzyme for obesity due to its involvement in the committed step of triglyceride biosynthesis. Amino biphenyl carboxylic acids, exemplified by compound 4, are known potent inhibitors of hDGAT1. However the high cLogP and poor solubility of these biphenyl analogs might tend to limit their development. We have synthesized and evaluated compounds containing 3-phenylisoxazole, 5-phenyloxazole, and 3-phenyl-1,2,4-oxadiazole biaryl units for their hDGAT1 inhibition. Our aim in synthesizing such heterocyclic analogs was to improve the cLogP and solubility of these molecules while retaining hDGAT1 potency. Several compounds within the 3-phenylisoxazole series exhibited potent hDGAT1 inhibition when evaluated using an in vitro enzymatic assay. Certain promising compounds were studied for their potential to reduce triglyceride levels using an in vivo fat tolerance test in mice and were also evaluated for any possible improvement to their solubility. Compound 40a (IC(50) = 64 nM) with an in vivo plasma triglyceride reduction of 90 percent, and a solubility of 0.43 mg/ml at pH 7.4 may serve as a new lead for developing newer anti-obesity agents.

Exploration of pyridine containing heteroaryl analogs of biaryl ureas as DGAT1 inhibitors.

The diacylglycerol acyltransferase enzyme, DGAT1, presents itself as a potential target for obesity as this enzyme is dedicated to the final committed step in triglyceride biosynthesis. Biphenyl ureas, exemplified by compound 4, have been reported to be potent hDGAT1 inhibitors. We have synthesized and evaluated 2-pyridyl and 3-pyridyl containing biaryl ureas as hDGAT1 inhibitors. Our aim was to incorporate a heteroaryl scaffold within these molecules thereby improving the cLogP profile and making these compounds more drug-like. Compounds within this series exhibited potent hDGAT1 inhibition when evaluated using an in vitro enzymatic assay. Selected compounds were also subjected to an oral fat tolerance test in mice where the percent triglyceride reduction versus a vehicle control was evaluated. Of the studied heteroaryl analogs compound 44 exhibited an in vitro IC(50) of 17nM and a plasma triglyceride reduction of 79% along with a 12-fold improvement in solubility over the biphenyl urea compound 4.

Novel derivatives of ISO-1 as potent inhibitors of MIF biological function.

A series of novel 1,2,4-oxadiazole, phthalimide, amide and other derivatives of ISO-1 were synthesized and probed for inhibition of macrophage migration inhibitory factor (MIF) activity. Several compounds inhibited MIF enzymatic activity at levels better than ISO-1. Of note, compounds 7, 22, 23, 24, 25 and 27 inhibited the spontaneous secretion/release/recognition of MIF from freshly isolated human peripheral blood mononuclear cells and, more importantly, inhibited the MIF-induced production of interleukin-6 (IL-6) and/or interleukin-1beta (IL-1beta) significantly better than ISO-1.

A fluorinated analog of ISO-1 blocks the recognition and biological function of MIF and is orally efficacious in a murine model of colitis.

A promising therapeutic approach to diminish pathological inflammation is to inhibit the synthesis and/or biological activity of macrophage migration inhibitory factor (MIF). Prior studies have shown that intraperitoneal administration of small-molecule inhibitors targeting the catalytic pocket of MIF (e.g., ISO-1) elicits a therapeutic effect in mouse inflammation models. However, it remains to be elucidated whether these tautomerase activity inhibitors block the synthesis and/or biological activity of MIF. In this study, we investigated and compared the activity of representative MIF inhibitors from isoxazole series (fluorinated analog of ISO-1; ISO-F) and substituted quinoline series (compound 7E; 7E). Our results demonstrate that ISO-F is a more potent MIF inhibitor than 7E. Both ISO-F and 7E do not inhibit MIF synthesis but "bind-onto" MIF thereby blocking its recognition. However, in contrast to 7E, ISO-F docks well in the active site of MIF and also has a stronger binding affinity towards MIF. In line with these observations, ISO-F, but not 7E, robustly inhibits the biological function of MIF. Most importantly, ISO-F, when administered orally in a therapeutic regimen, significantly suppresses dextran sulphate sodium (DSS)-induced murine colitis. This study, which provides mechanistic insights into the anti-inflammatory efficacy of ISO-F, is the first documented report of in vivo anti-inflammatory efficacy of a MIF inhibitor upon oral administration. Moreover, the findings from this study reinforce the potential of catalytic site of MIF as a target for eliciting therapeutic effect in inflammatory disorders. Compounds (e.g., ISO-F) that block not only the recognition but also the biological function of MIF are potentially attractive for reducing pathological inflammation.

Discovery of diacylphloroglucinols as a new class of GPR40 (FFAR1) agonists.

In this letter, we report discovery of diacylphloroglucinol compounds as a new class of GPR40 (FFAR1) agonists. Several diacylphloroglucinols with varying length of acyl functionality and substitution on aromatic hydroxyls were synthesized and evaluated for GPR40 agonism using functional calcium-flux assay. Out of 17 compounds evaluated, 14, 17, 19 and 25 exhibited good GPR40 agonistic activity with EC(50) values ranging from 0.07 to 8 microM (pEC(50) 7.12-5.09), respectively, with maximal agonistic response of 84-102%.

Cysteine repeat domains and adjacent sequences determine distinct bone morphogenetic protein modulatory activities of the Drosophila Sog protein.

The Drosophila short gastrulation gene (sog) encodes a large extracellular protein (Sog) that inhibits signaling by BMP-related ligands. Sog and its vertebrate counterpart Chordin contain four copies of a cysteine repeat (CR) motif defined by 10 cysteine residues spaced in a fixed pattern and a tryptophan residue situated between the first two cysteines. Here we present a structure-function analysis of the CR repeats in Sog, using a series of deletion and point mutation constructs, as well as constructs in which CR domains have been swapped. This analysis indicates that the CR domains are individually dispensable for Sog function but that they are not interchangeable. These studies reveal three different types of Sog activity: intact Sog, which inhibits signaling mediated by the ligand Glass bottom boat (Gbb), a more broadly active class of BMP antagonist referred to as Supersog, and a newly identified activity, which may promote rather than inhibit BMP signaling. Analysis of the activities of CR swap constructs indicates that the CR domains are required for full activity of the various forms of Sog but that the type of Sog activity is determined primarily by surrounding protein sequences. Cumulatively, our analysis suggests that CR domains interact physically with adjacent protein sequences to create forms of Sog with distinct BMP modulatory activities.

A screen for dominant mutations applied to components in the Drosophila EGF-R pathway.

The Drosophila epidermal growth factor receptor (EGF-R) controls many critical cell fate choices throughout development. Several proteins collaborate to promote localized EGF-R activation, such as Star and Rhomboid (Rho), which act sequentially to ensure the maturation and processing of inactive membrane-bound EGF ligands. To gain insights into the mechanisms underlying Rho and Star function, we developed a mutagenesis scheme to isolate novel overexpression activity (NOVA) alleles. In the case of rho, we isolated a dominant neomorphic allele, which interferes with Notch signaling, as well as a dominant-negative allele, which produces RNA interference-like flip-back transcripts that reduce endogenous rho expression. We also obtained dominant-negative and neomorphic Star mutations, which have phenotypes similar to those of rho NOVA alleles, as well as dominant-negative Egf-r alleles. The isolation of dominant alleles in several different genes suggests that NOVA mutagenesis should be widely applicable and emerge as an effective tool for generating dominant mutations in genes of unknown function.

Creation of a Sog morphogen gradient in the Drosophila embryo.

A variety of genetic evidence suggests that a gradient of Decapentaplegic (Dpp) activity determines distinct cell fates in the dorsal region of the Drosophila embryo, and that this gradient may be generated indirectly by an inverse gradient of the BMP antagonist Short gastrulation (Sog). It has been proposed that Sog diffuses dorsally from the lateral neuroectoderm where it is produced, and is cleaved and degraded dorsally by the metalloprotease Tolloid (Tld). Here we show directly that Sog is distributed in a graded fashion in dorsal cells and that Tld degradation limits the levels of Sog dorsally. In addition, we find that Dynamin-dependent retrieval of Sog acts in parallel with degradation by Tld as a dorsal sink for active Sog.