2-heterosubstituted-3-(4-methylsulfonyl)phenyl-5-trifluoromethyl pyridines as selective and orally active cyclooxygenase-2 inhibitors

Gut-Restricted Selective Cyclooxygenase-2 (COX-2) Inhibitors for Chemoprevention of Colorectal Cancer

Selective cyclooxygenase (COX)-2 inhibitors have been extensively studied for colorectal cancer (CRC) chemoprevention. Celecoxib has been reported to reduce the incidence of colorectal adenomas and CRC but is also associated with an increased risk of cardiovascular events. Here, we report a series of gut-restricted, selective COX-2 inhibitors characterized by high colonic exposure and minimized systemic exposure. By establishing acute ex vivo ¹⁸F-FDG uptake attenuation as an efficacy proxy, we identified a subset of analogues that demonstrated statistically significant in vivo dose-dependent inhibition of adenoma progression and survival extension in an APC^min/+ mouse model. However, in vitro-in vivo correlation analysis showed their chemoprotective effects were driven by residual systemic COX-2 inhibition, rationalizing their less than expected efficacies and highlighting the challenges associated with COX-2-mediated CRC disease chemoprevention.

Classification of Cyclooxygenase-2 Inhibitors Using Support Vector Machine and Random Forest Methods

This work reports the classification study conducted on the biggest COX-2 inhibitor data set so far. Using 2925 diverse COX-2 inhibitors collected from 168 pieces of literature, we applied machine learning methods, support vector machine (SVM) and random forest (RF), to develop 12 classification models. The best SVM and RF models resulted in MCC values of 0.73 and 0.72, respectively. The 2925 COX-2 inhibitors were reduced to a data set of 1630 molecules by removing intermediately active inhibitors, and 12 new classification models were constructed, yielding MCC values above 0.72. The best MCC value of the external test set was predicted to be 0.68 by the RF model using ECFP_4 fingerprints. Moreover, the 2925 COX-2 inhibitors were clustered into eight subsets, and the structural features of each subset were investigated. We identified substructures important for activity including halogen, carboxyl, sulfonamide, and methanesulfonyl groups, as well as the aromatic nitrogen atoms. The models developed in this study could serve as useful tools for compound screening prior to lab tests.

SAR and QSAR models of cyclooxygenase-1 (COX-1) inhibitors

Cyclooxygenase-1 (COX-1) is one isoform of COX, and it is a main target of nonsteroidal anti-inflammatory drugs (NSAIDs). It is important to develop efficient and selective COX-1 inhibitors. In this work, 12 classification models for 1530 cyclooxygenase-1 (COX-1) inhibitors were built by support vector machine (SVM), decision tree (DT) and random forest (RF) methods. The best classification model (model 1A) was built by SVM with MACCS fingerprints. The classification accuracies for the training and test sets were 99.67% and 97.39%, respectively. The Matthews correlation coefficient (MCC) of the test set was 0.94. We also divided the 1530 COX-1 inhibitors into nine subsets according to their different scaffolds using Kohonen's self-organizing map (SOM). In addition, six quantitative structure-activity relationship (QSAR) models for 181 COX-1 inhibitors whose IC₅₀ were measured by enzyme immunoassay were built by multiple linear regression (MLR) and SVM. The best QSAR model (model 5A) was built by SVM with CORINA Symphony descriptors. The correlation coefficients of the training and test sets are 0.93 and 0.84, respectively. The models built in this study can be obtained from the authors.

Heteroatom-Directed Acylation of Secondary Alcohols To Assign Absolute Configuration

Birman's HBTM catalyst is effective for the enantioselective acylation and kinetic resolution of benzylic secondary alcohols. The enantioselective acylation has now been extended to secondary alcohols bearing electron-withdrawing groups such as halides and other heteroatoms. The level of selectivity is modest to good and is sufficient for determining configuration using the competing enantioselective conversion method. A mathematical analysis identifies conditions for achieving maximum differences in conversion and, consequently, assigning configuration with greater confidence. The new method is effective for halohydrins and secondary-tertiary 1,2-diols and was used to confirm the configuration of two inoterpene natural products.

Noninvasive PET Imaging and Tracking of Engineered Human Muscle Precursor Cells for Skeletal Muscle Tissue Engineering

Transplantation of human muscle precursor cells (hMPCs) is envisioned for the treatment of various muscle diseases. However, a feasible noninvasive tool to monitor cell survival, migration, and integration into the host tissue is still missing.

METHODS

In this study, we designed an adenoviral delivery system to genetically modify hMPCs to express a signaling-deficient form of human dopamine D2 receptor (hD2R). The gene expression levels of the receptor were evaluated by reverse transcriptase polymerase chain reaction, and infection efficiency was evaluated by fluorescent microscopy. The viability, proliferation, and differentiation capacity of the transduced cells, as well as their myogenic phenotype, were determined by flow cytometry analysis and fluorescent microscopy. (18)F-fallypride and (18)F-fluoromisonidazole, two well-established PET radioligands, were assessed for their potential to image engineered hMPCs in a mouse model and their uptakes were evaluated at different time points after cell inoculation in vivo. Biodistribution studies, autoradiography, and PET experiments were performed to determine the extent of signal specificity. To address feasibility for tracking hMPCs in an in vivo model, the safety of the adenoviral gene delivery was evaluated. Finally, the harvested tissues were histologically examined to determine whether survival of the transplanted cells was sustained at different time points.

RESULTS

Adenoviral gene delivery was shown to be safe, with no detrimental effects on the primary human cells. The viability, proliferation, and differentiation capacity of the transduced cells were confirmed, and flow cytometry analysis and fluorescent microscopy showed that their myogenic phenotype was sustained. (18)F-fallypride and (18)F-fluoromisonidazole were successfully synthesized. Specific binding of (18)F-fallypride to hD2R hMPCs was demonstrated in vitro and in vivo. Furthermore, the (18)F-fluoromisonidazole signal was high at the early stages. Finally, sustained survival of the transplanted cells at different time points was confirmed histologically, with formation of muscle tissue at the site of injection.

CONCLUSION

Our proposed use of a signaling-deficient hD2R as a potent reporter for in vivo hMPC PET tracking by (18)F-fallypride is a significant step toward potential noninvasive tracking of hD2R hMPCs and bioengineered muscle tissues in the clinic.

Virtual Screening for Finding Novel COX-2 Inhibitors as Antitumor Agents

The cyclooxygenase-2 (COX-2) enzyme binds to arachidonic acid resulting in the release of metabolites that induce pain and inflammatory responses. Recent studies have shown that strong COX-2 expression is highly correlated with increased tumor risk. Therefore, the development of potent COX-2 inhibitors to relieve pain and treat cancers requires further investigation. We used virtual screening to find three COX-2 inhibitors (Phar-95239, T0511-4424 and Zu- 4280011) from a huge zinc database containing 2000000 compounds. The effects of the compounds on COX-2 were compared to those on COX-1 using a colorimetric COX (ovine) screening assay kit. The selectivity index, the ratio of IC₅₀ for COX-1 inhibition to that of COX-2, calculated were MTT assay was used to evaluate the cytotoxic activity of the compounds using different dilutions. The IC₅₀ values were calculated. Based on the results of the MTT assay, the IC₅₀ values for compounds Phar-95239, T0511-4424 and Zu-4280011 were 178.52, 143 and 97.61 µM, respectively, and the selectivity indices of the compounds were 11.36, 12.20 and 20.03, respectively. These results indicated a relationship between the selectivity index and anticancer activity. Zu-4280011 displayed the highest selectivity index and the best results in the MTT assay among selected componds.

Discovery of 2-phenyl-3-sulfonylphenyl-indole derivatives as a new class of selective COX-2 inhibitors

2-Sulfonylphenyl-3-phenyl-indole derivatives have been reported to be highly potent and selective COX-2 inhibitors previously. In this paper, the regio-isomeric analogues-2-phenyl-3-sulfonylphenyl-indoles were identified as potent and selective COX-2 inhibitors. This work led to the discovery of compounds 4a and 8a possessing higher activity than Celecoxib on cellular assay.

Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in a Regioselective Aniline Synthesis

Tri- and tetrasubstituted anilines are formed in good to excellent yields by the addition of ketones to vinamidinium salts (up to 98%). The reaction proceeds via the formation of dienone intermediates, which react to form an enamine with the liberated amine. In the case of a nitro, or dimethylaminomethylene substituent, the enamines undergo a facile electrocyclic ring closure to form a cyclohexadiene, which goes on to form anilines with a high degree of selectivity (up to 50:1) with a minor competing pathway proceeding via the enol providing phenols. Competition experiments using isotopic substitution reveal that the rate determining step en route to dienone is enol/enolate addition to the vinamidinium salt, which is characterized by an inverse secondary isotope effect (k(H/D) 0.7-0.9). Computational studies have been used to provide a framework for understanding the reaction pathway. The original proposal for a [1,5]-H shift was ruled out on the basis of the calculations, which did not locate a thermally accessible transition state. The minimum energy conformation of the enamine is such that a facile electrocyclic ring closure is ensured, which is corroborated by the experimental studies. A framework for understanding the reaction pathway is presented.

Synthesis and biological evaluation of substituted 2-sulfonyl-phenyl-3-phenyl-indoles: a new series of selective COX-2 inhibitors

A new series of substituted 2-sulfonyphenyl-3-phenyl-indole derivatives were synthesized and evaluated for their ability to inhibit COX-2 and COX-1enzymes. Most of the compounds synthesized were found to be highly potent and selective inhibitors of COX-2. This work led to the discovery of 2-aminosulfonylphenyl-3-phenyl-indole 5a which possesses higher activity and selectivity for COX-2 than Celecoxib both in vitro and in vivo.

Discovery of a potent and selective COX-2 inhibitor in the alkoxy lactone series with optimized metabolic profile

The COX-2 inhibitor DFP [5,5-dimethyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanone] was found to have a long half-life in humans. Analogues have been characterized in order to optimize pharmacokinetics. This has lead to the discovery of 5(S)-(5-ethyl-5-methyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanone analogue 11 a potent and selective COX-2 inhibitor which is metabolized to a greater extent than DFP upon incubation with rat and human hepatocytes, suggesting a shorter half-life in humans.

Annulation of ketones with vinamidinium hexafluorophosphate salts: an efficient preparation of trisubstituted pyridines

alpha-Aryl ketones react with vinamidinium hexafluorophosphate salts to give access to the corresponding 3-arylpyridines. The annulation reactions proceed in good to excellent yields with vinamidinium salts containing electron-withdrawing groups at the beta-position (R(2)). The reaction was applied to the preparation of the COX-2 specific inhibitor 5-chloro-3-(4-methylsulfonyl)phenyl-2-(2-methyl-5-pyridinyl)pyridine (1), as well as a series of analogues.