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Radiosumins are a structurally diverse family of low molecular weight natural products that are produced by cyanobacteria and exhibit potent serine protease inhibition. Members of this family are dipeptides characterized by the presence of two similar non-proteinogenic amino acids. Here we used a comparative bioinformatic analysis to identify radiosumin biosynthetic gene clusters from the genomes of 13 filamentous cyanobacteria. We used direct pathway cloning to capture and express the entire 16.8 kb radiosumin biosynthetic gene cluster from Dolichospermum planctonicum UHCC 0167 in Escherichia coli. Bioinformatic analysis demonstrates that radiosumins represent a new group of chorismate-derived non-aromatic secondary metabolites. High-resolution liquid chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy and chemical degradation analysis revealed that cyanobacteria produce a cocktail of novel radiosumins. We report the chemical structure of radiosumin D, an N-methyl dipeptide, containing a special Aayp (2-amino-3-(4-amino-2-cyclohexen-1-ylidene) propionic acid) with R configuration that differs from radiosumin A-C, an N-Me derivative of Aayp (Amyp) and two acetyl groups. Radiosumin C inhibits all three human trypsin isoforms at micromolar concentrations with preference for trypsin-1 and -3 (IC50 values from 1.7 mu M to >7.2 mu M). These results provide a biosynthetic logic to explore the genetic and chemical diversity of the radiosumin family and suggest that these natural products may be a source of drug leads for selective human serine proteases inhibitors.

Salt-inducible kinases 1-3 (SIK1-3) are key regulators of the LKB1-AMPK pathway and play an important role in cellular homeostasis. Dysregulation of any of the three isoforms has been associated with tumorigenesis in liver, breast, and ovarian cancers. We have recently developed the dual pan-SIK/group I p21-activated kinase (PAK) chemical probe MRIA9. However, inhibition of p21-activated kinases has been associated with cardiotoxicityin vivo, which complicates the use of MRIA9 as a tool compound. Here, we present a structure-based approach involving the back-pocket and gatekeeper residues, for narrowing the selectivity of pyrido[2,3-d]pyrimidin-7(8H)-one-based inhibitors towards SIK kinases, eliminating PAK activity. Optimization was guided by high-resolution crystal structure analysis and computational methods, resulting in a pan-SIK inhibitor, MR22, which no longer exhibited activity on STE group kinases and displayed excellent selectivity in a representative kinase panel. MR22-dependent SIK inhibition led to centrosome dissociation and subsequent cell-cycle arrest in ovarian cancer cells, as observed with MRIA9, conclusively linking these phenotypic effects to SIK inhibition. Taken together, MR22 represents a valuable tool compound for studying SIK kinase function in cells.

Farnesoid X receptor (FXR) is a nuclear receptor with an essential role in regulating bile acid synthesis and cholesterol homeostasis. FXR activation by agonists is explained by an alpha AF-2-trapping mechanism; however, antagonism mechanisms are diverse. We discuss microsecond molecular dynamics (MD) simulations investigating our recently reported FXR antagonists 2a and 2 h. We study the antagonist-induced conformational changes in the FXR ligand-binding domain, when compared to the synthetic (GW4064) or steroidal (chenodeoxycholic acid, CDCA) FXR agonists in the FXR monomer or FXR/RXR heterodimer r, and in the presence and absence of the coactivator. Our MD data suggest ligand-specific influence on conformations of different FXR-LBD regions, including the alpha 5/alpha 6 region, alpha AF-2, and alpha 9-11. Changes in the heterodimerization interface induced by antagonists seem to be associated with alpha AF-2 destabilization, which prevents both co-activator and co-repressor recruitment. Our results provide new insights into the conformational behaviour of FXR, suggesting that FXR antagonism/agonism shift requires a deeper assessment than originally proposed by crystal structures.

Multidrug resistance (MDR) is one of the major factors in the failure of many chemotherapy approaches. In cancer cells, MDR is mainly associated with the expression of ABC transporters such as P‐glycoprotein, MRP1 and ABCG2. Despite major efforts to develop new selective and potent inhibitors of ABC drug transporters, no ABCG2‐specific inhibitors for clinical use are yet available. Here, we report the evaluation of sixteen tetrahydroquinoline/4,5‐dihydroisoxazole derivatives as a new class of ABCG2 inhibitors. The affinity of the five best inhibitors was further investigated by the vanadate‐sensitive ATPase assay. Molecular modelling data, proposing a potential binding mode, suggest that they can inhibit the ABCG2 activity by binding on site S1, previously reported as inhibitors binding region, as well targeting site S2, a selective region for substrates, and by specifically interacting with residues Asn436, Gln398, and Leu555. Altogether, this study provided new insights into THQ/4,5‐dihydroisoxazole molecular hybrids, generating great potential for the development of novel most potent ABCG2 inhibitors., Tetrahydroquinoline/4,5‐dihydroisoxazole hybrids can inhibit the ABCG2 transporter activity and increase the ATP hydrolysis in cells overexpressing ABCG2. Molecular docking and molecular dynamics simulation results suggest that molecular hybrids inhibit ABCG2 activity by binding at the inhibitor binding region, as well as the substrate binding regions.

Structure-based virtual screening of the Enamine database of 1.7 million compounds followed by WaterMap calculations (a molecular-dynamics-simulation-based method) was applied to identify novel acetylcholinesterase (AChE) inhibitors. The inhibitory potency of 29 selected compounds against electric eel (ee) AChE was determined using Ellman's method. Three compounds were found to be active (success rate 10 %). For the most potent compound (∼40 % inhibition at 10 μM), 20 derivatives were discovered based on the Enamine similarity search. Finally, five compounds were found to be promising (IC

In this study, we investigated the delivery of synthetic neurosteroids into MCF-7 human breast adenocarcinoma cells via Organic Anionic Transporting Polypeptides (OATPs) (pH 7.4 and 5.5) to identify the structural components required for OATP-mediated cellular uptake and to get insight into brain drug delivery. Then, we identified structure-uptake relationships using in-house developed OATP1A2 homology model to predict binding sites and modes for the ligands. These binding modes were studied by molecular dynamics simulations to rationalize the experimental results. Our results show that carboxylic acid needs to be at least at 3 carbon-carbon bonds distance from amide bond at the C-3 position of the androstane skeleton and have an amino group to avoid efflux transport. Replacement of hydroxyl group at C-3 with any of the 3, 4, and 5-carbon chained terminal carboxylic groups improved the affinity. We attribute this to polar interactions between carboxylic acid and side-chains of Lys33 and Arg556. The additional amine group showed interactions with Glu172 and Glu200. Based on transporter capacities and efficacies, it could be speculated that the functionalization of acetyl group at the C-17 position of the steroidal skeleton might be explored further to enable OAT1A2-mediated delivery of neurosteroids into the cells and also across the blood-brain barrier.

Compounds simultaneously inhibiting two targets that are involved in the progression of the same complex disease may exhibit additive or even synergistic therapeutic effects. Here we unveil 2,4,5-trisubstituted imidazoles as dual inhibitors of p38α mitogen-activated protein kinase and glycogen synthase kinase 3β (GSK3β). Both enzymes are potential therapeutic targets for neurodegenerative disorders, like Alzheimer's disease. A set of 39 compounds was synthesized and evaluated in kinase activity assays for their ability to inhibit both target kinases. Among the synthesized compounds, potent dual-target-directed inhibitors showing IC50 values down to the low double-digit nanomolar range, were identified. One of the best balanced dual inhibitors presented in here is N-(4-(2-ethyl-4-(4-fluorophenyl)-1H-imidazol-5-yl)pyridin-2-yl)cyclopropanecarboxamide (20c) (p38α, IC50 = 16 nM; GSK3β, IC50 = 35 nM) featuring an excellent metabolic stability and an appreciable isoform selectivity over the closely related GSK3α. Our findings were rationalized by computational docking studies based on previously published X-ray structures.

This work aimed to construct 3D-QSAR CoMFA and CoMSIA models for a series of 31 FAAH inhibitors, containing the 1,3,4-oxadiazol-2-one moiety. The obtained models were characterized by good statistical parameters: CoMFA Q2 = 0.61, R2 = 0.98, CoMSIA Q2 = 0.64, R2 = 0.93. The CoMFA model field contributions were 54.1% and 45.9% for steric and electrostatic fields, respectively. In the CoMSIA model, electrostatic, steric, hydrogen bond donor, and hydrogen acceptor properties were equal to 34.6%, 23.9%, 23.4%, and 18.0%, respectively. These models were validated by applying the leave-one-out technique, the seven-element test set (CoMFA r2test-set = 0.91, CoMSIA r2test-set = 0.91), a progressive scrambling test, and external validation criteria developed by Golbraikh and Tropsha (CoMFA r20 = 0.98, k = 0.95, CoMSIA r20 = 0.98, k = 0.89). As the statistical significance of the obtained model was confirmed, the results of the CoMFA and CoMSIA field calculation were mapped onto the enzyme binding site. It gave us the opportunity to discuss the structure–activity relationship based on the ligand–enzyme interactions. In particular, examination of the electrostatic properties of the established CoMFA model revealed fields that correspond to the regions where electropositive substituents are not desired, e.g., in the neighborhood of the 1,3,4-oxadiazol-2-one moiety. This highlights the importance of heterocycle, a highly electronegative moiety in this area of each ligand. Examination of hydrogen bond donor and acceptor properties contour maps revealed several spots where the implementation of another hydrogen-bond-donating moiety will positively impact molecules’ binding affinity, e.g., in the neighborhood of the 1,3,4-oxadiazol-2-one ring. On the other hand, there is a large isopleth that refers to the favorable H-bond properties close to the terminal phenoxy group of a ligand, which means that, generally speaking, H-bond acceptors are desired in this area.

l-Type amino acid transporter 1 (LAT1) is an interesting protein due to its peculiar expression profile. It can be utilized not only as a carrier for improved or targeted drug delivery, e.g., into the brain but also as a target protein by which amino acid supply can be restricted, e.g., from the cancer cells. The recognition and binding processes of LAT1-ligands, such as amino acids and clinically used small molecules, including l-dopa, gabapentin, and melphalan, are today well-known. Binding to LAT1 is crucial, particularly when designing the LAT1-inhibitors. However, it will not guarantee effective translocation across the cell membrane via LAT1, which is a definite requirement for LAT1-substrates, such as drugs that elicit their pharmacological effects inside the cells. Therefore, in the present study, the accumulation of known LAT1-utilizing compounds into the selected LAT1-expressing cancer cells (MCF-7) was explored experimentally over a time period. The differences found among the transport efficiency and affinity of the studied compounds for LAT1 were subsequently explained by docking the ligands into the human LAT1 model (based on the recent cryo-electron microscopy structure). Thus, the findings of this study clarify the favorable structural requirements of the size, shape, and polarity of the ligands that support the translocation and effective transport across the cell membrane via LAT1. This knowledge can be applied in future drug design to attain improved or targeted drug delivery and hence, successful LAT1-utilizing drugs with increased therapeutic effects.

Drug-target Interactions (DTIs) prediction plays a central role in drug discovery. Computational methods in DTIs prediction have gained more attention because carrying out in vitro and in vivo experiments on a large scale is costly and time-consuming. Machine learning methods, especially deep learning, are widely applied to DTIs prediction. In this study, the main goal is to provide a comprehensive overview of deep learning-based DTIs prediction approaches. Here, we investigate the existing approaches from multiple perspectives. We explore these approaches to find out which deep network architectures are utilized to extract features from drug compound and protein sequences. Also, the advantages and limitations of each architecture are analyzed and compared. Moreover, we explore the process of how to combine descriptors for drug and protein features. Likewise, a list of datasets that are commonly used in DTIs prediction is investigated. Finally, current challenges are discussed and a short future outlook of deep learning in DTI prediction is given.

Water networks within kinase inhibitor design and more widely within drug discovery are generally poorly understood. The successful targeting of these networks prospectively has great promise for all facets of inhibitor design, including potency and selectivity on target. Here we describe the design and testing of a targeted library of 4-anilinoquinolines for use as inhibitors of cyclin G associated kinase (GAK). The GAK cellular target engagement assays, ATP binding site modelling and extensive water mapping provide a clear route to access potent inhibitors for GAK and beyond.

Made available in DSpace on 2020-12-10T20:04:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The enzyme dihydrofolate reductase from M. tuberculosis (MtDHFR) has a high unexploited potential to be a target for new drugs against tuberculosis (TB), due to its importance for pathogen survival. Preliminary studies have obtained fragment-like molecules with low affinity to MtDHFR which can potentially become lead compounds. Taking this into account, the fragment MB872 was used as a prototype for analogue development by bioisosterism/retro-bioisosterism, which resulted in 20 new substituted 3-benzoic acid derivatives. Compounds were active against MtDHFR, with IC50, values ranging from 7 to 40 mu M, where compound 4e not only had the best inhibitory activity (IC50 = 7 mu M), but also was 71-fold more active than the original fragment MB872. The 4e inhibition kinetics indicated an uncompetitive mechanism, which was supported by molecular modeling which suggested that the compounds can access an independent backpocket from the substrate and competitive inhibitors. Thus, based on these results, substituted 3-benzoic acid derivatives have strong potential to be developed as novel MtDHFR inhibitors and also anti-TB agents. Univ Hosp Tubingen, Dept Oncol & Pneurnonol, Internal Med 8, Otfried Muller Str 10, DE-72076 Tubingen, Germany Univ Eastern Finland, Fac Hlth Sci, Sch Pharm, Kuopio 70211, Finland Univ Sao Paulo, Fac Pharmaceut Sci, Dept Pharm, Lab Mol Biol Appl Diag LBMAD, Sao Paulo, SP, Brazil Univ Sao Paulo, Fac Pharmaceut Sci, Lab Design & Synth Bioact Subst LAPESSB, Prof Lineu Prestes Ave 580,Bl 13, Sao Paulo, SP, Brazil Univ Sao Paulo, Fac Pharmaceut Sci, Dept Pharm, Lab Design & Synth Chemotherapeut Potentially Act, Sao Paulo, SP, Brazil Univ Sao Paulo, Inst Biomed Sci, Dept Microbiol, Sao Paulo, SP, Brazil Sao Paulo State Univ, UNESP Amraquara, Dept Biol Sci, Sch Pharmaceut Sci, Sao Paulo, Brazil Univ Sao Paulo, Fac Pharmaceut Sci, Dept Pharm, Prof Lineu Prestes Ave 580,Bl 13, Sao Paulo, SP, Brazil Univ Warwick, Dept Chem, Coventry CV4 7AL, W Midlands, England Sao Paulo State Univ, UNESP Amraquara, Dept Biol Sci, Sch Pharmaceut Sci, Sao Paulo, Brazil CNPq: 153232/2018-8 CNPq: 436791/2018-8 CNPq: 310232/2017-1 FAPESP: 2013/15906-5 FAPESP: 2013/18160-4 FAPESP: 2017/00689-0 FAPESP: 2017/25543-8

A quantitative structure-property relationship (QSPR) between protein stability and the physicochemical properties of excipients was investigated to enable a more rational choice of stabilizing excipients than prior knowledge. The thermal transition temperature and aggregation time were determined for lysozyme in combination with 13 different amino acids using high throughput fluorescence spectroscopy and kinetic static light scattering measurements. On the theoretical side, around 200 2D and 3D molecular descriptors were calculated based on the amino acids’ chemical structure. Multivariate data analysis was applied to correlate the descriptors with the experimental results. It was possible to identify descriptors, i.e. amino acids properties, with a positive influence on either transition temperature or aggregation onset time, or both. A high number of hydrogen bond acceptor moieties was the most prominent stabilizing factor for both responses, whereas hydrophilic surface properties and high molecular mass density mostly had a positive influence on the unfolding temperature. A high partition coefficient (logP(o/w)) was identified as the most prominent destabilizing factor for both responses. The QSPR shows good correlation between calculated molecular descriptors and the measured stabilizing effect of amino acids on lysozyme., final draft, peerReviewed

Enoyl‐acyl carrier protein reductase (FabI) is the limiting step to complete the elongation cycle in type II fatty acid synthase (FAS) systems and is a relevant target for antibacterial drugs. E. coli FabI has been employed as a model to develop new inhibitors against FAS, especially triclosan and diphenyl ether derivatives. Chemical similarity models (CSM) were used to understand which features were relevant for FabI inhibition. Exhaustive screening of different CSM parameter combinations featured chemical groups, such as the hydroxy group, as relevant to distinguish between active/decoy compounds. Those chemical features can interact with the catalytic Tyr156. Further molecular dynamics simulation of FabI revealed the ionization state as a relevant for ligand stability. Also, our models point the balance between potency and the occupancy of the hydrophobic pocket. This work discusses the strengths and weak points of each technique, highlighting the importance of complementarity among approaches to elucidate EcFabI inhibitor's binding mode and offers insights for future drug discovery., Enoyl‐acyl carrier protein reductase (FabI) is an enzyme from the fatty acid synthesis pathway and is considered a relevant target for antibacterial drugs. Triclosan and diphenyl ether derivatives are known to exert their antibacterial activity by inhibiting FabI. In this sense, exhaustive chemical similarity models (CSM) and 200‐ns‐long molecular dynamics simulations were used to understand which features and intermolecular interactions were relevant for FabI inhibition.

Focused libraries of multi-substituted epidithiodiketopiperazines (ETP) were prepared and evaluated for efficacy of inhibiting the nucleocapsid protein function of the Feline Immunodeficiency Virus (FIV) as a model for HIV. This activity was compared and contrasted to observed toxicity utilising an in-vitro cell culture approach. This resulted in the identification of several promising lead compounds with nanomolar potency in cells with low toxicity and a favorable therapeutic index.

The 4-anilinoquinoline and 4-anilinoquinazoline ring systems have been the focus of significant efforts in prior kinase drug discovery programs, which have led to approved medicines. Broad kinome profiles of these compounds have now been assessed with the advent of advanced screening technologies. These ring systems, while originally designed for specific targets including epidermal growth factor receptor (EGFR), but actually display a number of potent collateral kinase targets, some of which have been associated with negative clinical outcomes. We have designed and synthesized a series of 4-anilinoquin(az)olines in order to better understand the structure-activity relationships of three main collateral kinase targets of quin(az)oline-based kinase inhibitors: cyclin G associated kinase (GAK), STE20-like serine/threonine-protein kinase (SLK) and serine/threonine-protein kinase 10 (STK10). This was achieved through a series of quantitative structure-activity relationship (QSAR) analysis, water mapping of the kinase ATP binding sites and extensive small-molecule X-ray structural analysis.

In order to search for novel antipsychotics acting through the D2 receptor, it is necessary to know the structure&ndash, activity relationships for dopamine D2 receptor antagonists. In this context, we constructed the universal three-dimensional quantitative structure&ndash, activity relationship (3D- QSAR) model for competitive dopamine D2 receptor antagonists. We took 176 compounds from chemically different groups characterized by the half maximal inhibitory concentration (IC50)from the CHEMBL database and docked them to the X-ray structure of the human D2 receptor in the inactive state. Selected docking poses were applied for Comparative Molecular Field Analysis (CoMFA) alignment. The obtained CoMFA model is characterized by a cross-validated coefficient Q2 of 0.76 with an optimal component of 5, R2 of 0.92, and an F value of 338.9. The steric and electrostatic field contributions are 67.4% and 32.6%, respectively. The statistics obtained prove that the CoMFA model is significant. Next, the IC50 of the 16 compounds from the test set was predicted with R2 of 0.95. Finally, a progressive scrambling test was carried out for additional validation. The CoMFA fields were mapped onto the dopamine D2 receptor binding site, which enabled a discussion of the structure&ndash, activity relationship based on ligand&ndash, receptor interactions. In particular, it was found that one of the desired steric interactions covers the area of a putative common allosteric pocket suggested for some other G protein-coupled receptors (GPCRs), which would suggest that some of the known dopamine receptor antagonists are bitopic in their essence. The CoMFA model can be applied to predict the potential activity of novel dopamine D2 receptor antagonists.

We report the first biological evaluation the 1,2,3-thiaselenazole class of compound and utilising a concise synthetic approach of sulfur extrusion, selenium insertion of the 1,2,3-dithiazoles. We created a small diverse library of compounds to contrast the two ring systems. This approach has highlighted new structure activity relationship insights and lead to the development of sub-micro molar anti-viral compounds with reduced toxicity. The 1,2,3-thiaselenazole represents a new class of potential compounds for the treatment of FIV and HIV.

A diverse library of 5-thieno-, 5-oxo-, and 5-imino-1,2,3-dithiazole derivatives was synthesized and evaluated for efficacy against the feline immunodeficiency virus (FIV) as a model for HIV in cells. Several diverse compounds from this series displayed nanomolar activity and low toxicity, representing a potential new class of compounds for the treatment of FIV and HIV.

Structure-based virtual screening using a D2 receptor homology model was performed to identify dopamine D2 receptor ligands as potential antipsychotics. From screening a library of 6.5 million compounds, 21 were selected and were subjected to experimental validation. From these 21 compounds tested, ten D2 ligands were identified (47.6% success rate, among them D2 receptor antagonists, as expected) that have additional affinity for other receptors tested, in particular 5-HT2A receptors. The affinity (Ki values) of the compounds ranged from 58 nm to about 24 μM. Similarity and fragment analysis indicated a significant degree of structural novelty among the identified compounds. We found one D2 receptor antagonist that did not have a protonatable nitrogen atom, which is a key structural element of the classical D2 pharmacophore model necessary for interaction with the conserved Asp(3.32) residue. This compound exhibited greater than 20-fold binding selectivity for the D2 receptor over the D3 receptor. We provide additional evidence that the amide hydrogen atom of this compound forms a hydrogen bond with Asp(3.32), as determined by tests of its derivatives that cannot maintain this interaction.

In order to apply structure-based drug design techniques to GPCR complexes, it is essential to model their 3D structure. For this purpose, a multi-component protocol was derived based on protein-protein docking which generates populations of dimers compatible with membrane integration, considering all reasonable interfaces. At the next stage, we applied a scoring procedure based on up to eleven different parameters including shape or electrostatics complementarity. Two methods of consensus scoring were performed: (i) average scores of 100 best scored dimers with respect to each interface, and (ii) frequencies of interfaces among 100 best scored dimers. In general, our multi-component protocol gives correct indications for dimer interfaces that have been observed in X-ray crystal structures of GPCR dimers (opsin dimer, chemokine CXCR4 and CCR5 dimers, κ opioid receptor dimer, β1 adrenergic receptor dimer and smoothened receptor dimer) but also suggests alternative dimerization interfaces. Interestingly, at times these alternative interfaces are scored higher than the experimentally observed ones suggesting them to be also relevant in the life cycle of studied GPCR dimers. Further results indicate that GPCR dimer and higher-order oligomer formation may involve transmembrane helices (TMs) TM1-TM2-TM7, TM3-TM4-TM5 or TM4-TM5-TM6 but not TM1-TM2-TM3 or TM2-TM3-TM4 which is in general agreement with available experimental and computational data.

In the era of increased antibiotic resistance, targeting enzymes involved in bacterial communication (quorum sensing) represents a new strategy to fight bacterial infections. LsrK is a kinase responsible for the phosphorylation of autoinducer-2, a signaling molecule involved in quorum sensing. Inhibiting LsrK would lead to quorum sensing inactivation and interfere with the pathogenesis. In this study, we built the first LsrK 3D model and performed virtual screening of a locally available database. Selected compounds were tested against LsrK, and the analogue search conducted based on the positive hits led to the identification of low-micromolar LsrK inhibitors. These results prove the utility of the model and provide the first class of LsrK inhibitors to be further optimized as antivirulence agents.

9 N-alkylated derivatives of dextromethorphan are synthesized and studied as non-competitive inhibitors of α3β4 nicotinic acetylcholine receptors (nAChRs). In vitro activity towards α3β4 nicotinic acetylcholine receptor is determined using a patch-clamp technique and is in the micromolar range. Homology modeling, molecular docking and molecular dynamics of ligand-receptor complexes in POPC membrane are used to find the mode of interactions of N-alkylated dextromethorphan derivatives with α3β4 nAChR. The compounds, similarly as dextromethorphan, interact with the middle portion of α3β4 nAChR ion channel. Finally, behavioral tests confirmed potential application of the studied compounds for the treatment of addiction.

L-Type amino acid transporter 1 (LAT1) is a transmembrane protein expressed abundantly at the blood-brain barrier (BBB), where it ensures the transport of hydrophobic acids from the blood to the brain. Due to its unique substrate specificity and high expression at the BBB, LAT1 is an intriguing target for carrier-mediated transport of drugs into the brain. In this study, a comparative molecular field analysis (CoMFA) model with considerable statistical quality (Q(2) =0.53, R(2) =0.75, Q(2) SE=0.77, R(2) SE=0.57) and good external predictivity (CCC=0.91) was generated. The model was used to guide the synthesis of eight new prodrugs whose affinity for LAT1 was tested by using an in situ rat brain perfusion technique. This resulted in the creation of a novel LAT1 prodrug with L-tryptophan as the promoiety; it also provided a better understanding of the molecular features of LAT1-targeted high-affinity prodrugs, as well as their promoiety and parent drug. The results obtained will be beneficial in the rational design of novel LAT1-binding prodrugs and other compounds that bind to LAT1.

Herein, we report the development of novel functionalized congeners of ropinirole toward the design of pharmacological tools to probe structural requirements at the dopamine D2 receptor. Subsequently, we have used the functionalized amine congener 11 and synthesized and pharmacologically evaluated a series of homobivalent ligands of ropinirole with designated spacer lengths ranging from 14 to 30 atoms. The most potent homobivalent ligands (22-, 26- and 30-atom spacers) showed approximately 20- to 80-fold greater potency (EC50 = 3.9, 6.2 and 14 nM, respectively) than ropinirole (304 nM) in a [35S]GTPγS functional assay. Molecular modeling studies suggest that the observed increase in potency of the homobivalent ligands is possibly due to a bitopic binding mode involving the orthosteric site and an allosteric interaction at the dopamine D2 receptor protomer rather than bridging interactions at two orthosteric sites across a dopamine D2 receptor dimer. This research has the potential to advance the development of structurally related bitopic ligands, biomarkers such as radioligands and fluorescently labeled probes, and furnish new homo- and heterobivalent ligands towards a better understanding of the dopamine D2 receptor and potential novel treatment for Parkinson's disease.

The tautomerism of N-substituted 3-amino-5-oxo-4-phenyl-1H-pyrazolo-1-carboxamides with antibacterial activity is studied with X-ray crystallography, IR, 1H and 13C NMR (including NOESY spectra) and quantum chemical calculations. It is found that the form with the keto group at position 5 is the preferred one in the crystalline state and in DMSO, although some fraction with the corresponding hydroxy group also occurs in both states. This finding was related to the antibacterial activity of the studied compounds as the energetic stabilization of the keto group may determine their proper hydrogen bond interactions with the bacterial enzyme.

Kallikrein-related peptidase 3 (KLK3) is a prostatic serine protease shown to possess antiangiogenic properties which are exerted via its proteolytic activity. The antiangiogenic effect indicates that KLK3 may slow down the growth of prostate cancer; this makes it an interesting target for new therapies for prostate cancer. In this work, new drug-like compounds were discovered that stimulate the proteolytic activity of KLK3. The compounds were identified using 2D similarity search and 3D pharmacophore-based virtual screening, and their ability to stimulate KLK3 was verified by enzymatic activity assays. The effect of the molecules alone was modest, but in synergy with a cyclic peptide the most potent molecule was found to stimulate KLK3 activity significantly: up to 351 % of the activity of KLK3. This demonstrates that small drug-like compounds can be beneficial tools in studying the antiangiogenic properties of KLK3.

SIRT6 belongs to the family of histone deacetylases (class III), but it also has mono-ADP-ribosyltransferase activity. SIRT6 is a nuclear sirtuin that has been associated with aging, cellular protection, and sugar metabolism. Despite these important roles for SIRT6, thus far, there are only a few weak SIRT6 inhibitors available, and no structure-activity relationship (SAR) studies have been published. This is the first study concerning peptides and pseudopeptides as SIRT6 deacetylation inhibitors and the first SAR data concerning SIRT6. We also investigated the molecular interactions using a homology model. We report three compounds exhibiting 62-91% SIRT6 inhibition at 200 μM concentration. These compounds can serve as starting points for systematic SAR studies and SIRT6 inhibitor design.

Sirtuins catalyze the NAD+ dependent deacetylation of Ne-acetyl lysine residues to nicotinamide, O′-acetyl-ADP-ribose (OAADPR) and Ne-deacetylated lysine. Here, an easy-to-synthesize Ac-Ala-Lys-Ala sequence has been used as a probe for the screening of novel Ne-modified lysine containing inhibitors against SIRT1 and SIRT2. Ne-Selenoacetyl and Ne-isothiovaleryl were the most potent moieties found in this study, comparable to the widely studied Ne-thioacetyl group. The Ne-3,3-dimethylacryl and Ne-isovaleryl moieties gave significant inhibition in comparison to the Ne-acetyl group present in the substrates. In addition, the studied Ne-alkanoyl, Ne-α,β-unsaturated carbonyl and Ne-aroyl moieties showed that the acetyl binding pocket can accept rather large groups, but is sensitive to even small changes in electronic and steric properties of the Ne-modification. These results are applicable for further screening of Ne-acetyl analogues.

Carbamates are a well-established class of fatty acid amide hydrolase (FAAH) inhibitors. Here we describe the synthesis of meta-substituted phenolic N-alkyl/aryl carbamates and their in vitro FAAH inhibitory activities. The most potent compound, 3-(oxazol-2yl)phenyl cyclohexylcarbamate (2 a), inhibited FAAH with a sub-nanomolar IC(50) value (IC(50)=0.74 nM). Additionally, we developed and validated three-dimensional quantitative structure-activity relationships (QSAR) models of FAAH inhibition combining the newly disclosed carbamates with our previously published inhibitors to give a total set of 99 compounds. Prior to 3D-QSAR modeling, the degree of correlation between FAAH inhibition and in silico reactivity was also established. Both 3D-QSAR methods used, CoMSIA and GRID/GOLPE, produced statistically significant models with coefficient of correlation for external prediction (R(2) (PRED)) values of 0.732 and 0.760, respectively. These models could be of high value in further FAAH inhibitor design.

To date, many known G protein-coupled receptor 55 (GPR55) ligands are those identified among the cannabinoids. In order to further study the function of GPR55, new potent and selective ligands are needed. In this study, we utilized the screening results from PubChem bioassay AID 1961 which reports the results of Image-based HTS for Selective Agonists of GPR55. Three compounds, CID1792579, CID1252842 and CID1011163, were further evaluated and used as a starting point to create a series of nanomolar potency GPR55 agonists with N-(4-sulfamoylphenyl)thiourea scaffold. The GPR55 activity of the compounds were screened by using a commercial β-arrestin PathHunter assay and the potential compounds were further evaluated by using a recombinant HEK cell line exhibiting GPR55-mediated effects on calcium signalling. The designed compounds were not active when tested against various endocannabinoid targets (CB1R, CB2R, FAAH, MGL, ABHD6 and ABHD12), indicating compounds' selectivity for the GPR55. Finally, structure-activity relationships of these compounds were explored.

Results from a factor analysis and activity studies of commercially available endocannabinoid-type compounds set the starting point for the current study where dimethylheptyl (DMH) analogues of two endocannabinoids, 2-arachidonoyl glycerol (2-AG) and 2-arachidonyl glyceryl ether (2-AGE), were synthesized and their ability to activate the CB1 receptors was determined by the [35S]GTPgammaS binding assay using rat cerebellar membranes. The main goal of the study was to examine how the DMH end tail affects the activity properties of 2-AG (1) and its stable ether (2) and urea analogues (5). The importance of the chain length was also explored by synthesizing 2-AG and 2-AGE derivatives (3 and 4) possessing the chain length C21 instead of C22. Replacement of the pentyl end chain with the DMH resulted in distinct potency decrease as compared to the reference compounds. The modification did not have such a strong impact on the efficacy values. In fact, the efficacy of the derivatives of 2-AGE (2 and 4) was comparable or even improved. Introducing a more stable and hydrophilic urea bond led to a dramatic decrease in biological activity.

Since the discovery of the cannabinoid CB2 receptor in 1993, there has been a growing interest to clarify the importance of this G-protein coupled receptor (GPCR) for human physiology, and to investigate it as a possible target for current and future drug development. Several mutation studies have examined the receptor activation and structure of the receptor binding cavity. Additionally, 3D models for the CB2 receptor have been constructed to aid in perceiving important ligand-receptor interactions. In recent years, many research groups have succeeded in synthesizing new CB2 selective ligands. This review focuses on (i) important features for ligand recognition and/or receptor activation at CB2, derived from mutation and modeling studies, and (ii) recent advances in the field of CB2 selective ligands.

The constitutive androstane receptor (CAR) belongs to the superfamily of nuclear-hormone receptors that function as ligand-activated transcription factors. CAR plays an essential role in the metabolism of xenobiotics and shows—in contrast to related receptors—constitutive activity. However, the molecular basis for the constitutive activity remains unclear. In the present study, homology models of the ligand binding domain (LBD) were generated based on the crystal structures of the related pregnane X (PXR) and the vitamin D receptor (VDR). The models were used to investigate the basal activity of CAR and the effect of coactivator binding. Molecular dynamics (MD) simulations of complexed and uncomplexed receptor revealed a hypothesis for the activation mechanism. The suggested mechanism is supported by experimental results from site-directed mutagenesis. The basal activity of CAR can be explained by specific van-der-Waals interactions between amino acids on the LBD and its C-terminal activation domain (AF-2). Docking studies with the GOLD program yielded the interaction modes of structurally diverse agonists, giving insight into mechanisms by which ligands enhance CAR activity. Figure The constitutive activity. Favorable regions of interactions between the GRID methyl probe and the AF-2 truncated LBD (colored magenta, contour level -2.5 kcal mol 1). Only the MOLCAD surface of the LBD is shown, colored according to the lipophilic potential (blue polar, brown lipophilic). The position of the two hydrophobic residues Leu343 and Ile346 from the AF-2 helix (colored cyan) is in close agreement with the GRID results.

A novel series of fused tetrathiocines were prepared for evaluation of activity against the nucleocapsid protein of the feline immunodeficiency virus (FIV) in an in vitro cell culture approach. The results demonstrated that the compounds display potent nanomolar activity and low toxicity against this key model of HIV infection.

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA-blocked mutant with all possible monofluoro 3-aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.

A diverse library of bis[1,2]dithiolo[1,4]thiazines and bis[1,2]dithiolopyrrole derivatives were prepared for evaluation of activity against the nucleocapsid protein of the Feline Immunodeficiency Virus (FIV) as a model for HIV, using an in vitro cell culture approach, yielding nanomolar active compounds with low toxicity.

Purpose. In polymeric coatings, plasticizers are used to improve the film-forming characteristic of the polymers. In this study, a computerized method (VolSurf with GRID) was used as a novel tool for the prediction plasticization efficiency (β) of test compounds, and for determining the critical molecular properties needed for polymer plasticization.

Purpose. The deformation behaviors of compressedfreeze-dried and spray-dried tolbutamide/hydroxypropyl-β-cyclodextrinmolecular dispersions were evaluated and compared with similarly preparedtolbutamides (TBM), hydroxypropyl-β-cyclodextrins (HP-β-CD) and astheir physical dispersions.