Pliability in the m6A-Binding Region Extends Druggability of YTH Domains.

Epitranscriptomic mRNA modifications affect gene expression, with their altered balance detected in various cancers. YTHDF proteins contain the YTH reader domain recognizing the m6A mark on mRNA and represent valuable drug targets. Crystallographic structures have been determined for all three family members; however, discrepancies are present in the organization of the m6A-binding pocket. Here, we present new crystallographic structures of the YTH domain of YTHDF1, accompanied by computational studies, showing that this domain can exist in different stable conformations separated by a significant energetic barrier. During the transition, additional conformations are explored, with peculiar druggable pockets appearing and offering new opportunities for the design of YTH-interfering small molecules.

Novel Pyrimidine Derivatives as Antioxidant and Anticancer Agents: Design, Synthesis and Molecular Modeling Studies.

The heterocyclic ring system of pyrido [2,3-d]pyrimidines is a privileged scaffold in medicinal chemistry, possessing several biological activities. The synthesis of the pyrimidine derivatives was performed via the condensation of a suitable α,ß-unsaturated ketone with 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate in glacial acetic acid. Chalcones were synthesized, as starting materials, via the Claisen-Schmidt condensation of an appropriately substituted ketone and an appropriately substituted aldehyde in the presence of aqueous KOH 40% w/v in ethanol. All the synthesized compounds were characterized using IR, 1H-NMR, 13C-NMR, LC-MS and elemental analysis. The synthesized compounds were evaluated for their antioxidant (DPPH assay), anti-lipid peroxidation (AAPH), anti-LOX activities and ability to interact with glutathione. The compounds do not interact significantly with DPPH but strongly inhibit lipid peroxidation. Pyrimidine derivatives 2a (IC50 = 42 µΜ), 2f (IC50 = 47.5 µΜ) and chalcone 1g (IC50 = 17 µM) were the most potent lipoxygenase inhibitors. All the tested compounds were found to interact with glutathione, apart from 1h. Cell viability and cytotoxicity assays were performed with the HaCaT and A549 cell lines, respectively. In the MTT assay towards the HaCaT cell line, none of the compounds presented viability at 100 µM. On the contrary, in the MTT assay towards the A549 cell line, the tested compounds showed strong cytotoxicity at 100 µM, with derivative 2d presenting the strongest cytotoxic effects at the concentration of 50 µΜ.

Discovery and antiviral profile of new sulfamoylbenzamide derivatives as HBV capsid assembly modulators.

Chronic hepatitis B (CHB) is a major worldwide public health problem and novel anti-HBV therapies preventing liver disease progression to cirrhosis and hepatocellular carcinoma are urgently needed. Over the last several years, capsid assembly modulators (CAM) have emerged as clinically effective anti-HBV agents which can inhibit HBV replication in CHB patients. As part of a drug discovery program aimed at obtaining novel CAM endowed with high in vitro and in vivo antiviral activity, we identified a novel series of sulfamoylbenzamide (SBA) derivatives. Compound 10, one of the most in vitro potent SBA-derived CAM discovered to date, showed excellent pharmacokinetics in mice suitable for oral dosing. When studied in a transgenic mouse model of hepatic HBV replication, it was considerably more potent than NVR 3-778, the first sulfamoylbenzamide (SBA) CAM that entered clinical trials for CHB, at reducing viral replication in a dose-dependent fashion. We present herein the discovery process, the SAR analysis and the pre-clinical profile of this novel SBA CAM.

Machine Learning Analyses on Data including Essential Oil Chemical Composition and In Vitro Experimental Antibiofilm Activities against Staphylococcus Species.

Biofilm resistance to antimicrobials is a complex phenomenon, driven not only by genetic mutation induced resistance, but also by means of increased microbial cell density that supports horizontal gene transfer across cells. The prevention of biofilm formation and the treatment of existing biofilms is currently a difficult challenge; therefore, the discovery of new multi-targeted or combinatorial therapies is growing. The development of anti-biofilm agents is considered of major interest and represents a key strategy as non-biocidal molecules are highly valuable to avoid the rapid appearance of escape mutants. Among bacteria, staphylococci are predominant causes of biofilm-associated infections. Staphylococci, especially Staphylococcus aureus (S. aureus) is an extraordinarily versatile pathogen that can survive in hostile environmental conditions, colonize mucous membranes and skin, and can cause severe, non-purulent, toxin-mediated diseases or invasive pyogenic infections in humans. Staphylococcus epidermidis (S. epidermidis) has also emerged as an important opportunistic pathogen in infections associated with medical devices (such as urinary and intravascular catheters, orthopaedic implants, etc.), causing approximately from 30% to 43% of joint prosthesis infections. The scientific community is continuously looking for new agents endowed of anti-biofilm capabilities to fight S. aureus and S epidermidis infections. Interestingly, several reports indicated in vitro efficacy of non-biocidal essential oils (EOs) as promising treatment to reduce bacterial biofilm production and prevent the inducing of drug resistance. In this report were analyzed 89 EOs with the objective of investigating their ability to modulate bacterial biofilm production of different S. aureus and S. epidermidis strains. Results showed the assayed EOs to modulated the biofilm production with unpredictable results for each strain. In particular, many EOs acted mainly as biofilm inhibitors in the case of S. epidermidis strains, while for S. aureus strains, EOs induced either no effect or stimulate biofilm production. In order to elucidate the obtained experimental results, machine learning (ML) algorithms were applied to the EOs' chemical compositions and the determined associated anti-biofilm potencies. Statistically robust ML models were developed, and their analysis in term of feature importance and partial dependence plots led to indicating those chemical components mainly responsible for biofilm production, inhibition or stimulation for each studied strain, respectively.

Disruptor of telomeric silencing 1-like (DOT1L): disclosing a new class of non-nucleoside inhibitors by means of ligand-based and structure-based approaches.

Chemical inhibition of chromatin-mediated signaling involved proteins is an established strategy to drive expression networks and alter disease progression. Protein methyltransferases are among the most studied proteins in epigenetics and, in particular, disruptor of telomeric silencing 1-like (DOT1L) lysine methyltransferase plays a key role in MLL-rearranged acute leukemia Selective inhibition of DOT1L is an established attractive strategy to breakdown aberrant H3K79 methylation and thus overexpression of leukemia genes, and leukemogenesis. Although numerous DOT1L inhibitors have been several structural data published no pronounced computational efforts have been yet reported. In these studies a first tentative of multi-stage and LB/SB combined approach is reported in order to maximize the use of available data. Using co-crystallized ligand/DOT1L complexes, predictive 3-D QSAR and COMBINE models were built through a python implementation of previously reported methodologies. The models, validated by either modeled or experimental external test sets, proved to have good predictive abilities. The application of these models to an internal library led to the selection of two unreported compounds that were found able to inhibit DOT1L at micromolar level. To the best of our knowledge this is the first report of quantitative LB and SB DOT1L inhibitors models and their application to disclose new potential epigenetic modulators.

Antimicrobial and Antibiofilm Activity and Machine Learning Classification Analysis of Essential Oils from Different Mediterranean Plants against Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a ubiquitous organism and opportunistic pathogen that can cause persistent infections due to its peculiar antibiotic resistance mechanisms and to its ability to adhere and form biofilm. The interest in the development of new approaches for the prevention and treatment of biofilm formation has recently increased. The aim of this study was to seek new non-biocidal agents able to inhibit biofilm formation, in order to counteract virulence rather than bacterial growth and avoid the selection of escape mutants. Herein, different essential oils extracted from Mediterranean plants were analyzed for their activity against P. aeruginosa. Results show that they were able to destabilize biofilm at very low concentration without impairing bacterial viability. Since the action is not related to a bacteriostatic/bactericidal activity on P. aeruginosa, the biofilm change of growth in presence of the essential oils was possibly due to a modulation of the phenotype. To this aim, application of machine learning algorithms led to the development of quantitative activity-composition relationships classification models that allowed to direct point out those essential oil chemical components more involved in the inhibition of biofilm production. The action of selected essential oils on sessile phenotype make them particularly interesting for possible applications such as prevention of bacterial contamination in the community and in healthcare environments in order to prevent human infections. We assayed 89 samples of different essential oils as P. aeruginosa anti-biofilm. Many samples inhibited P. aeruginosa biofilm at concentrations as low as 48.8 µg/mL. Classification of the models was developed through machine learning algorithms.

Understanding the Molecular Determinant of Reversible Human Monoamine Oxidase B Inhibitors Containing 2H-Chromen-2-One Core: Structure-Based and Ligand-Based Derived Three-Dimensional Quantitative Structure-Activity Relationships Predictive Models.

Monoamine oxidase B (MAO B) catalyzes the oxidative deamination of aryalkylamines neurotransmitters with concomitant reduction of oxygen to hydrogen peroxide. Consequently, the enzyme's malfunction can induce oxidative damage to mitochondrial DNA and mediates development of Parkinson's disease. Thus, MAO B emerges as a promising target for developing pharmaceuticals potentially useful to treat this vicious neurodegenerative condition. Aiming to contribute to the development of drugs with the reversible mechanism of MAO B inhibition only, herein, an extended in silico-in vitro procedure for the selection of novel MAO B inhibitors is demonstrated, including the following: (1) definition of optimized and validated structure-based three-dimensional (3-D) quantitative structure-activity relationships (QSAR) models derived from available cocrystallized inhibitor-MAO B complexes; (2) elaboration of SAR features for either irreversible or reversible MAO B inhibitors to characterize and improve coumarin-based inhibitor activity (Protein Data Bank ID: 2V61 ) as the most potent reversible lead compound; (3) definition of structure-based (SB) and ligand-based (LB) alignment rule assessments by which virtually any untested potential MAO B inhibitor might be evaluated; (4) predictive ability validation of the best 3-D QSAR model through SB/LB modeling of four coumarin-based external test sets (267 compounds); (5) design and SB/LB alignment of novel coumarin-based scaffolds experimentally validated through synthesis and biological evaluation in vitro. Due to the wide range of molecular diversity within the 3-D QSAR training set and derived features, the selected N probe-derived 3-D QSAR model proves to be a valuable tool for virtual screening (VS) of novel MAO B inhibitors and a platform for design, synthesis and evaluation of novel active structures. Accordingly, six highly active and selective MAO B inhibitors (picomolar to low nanomolar range of activity) were disclosed as a result of rational SB/LB 3D QSAR design; therefore, D123 (IC50 = 0.83 nM, Ki = 0.25 nM) and D124 (IC50 = 0.97 nM, Ki = 0.29 nM) are potential lead candidates as anti-Parkinson's drugs.

Exploring the first Rimonabant analog-opioid peptide hybrid compound, as bivalent ligand for CB1 and opioid receptors.

Cannabinoid (CB) and opioid systems are both involved in analgesia, food intake, mood and behavior. Due to the co-localization of µ-opioid (MOR) and CB1 receptors in various regions of the central nervous system (CNS) and their ability to form heterodimers, bivalent ligands targeting to both these systems may be good candidates to investigate the existence of possible cross-talking or synergistic effects, also at sub-effective doses. In this work, we selected from a small series of new Rimonabant analogs one CB1R reverse agonist to be conjugated to the opioid fragment Tyr-D-Ala-Gly-Phe-NH2. The bivalent compound (9) has been used for in vitro binding assays, for in vivo antinociception models and in vitro hypothalamic perfusion test, to evaluate the neurotransmitters release.

Vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors: development and validation of predictive 3-D QSAR models through extensive ligand- and structure-based approaches.

Vascular endothelial growth factor receptor-2, (VEGFR-2), is a key element in angiogenesis, the process by which new blood vessels are formed, and is thus an important pharmaceutical target. Here, 3-D quantitative structure-activity relationship (3-D QSAR) were used to build a quantitative screening and pharmacophore model of the VEGFR-2 receptors for design of inhibitors with improved activities. Most of available experimental data information has been used as training set to derive optimized and fully cross-validated eight mono-probe and a multi-probe quantitative models. Notable is the use of 262 molecules, aligned following both structure-based and ligand-based protocols, as external test set confirming the 3-D QSAR models' predictive capability and their usefulness in design new VEGFR-2 inhibitors. From a survey on literature, this is the first generation of a wide-ranging computational medicinal chemistry application on VEGFR2 inhibitors.

Studies on the antiplatelet and antithrombotic profile of anti-inflammatory coumarin derivatives.

The interest towards coumarin-based structures stems from their polypharmacological profile. Herein, we present a series of Mannich bases and 7-azomethine-linked coumarin derivatives exhibiting antiplatelet and antithrombotic activities, in addition to the already known anti-inflammatory and antioxidant activities. Among others, compounds 15 and 16 were found to be the most potent and selective inhibitors of platelet aggregation whereas compound 3 also proved to be the most potent in the clot retraction assay. Structure-activity relationship studies were conducted to elucidate the molecular determinants responsible for the herein observed activities. The chance of inhibiting cyclooxygenase-1 was also investigated for evaluating the platelet aggregation induced by arachidonic acid. Taken together, these results suggest that the investigation of other targets connected to the antiplatelet activity, such as phosphodiesterase-3 (PDE3), could be a viable strategy to shed light on the polypharmacological profile of coumarin-based compounds. Docking simulations towards PDE3 were also carried out.

Decreasing acidity in a series of aldose reductase inhibitors: 2-Fluoro-4-(1H-pyrrol-1-yl)phenol as a scaffold for improved membrane permeation.

Targeting long-term diabetic complications, as well as inflammatory pathologies, aldose reductase inhibitors (ARIs) have been gaining attention over the years. In the present work, in order to address the poor membrane permeation of previously reported ARIs, derivatives of N-phenylpyrrole, bearing groups with putative pKa≥7.4, were synthesized and evaluated for aldose reductase inhibitory activity. The 2-fluorophenol group proved the most promising moiety, and further modifications were explored. The most active compound (31), identified as a submicromolar inhibitor (IC50=0.443µM), was also selective against the homologous enzyme aldehyde reductase. Cross-docking revealed that 31 displays a peculiar interaction network that may be responsible for high affinity. Physicochemical profiling of 31 showed a pKa of 7.64, rendering it less than 50% ionized in the physiological pH range, with potentially favorable membrane permeation. The latter was supported from the successful inhibition of sorbitol formation in rat lenses and the ability to permeate rat jejunum.

Targeting the anti-apoptotic Bcl-2 family proteins: machine learning virtual screening and biological evaluation of new small molecules.

Bcl-2 family anti-apoptotic proteins are overexpressed in several hematological and solid tumors, and contribute to tumor formation, progression, and resistance to therapy. They represent a promising therapeutic avenue to explore for cancer treatment. Venetoclax, a Bcl-2 inhibitor is currently used for hematological malignancies or is undergoing clinical trials for either hematological or solid tumors. Despite these progresses, ongoing efforts are focusing on the identification and development of new molecules targeting Bcl-2 protein and/or other family members. Methods: Machine learning guided virtual screening followed by surface plasmon resonance, molecular docking and pharmacokinetic analyses were performed to identify new inhibitors of anti-apoptotic members of Bcl-2 family and their pharmacokinetic profile. The sensitivity of cancer cells from different origin to the identified compounds was evaluated both in in vitro (cell survival, apoptosis, autophagy) and in vivo (tumor growth in nude mice) preclinical models. Results: IS20 and IS21 were identified as potential new lead compounds able to bind Bcl-2, Bcl-xL and Mcl-1 recombinant proteins. Molecular docking investigation indicated IS20 and IS21 could bind into the Beclin-1 BH3 binding site of wild type Bcl-2, Bcl-xL and Mcl-1 proteins. In particular, although the IS21 docked conformation did not show a unique binding mode, it clearly showed its ability in flexibly adapting to either BH3 binding sites. Moreover, both IS20 and IS21 reduced cell viability, clonogenic ability and tumor sphere formation, and induced apoptosis in leukemic, melanoma and lung cancer cells. Autophagosome formation and maturation assays demonstrated induction of autophagic flux after treatment with IS20 or IS21. Experiments with z-VAD-fmk, a pan-caspase inhibitor, and chloroquine, a late-stage autophagy inhibitor, demonstrated the ability of the two compounds to promote apoptosis by autophagy. IS21 also reduced in vivo tumor growth of both human leukemia and melanoma models. Conclusion: Virtual screening coupled with in vitro and in vivo experimental data led to the identification of two new promising inhibitors of anti-apoptotic proteins with good efficacy in the binding to recombinant Bcl-2, Bcl-xL and Mcl-1 proteins, and against different tumor histotypes.

Essential oils against bacterial isolates from cystic fibrosis patients by means of antimicrobial and unsupervised machine learning approaches.

Recurrent and chronic respiratory tract infections in cystic fibrosis (CF) patients result in progressive lung damage and represent the primary cause of morbidity and mortality. Staphylococcus aureus (S. aureus) is one of the earliest bacteria in CF infants and children. Starting from early adolescence, patients become chronically infected with Gram-negative non-fermenting bacteria, and Pseudomonas aeruginosa (P. aeruginosa) is the most relevant and recurring. Intensive use of antimicrobial drugs to fight lung infections inevitably leads to the onset of antibiotic resistant bacterial strains. New antimicrobial compounds should be identified to overcome antibiotic resistance in these patients. Recently interesting data were reported in literature on the use of natural derived compounds that inhibited in vitro S. aureus and P. aeruginosa bacterial growth. Essential oils, among these, seemed to be the most promising. In this work is reported an extensive study on 61 essential oils (EOs) against a panel of 40 clinical strains isolated from CF patients. To reduce the in vitro procedure and render the investigation as convergent as possible, machine learning clusterization algorithms were firstly applied to pick-up a fewer number of representative strains among the panel of 40. This approach allowed us to easily identify three EOs able to strongly inhibit bacterial growth of all bacterial strains. Interestingly, the EOs antibacterial activity is completely unrelated to the antibiotic resistance profile of each strain. Taking into account the results obtained, a clinical use of EOs could be suggested.

Combined Peptide and Small-Molecule Approach toward Nonacidic THIQ Inhibitors of the KEAP1/NRF2 Interaction.

The NRF2-ARE pathway is an intrinsic mechanism of defense against oxidative stress. Inhibition of the interaction between NRF2 and its main negative regulator KEAP1 is an attractive strategy toward neuroprotective agents. We report here the identification of nonacidic tetrahydroisoquinolines (THIQs) that inhibit the KEAP1/NRF2 protein-protein interaction. Peptide SAR at one residue is utilized as a tool to probe structural changes within a specific pocket of the KEAP1 binding site. We used structural information from peptide screening at the P2 pocket, noncovalent small-molecules inhibitors, and the outcome from an explorative SAR at position 5 of THIQs to identify a series of neutral THIQ analogs that bind to KEAP1 in the low micromolar range. These analogs establish new H-bond interactions at the P3 and P2 pockets allowing the replacement of the carboxylic acid functionality by a neutral primary carboxamide. X-ray crystallographic studies reveal the novel binding mode of these molecules to KEAP1.

Shmt2: A Stat3 Signaling New Player in Prostate Cancer Energy Metabolism.

Prostate cancer (PCa) is a multifactorial disease characterized by the aberrant activity of different regulatory pathways. STAT3 protein mediates some of these pathways and its activation is implicated in the modulation of several metabolic enzymes. A bioinformatic analysis indicated a STAT3 binding site in the upstream region of SHMT2 gene. We demonstrated that in LNCaP, PCa cells' SHMT2 expression is upregulated by the JAK2/STAT3 canonical pathway upon IL-6 stimulation. Activation of SHTM2 leads to a decrease in serine levels, pushing PKM2 towards the nuclear compartment where it can activate STAT3 in a non-canonical fashion that in turn promotes a transient shift toward anaerobic metabolism. These results were also confirmed on FFPE prostate tissue sections at different Gleason scores. STAT3/SHMT2/PKM2 loop in LNCaP cells can modulate a metabolic shift in response to inflammation at early stages of cancer progression, whereas a non-canonical STAT3 activation involving the STAT3/HIF-1α/PKM2 loop is responsible for the maintenance of Warburg effect distinctive of more aggressive PCa cells. Chronic inflammation might thus prime the transition of PCa cells towards more advanced stages, and SHMT2 could represent a missing factor to further understand the molecular mechanisms responsible for the transition of prostate cancer towards a more aggressive phenotype.

Effect of α-Methoxy Substitution on the Anti-HIV Activity of Dihydropyrimidin-4(3 H)-ones.

Conformational restriction applied to dihydrobenzylpyrimidin-4-(3 H)-ones (DABOs) by the intoduction of a methyl group at the α-benzylic position is known to massively improve the anti-HIV-1 activity of these compounds. Here, we report the effects of methoxy substitution at the α-benzylic position in S-, NH-, and N, N-DABOs carrying 2,6-difluoro, 2-chloro-6-fluoro, or 2,6-dichloro substituted benzyl moieties. The various α-methoxy DABO series (12-14) present different SAR at the dihalo benzyl substitution, with the most potent compounds (12d,e and 13c) showing similar (picomolar/nanomolar) anti-HIV-1 potency as the corresponding α-methyl analogues against wt HIV-1, and 10-100-fold increased potency (up to low nanomolar) against clinically relevant K103N, Y181C, Y188L, IRLL98, and K103N+Y181C HIV-1 mutant strains, highlighting the importance of the α-methoxy substitution to provide highly efficient DABOs as "second generation" NNRTIs. HPLC enantioseparation of three of the most potent derivatives (12d, 13c, and 14c) provided single enantiomers with significant enantioselectivity in HIV-1 inhibition. Computational studies allowed to correlate the best antiviral activity with the ( R) absolute configuration at the α-methoxy stereogenic center.

Development of alkyl glycerone phosphate synthase inhibitors: Structure-activity relationship and effects on ether lipids and epithelial-mesenchymal transition in cancer cells.

In aggressive tumors, alkylglyceronephosphate synthase (AGPS) controls cellular ether phospholipid utilization and metabolism to promote cancer cell proliferation and motility. SAR studies on the first-in-class AGPS inhibitor 1, discovered by our group, led to the 2,6-difluoro analog 2i which showed higher binding affinity than 1in vitro. In 231MFP cancer cells, 2i reduced ether lipids levels and cell migration rate. When tested in PC-3 and MDA-MB-231 cancer cells, 2i specifically impaired epithelial to mesenchymal transition (EMT) by modulating E-cadherin, Snail and MMP2 expression levels. Moreover, the combination of siRNAs against AGPS and 2i provided no additive effect, confirming that the modulation of 2i on EMT specifically relies on AGPS inhibition. Finally, this compound also affected cancer cell proliferation especially in MDA-MB-231 cells expressing higher AGPS level, whereas it provided negligible effects on MeT5A, a non-tumorigenic cell line, thus showing cancer specificity.

Carotenoid content of Goji berries: CIELAB, HPLC-DAD analyses and quantitative correlation.

Fruits of Lycium barbarum L. have been used in Chinese traditional medicine for centuries. In the last decade, there has been much interest in the potential health benefits of many biologically constituents of these fruits. The high level of carotenoids offers protection against development of cardiovascular diseases, diabetes and related comorbidities. In the present work two different selections of Lycium barbarum L., cultivated in Italy and coming from three discrete harvest stages, were subjected to two different grinding procedure and to a simplified extraction method of carotenoid component. CIELAB colorimetric analysis of the freshly prepared purees and HPLC-DAD analysis of carotenoid extracts were performed and compared. Different harvesting dates and grinding procedures deeply influence the carotenoids content and statistical analysis showed high correlation between carotenoid content and colorimetric data. The final model provides a reliable tool to directly assess carotenoid content by performing cheap and routinely colorimetric analyses for food industry.

Synthesis, biological evaluation and quantitative structure-active relationships of 1,3-thiazolidin-4-one derivatives. A promising chemical scaffold endowed with high antifungal potency and low cytotoxicity.

With reference to recent studies reporting on the various biological properties of the thiazolidinone scaffold, we synthesized more than a hundred compounds characterized by a 1,3-thiazolidin-4-one nucleus derivatised at the C2 with a hydrazine bridge linked to (cyclo)aliphatic or hetero(aryl) moieties, and their N-benzylated derivatives. These molecules were assayed as potential anti-Candida agents and they were shown to possess comparable, and in some cases higher biological activity than well-established topical and systemic antimycotic drugs (i.e. clotrimazole, fluconazole, ketoconazole, miconazole, tioconazole, amphotericin B). Compounds endowed with the lowest MICs underwent further testing in order to assess their cytotoxic effect (CC50) on Hep2 cells, which demonstrated their relative safety. Finally, QSAR and 3-D QSAR models were used to predict putative chemical modifications of the 1,3-thiazolidin-4-one scaffold in order to design new and potential more active compounds against Candida spp.

Enhancing activity and selectivity in a series of pyrrol-1-yl-1-hydroxypyrazole-based aldose reductase inhibitors: The case of trifluoroacetylation.

Aldose reductase (ALR2) has been the target of therapeutic intervention for over 40 years; first, for its role in long-term diabetic complications and more recently as a key mediator in inflammation and cancer. However, efforts to prepare small-molecule aldose reductase inhibitors (ARIs) have mostly yielded carboxylic acids with rather poor pharmacokinetics. To address this limitation, the 1-hydroxypyrazole moiety has been previously established as a bioisostere of acetic acid in a group of aroyl-substituted pyrrolyl derivatives. In the present work, optimization of this new class of ARIs was achieved by the addition of a trifluoroacetyl group on the pyrrole ring. Eight novel compounds were synthesized and tested for their inhibitory activity towards ALR2 and selectivity against aldehyde reductase (ALR1). All compounds proved potent and selective inhibitors of ALR2 (IC50/ALR2 = 0.043-0.242 µΜ, Selectivity index = 190-858), whilst retaining a favorable physicochemical profile. The most active (4g) and selective (4d) compounds were further evaluated for their ability to inhibit sorbitol formation in rat lenses ex vivo and to exhibit substrate-specific inhibition.