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Inhibitors of the coagulation factor XIIa (FXIIa) are attractive to detail the roles of this protease in hemostasis and thrombosis, to suppress artifact due to contact pathway activation in blood coagulation assays, and they are promising as antithrombotic therapy. The 3-carboxamide coumarins have been previously described as small-molecular-weight FXIIa inhibitors. In this study, we report a structure-activity relationship (SAR) study around this scaffold with the aim to discover new selective FXIIa inhibitors with an improved physico-chemical profile. To better understand these SAR, docking experiments were undertaken. For this purpose, we built an original hybrid model of FXIIa. This model has the advantage to gather the best features from the recently published crystal structure of FXIIa in its zymogen form and a more classical homology model. Results with the hybrid model are encouraging as they help understanding the activity and selectivity of our best compounds.

Highly functionalized 5-bromo-2-amino-1,3-thiazoles bearing various substituents could be easily prepared by a rapid and efficient one-pot method, using simple starting materials and mild conditions while avoiding the use of metal catalysts or inconvenient reagents such as elemental halogens. These useful products can serve as starting materials for other reactions or as pharmacologically interesting compounds. In our work we have shown that the resulting 5-bromothiazole compounds could lead to monoacylglycerol lipase (MAGL) inhibition in the μM range.

Introduction: The inhibition of indoleamine 2,3-dioxygenase (IDO) has emerged as a key area in cancer immunotherapy in the past decade. Despite the large variety of potential inhibitors screened so far, the number of active scaffolds remains limited. Areas covered: All relevant patent literature published between 2008 and 2012 is reviewed. Representative examples are given for each patent and/or class of compounds along with data (if available) on their inhibitory activity. The presentation is deepened by additional data published in peer-reviewed literature. Expert opinion: Key events that stimulated the search of IDO inhibitors are presented. To date, however, the number of available scaffolds remains limited with only one confirmed inhibitor (from Incyte Corp.) in the clinic. Major challenges in the search for IDO inhibitors are discussed as well as the relevance of selectivity of IDO inhibition versus inhibition of tryptophan 2,3-dioxygenase. © 2013 Informa UK, Ltd.

Tsitsikammamines are marine alkaloids whose structure is based on the pyrroloiminoquinone scaffold. These and related compounds have attracted attention due to various interesting biological properties, including cytotoxicity, topoisomerase inhibition, antimicrobial, antifungal and antimalarial activity. Indoleamine 2,3-dioxygenase (IDO1) is a well-established therapeutic target as an important factor in the tumor immune evasion mechanism. In this preliminary communication, we report the inhibitory activity of tsitsikammamine derivatives against IDO1. Tsitsikammamine A analogue 11b displays submicromolar potency in an enzymatic assay. A number of derivatives are also active in a cellular assay while showing little or no activity towards tryptophan 2,3-dioxygenase (TDO), a functionally related enzyme. This IDO1 inhibitory activity is rationalized by molecular modeling studies. An interest is thus established in this class of compounds as a potential source of lead compounds for the development of new pharmaceutically useful IDO1 inhibitors.

Three isomers of chloro-3-(2-pyridin-3-ylvinyl)-1H-indole were synthesized and tested as inhibitors of human tryptophan 2,3-dioxygenase (hTDO). The crystal structures of two of them were solved by X-ray diffraction. The solubility of the molecules also was determined experimentally. The molecular electrostatic potentials and dipole moments of the three isomers were calculated by ab initio quantum mechanics (HF/6-311G). The single crystal X-ray analyses reveal non-planar structures. This non-coplanarity is retained during docking of the compounds into a model of hTDO, the molecular target of this series. The position of the Cl atom does not significantly affect the electronic delocalization. Nevertheless, the position of the Cl atom produces a local variation of bond lengths inducing different dipole moments for these isomers. Variations in dipole moments are consistent with the different melting points and crystal packings. Differences in aqueous solubilities are best explained by subtle changes in H-bonds resulting from different accessibilities of the indole NH's due to steric effects of the Cl substituent. The non-coplanarity plays an important role in the crystalline packing of the molecules in contrast to the position of the Cl. This study leads to a better understanding of the structural and electronic characteristics of this chemical series and can potentially help to better understand their inhibitory activity. © 2012 Elsevier Masson SAS. All rights reserved.

Tryptophan catabolism mediated by indoleamine 2,3-dioxygenase (IDO1) is an important mechanism of peripheral immune tolerance contributing to tumoral immune resistance, and IDO1 inhibition is an active area of drug development. Tryptophan 2,3-dioxygenase (TDO) is an unrelated hepatic enzyme that also degrades tryptophan along the kynurenine pathway. Here, we show that enzymatically active TDO is expressed in a significant proportion of human tumors. In a preclinical model, TDO expression by tumors prevented their rejection by immunized mice. We developed a TDO inhibitor, which, upon systemic treatment, restored the ability of mice to reject TDO-expressing tumors. Our results describe a mechanism of tumoral immune resistance based on TDO expression and establish proof-of-concept for the use of TDO inhibitors in cancer therapy.

Tryptophan catabolism mediated by indoleamine 2,3-dioxygenase (IDO) is an important mechanism of peripheral immune tolerance contributing to tumoral immune resistance. IDO inhibition is thus an active area of research in drug development. Recently, our group has shown that tryptophan 2,3-dioxygenase (TDO), an unrelated hepatic enzyme also catalyzing the first step of tryptophan degradation, is also expressed in many tumors and that this expression prevents tumor rejection by locally depleting tryptophan. Herein, we report a structure-activity study on a series of 3-(2-(pyridyl)ethenyl)indoles. More than 70 novel derivatives were synthesized, and their TDO inhibitory potency was evaluated. The rationalization of the structure-activity relationships (SARs) revealed essential features to attain high TDO inhibition and notably a dense H-bond network mainly involving His(55) and Thr(254) residues. Our study led to the identification of a very promising compound (58) displaying good TDO inhibition (K(i) = 5.5 μM), high selectivity, and good oral bioavailability. Indeed, 58 was chosen for preclinical evaluation.

Indoleamine 2,3-dioxygenase (IDO) is an important new therapeutic target for the treatment of cancer. With the aim of discovering novel IDO inhibitors, a virtual screen was undertaken and led to the discovery of the keto-indole derivative 1a endowed with an inhibitory potency in the micromolar range. Detailed kinetics were performed and revealed an uncompetitive inhibition profile. Preliminary SARs were drawn in this series and corroborated the putative binding orientation as suggested by docking. © 2011 Elsevier Masson SAS. All rights reserved.

International audience; Atomic force microscopy (AFM) was used to measure single interaction forces between corrole (host) and phenol derivatives (guests) in aqueous media. A gold tip was modified with thiol derivatives of corrole via the Au-S covalent bond. Such a tip was used to measure adhesion forces with a planar gold substrate modified with thiol-derivatives of phenol and ortho–nitrophenol in aqueous solutions. The mean force between the corrole and ortho–nitrophenol was higher than that between corrole and phenol, probably reflecting stronger hydrogen bond interaction in the former complex. In the presence of supporting electrolyte (0.1 M K2SO4), the mean force increased, suggesting that electrostatic and π-π interactions play an essential role in the adhesion force. In addition, adhesion force measured at pH 6.0 was larger than that at pH 10, reflecting the electrostatic repulsion at the higher pH. These behaviors are consistent with the potentiometric responses of a liquid membrane based on corrole to phenolic compounds. Also, the values of forces for interaction between corrole – phenol derivatives showed the same tendency as energy calculated for these complexes. The Poisson method was used for the calculation of the single force of the chemical bond between the corrole host and the phenolic guests.

Here, we report on an ion-channel mimetic sensor using self-assembly monolayers deposited onto gold electrodes for electrochemical determination of dopamine. The different compositions of the modification solution consist of corrole-SH and other thiol derivatives used as the "background compounds" such as 1-dodecanethiol (DDT), 6-mercapto-1-hexanol (HS(CH(2))(6)OH), or 11-mercapto-1-undecanol (HS(CH(2))(11)OH) were explored to find the best self-assembled monolayer (SAM) suitable for dopamine determination. Among them, the mixed SAM consisting of corroles with the -SH group and 6-mercapto-1-hexanol (HS(CH(2))(6)OH) in the molar ratio 1:10 was the most sensitive. The signals generated by the formation of a complex between the corrole host and the dopamine guest were measured by Osteryoung square-wave voltammetry (OSWV) and electrochemical impedance spectroscopy (EIS) with [Ru(NH(3))(6)](3+) as an electroactive marker. The developed sensor was free of interferences of components of human plasma such as ascorbic acid, creatinine, creatine, and uric acid. The detection limits observed by EIS in buffer solution and in the presence of centrifuged human plasma 80 times diluted with a 0.9% NaCl containing 0.01 M borate buffer solution of pH 7.0 were 3.3 x 10(-12) and 5.3 x 10(-12) M, respectively.

Here, we report on the application of corroles as analytically active compounds in liquid membrane electrodes (ISE) that are sensitive towards salicylic acid and salicylate. The potentiometric signals generated by corrole-incorporated ISEs strongly depend on the pH of the aqueous sample solution and the membrane composition, such as the presence of lipophilic sites. Corrole incorporating ISEs are characterised by a low detection limit (4.0 × 10−5 M) and a wide linear range (4.0 × 10−5 to 5.3 × 10−3 M). Also, they are free from interference versus other organic anions. The mechanism of the generation of the potentiometric signals of corrole incorporating ISEs in the presence of salicylate anion, as well salicylic acid, will be discussed.

2-Methylindole-3-acetic acid (2-Me-IAA) is a known auxin, but its 2-ethyl homologue has been considered inactive. Here we show that the compound previously bioassayed as ‘2-ethylindole-3-acetic acid’ (2-Et-IAA) was, in fact, 3-(3-methylindol-2-yl)propionic acid. The proper 2-Et-IAA and its 2-(n-propyl) homologue (2-Pr-IAA) are prepared, unambiguously characterized, and their auxin activity is demonstrated in the Avena coleoptile-section straight-growth test. Their half-optimal concentrations are approximately the same as for 2-Me-IAA (2 × 10−5mol L−1), and hence about ten times larger than for unsubstituted indole-3-acetic acid (IAA) and its derivatives alkylated in positions 4, 5, 6 or 7. The optimal response elicited by 2-Et-IAA and 2-Pr-IAA is about half that observed for 2-Me-IAA. These characteristics place the three 2-alkyl-IAAs along the borderline between the classes of strong and weak auxins, thus corroborating the results of interaction similarity analysis, a mathematical approach based on the capability of auxin molecules to participate in non-bonding interactions with a generalized receptor protein. X-ray diffraction analysis shows no explicit structural features to be blamed for the decrease in auxin activity caused by attaching a 2-alkyl substituent to the IAA molecule; sterical interference of the 3-CH2COOH group and the 2-alkyl moiety is barely recognizable in the crystalline state. Quantum-chemical calculations and molecular dynamics simulations suggest that 2-alkyl-IAAs, in the absence of crystal-packing restraints, prefer conformations with the CH2-COOH bond tilted to the heterocyclic ring system. Substantially higher conformational energy (and hence lower abundance) is predicted for planar conformers which were previously shown to prevail for IAA and many of its derivatives substituted in the benzene moiety of the indole nucleus. This shift in the rotational preferences of the -CH2COOH moiety may be one of the reasons for the reduced plant-growth promoting activity of 2-alkyl-IAAs.

Tryptophan catabolism mediated by indoleamine 2,3-dioxygenase (IDO) is an important mechanism of peripheral immune tolerance contributing to tumoral immune resistance.1 IDO inhibition has been an active area of research in drug development for a number of years.2 Recently, our group has shown that tryptophan 2,3 dioxygenase (TDO), an unrelated hepatic enzyme also catalyzing the first step of tryptophan degradation, is as well expressed in many tumors preventing their rejection by locally depleting tryptophan.3 The role of tryptophan catabolites was demonstrated by another group.4 Herein, we report the syntheses and structure-activity studies around a series of 3-(2-(pyridyl)ethenyl)indoles.5 Some 80 novel heterocyclic compounds were synthesized. Their TDO inhibitory potency was evaluated and rationalized by molecular modeling studies. The best candidate in terms of potency, selectivity, solubility and oral bioavailability was evaluated in a preclinical model in mice. Upon systemic treatment, the compound reversed TDO-mediated tumoral immune resistance.6 References This work was supported in part by FNRS-Télévie (7.4.543.07). 1) Uyttenhove, C., et al, Nat. Med. 2003, 9, 1269-1274. 2) Macchiarulo, A., et al, Amino Acids 2009, 37, 219-229; Röhrig, U. F., et al, J. Med. Chem. 2010, 53, 1172-1189. 3) Van den Eynde, B., et al, WO2010008427, 2010. 4) Opitz, C. A., et al, Nature 2011, 478, 197-203. 5) Dolusic, E., et al, J. Med. Chem. 2011, 54, 5320-5334. 6) Pilotte, L., et al, Proc. Natl. Acad. Sci. USA 2012, 109, 2497 - 2502.

Tetrapyrrole macrocycles, of which the pyrroles are connected by sp2 centers, were readily obtained from porphyrin tetraphenols by air oxidation under basic conditions, followed by N-alkylation. The degree of N-alkylation could be controlled and either di- or tetraalkylated derivatives are obtained in high yields. (C) 2003 Elsevier Science Ltd. All rights reserved.

Biotinylated indoles were prepared for application as bifunctional probes for the detection of indole-binding proteins which participate in the life processes of humans, animals, plants, and bacteria. The indole nucleus was functionalized, at ring positions 3, 5, or 6, by attachment of a 2-aminoethyl group, which was then coupled to the carboxyl moiety of biotin, via a spacer composed of 3 or 4 concatenated beta-alanine residues. The constructs thus obtained were able to inhibit tryptophanase activity, similarly to indole in a concentration-dependent manner. They also bound strongly to lysozyme and weakly to bovine and human serum albumins, in accordance with the known affinities of these proteins for indole and 3-(2-aminoethyl)indole (tryptamine). The biotin end of the protein-bound bifunctional probes could then be detected by coupling to (strept)avidin conjugated to alkaline phosphatase or horseradish peroxidase, followed by incubation with substrates which are converted by these enzymes to intensely colored or chemiluminescent products.

Corrigendum to ‘‘Indol-2-yl ethanones as novel indoleamine 2,3-dioxygenase (IDO) inhibitors’’ [Bioorg. Med. Chem. (2011) 1550–1561] Eduard Dolusic , Pierre Larrieu , Sebastien Blanc , Frederic Sapunaric , Bernadette Norberg , Laurence Moineaux , Delphine Colette , Vincent Stroobant , Luc Pilotte , Didier Colau , Thierry Ferain , Graeme Fraser , Moreno Galleni , Jean-Marie Frere , Bernard Masereel , Benoit Van den Eynde , Johan Wouters , Raphael Frederick a,⇑

The plant hormone auxin is involved in almost every aspect of plant development; auxin homeostasis and auxin signaling are thus of crucial importance. The wider auxin family includes endogenous growth promoters, such as indole-3-acetic acid (IAA), and chemically diverse synthetic analogues; minor structural modifications afford growth inhibitors (antiauxins). As proper classification is of technological relevance (growth regulators, herbicides) we developed a classification by interaction similarity indices, based on the evaluation of two distinctive molecular conformations (planar and tilted) of indole-3-acetic acid in comparison with the optimized conformations of 50 compounds. Then we extended the method to a larger set of compounds using similarity of molecular interaction fields and lipophilicity predictions (log P). In addition to theoretical approaches based on the evaluation of molecular conformations of possible relevance for binding to the auxin receptor(s), we used experimental methods, such as X-ray structure analysis and spectroscopic methods to characterize the molecules of interest: alkylated IAAs, halogenated IAAs (F, Cl, Br), and dihalogenated IAAs. Systematic analysis of physico-chemical and structural properties provided indirect insight into the topology of the substrate-binding site of the, so far hypothetical, common auxin receptor. Our findings are in reasonable accord with the models proposed by previous researchers. The question of molecular fit to the receptor active site will, however, remain open until the coordinates of the first structurally characterized auxin binding protein, ABP1, will be in the public domain.

Attempts to synthesize substituted thiazole N-oxides by treatment of 1,3-thiazoles with mCPBA(1,2) did not afford the expected products. Spectral analyses proved that corresponding 5-bromothiazoles were formed instead in very good yields. This can be explained by the fact that the starting compounds were, in fact, obtained as hydrobromide salts. Oxidative bromination mediated by mCPBA then occurred in the 5-position of the thiazole ring. Highly functionalized 5-bromo-2-amino-1,3-thiazoles bearing various substituents in the 4-position and on the 2-nitrogen could be easily prepared by this rapid and efficient one-pot method, using simple starting materials and mild conditions while avoiding the use of metal catalysts or hazardous reagents like elemental bromine. A number of oxidants, solvents and reaction conditions were next studied. The synthesis scope was successfully extended to 5-chlorothiazoles. Attempts were undertaken to further elaborate the 5-halothiazoles to pharmacologically interesting compounds.1. Campeau, L.-C. et al; J. Am. Chem. Soc. 2009, 131, 3291-3306. 2. Campeau, L.-C. et al; J. Am. Chem. Soc. 2008, 130, 3276-3277. This work is supported by the Belgian Fonds National pour la Recherche Scientifique (FNRS) and the Walloon Region (BioWin project CANTOL: Convention n° 5678).