Design, Synthesis, and Structure-Activity Relationships of Biaryl Anilines as Subtype-Selective PPAR-alpha Agonists.

The role of peroxisome proliferator-activated receptor alpha (PPARα) in retinal biology is clarifying, and evidence demonstrates that novel PPARα agonists hold promising therapeutic utility for diseases like diabetic retinopathy and age-related macular degeneration. Herein, we disclose the design and initial structure-activity relationships for a new biaryl aniline PPARα agonistic chemotype. Notably, this series exhibits subtype selectivity for PPARα over other isoforms, a phenomenon postulated to be due to the unique benzoic acid headgroup. This biphenyl aniline series is sensitive to B-ring functionalization but allows isosteric replacement, and provides an opportunity for C-ring extension. From this series, 3g, 6j, and 6d were identified as leads with <90 nM potency in a cell-based luciferase assay cell and exhibited efficacy in various disease-relevant cell contexts, thereby setting the stage for further characterization in more advanced in vitro and in vivo models.

Smoking Induces the Circulating Levels of Matrix Metalloproteinase-9 and Its Association with Cardiovascular Risk in Young Smokers.

Objective: Smoking causes cardiovascular risk, which may alter the stability between the production and degradation of the extracellular matrix. Matrix metalloproteinase-9 (MMP-9) is a zinc-containing endopeptidase that degrades the extracellular matrix and is involved in tissue remodelling and several physiological processes. As a result, smoking-induced elevated serum MMP-9 levels, particularly at a younger age, raise the risk of coronary heart disease (CHD). Thus, this study aimed to determine the possible relationship between smoking-induced circulating MMP-9 and the risk of cardiovascular disease in young smokers. Methods: In this cross-sectional study, the patients were divided into three groups. Each group contains 120 study participants. Group one consisted of 120 healthy individuals with no physical and mental illness, group two consisted of 120 active smokers with a heart disease, and group three consisted of 120 active smokers with a heart disease and diabetes, who attended Sri Ramaswamy Memorial Hospital for cardiology checkup at the age of 20-55 years. The serum MMP-9, high-sensitivity C-reactive protein (hs-CRP), and apolipoprotein-E (APO-E) levels were analyzed using the ELISA method, and the lipid levels were measured enzymatically using AU480 automatic analyzer (Beckman Coulter). Results: Compared with non-smokers, the study shows that the mean serum MMP-9, hs-CRP, and APO-E levels were significantly higher in smokers (p<0.001). A strong relationship was also found between MMP-9 and hs-CRP, APO-E, smoking load, and smoking intensity. Conclusions: A significant association was found between cigarette smoking with MMP-9, and relative exposure to circulating inflammation markers plays a potential role in the pathogenesis of CHD.

Role of Cigarette Smoking on Serum Angiotensin-Converting Enzyme and Its Association With Inflammation and Lipid Peroxidation.

Introduction Cigarette smoking promotes angiotensin-converting enzyme (ACE) production and causes a substantial change in inflammation and oxidative stress, resulting in an increase in antioxidant activity and lipid peroxidation. Objective The study's goal is to determine the role of cigarette smoking on serum ACE and its relation with inflammatory markers and lipid peroxidation. Methods The cross-sectional study consists of three groups. The study participants are all men between the age group of 20 to 55 years. Group 1 includes 120 healthy controls as nonsmokers, Group 2 consists of 120 active smokers with coronary heart disease (CHD) and Group 3 includes 120 active smokers with diabetic CHD patients attending the SRM Medical College Hospital in Tamil Nadu for cardiology and medical Outpatient. Measurements of serum ACE, oxidized low-density lipoprotein (oxLDL), high-sensitivity C-reactive protein (hsCRP), and matrix metalloprotease-9 (MMP-9) were performed using the ELISA method (enzyme-linked immunosorbent assay). Using a spectrophotometric approach, the total antioxidant capacity and lipid peroxidation, particularly Malondialdehyde (MDA), were assessed. Results The mean serum ACE (92.35±10.28), oxLDL (48.59±8.56), hs-CRP (5.87±1.62), MMP-9 (89.20±30.19), and MDA (1.146±0.198) levels were significantly (p-value <0.0001) higher in smokers with CHD and diabetes (group 3) when compared to group 1 and group 2. On the other hand, the total antioxidant capacity (0.413±0.097) of smokers of group 3 was found to be (p<0.0001) significantly lower than those of group 1 and group 2. The study also demonstrated a significant correlation between ACE with MDA, ox-LDL, total antioxidant capacity, hs-CRP, MMP-9, smoking load, and smoking intensity in smokers. Conclusion The study concludes a substantial correlation exists in smokers owing to ACE modification, which results in inflammation and lipid peroxidation activation. This is strongly associated with an increased risk of major cardiovascular events.

Property space mapping of Pseudomonas aeruginosa permeability to small molecules.

Two membrane cell envelopes act as selective permeability barriers in Gram-negative bacteria, protecting cells against antibiotics and other small molecules. Significant efforts are being directed toward understanding how small molecules permeate these barriers. In this study, we developed an approach to analyze the permeation of compounds into Gram-negative bacteria and applied it to Pseudomonas aeruginosa, an important human pathogen notorious for resistance to multiple antibiotics. The approach uses mass spectrometric measurements of accumulation of a library of structurally diverse compounds in four isogenic strains of P. aeruginosa with varied permeability barriers. We further developed a machine learning algorithm that generates a deterministic classification model with minimal synonymity between the descriptors. This model predicted good permeators into P. aeruginosa with an accuracy of 89% and precision above 58%. The good permeators are broadly distributed in the property space and can be mapped to six distinct regions representing diverse chemical scaffolds. We posit that this approach can be used for more detailed mapping of the property space and for rational design of compounds with high Gram-negative permeability.

Evolution of a 4-Benzyloxy-benzylamino Chemotype to Provide Efficacious, Potent, and Isoform Selective PPARα Agonists as Leads for Retinal Disorders.

Peroxisome proliferator-activated receptor alpha (PPARα) is expressed in retinal Müller cells, endothelial cells, and in retinal pigment epithelium; agonism of PPARα with genetic or pharmacological tools ameliorates inflammation, vascular leakage, neurodegeneration, and neovascularization associated with retinal diseases in animal models. As such, PPARα is a promising drug target for diabetic retinopathy and age-related macular degeneration. Herein, we report proof-of-concept in vivo efficacy in an streptozotocin-induced vascular leakage model (rat) and preliminary pharmacokinetic assessment of a first-generation lead 4a (A91). Additionally, we present the design, synthesis, and evaluation of second-generation analogues, which led to the discovery of 4u and related compounds that reach cellular potencies <50 nM and exhibit >2,700-fold selectivity for PPARα over other PPAR isoforms. These studies identify a pipeline of candidates positioned for detailed PK/PD and pre-clinical evaluation.

Structure-guided evolution of a 2-phenyl-4-carboxyquinoline chemotype into PPARα selective agonists: New leads for oculovascular conditions.

Small molecule agonism of PPARα represents a promising new avenue for the development of non-invasive treatments for oculovascular diseases like diabetic retinopathy and age-related macular degeneration. Herein we report initial structure-activity relationships for the newly identified quinoline-based PPARα agonist, Y-0452. Preliminary computational studies led to the hypothesis that carboxylic acid transposition and deconstruction of the Y-0452 quinoline system would enhance ligand-protein interactions and better complement the nature of the binding pocket. A focused subset of analogs was designed, synthesized, and assessed for PPARα agonism. Two key observations arose from this work 1) contrary to other PPARα agonists, incorporation of the fibrate "head-group" decreases PPARα selectivity and instead provides pan-PPAR agonists and 2) computational models reveal a relatively unexploited amphiphilic pocket in PPARα that provides new opportunities for the development of novel agonists. As an example, compound 10 exhibits more potent PPARα agonism (EC50 = ∼6 µM) than Y-0452 (EC50 = ∼50 µM) and manifests >20-fold selectivity for PPARα over the PPARγ and PPARδ isoforms. More detailed biochemical analysis of 10 confirms typical downstream responses of PPARα agonism including PPARα upregulation, induction of target genes, and inhibition of cell migration.

Sulfone-Metal Exchange and Alkylation of Sulfonylnitriles.

The first general sulfone-metal exchange is described. Treating substituted 2-pyridylsulfonylacetonitriles with either BuLi or Bu3 MgLi generates metalated nitriles that efficiently intercept a variety of electrophiles to afford quaternary nitriles. The 2-pyridylsulfone is critical for the sulfone-metal exchange because chelation anchors the organometallic proximal to the electrophilic, tetrasubstituted sulfone to override complex-induced deprotonation. Alkylating commercial 2-pyridinesulfonylacetonitrile with mild bases, either K2 CO3 or DBU, and subsequent sulfone-metal exchange and alkylation rapidly assembles quaternary nitriles by three alkylations, only one of which requires an organometallic reagent.

Cyclic Alkenenitriles: Copper-Catalyzed Deconjugative α-Alkylation.

An amido cuprate formed from CuCN and LDA allows a general deconjugative α-alkylation of cyclic alkenenitriles. Deprotonating cyclic alkenenitriles with LDA-CuCN avoids polymerization that otherwise plagues these alkylations and generates a reactive metalated nitrile for alkylations with a range of carbon and heteroatom electrophiles. The strategy provides an effective synthesis of quaternary 5-, 6-, and 7-membered cycloalk-1-enecarbonitriles substituted on the nitrile-bearing carbon.

Chemoselective Alkylations with N- and C-Metalated Nitriles.

Metalated nitriles exhibit complementary chemoselectivities in electrophilic alkylations. N-Lithiated or C-magnesiated nitriles can be prepared from the same nitrile precursor and selectively reacted with a 1:1 mixture of methyl cyanoformate and benzyl bromide or bifunctional electrophiles through chemoselective attack onto either an alkyl halide or a carbonyl electrophile. A mechanistic explanation for the chemoselectivity preferences is provided that rests on the structural and complexation differences between N- and C-metalated nitriles.

Arylthio-metal exchange of α-arylthioalkanenitriles.

The addition of BuLi, Bu3MgLi, Et2ZnBuLi, or Me2CuLi to α-arylthioalkanenitriles triggers an arylthio-metal exchange. NMR spectroscopic analyses implicate organometallic attack on sulfur forming a three-coordinate sulfidate as the key intermediate. Electrophilic trapping affords tertiary and quaternary nitriles in high yield. The method addresses the challenge of improving the functional group tolerance and preventing polyalkylations.

Sulfinylnitriles: sulfinyl-metal exchange-alkylation strategies.

Adding organolithiums, Grignard reagents, or zincates to sulfinylnitriles triggers a facile sulfinyl-metal exchange to afford N- or C-metalated nitriles. Sulfinyl-magnesium exchange-alkylations efficiently install quaternary and tertiary centers, even in the case of tertiary sulfinylnitriles that contain a highly acidic methine proton. α-Sulfinylalkenenitriles afford moderately nucleophilic magnesiated nitriles, and the reactivity can be dramatically increased by conversion to the corresponding magnesiates. The sulfinyl-metal exchange is extremely fast, proceeds efficiently with quaternary, tertiary, and vinylic α-sulfinylnitriles, and exhibits an exceptional functional group tolerance in nitrile alkylations.