Crystal Structure of the Human Cannabinoid Receptor CB1.

Cannabinoid receptor 1 (CB1) is the principal target of Δ9-tetrahydrocannabinol (THC), a psychoactive chemical from Cannabis sativa with a wide range of therapeutic applications and a long history of recreational use. CB1 is activated by endocannabinoids and is a promising therapeutic target for pain management, inflammation, obesity, and substance abuse disorders. Here, we present the 2.8 Å crystal structure of human CB1 in complex with AM6538, a stabilizing antagonist, synthesized and characterized for this structural study. The structure of the CB1-AM6538 complex reveals key features of the receptor and critical interactions for antagonist binding. In combination with functional studies and molecular modeling, the structure provides insight into the binding mode of naturally occurring CB1 ligands, such as THC, and synthetic cannabinoids. This enhances our understanding of the molecular basis for the physiological functions of CB1 and provides new opportunities for the design of next-generation CB1-targeting pharmaceuticals.

Deacylative transformations of ketones via aromatization-promoted C-C bond activation.

Carbon-hydrogen (C-H) and carbon-carbon (C-C) bonds are the main constituents of organic matter. Recent advances in C-H functionalization technology have vastly expanded our toolbox for organic synthesis1. By contrast, C-C activation methods that enable editing of the molecular skeleton remain limited2-7. Several methods have been proposed for catalytic C-C activation, particularly with ketone substrates, that are typically promoted by using either ring-strain release as a thermodynamic driving force4,6 or directing groups5,7 to control the reaction outcome. Although effective, these strategies require substrates that contain highly strained ketones or a preinstalled directing group, or are limited to more specialist substrate classes5. Here we report a general C-C activation mode driven by aromatization of a pre-aromatic intermediate formed in situ. This reaction is suitable for various ketone substrates, is catalysed by an iridium/phosphine combination and is promoted by a hydrazine reagent and 1,3-dienes. Specifically, the acyl group is removed from the ketone and transformed to a pyrazole, and the resulting alkyl fragment undergoes various transformations. These include the deacetylation of methyl ketones, carbenoid-free formal homologation of aliphatic linear ketones and deconstructive pyrazole synthesis from cyclic ketones. Given that ketones are prevalent in feedstock chemicals, natural products and pharmaceuticals, these transformations could offer strategic bond disconnections in the synthesis of complex bioactive molecules.

A screen of repurposed drugs identifies AMHR2/MISR2 agonists as potential contraceptives.

We identified the anti-Mullerian hormone (also known as Müllerian inhibiting substance or MIS) as an inhibitory hormone that induces long-term contraception in mammals. The type II receptor to this hormone, AMHR2 (also known as MISR2), represents a promising druggable target for the modulation of female reproduction with a mechanism of action distinct from steroidal contraceptives. We designed an in vitro platform to screen and validate small molecules that can activate MISR2 signaling and suppress ovarian folliculogenesis. Using a bone morphogenesis protein (BMP)­response element luciferase reporter cell­based assay, we screened 5,440 compounds from a repurposed drug library. Positive hits in this screen were tested for specificity and potency in luciferase dose­response assays, and biological activity was tested in ex vivo Mullerian duct regression bioassays. Selected candidates were further evaluated in ex vivo follicle/ovary culture assays and in vivo in mice and rats. Here, we report that SP600125, CYC-116, gandotinib, and ruxolitinib can specifically inhibit primordial follicle activation and repress folliculogenesis by stimulating the MISR2 pathway.

RuBi-Ruxolitinib: A Photoreleasable Antitumor JAK Inhibitor.

We describe the synthesis and biological testing of ruthenium-bipyridine ruxolitinib (RuBiRuxo), a photoreleasable form of ruxolitinib, a JAK inhibitor used as an antitumoral agent in cutaneous T-cell lymphomas (CTCL). This novel caged compound is synthesized efficiently, is stable in aqueous solution at room temperature, and is photoreleased rapidly by visible light. Irradiation of RuBiRuxo reduces cell proliferation and induces apoptosis in a light- and time-dependent manner in a CTCL cell line. This effect is specific and is mediated by a decreased phosphorylation of STAT proteins. Our results demonstrate the potential of ruthenium-based photocompounds and light-based therapeutic approaches for the potential treatment of cutaneous lymphomas and other pathologies.

Mononuclear η6-arene ruthenium(II) complexes with pyrazolyl-pyridazine ligands: synthesis, CT-DNA binding, reactivity towards glutathione, and cytotoxicity.

Organometallic η6-arene ruthenium(II) complexes with 3-chloro-6-(1H-pyrazol-1-yl)pyridazine (Ru1, Ru2, and Ru5) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridazine (Ru3-4) N,N' heterocyclic and η6-arene (cymene (Ru1-4) or toluene (Ru 5)) have been synthesized. The ruthenium(II) complexes have common "three-legged piano-stool" pseudo-octahedral structures known for half-sandwich complexes. Evolution of their UV-Visible absorption spectra in PBS buffer or DMSO over 24 h confirmed their good solvolysis stability. Titrations of the complexes with the calf thymus DNA (CT-DNA) were monitored using UV-Visible absorption and fluorescence spectroscopies. The complexes interact moderately with CT-DNA and their binding constants are in the order of 104 M-1. Competitive binding of the complexes to a DNA-Hoechst 33,258 depicted competitive displacement of Hoechst from DNA's minor grooves. These complexes bind to glutathione forming GSH-adducts through S coordination by replacement of a halide, with the iodo-analogues having higher binding constants than the chloro-complexes. Cyclic voltammograms of the complexes exhibited one electron-transfer quasi-reversible process. Trends in the molecular docking data of Ru1-5/DNA were similar to those for DNA binding constants. Of the five, only Ru1, Ru3 and Ru5 showed some activity (moderate) against the MCF-7 breast cancer cells with IC50 values in the range of 59.2-39.9 for which Ru5 was the most active. However, the more difficult-to-treat cell line, MDA-MB 231 cell was recalcitrant to the treatment by these complexes.

Monitoring of DNA structural changes after incorporation of the phenylpyrazole insecticide fipronil.

The use of insecticides presents a risk to the environment because they can accumulate in the water, soil, air, and organisms, endangering human and animal health. It is therefore essential to investigate the effects of different groups of insecticides on individual biomacromolecules such as DNA. We studied fipronil, which belongs to the group of phenylpyrazole insecticides. The interaction of fipronil with calf thymus DNA was investigated using spectroscopic methods (absorption and fluorescence spectroscopy) complemented with infrared spectroscopy and viscosity measurement. Fluorescence emission spectroscopy showed the formation of a fipronil/DNA complex with a combined static and dynamic type of quenching. The binding constant was 4.15 × 103 L/mol. Viscosity changes were recorded to confirm/disconfirm the intercalation mode of interaction. A slight change in DNA viscosity in the presence of fipronil was observed. The phenylpyrazole insecticide does not cause significant conformational changes in DNA structure or increase of its chain length. We hypothesize that fipronil is incorporated into the minor groove of the DNA macromolecule via hydrogen interactions as indicated by FT-IR and CD measurements.

Biocatalytic Synthesis of Ruxolitinib Intermediate via Engineered Imine Reductase.

An enzyme catalyzed strategy for the synthesis of a chiral hydrazine from 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 is presented. An imine reductase (IRED) from Streptosporangium roseum was identified to catalyze the reaction between 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 to produce trace amounts of (R)-3-cyclopentyl-3-hydrazineylpropanenitrile 4. We employed a 2-fold approach to optimize the catalytic performance of this enzyme. First, a transition state analogue (TSA) model was constructed to illuminate the enzyme-substrate interactions. Subsequently, the Enzyme_design and Funclib methods were utilized to predict mutants for experimental evaluation. Through three rounds of site-directed mutagenesis, site saturation mutagenesis, and combinatorial mutagenesis, we obtained mutant M6 with a yield of 98% and an enantiomeric excess (ee) of 99%. This study presents an effective method for constructing a hydrazine derivative via IRED-catalyzed reductive amination of ketone and hydrazine. Furthermore, it provides a general approach for constructing suitable enzymes, starting from nonreactive enzymes and gradually enhancing their catalytic activity through active site modifications.

Optimizing and characterizing 4-methyl substituted pyrazol-3-carboxamides leading to the peripheral cannabinoid 1 receptor inverse agonist TM38837.

Several series of diverse pyrazole-3-carboxamides functionalized with 4-methylamides, 4-methylcarboxylic acids and 4-methyltetrazoles were prepared from the corresponding 4-cyanomethylpyrazoles and investigated as Cannabinoid receptor 1 (CB1) antagonists and inverse agonists with the aim of making compounds with less CNS (Central Nervous System) mediated side-effects compared to rimonabant. The compounds were evaluated and optimized with respect to lipophilicity, solubility, CB1 potency, metabolism, distribution to brain and liver, effect on weight loss in diet-induced mice models. A few carboxylic acids and tetrazoles were selected as especially promising with the tetrazole TM38837 subsequently demonstrating impressive efficacy in various animal models of obesity, producing considerable weight loss and improvements on plasma markers of inflammation and glucose homeostasis, at doses apparently producing negligible brain exposure. TM38837 became the first peripherally restricted CB1 antagonist or inverse agonist to enter clinical trials supporting its lack of CNS effects and it is now believed that the non-CNS mediated efficacy is linked to high liver exposure. This opens opportunities to be explored in other indications such as nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH). Note that this is a first-time disclosure of the structure of TM38837 and other structures appearing in literature are not connected with this program.

A chemical platform for the efficient screening of arylazopyrazole-based photoswitchable CENP-E inhibitors using mild cyclization reactions.

A set of arylazopyrazole-based inhibitors targeting the mitotic motor protein CENP-E was discovered through the chemical platform using the quantitative cyclization of 1,3-diketone intermediate with various hydrazines under mild conditions. Through this efficient platform, the structure-activity relationship pertaining to the pyrazole photoswitch in photoswitchable CENP-E inhibitors not only in vitro but also in cells was successfully clarified.

Discovery of a potent orally available pyrazolopyridone derivative as a novel selective bromodomain and extra-terminal domain (BET)-first bromodomain (BD1) inhibitor.

Clinical studies have shown that inhibitors of bromodomain and extra-terminal domain (BET) proteins, particularly BRD4, have antitumor activity and efficacy. The BET protein has two domains, BD1 and BD2, and we previously focused on BD1 and reported orally bioavailable BD1-selective inhibitors. In this study, we obtained a BD1 inhibitor, a more potent and highly selective pyrazolopyridone derivative 13a, and confirmed its in vivo efficacy.

Synthesis, fungicidal activity and molecular docking of novel pyrazole-carboxamides bearing a branched alkyl ether moiety.

Succinate dehydrogenase inhibitors are essential fungicides used in agriculture. To explore new pyrazole-carboxamides with high fungicidal activity, a series of N-substitutedphenyl-3-di/trifluoromethyl-1-methyl-1H-pyrazole-4-carboxamides bearing a branched alkyl ether moiety were designed and synthesized. The in vitro bioassay indicated that some target compounds displayed appreciable fungicidal activity. For example, compounds 5d and 5e showed high efficacy against S. sclerotiorum with EC50 values of 3.26 and 1.52 µg/mL respectively, and also exhibited excellent efficacy against R. solani with EC50 values of 0.27 and 0.06 µg/mL respectively, which were comparable or superior to penflufen. The further in vivo bioassay on cucumber leaves demonstrated that 5e provided strong protective activity of 94.3 % against S. sclerotiorum at 100 µg/mL, comparable to penflufen (99.1 %). Cytotoxicity assessment against human renal cell lines (239A cell) revealed that 5e had low cytotoxicity within the median effective concentrations. Docking study of 5e with succinate dehydrogenase illustrated that R-5e formed one hydrogen bond and two π-π stacking interactions with amino acid residues of target enzyme, while S-5e formed only one π-π stacking interaction with amino acid residue. This study provides a valuable reference for the design of new succinate dehydrogenase inhibitor.

In-cell chemical construction of a photoswitchable CENP-E using a photochromic covalent inhibitor.

An arylazopyrazole-based covalent inhibitor targeting the mitotic motor protein of centromere-associated protein E (CENP-E) was developed. Using this photoswitchable inhibitor, a photoswitchable CENP-E was chemically constructed in cells, which enabled to local control of mitotic cell division with light illumination.

Understanding the Differences of Danusertib's Residence Time in Aurora Kinases A/B: Dissociation Paths and Key Residues Identified using Conventional and Enhanced Molecular Dynamics Simulations.

The accurate experimental estimation of protein-ligand systems' residence time (τ) has become very relevant in drug design projects due to its importance in the last stages of refinement of the drug's pharmacodynamics and pharmacokinetics. It is now well-known that it is not sufficient to estimate the affinity of a protein-drug complex in the thermodynamic equilibrium process in in vitro experiments (closed systems), where the concentrations of the drug and protein remain constant. On the contrary, it is mandatory to consider the conformational dynamics of the system in terms of the binding and unbinding processes between protein and drugs in in vivo experiments (open systems), where their concentrations are in constant flux. This last model has been proven to dictate much of several drugs' pharmacological activities in vivo. At the atomistic level, molecular dynamics simulations can explain why some drugs are more effective than others or unveil the molecular aspects that make some drugs work better in one molecular target. Here, the protein kinases Aurora A/B, complexed with its inhibitor Danusertib, were studied using conventional and enhanced molecular dynamics (MD) simulations to estimate the dissociation paths and, therefore, the computational τ values and their comparison with experimental ones. Using classical molecular dynamics (cMD), three differential residues within the Aurora A/B active site, which seems to play an essential role in the observed experimental Danusertib's residence time against these kinases, were characterized. Then, using WT-MetaD, the relative Danusertib's residence times against Aurora A/B kinases were measured in a nanosecond time scale and were compared to those τ values observed experimentally. In addition, the potential dissociation paths of Danusertib in Aurora A and B were characterized, and differences that might be explained by the differential residues in the enzyme's active sites were found. In perspective, it is expected that this computational protocol can be applied to other protein-ligand complexes to understand, at the molecular level, the differences in residence times and amino acids that may contribute to it.

Structure optimization of Cmpd-15 as negative allosteric modulators for the ß2-adrenergic receptor.

19 derivatives of 1-benzyl-3-arylpyrazole-5-carboxamides (H1-H19) and 5 derivatives of 1-benzyl-5-arylpyrazole-3-carboxamides (J1-J5) have been designed and synthesized as potential negative allosteric modulators (NAMs) for the ß2-adrenergic receptor (ß2AR). The new pyrazole derivatives were screened on the classic G-protein dependent signaling pathway at ß2AR. The majority of 1-benzyl-3-aryl-pyrazole-5-carboxamide derivatives show more potent allosteric antagonistic activity against ß2AR than Cmpd-15, the first reported ß2AR NAM. However, the 1-benzyl-5-arylpyrazole-3-carboxamide derivatives exhibit very poor or even no allosteric antagonistic activity for ß2AR. Furthermore, the active pyrazole derivatives have relative better drug-like profiles than Cmpd-15. Taken together, we discovered a series of derivatives of 1-benzyl-3-arylpyrazole-5-carboxamides as a novel scaffold of ß2AR NAM.

Anle138b interaction in α-synuclein aggregates by dynamic nuclear polarization NMR.

Small molecules that bind to oligomeric protein species such as membrane proteins and fibrils are of clinical interest for development of therapeutics and diagnostics. Definition of the binding site at atomic resolution via NMR is often challenging due to low binding stoichiometry of the small molecule. For fibrils and aggregation intermediates grown in the presence of lipids, we report atomic-resolution contacts to the small molecule at sub nm distance via solid-state NMR using dynamic nuclear polarization (DNP) and orthogonally labelled samples of the protein and the small molecule. We apply this approach to α-synuclein (αS) aggregates in complex with the small molecule anle138b, which is a clinical drug candidate for disease modifying therapy. The small central pyrazole moiety of anle138b is detected in close proximity to the protein backbone and differences in the contacts between fibrils and early intermediates are observed. For intermediate species, the 100 K condition for DNP helps to preserve the aggregation state, while for both fibrils and oligomers, the DNP enhancement is essential to obtain sufficient sensitivity.

Synthesis, molecular docking analysis, drug-likeness evaluation, and inhibition potency of new pyrazole-3,4-dicarboxamides incorporating sulfonamide moiety as carbonic anhydrase inhibitors.

A series of novel pyrazole-dicarboxamides were synthesized from pyrazole-3,4-dicarboxylic acid chloride and various primary and secondary sulfonamides. The structures of the new compounds were confirmed by FT-IR, 1H-NMR, 13C-NMR, and HRMS. Then the inhibition effects of newly synthesized molecules on human erythrocyte hCA I and hCA II isoenzymes were investigated. Ki values of the compounds were in the range of 0.024-0.496 µM for hCA I and 0.006-5.441 µM for hCA II. Compounds 7a and 7i showed nanomolar level of inhibition of hCA II, and these compounds exhibited high selectivity for this isoenzyme. Molecular docking studies were performed between the most active compounds 7a, 7b, 7i, and the reference inhibitor AAZ and the hCAI and hCAII to investigate the binding mechanisms between the compounds and the isozymes. These compounds showed better interactions than the AAZ. ADMET and drug-likeness analyses for the compounds have shown that the compounds can be used pharmacologically in living organisms.

Novel heptafluoroisopropyl N-phenylpyrazole aryl amides containing cyanoalkyl groups: Design, synthesis, insecticidal activity, docking studies and theoretical calculations.

To discover and develop new insecticides of the phenylpyrazole class, a series of heptafluoroisopropyl N-phenylpyrazole aryl amide compounds bearing cyanoalkyl groups were synthesized based on the lead compound nicofluprole. Their structures were established by HRMS, 1H NMR and 13C NMR. Bioassay results indicated that several of these compounds exhibited remarkable acaricidal and insecticidal activities. The LC50 values for compounds A1, A2 and A5 against Tetranychus cinnabarinus (T. cinnabarinus) were 1.7-4.2 times lower than that of nicofluprole (3.124 mg/L). Compounds A1, A2, A4 and A7 against Myzus persicae (M. persicae) had LC50 values of 0.261, 1.292, 0.589 and 1.133 mg/L respectively, exceeding that of nicofluprole (LC50 = 4.200 mg/L). Some compounds also demonstrated good insecticidal activity against Plutella xylostella (P. xylostella). For example, compounds A1-A4, A6, and A7 had a mortality rate of 100 % at a low concentration of 1.25 mg/L, which was comparable to nicofluprole (93.3%). Compound A1 exhibited insecticidal activity against Chilo suppressalis (C. suppressalis) with an LC50 value of 2.271 mg/L, which was superior to both nicofluprole (6.021 mg/L) and the positive control broflanilide (6.895 mg/L). Taking compound A5 as a representative, we tested the insecticidal activity against Aphis fabae (A. fabae), Aphis gossypii Glover (A. gossypii Glover), Nilaparvata lugens (N. lugens) and Laodelphax striatellus (L. striatellus) at 10 mg/L, and our results revealed that compound A5 exhibited broad-spectrum insecticidal activity. Molecular docking studies suggested that A1 had a lower binding energy of -7.764 kcal/mol with the P. xylostella gamma-aminobutyric acid receptors (GABAR). Density functional theory calculations (DFT) provided insights into the design of new compounds. This research suggested that the novel phenylpyrazoles featuring cyanoalkyl moieties in this work hold potential as novel insecticides for further research and development.

Design, synthesis, molecular docking and biological evaluation of 1,3,5-trisubstituted-1H-pyrazole derivatives as anticancer agents with cell cycle arrest, ERK and RIPK3- kinase activities.

The need for new ERK and RIPK3 kinase modulators arises from their central roles in cellular processes, especially in diseases like cancer. This research focused on a ligand-based strategy, incorporating previously documented 1,3,5-trisubstituted-1H-pyrazole derivatives, to craft innovative inhibitors specifically targeting ERK and RIPK3 kinases. Compounds 6, 7, 10a, 10c, and 10d exhibited significant cytotoxicity against PC-3 and MCF-7 cancer cell lines, with IC50 values ranging from 21.9 to 28.6 µM and 3.90-35.5 µM, respectively values surpassing those of the reference compound Doxorubicin. Additionally, cell cycle analysis revealed intriguing results, particularly with 10d inducing cell cycle arrest at the S phase in treated PC-3 cells, indicating potential DNA replication phase inhibition. Moreover, compounds 6, 10a, and 10d exhibited promising results in the in vitro kinase assay supported by molecular docking studies. The core scaffold of these compounds established interactions with vital amino acids within the active pockets of ERK and RIPK3 kinases, thereby securely anchoring them in place. These findings underscore the development of promising modulators for ERK and RIPK3 kinases, suggesting their potential for future contributions to cancer treatments.

Discovery of indoleninyl-pyrazolo[3,4-b]pyridines as potent chemotherapeutic agents against colorectal cancer cells.

A new series of indolenines decorated with pyrazolo[3,4-b]pyridines were designed and synthesized in up to 96% yield from the acid-catalyzed cyclocondensation of 1,3-dialdehydes with 3-aminopyrazoles. X-ray crystallography on a representative derivative, 5n, revealed two close to planar conformations whereby the N-atom of the pyridyl residue was syn or anti to the pyrrole-N atom in the two independent molecules of the asymmetric unit. The computational and DNA binding data suggest that 5n is a strong DNA intercalator with the results in agreement with its potent cytotoxicity against two colorectal cancer cell lines (HCT 116 and HT-29). In contrast to doxorubicin, compounds 5k-o have higher druggability (compliance to more criteria stated in Lipinski's rule of five and Veber's rule), higher bioavailability, and better medicinal chemistry properties, indicative of their potential application as chemotherapeutical agents.

N- and s-substituted Pyrazolopyrimidines: A promising new class of potent c-Src kinase inhibitors with prominent antitumor activity.

In this work, readily achievable synthetic pathways were utilized for construction of a library of N/S analogues based on the pyrazolopyrimidine scaffold with terminal alkyl or aryl fragments. Subsequently, we evaluated the anticancer effects of these novel analogs against the proliferation of various cancer cell lines, including breast, colon, and liver lines. The results were striking, most of the tested molecules exhibited strong and selective cytotoxic activity against the MDA-MB-231 cancer cell line; IC50 1.13 µM. Structure-activity relationship (SAR) analysis revealed that N-substituted derivatives generally enhanced the cytotoxic effect, particularly with aliphatic side chains that facilitated favorable target interactions. We also investigated apoptosis, DNA fragmentation, invasion assay, and anti-migration effects, and discussed their underlying molecular mechanisms for the most active compound 7c. We demonstrated that 7c N-propyl analogue could inhibit MDA-MB-231 TNBC cell proliferation by inducing apoptosis through the regulation of vital proteins, namely c-Src, p53, and Bax. In addition, our results also revealed the potential of these compounds against tumor metastasis by downregulating the invasion and migration modes. Moreover, the in vitro inhibitory effect of active analogs against c-Src kinase was studied and proved that might be the main cause of their antiproliferative effect. Overall, these compelling results point towards the therapeutic potential of these derivatives, particularly those with N-substitution as promising candidates for the treatment of TNBC type of breast cancer.