Combinatorial Chemistry & High Throughput Screening - Volume 20, Issue 9, 2017

Aim and Objective: 4-Hydroxyphenylpyruvate dioxygenase (HPPD), converting phydroxyphenylpyruvate (HPPA) to homogentisate (HGA), is an important target for treating type I tyrosinemia and synthesizing novel herbicides due to its significant role in tyrosine catabolism. Hence, it is imperative to design novel HPPD inhibitors that can block HPPA–HGA conversion, which leads to the deficiency in isoprenoid redox cofactors such as plastoquinone and tocopherol, and finally caused growth inhibition. This study was undertaken to investigate structural requirements for their HPPD inhibition with better biological activity. Materials and Methods: Based on the structure-activity relationships, a series of quinolinone-2,4- diones derivatives were studied using combined of 2D multiple linear regression (2D-MLR) and 3D quantitative structure-activity relationship (3D-QSAR). Firstly, genetic algorithm (GA) was applied and descriptors generated in DRAGON 5.5 software were used for building 2D-MLR models in the QSARINGS. Then CoMFA and CoMSIA models were performed by using alignment of the common framework and the pharmacophore model. The obtained models were validated through internal and external validation to verify predictive abilities. Especially, the CoMFA and CoMSIA contour maps were used to show vital structural characteristics related to HPPD inhibitors activities. Results: The 2D-MLR liner equation and corresponding parameters were listed as follows: pKi = -38.2034Me+22.4078GATS2m-1.4265EEig15r-2.1849Hy+32.9158 ntr=28, npred=6, R2=0.863, Q2 LOO=0.787, Q2 LMO=0.607, Q2 F1=0.780, Q2 F2=0.780, Q2 F3=0.860, CCCpred=0.920. RMSEtr=0.253, RMSEpred=0.555, F=36.289 The steric contours graph indicated that small and negative electrostatic substitutions at R1 and R2 regions were favorable for the better activity, and hydrogen-bond donors at this region would also increase the activity. Positive electrostatic and bulky substitutions in the R3 position would enhance the activity. The analysis of these models suggested that the steric factor of R4 position was crucial for activity of quinazoline-2,4-diones HPPD inhibitors, bulky substitutions might improve the bioactivity of these inhibitors greatly, meanwhile, hydrogen-bond acceptor groups in this position were required for higher activity. Conclusion: In this study, a combined 2D-MLR, CoMFA and CoMSIA models demonstrated satisfying results through internal and external validation, especially good predictive abilities and the CoMFA and CoMSIA contour maps showed vital structural characteristics related to HPPD inhibitors activities.

Background: Anthocephalus cadamba is used in traditional and folklore medicinal system. Objectives: In order to validate its traditional medicinal claim, the present study was designed to assess antioxidant, antigenotoxic and cytotoxic activity of fractions from Anthocephalus cadamba bark and to identify their active phytoconstituents. Methods: The four fractions viz. hexane (HACB), chloroform (CACB), ethylacetate (EACB) and nbutanol (NACB) were fractionated from the crude methanol extract from bark of A. cadamba. All fractions were evaluated for antiradical efficacy using various in vitro antioxidant assays and for antigenotoxicity by SOS chromotest using E. coli PQ37 tester strain. Cytotoxic potential was checked using MTT assay. Results: Among the four fractions, EACB and NACB exhibited promising radical quenching potential in DPPH, ABTS, superoxide anion radical scavenging and pBR322 plasmid DNA nicking assays. All the fractions were evaluated for genotoxic and antigenotoxic activity in SOS chromotest using E. coli PQ37 tester strain. Results revealed that fractions were non-genotoxic and have potential to suppress the genotoxicity induced by 4NQO (4-nitroquinoline-1-oxide) and AFB1 (aflatoxin B1). NACB was found to inhibit the growth of colon (COLO 205) cancer cells with GI50 of 54.36 μg/ml. To identify bioactive principles in the active fractions, NACB and EACB were subjected to UPLC-electrospray-ionization-quadrupole time-of-flight mass spectrometry which revealed the presence of 3β-isodihyrocadambine-oxide, cadambine, phelasin A/B, 3β- dihydrocadambine and 3'-O-caffeoylsweroside like compounds. Conclusions: Overall results revealed that A. cadamba is a rich source of antioxidant, antigenotoxic and cytotoxic constituents which may find their significance in various food and pharmaceutical products.

Aims and Objectives: The importance of acridine core structure and other heterocycles containing its framework is well known, as they are found in numerous compounds with a variety of biological effects. Pyridine is also an important solvent and heterocyclic nucleus for the design and synthesis of novel molecules with biological properties. It occurs in several natural compounds which are used as a precursor in agrochemicals and pharmaceuticals. The utility of nanostructured metal salts because of their small size and high surface area as catalysts in organic synthesis has drawn special attention due to their better properties such as slower reaction rate, reusability of the catalyst, and higher yields of products compared to the bulk size. Nanosized copper iodide is one reusable Lewis acid catalyst which has revealed several catalytic activities for the synthesis of organic compounds and others. As part of our recent study to develop heterocyclic syntheses using nanostructured catalysts, we now report an efficient and clean synthetic route to 4-arylacridinediones and 6-aryldiindeno[1,2-b:2,1-e]pyridinediones via a condensation reaction catalyzed by CuI nanoparticles under solvent-free conditions. Materials and Methods: The present work deals with the condensation reaction of aromatic aldehydes, ammonium acetate and active methylene compounds comprising dimedone or 1,3- indanedione in the presence of a catalytic amount of the synthesized CuI nanoparticles could be applied for the solvent-free preparation of 4-arylacridinediones and 6-aryldiindeno[1,2-b:2,1- e]pyridinediones at 70 °C within 60 min. Results: A series of 9-aryl-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H)-acridinediones and 6-aryldiindeno[1,2-b:2,1-e]pyridine-5,7-diones were synthesized in high to excellent yields via a simple one-pot three-component coupling reaction using the synthesized CuI nanoparticles as an efficient and recyclable catalyst. All synthesized compounds were well characterized by their satisfactory elemental analyses, IR, 1H and 13C NMR spectroscopy. The synthesized catalyst was fully characterized by XRD, TEM and SEM techniques. Conclusion: A solvent-free condensation between aromatic aldehydes, ammonium acetate and active methylene compounds comprising dimedone or 1,3-indanedione, in the presence of CuI nanoparticles as an efficient and recyclable catalyst leads to the formation of 4-arylacridinediones and 6-aryldiindeno[1,2-b:2,1-e]pyridinediones. This novel and practical approach has a number of advantages for instance, the condensation itself is solvent-free, the total amount of solvent used in the whole process is significantly decreased, the yields of pure products are high to excellent without any by-products, the catalyst is reusable, and the work-up is very simple.

Objective: Functionalized benzenes are prepared from the reaction of sulfonoketenimides that is produced from the Copper catalyzed reaction of terminal alkynes and sulfonyl azides with zwitterionic intermediate that is generated from the reaction of dialkyl acetylenedicarboxylates, alkyl bromides and triphenylphosphine in the presence of ZnO-nanoparticles in good yields. Material and Methods: All chemicals employed in this work were prepared from Fluka (Buchs, Switzerland) and were used without further purification. Nanoparticles of ZnO were synthesized according to literature report. Melting points were measured on an Electrothermal 9100 apparatus. Elemental analyses for C, H, and N were performed using a Heraeus CHN–O-Rapid analyzer. Mass spectra were recorded on a FINNIGAN-MAT 8430 spectrometer operating at an ionization potential of 70 eV. IR spectra were measured on a Shimadzu IR-460 spectrometer. 1H, and 13C NMR spectra were measured with a BRUKER DRX-500 AVANCE spectrometer at 500.1 and 125.8 MHz, respectively. Results: In these reactions, the first step is optimization of reaction conditions for achieving best conditions. For this reason, solvent, catalyst, and reaction time is changed so that the best result is obtained. For optimization, several catalysts such as CuI, CuBr, CuCl, ZnO-nanoparticles, CM-ZnO, pyridine, piperidine, CuO-NPs, TiO2-NPs and copper powder were checked. Among them CuI and ZnO-NPs give the best results. Also, several solvents such as CH3CN, H2O, solvent-free conditions, toluene and diethyl ether are employed and CH3CN is the best solvent. Conclusion: In summary, sulfonoketenimides react with intermediate that is generated from the reaction of dialkyl acetylenedicarboxylate, alkyl bromides and triphenylphosphine in the presence of ZnO-NPs (10 mol%) to produce benzene derivatives in good yields.

Objective: Palladium nanoparticles (Pd NPs) supported on the TiO2 NPs were prepared using Euphorbia thymifolia L. leaf extract. The Pd/TiO2 NPs were characterized by FESEM, EDS, TEM and XRD analysis and were used as nanocatalysts for the reduction of a variety of organic dyes. To the best of the author’s knowledge, this study explains the first report to the synthesis of Pd/TiO2 NPs using Euphorbia thymifolia L. leaf extract. Method: 1.0 G of TiO2 was dispersed in 40 mL of 0.3 Mm PdCl2 solution and sonicated for 30 min. Then, 20 mL of the plant extract was mixed under continuous stirring at 60 °C for 2 h. The prepared Pd/TiO2 NPs were centrifuged, washed and then dried. Results: FESEM imaging showed the formation of NPs in the size range of 19-29 nm. The Pd/TiO2 NPs exhibited high activity towards the reduction of Methyl Orange, Congo red and Rhodamine B in the presence of NaBH4 in aqueous medium during 4, 1 and 54 s, respectively. Conclusion: The synthesis of the Pd/TiO2 NPs by this route is rapid, simple, less time consuming, environmentally safe and compatibility for medical and pharmaceutical applications because of minimizing the use of toxic or hazardous organic solvents and reagents. Furthermore, the biosyenthesized nanocatalyst can catalyze the reduction of organic dyes during short-time and can be recovered and recycled several times without significant loss of activity.

Aim and Objective: Mitragynine, a major active alkaloid of Mitragyna speciosa, acts as an agonist on μ-opioid receptors, producing effects similar to morphine and other opioids. It has been traditionally utilized to alleviate opiate withdrawal symptoms. Besides consideration about potency and selectivity, a good drug must possess a suitable pharmacokinetic profile, with suitable absorption, distribution, metabolism, excretion and toxicity (ADME-Tox) profile, in order to have a high chance of success in clinical trials. Material and Method: The purity of mitragynine in a Mitragyna speciosa alkaloid extract (MSAE) was determined using Ultra-Fast Liquid Chromatography (UFLC). In vitro high throughput ADMETox studies such as aqueous solubility, plasma protein binding, metabolic stability, permeability and cytotoxicity tests were carried out to analyze the physicochemical properties of MSAE and mitragynine. The UFLC quantification revealed that the purity of mitragynine in the MSAE was 40.9%. Results: MSAE and mitragynine are highly soluble in aqueous solution at pH 4.0 but less soluble at pH 7.4. A parallel artificial membrane permeability assay demonstrated that it is extensively absorbed through the semi-permeable membrane at pH 7.4 but very poorly at pH 4.0. Both are relatively highly bound to plasma proteins (> 85 % bound) and are metabolically stable to liver microsomes (> 84 % remained unchanged). In comparison to MSAE, mitragynine showed higher cytotoxicity against WRL 68, HepG2 and Clone 9 hepatocytes after 72 h treatment. Conclusion: The obtained ADME and cytotoxicity data demonstrated that both MSAE and mitragynine have poor bioavailability and have the potential to be significantly cytotoxic.

Objective: Herein we demonstrate the successful development of a new RORγt-enhanced IL-17F promoter-luciferase reporter assay and its use in a parallel high throughput screening approach, alongside a RORγt TR-FRET assay, to rapidly identify new small molecule RORγt/IL-17 inhibitors and evaluate their mode of action. Material & Methods: We sought to identify cell-permeable small-molecule inhibitors of RORγt for rapid progression into hit-to-lead chemistry. As such, we developed the IL-17F promoter luciferase reporter assay in a stable human T-cell (Jurkat) line expressing the RORγt receptor and miniaturised it to a final volume of 8 μL in 1536 well plates for HTS use in screening a library of > 350k compounds. In parallel, a RORγt TR-FRET binding assay was employed to cross-screen the same set of compounds. This enabled the rapid identification of a small number of cell permeable RORγt antagonists showing promising activity in both assays and also highlighted a larger group of potentially very interesting hits which inhibited IL-17 reporter activity, but did not appear to modulate RORγt directly. Result: A rigorous triaging process of the novel non-RORγt IL-17 antagonists was followed, making use of in-silico filtering, historical screening data, selectivity screening using an IL-2 reporter assay with an identical cellular background, and final profiling in a phenotypic PBMC IL-17A production assay. This resulted in the identification of a set of promising small molecule compounds which show IL-17 inhibition via potentially novel pathways. Conclusion: This technique for the fast identification of cell-permeable IL-17 modulators acting through different mechanisms, highlights the benefits of adopting a parallel approach combining high throughput profiling of hits in multiple assay formats, with robust in-silico triaging.

Background: One key step in the development of inhibitors for an enzyme is the application of computational methodologies to predict protein-ligand interactions. The abundance of structural and ligand-binding information for HIV-1 protease opens up the possibility to apply computational methods to develop scoring functions targeted to this enzyme. Objective: Our goal here is to develop an integrated molecular docking approach to investigate protein-ligand interactions with a focus on the HIV-1 protease. In addition, with this methodology, we intend to build target-based scoring functions to predict inhibition constant (Ki) for ligands against the HIV-1 protease system. Methods: Here, we described a computational methodology to build datasets with decoys and actives directly taken from crystallographic structures to be applied in evaluation of docking performance using the program SAnDReS. Furthermore, we built a novel function using as terms MolDock and PLANTS scoring functions to predict binding affinity. To build a scoring function targeted to the HIV-1 protease, we have used machine-learning techniques. Results: The integrated approach reported here has been tested against a dataset comprised of 71 crystallographic structures of HIV protease, to our knowledge the largest HIV-1 protease dataset tested so far. Comparison of our docking simulations with benchmarks indicated that the present approach is able to generate results with improved accuracy. Conclusion: We developed a scoring function with performance higher than previously published benchmarks for HIV-1 protease. Taken together, we believe that the approach here described has the potential to improve docking accuracy in drug design projects focused on HIV-1 protease.