Development of Novel Benzomorpholine Class of Diacylglycerol Acyltransferase I Inhibitors

Diacylglycerol acyltransferase 1 (DGAT1) presents itself as a potential therapeutic target for obesity and diabetes for its important role in triglyceride biosynthesis. Herein we report the rational design of a novel class of DGAT1 inhibitors featuring a benzomorpholine core (<b>23n</b>). SAR exploration yielded compounds with good potency and selectivity as well as reasonable physical and pharmacokinetic properties. This class of DGAT1 inhibitors was tested in rodent models to evaluate DGAT1 inhibition as a novel approach for the treatment of metabolic diseases. Compound <b>23n</b> conferred weight loss and a reduction in liver triglycerides when dosed chronically in mice with diet-induced obesity and depleted serum triglycerides following a lipid challenge

RNA biomarkers for sebaceous gland atrophy in skin.

<p>Shown are the 42 probesets, identified in the Training Set (Studies 1 and 2), that were regulated by skin-positive compound treatments (those that produced sebaceous gland atrophy) but not by the skin-negative compound treatments (the one that did <i>not</i> produce sebaceous gland atrophy). After excluding the absent probes (low intensity), these 42 probesets met the following cutoffs: 1.2 fold change and ANOVA p<0.01 between all 3 skin-positive compound treatments (red arrows) and their respective vehicle treatments, and ANOVA p>0.1 between the skin negative compound treatment (black arrow) and its respective vehicle treatment. The probesets for RIKEN genes were excluded. Plotted are the LogRatio values (+/− 4 fold fold scale) with magenta representing up-regulated probesets and cyan representing down-regulated probesets. Treatments from the independent Test Set (Study 4) are included for comparison but were not used to identify the 42 probesets.</p

DGAT1 inhibitors with high lipophilicity induce sebaceous gland atrophy.

<p>Shown are hematoxylin and eosin stains of dorsal skin biopsies from DIO mice treated with either vehicle (A), Cpd1 (B), Cpd2 (C), or Cpd3 (D) for 14 days at doses indicated. Scoring refers to the histological adverse effect score as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088908#pone-0088908-t001" target="_blank">Table 1</a>. Bar  = 50 µm. The corresponding sebaceous gland sizes (area) are plotted in (E) (and shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088908#pone.0088908.s002" target="_blank">Table S1</a>).</p

Representative compound structures from three chemical compound series as shown in Table 1.

<p>Representative compound structures from three chemical compound series as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088908#pone-0088908-t001" target="_blank">Table 1</a>.</p

RNA biomarkers for sebaceous gland atrophy in skin. Listed are the 41 unique genes from the 42 probesets identified in the Training Set as shown in Figure 4 (Cxcl16 had 2 probesets).

<p>Fold change and ANOVA p values for compound treatments compared to their respective vehicle treatments, for both the Training and Test Sets, are included. The 26 probesets that are also significantly regulated in the Test Set are shown in bold. **  = ANOVA p<0.01; *  = ANOVA p<0.05; $ = ANOVA p<0.1.</p

Histopathology versus lipophilicity.

<p>Calculated logD (clogD, A) or measured logD (mlogD, B) versus observed skin adverse effects. Data is jittered on the y-axis to improve visualization.</p

Immune-regulated genes are up-regulated, while lipid metabolism genes are down-regulated, with sebaceous gland atrophy.

<p>Box plots of probesets regulated by the skin-positive DGAT1 inhibitors (those that produce sebaceous gland atrophy) but not by the skin-negative compounds (those that do <i>not</i> produce sebaceous gland atrophy). Plotted are the LogIntensity values across the replicates in each group, and across the three studies. Ccl1 (A; chemokine (C-C motif) ligand 1) is involved in the recruitment of T cells in skin inflammation; and Scd3 (B; stearoyl-coenzyme A desaturase 3) is a sebaceous gland specific gene.</p

Validation of the 42 probeset-composite score in an independent Test Set.

<p>The 42 probesets from the Training Set, shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088908#pone-0088908-g005" target="_blank">Figure 5</a>, were used to generate a composite score across the treatments from the independent Test Set (Study 4). The p value between Cpd6 treatment (skin-positive) and Cpd18 treatment (skin-negative), in Study 4, is less than 0.0001. Expression data from this set of RNA biomarkers is predictive for sebaceous gland atrophy in mice following DGAT inhibitor treatment.</p

Compound characteristics. Cpd1 is the same as DGAT1i in Lin, H et al (2013) [4], while Cpd2 is the same as Compound L in Liu, J et al (2013) [3].

<p>Plasma  =  plasma concentration; Skin  =  skin concentration; Skin/Plasma Ratio  =  skin to plasma concentration ratio; Fu Plasma  =  unbound fraction in plasma; mlogD  =  measured logD; clogD  =  calculated logD using ACD (measure of lipophilicity); mDGAT1 IC50  =  in vitro potency; Skin/IC50 =  skin concentration vs in vitro potency; Scoring  =  histological adverse effect score; clogD/mIC50 =  calculated logD vs in vitro potency; BLQ  =  below detection. Bold  =  compounds causing atrophy.</p

Discovery of Novel Tricyclic Heterocycles as Potent and Selective DPP‑4 Inhibitors for the Treatment of Type 2 Diabetes

In our efforts to develop second generation DPP-4 inhibitors, we endeavored to identify distinct structures with long-acting (once weekly) potential. Taking advantage of X-ray cocrystal structures of sitagliptin and other DPP-4 inhibitors, such as alogliptin and linagliptin bound to DPP-4, and aided by molecular modeling, we designed several series of heterocyclic compounds as initial targets. During their synthesis, an unexpected chemical transformation provided a novel tricyclic scaffold that was beyond our original design. Capitalizing on this serendipitous discovery, we have elaborated this scaffold into a very potent and selective DPP-4 inhibitor lead series, as highlighted by compound <b>17c</b>