Artykuły w czasopismach: „Cocrystallization studies”

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Ren, Zhongqi, Xinjian Chen, Guojia Yu, Yinglei Wang, Bin Chen i Zhiyong Zhou. "Molecular simulation studies on the design of energetic ammonium dinitramide co-crystals for tuning hygroscopicity". CrystEngComm 22, nr 31 (2020): 5237–44. http://dx.doi.org/10.1039/d0ce00602e.

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Timofeeva, Tatiana, Sofia Antal, Sergiu Draguta, Karla Ordonez, Raul Castaneda i Evgeniya Leonova. "Cocrystallization of acetaminophen and glutaric acid with different coformers". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C1028. http://dx.doi.org/10.1107/s2053273314089712.

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Recently cocrystallization became a popular tool for crystal engineering that allows, for instance, improving properties of pharmaceutical materials, creating new materials for nonlinear optical applications and solar cell technologies. To attract students to crystallographic studies we carried out project that included crystal growth of two series of cocrystals with acetaminophen and with dicarbonic glutaric acid. We attempted cocrystallization of acetaminophen with more than ten different coformers which gave no cocrystals or salts. However, as a result of cocrystallization we obtained new polymorph modification of hydroxyquinoline. On the contrary, cocrystallization of glutaric acid with basic organic compounds gave several new salts. Interesting examples among them are systems of glutaric acid with 2-pyridinamine and with 6-methyl-2-pyridinamine. In spite of the presence of the same substituents that are prone to H-bond formation, cocrystals have different H-bonding systems and even different molecular conformation of glutaric acid. Details of physical properties, such as spectral characteristics and melting points, of obtained multicomponent materials are discussed.

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Manoj, K., Rui Tamura, Hiroki Takahashi i Hirohito Tsue. "Crystal engineering of homochiral molecular organization of naproxen in cocrystals and their thermal phase transformation studies". CrystEngComm 16, nr 26 (2014): 5811–19. http://dx.doi.org/10.1039/c3ce42415d.

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Duan, Binghui, Yuanjie Shu, Ning Liu, Yingying Lu, Bozhou Wang, Xianming Lu i Jiaoqiang Zhang. "Comparative studies on structure, sensitivity and mechanical properties of CL-20/DNDAP cocrystal and composite by molecular dynamics simulation". RSC Advances 8, nr 60 (2018): 34690–98. http://dx.doi.org/10.1039/c8ra07387b.

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Asojo, Oluwatoyin Ajibola, Oluyomi Adebola Asojo, Michelle N. Ngamelue, Kohei Homma i Oksana Lockridge. "Cocrystallization studies of full-length recombinant butyrylcholinesterase (BChE) with cocaine". Acta Crystallographica Section F Structural Biology and Crystallization Communications 67, nr 4 (24.03.2011): 434–37. http://dx.doi.org/10.1107/s1744309111004805.

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Xu, Jia, Qin Shi, Yanan Wang, Yong Wang, Junbo Xin, Jin Cheng i Fang Li. "Recent Advances in Pharmaceutical Cocrystals: A Focused Review of Flavonoid Cocrystals". Molecules 28, nr 2 (6.01.2023): 613. http://dx.doi.org/10.3390/molecules28020613.

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Cocrystallization is currently an attractive technique for tailoring the physicochemical properties of active pharmaceutical ingredients (APIs). Flavonoids are a large class of natural products with a wide range of beneficial properties, including anticancer, anti-inflammatory, antiviral and antioxidant properties, which makes them extensively studied. In order to improve the properties of flavonoids, such as solubility and bioavailability, the formation of cocrystals may be a feasible strategy. This review discusses in detail the possible hydrogen bond sites in the structure of APIs and the hydrogen bonding networks in the cocrystal structures, which will be beneficial for the targeted synthesis of flavonoid cocrystals. In addition, some successful studies that favorably alter the physicochemical properties of APIs through cocrystallization with coformers are also highlighted here. In addition to improving the solubility and bioavailability of flavonoids in most cases, flavonoid cocrystals may also alter their other properties, such as anti-inflammatory activity and photoluminescence properties.

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Hiendrawan, Stevanus, Bambang Veriansyah i Raymond R. Tjandrawinata. "SOLID-STATE PROPERTIES AND SOLUBILITY STUDIES OF NOVEL PHARMACEUTICAL COCRYSTAL OF ITRACONAZOLE". International Journal of Applied Pharmaceutics 10, nr 5 (8.09.2018): 97. http://dx.doi.org/10.22159/ijap.2018v10i5.26663.

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Objective: Pharmaceutical cocrystal is a promising method to improve the solubility of active pharmaceutical ingredients (APIs). Itraconazole (ITZ) is a BCS class II antifungal drug with poor aqueous solubility, therefore an attempt was made to improve the solubility of ITZ using cocrystallization technique. In this work, six novel pharmaceutical cocrystals of ITZ with various coformers, including 4-hydroxybenzoic acid (4HBA), trans-cinnamic acid (TCA), suberic acid (SUB), sebacic acid (SBC), 1-hydroxy-2-naphthoic acid (1H2N), and benzamide (BZD) were prepared.Methods: ITZ cocrystals was prepared by solvent evaporation process. The cocrystals produced were characterized using powder x-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and fourier transform infrared (FTIR) spectroscopy. Solubility analysis was performed to evaluate the cocrystals.Results: PXRD and DSC analysis revealed that the pattern of all ITZ cocrystals was distinguishable from the individual compounds which indicates the formation of new phase. The solubility of ITZ and its cocrystals from highest to lowest after 24 h in 0.1 N HCl solution (pH 1.2) follows the order ITZ-TCA (1.97-fold), ITZ-SBC (1.09-fold), ITZ, ITZ-1H2N (0.58-fold) and ITZ-4HBA (0.46-fold).Conclusion: This study demonstrates that the selection of coformers has pronounced an impact on the physicochemical properties of ITZ. Based on this study, it can be concluded that cocrystallization offers a valuable way to improve the solubility of ITZ.

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Mikheev, N. B., I. V. Melikhov i S. A. Kulyukhin. "Cocrystallization processes in physicochemical studies of radioactive elements in various media". Radiochemistry 49, nr 6 (grudzień 2007): 549–60. http://dx.doi.org/10.1134/s106636220706001x.

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Shahbaz, Muhammad, Umair Ahmed Khan, M. Iqbal Chaudhary i Sammer Yousuf. "A new bioactive cocrystal of coumarin-3-carboxylic acid and thiourea: detailed structural features and biological activity studies". Acta Crystallographica Section C Structural Chemistry 78, nr 3 (16.02.2022): 192–200. http://dx.doi.org/10.1107/s205322962200081x.

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Cocrystallization is a phenomenon widely used to enhance the biological and physicochemical properties of active pharmaceutical ingredients (APIs). The present study deals with the synthesis of a cocrystal of coumarin-3-carboxylic acid (2-oxochromene-3-carboxylic acid, C10H6O4), a synthetic analogue of the naturally occurring antioxidant coumarin, with thiourea (CH4N2S) using the neat grinding method. The purity and homogeneity of the coumarin-3-carboxylic acid–thiourea (1/1) cocrystal was confirmed by single-crystal X-ray diffraction, FT–IR analysis and thermal stability studies based on differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Detailed geometry analysis via density functional theory (DFT) demonstrated that the 1:1 cocrystal stoichiometry is sustained by N—H...O hydrogen bonding between the amine (–NH2) groups of thiourea and the carbonyl group of coumarin. The synthesized cocrystal exhibited potent antioxidant activity (IC50 = 127.9 ± 5.95 µM) in a DPPH radical scavenger assay in vitro in comparison with the standard N-acetyl-L-cysteine (IC50 = 111.6 ± 2.4 µM). The promising results of the present study highlight the significance of cocrystallization as a crystal engineering tool to improve the efficacy of pharmaceutical ingredients.

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Carlucci, Lucia, i Angelo Gavezzotti. "A quantitative measure of halogen bond activation in cocrystallization". Physical Chemistry Chemical Physics 19, nr 28 (2017): 18383–88. http://dx.doi.org/10.1039/c7cp03322b.

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Salgado-Moran, Guillermo, Rodrigo Ramirez-Tagle, Daniel Glossman-Mitnik, Samuel Ruiz-Nieto, Pran Kishore-Deb, Marta Bunster i Francisco Lobos-Gonzalez. "Docking Studies of Binding of Ethambutol to the C-Terminal Domain of the Arabinosyltransferase fromMycobacterium tuberculosis". Journal of Chemistry 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/601270.

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The binding of ethambutol to the C-terminal domain of the arabinosyltransferase fromMycobacterium tuberculosiswas studied. The analysis was performed using anin silicoapproach in order to find out, by docking calculations and energy descriptors, the conformer of Ethambutol that forms the most stable complex with the C-terminal domain of arabinosyltransferase. The complex shows that location of the Ethambutol coincides with the cocrystallization ligand position and that amino acid residues ASH1051, ASN740, ASP1052, and ARG1055 should be critical in the binding of Ethambutol to C-terminal domain EmbC.

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CHAMPAGNE, Claude P., Yves RAYMOND, Francine MONDOU i Jean-Paul JULIEN. "Studies on the Encapsulation of Bifidobacterium longum Cultures by Spray-Coating or Cocrystallization". Bifidobacteria and Microflora 14, nr 1 (1995): 7–14. http://dx.doi.org/10.12938/bifidus1982.14.1_7.

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Mashhadi, Syed Muddassir Ali, Andrei S. Batsanov, Syed Arslan Sajjad, Yasir Nazir, Moazzam Hussain Bhatti i Uzma Yunus. "Isoniazid-Gentisic acid cocrystallization: Solubility, Stability, Dissolution rate, Antioxidant and Flowability Properties Studies". Journal of Molecular Structure 1226 (luty 2021): 129388. http://dx.doi.org/10.1016/j.molstruc.2020.129388.

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Gołdyn, Mateusz, Anna Komasa, Mateusz Pawlaczyk, Aneta Lewandowska i Elżbieta Bartoszak-Adamska. "Salts of purine alkaloids caffeine and theobromine with 2,6-dihydroxybenzoic acid as coformer: structural, theoretical, thermal and spectroscopic studies". Acta Crystallographica Section C Structural Chemistry 77, nr 11 (27.10.2021): 713–24. http://dx.doi.org/10.1107/s2053229621010883.

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The study of various forms of pharmaceutical substances with specific physicochemical properties suitable for putting them on the market is one of the elements of research in the pharmaceutical industry. A large proportion of active pharmaceutical ingredients (APIs) occur in the salt form. The use of an acidic coformer with a given structure and a suitable pK a value towards purine alkaloids containing a basic imidazole N atom can lead to salt formation. In this work, 2,6-dihydroxybenzoic acid (26DHBA) was used for cocrystallization of theobromine (TBR) and caffeine (CAF). Two novel salts, namely, theobrominium 2,6-dihydroxybenzoate, C7H9N4O2 +·C7H5O4 − (I), and caffeinium 2,6-dihydroxybenzoate, C8H11N4O2 +·C7H5O4 − (II), were synthesized. Both salts were obtained independently by slow evaporation from solution, by neat grinding and also by microwave-assisted slurry cocrystallization. Powder X-ray diffraction measurements proved the formation of the new substances. Single-crystal X-ray diffraction studies confirmed proton transfer between the given alkaloid and 26DHBA, and the formation of N—H...O hydrogen bonds in both I and II. Unlike the caffeine cations in II, the theobromine cations in I are paired by noncovalent N—H...O=C interactions and a cyclic array is observed. As expected, the two hydroxy groups in the 26DHBA anion in both salts are involved in two intramolecular O—H...O hydrogen bonds. C—H...O and π–π interactions further stabilize the crystal structures of both compounds. Steady-state UV–Vis spectroscopy showed changes in the water solubility of xanthines after ionizable complex formation. The obtained salts I and II were also characterized by theoretical calculations, Fourier-transform IR spectroscopy (FT–IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis.

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Kyu, Thein, i Parimal Vadhar. "Cocrystallization and miscibility studies of blends of ultrahigh molecular weight polyethylene with conventional polyethylenes". Journal of Applied Polymer Science 32, nr 6 (5.11.1986): 5575–84. http://dx.doi.org/10.1002/app.1986.070320625.

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Gao, Lei, i Xianrui Zhang. "Cocrystallization of Febuxostat with Pyridine Coformers: Crystal Structural and Physicochemical Properties Analysis". Journal of Chemistry 2021 (16.12.2021): 1–8. http://dx.doi.org/10.1155/2021/3834368.

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Drug cocrystals and salts have promising applications for modulating the physicochemical properties and solubility of pharmaceuticals. In this study, a cocrystal and two salts of febuxostat (FEB) with pyridine nitrogen coformers, including 4, 4′-bipyridine (BIP), 3-aminopyridine (3AP) and 4-hydroxypyridine (4HP), were designed to improve the solubility of FEB. The single-crystal structures were elucidated, and their physical and chemical properties were investigated by IR, PXRD, and DSC. In addition, drug-related properties, including the solubility and powder dissolution rate were assessed. The solubility and powder dissolution studies showed that the FEB-BIP cocrystal and FEB-3AP salt have superior dissolution compared to FEB.

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Brandt, Ali K., Derek J. Boyle, Jacob P. Butler, Abigail R. Gillingham, Scott E. Penner, Jacqueline M. Spaniol, Alaina K. Stockdill i in. "Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates". Crystals 11, nr 12 (20.12.2021): 1596. http://dx.doi.org/10.3390/cryst11121596.

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Families of quasiracemic materials constructed from 3- and 4-substituted chiral diarylamide molecular frameworks were prepared, where the imposed functional group differences systematically varied from H to CF3–9 unique components for each isomeric framework. Cocrystallization from the melt via hot stage thermomicroscopy using all possible racemic and quasiracemic combinations probed the structural boundaries of quasiracemate formation. The crystal structures and lattice energies (differential scanning calorimetry and lattice energy calculations) for many of these systems showed that quasienantiomeric components organize with near inversion symmetry and lattice energetics closely resembling those found in the racemic counterparts. This study also compared the shape space of pairs of quasienantiomers using an in silico alignment-based method to approximate the differences in molecular shape and provide a diagnostic tool for quasiracemate prediction. Comparing these results to our recent report on related 2-substituted diarylamide quasiracemates shows that functional group position can have a marked effect on quasiracemic behavior and provide critical insight to a more complete shape space, essential for defining molecular recognition processes.

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Dalgarno, Scott J., Daniel B. Bassil, Sheryl A. Tucker i Jerry L. Atwood. "Cocrystallization and Encapsulation of a Fluorophore with Hexameric Pyrogallol[4]arene Nanocapsules: Structural and Fluorescence Studies". Angewandte Chemie 118, nr 42 (27.10.2006): 7177–80. http://dx.doi.org/10.1002/ange.200601961.

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Dalgarno, Scott J., Daniel B. Bassil, Sheryl A. Tucker i Jerry L. Atwood. "Cocrystallization and Encapsulation of a Fluorophore with Hexameric Pyrogallol[4]arene Nanocapsules: Structural and Fluorescence Studies". Angewandte Chemie International Edition 45, nr 42 (27.10.2006): 7019–22. http://dx.doi.org/10.1002/anie.200601961.

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Emami, Shahram, Mohammadreza Siahi-Shadbad, Khosro Adibkia i Mohammad Barzegar-Jalali. "Recent advances in improving oral drug bioavailability by cocrystals". BioImpacts 8, nr 4 (31.05.2018): 305–20. http://dx.doi.org/10.15171/bi.2018.33.

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Introduction: Oral drug delivery is the most favored route of drug administration. However, poor oral bioavailability is one of the leading reasons for insufficient clinical efficacy. Improving oral absorption of drugs with low water solubility and/or low intestinal membrane permeability is an active field of research. Cocrystallization of drugs with appropriate coformers is a promising approach for enhancing oral bioavailability. Methods: In the present review, we have focused on recent advances that have been made in improving oral absorption through cocrystallization. The covered areas include supersaturation and its importance on oral absorption of cocrystals, permeability of cocrystals through membranes, drug-coformer pharmacokinetic (PK) interactions, conducting in vivo-in vitro correlations for cocrystals. Additionally, a discussion has been made on the integration of nanocrystal technology with supramolecular design. Marketed cocrystal products and PK studies in human subjects are also reported. Results: Considering supersaturation and consequent precipitation properties is necessary when evaluating dissolution and bioavailability of cocrystals. Appropriate excipients should be included to control precipitation kinetics and to capture solubility advantage of cocrystals. Beside to solubility, cocrystals may modify membrane permeability of drugs. Therefore, cocrystals can find applications in improving oral bioavailability of poorly permeable drugs. It has been shown that cocrystals may interrupt cellular integrity of cellular monolayers which can raise toxicity concerns. Some of coformers may interact with intestinal absorption of drugs through changing intestinal blood flow, metabolism and inhibiting efflux pumps. Therefore, caution should be taken into account when conducting bioavailability studies. Nanosized cocrystals have shown a high potential towards improving absorption of poorly soluble drugs. Conclusions: Cocrystals have found their way from the proof-of-principle stage to the clinic. Up to now, at least two cocrystal products have gained approval from regulatory bodies. However, there are remaining challenges on safety, predicting in vivo behavior and revealing real potential of cocrystals in the human.

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Hoffmann, Sven, Bert Vanhaecht, Jan Devroede, Wim Bras, Cor E. Koning i Sanjay Rastogi. "Cocrystallization in Piperazine-Based Polyamide Copolymers: Small- and Wide-Angle X-ray Diffraction Studies at 30 °C". Macromolecules 38, nr 5 (marzec 2005): 1797–803. http://dx.doi.org/10.1021/ma048456e.

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Faizan, Mohd, Vítor Hugo Nunes Rodrigues i Shabbir Ahmad. "Cocrystallization of 2,3-dimethylquinoxaline with 3,5-dinitrobenzoic acid: Crystal structure, Hirshfeld surface, spectroscopic features and DFT studies". Journal of Molecular Structure 1198 (grudzień 2019): 126894. http://dx.doi.org/10.1016/j.molstruc.2019.126894.

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Saikia, Prakash J., Narendra N. Dass i Shashi D. Baruah. "Cocrystallization behavior of poly(n-docosyl acrylate) withn-docosanoic acid by X-ray and differential scanning calorimetry studies". Journal of Applied Polymer Science 97, nr 5 (2005): 2140–46. http://dx.doi.org/10.1002/app.21951.

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Wróblewska, Aneta, Justyna Śniechowska, Sławomir Kaźmierski, Ewelina Wielgus, Grzegorz D. Bujacz, Grzegorz Mlostoń, Arkadiusz Chworos, Justyna Suwara i Marek J. Potrzebowski. "Application of 1-Hydroxy-4,5-Dimethyl-Imidazole 3-Oxide as Coformer in Formation of Pharmaceutical Cocrystals". Pharmaceutics 12, nr 4 (15.04.2020): 359. http://dx.doi.org/10.3390/pharmaceutics12040359.

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Two, well defined binary crystals with 1-Hydroxy-4,5-Dimethyl-Imidazole 3-Oxide (HIMO) as coformer and thiobarbituric acid (TBA) as well barbituric acid (BA) as Active Pharmaceutical Ingredients (APIs) were obtained by cocrystallization (from methanol) or mechanochemically by grinding. The progress of cocrystal formation in a ball mill was monitored by means of high-resolution, solid state NMR spectroscopy. The 13C CP/MAS, 15N CP/MAS and 1H Very Fast (VF) MAS NMR procedures were employed to inspect the tautomeric forms of the APIs, structure elucidation of the coformer and the obtained cocrystals. Single crystal X-ray studies allowed us to define the molecular structure and crystal packing for the coformer as well as the TBA/HIMO and BA/HIMO cocrystals. The intermolecular hydrogen bonding, π–π interactions and CH-π contacts responsible for higher order organization of supramolecular structures were determined. Biological studies of HIMO and the obtained cocrystals suggest that these complexes are not cytotoxic and can potentially be considered as therapeutic materials.

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Tilborg, Anaelle, Andrea Carletta i Johan Wouters. "Structural and energy insights on solid-state complexes with trimethoprim: a combined theoretical and experimental investigation". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 71, nr 4 (14.07.2015): 406–15. http://dx.doi.org/10.1107/s2052520615008422.

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We present here a new structure of a 1:1 salt of trimethoprim with hemifumarate, highlighted by single-crystal X-ray diffraction and computational conformational studies. This salt was formed during cocrystallization assays conducted to combine trimethoprim and other APIs whose combination exhibits interesting properties. Theoreticalin vacuoinvestigations have been performed on the organic salt through a DFT two-dimensional conformational scan of torsion angles between the two aromatic moieties of trimethoprim. The evaluation of relative energies for hydrogen-bond interactions in the structure has also been performed. Comparison with conformational data from structures implying trimethoprim retrieved from the Cambridge Structural Database (CSD) shows good agreement with theoretical results, proving the validity of vacuumab initiocalculations in describing the energetic landscape of the molecule and thereby gain initial insight into the prediction process for possible new conformations and therefore potential new polymorphs.

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Mohana, Marimuthu, Packianathan Thomas Muthiah i Colin D. McMillen. "Supramolecular architectures in two 1:1 cocrystals of 5-fluorouracil with 5-bromothiophene-2-carboxylic acid and thiophene-2-carboxylic acid". Acta Crystallographica Section C Structural Chemistry 73, nr 6 (25.05.2017): 481–85. http://dx.doi.org/10.1107/s2053229617007550.

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In solid-state engineering, cocrystallization is a strategy actively pursued for pharmaceuticals. Two 1:1 cocrystals of 5-fluorouracil (5FU; systematic name: 5-fluoro-1,3-dihydropyrimidine-2,4-dione), namely 5-fluorouracil–5-bromothiophene-2-carboxylic acid (1/1), C5H3BrO2S·C4H3FN2O2, (I), and 5-fluorouracil–thiophene-2-carboxylic acid (1/1), C4H3FN2O2·C5H4O2S, (II), have been synthesized and characterized by single-crystal X-ray diffraction studies. In both cocrystals, carboxylic acid molecules are linked through an acid–acid R 2 2(8) homosynthon (O—H...O) to form a carboxylic acid dimer and 5FU molecules are connected through two types of base pairs [homosynthon, R 2 2(8) motif] via a pair of N—H...O hydrogen bonds. The crystal structures are further stabilized by C—H...O interactions in (II) and C—Br...O interactions in (I). In both crystal structures, π–π stacking and C—F...π interactions are also observed.

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P. Ahirrao, Sapana, Mayur P. Sonawane, Deepak S. Bhambere, Pavan B. Udavant, Eknath D. Ahire, Rupali Kanade i Dinesh kuber. "Cocrystal Formulation: A Novel Approach to Enhance Solubility and Dissolution of Etodolac". Biosciences Biotechnology Research Asia 19, nr 1 (31.03.2022): 111–19. http://dx.doi.org/10.13005/bbra/2971.

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Etodolac (ETD) is a non-steroidal anti-inflammatory drug (NSAID) given in rheumatoid arthritis treatment. As it comes under BCS class II drug hence it exhibits low water solubility. Also, its dissolution rate-limited oral absorption results in delayed onset of action. The Novel approach in the solubility enhancement field; crystal engineering was preferred to prepare pharmaceutical cocrystals of etodolac with GRAS (generally recognized as safe) molecules. Pharmaceutical cocrystals of etodolac were prepared with p-hydroxybenzoic acid and glutaric acid with the drug: coformer ratio 1:1 and 1:2. Cooling cocrystallization was used to prepare etodolac cocrystals. Cocrystal formulations were characterized by saturation solubility study, in-vitro dissolution studies, and stability study. Cocrystal was also characterized by analytical parameters like Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). Optimized Cocrystal formulation dissolved more rapidly and their equilibrium solubility is greater than the plain drug.

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Kaplan, Nachum, Monique Albert, Donald Awrey, Elias Bardouniotis, Judd Berman, Teresa Clarke, Mandy Dorsey i in. "Mode of Action,In VitroActivity, andIn VivoEfficacy of AFN-1252, a Selective Antistaphylococcal FabI Inhibitor". Antimicrobial Agents and Chemotherapy 56, nr 11 (4.09.2012): 5865–74. http://dx.doi.org/10.1128/aac.01411-12.

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ABSTRACTThe mechanism of action of AFN-1252, a selective inhibitor ofStaphylococcus aureusenoyl-acyl carrier protein reductase (FabI), which is involved in fatty acid biosynthesis, was confirmed by using biochemistry, macromolecular synthesis, genetics, and cocrystallization of an AFN-1252–FabI complex. AFN-1252 demonstrated a low propensity for spontaneous resistance development and a time-dependent reduction of the viability of both methicillin-susceptible and methicillin-resistantS. aureus, achieving a ≥2-log10reduction inS. aureuscounts over 24 h, and was extremely potent against clinical isolates ofS. aureus(MIC90, 0.015 μg/ml) and coagulase-negative staphylococci (MIC90, 0.12 μg/ml), regardless of their drug resistance, hospital- or community-associated origin, or other clinical subgroup. AFN-1252 was orally available in mouse pharmacokinetic studies, and a single oral dose of 1 mg/kg AFN-1252 was efficacious in a mouse model of septicemia, providing 100% protection from an otherwise lethal peritoneal infection ofS. aureusSmith. A median effective dose of 0.15 mg/kg indicated that AFN-1252 was 12 to 24 times more potent than linezolid in the model. These studies, demonstrating a selective mode of action, potentin vitroactivity, andin vivoefficacy, support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections.

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Temel, Ersin, Can Alaşalvar, Hande Eserci i Erbil Ağar. "Experimental (X-ray, IR and UV–vis.) and DFT studies on cocrystallization of two tautomers of a novel Schiff base compound". Journal of Molecular Structure 1128 (styczeń 2017): 5–12. http://dx.doi.org/10.1016/j.molstruc.2016.08.038.

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Rodríguez-Ruiz, Christian, Pedro Montes-Tolentino, Jorge Guillermo Domínguez-Chávez, Hugo Morales-Rojas, Herbert Höpfl i Dea Herrera-Ruiz. "Tailoring Chlorthalidone Aqueous Solubility by Cocrystallization: Stability and Dissolution Behavior of a Novel Chlorthalidone-Caffeine Cocrystal". Pharmaceutics 14, nr 2 (30.01.2022): 334. http://dx.doi.org/10.3390/pharmaceutics14020334.

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A cocrystal of the antihypertensive drug chlorthalidone (CTD) with caffeine (CAF) was obtained (CTD-CAF) by the slurry method, for which a 2:1 stoichiometric ratio was found by powder and single-crystal X-ray diffraction analysis. Cocrystal CTD-CAF showed a supramolecular organization in which CAF molecules are embedded in channels of a 3D network of CTD molecules. The advantage of the cocrystal in comparison to CTD is reflected in a threefold solubility increase and in the dose/solubility ratios, which diminished from near-unit values for D0D to 0.29 for D0CC. Furthermore, dissolution experiments under non-sink conditions showed improved performance of CTD-CAF compared with pure CTD. Subsequent studies showed that CTD-CAF cocrystals transform to CTD form I where CTD precipitation inhibition could be achieved in the presence of pre-dissolved polymer HPMC 80–120 cPs, maintaining supersaturation drug concentrations for at least 180 min. Finally, dissolution experiments under sink conditions unveiled that the CTD-CAF cocrystal induced, in pH-independent manner, faster and more complete CTD dissolution when compared to commercial tablets of CTD. Due to the stability and dissolution behavior of the novel CTD-CAF cocrystal, it could be used to develop solid dosage forms using a lower CTD dose to obtain the same therapeutic response and fewer adverse effects.

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Guan, Danyingzi, Bianfei Xuan, Chengguang Wang, Ruitao Long, Yaqin Jiang, Lina Mao, Jinbing Kang, Ziwen Wang, Shing Fung Chow i Qun Zhou. "Improving the Physicochemical and Biopharmaceutical Properties of Active Pharmaceutical Ingredients Derived from Traditional Chinese Medicine through Cocrystal Engineering". Pharmaceutics 13, nr 12 (15.12.2021): 2160. http://dx.doi.org/10.3390/pharmaceutics13122160.

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Active pharmaceutical ingredients (APIs) extracted and isolated from traditional Chinese medicines (TCMs) are of interest for drug development due to their wide range of biological activities. However, the overwhelming majority of APIs in TCMs (T-APIs), including flavonoids, terpenoids, alkaloids and phenolic acids, are limited by their poor physicochemical and biopharmaceutical properties, such as solubility, dissolution performance, stability and tabletability for drug development. Cocrystallization of these T-APIs with coformers offers unique advantages to modulate physicochemical properties of these drugs without compromising the therapeutic benefits by non-covalent interactions. This review provides a comprehensive overview of current challenges, applications, and future directions of T-API cocrystals, including cocrystal designs, preparation methods, modifications and corresponding mechanisms of physicochemical and biopharmaceutical properties. Moreover, a variety of studies are presented to elucidate the relationship between the crystal structures of cocrystals and their resulting properties, along with the underlying mechanism for such changes. It is believed that a comprehensive understanding of cocrystal engineering could contribute to the development of more bioactive natural compounds into new drugs.

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Speetzen, Erin D., Chideraa I. Nwachukwu, Nathan P. Bowling i Eric Bosch. "Complementary, Cooperative Ditopic Halogen Bonding and Electron Donor-Acceptor π-π Complexation in the Formation of Cocrystals". Molecules 27, nr 5 (24.02.2022): 1527. http://dx.doi.org/10.3390/molecules27051527.

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This study expands and combines concepts from two of our earlier studies. One study reported the complementary halogen bonding and π-π charge transfer complexation observed between isomeric electron rich 4-N,N-dimethylaminophenylethynylpyridines and the electron poor halogen bond donor, 1-(3,5-dinitrophenylethynyl)-2,3,5,6-tetrafluoro-4-iodobenzene while the second study elaborated the ditopic halogen bonding of activated pyrimidines. Leveraging our understanding on the combination of these non-covalent interactions, we describe cocrystallization featuring ditopic halogen bonding and π-stacking. Specifically, red cocrystals are formed between the ditopic electron poor halogen bond donor 1-(3,5-dinitrophenylethynyl)-2,4,6-triflouro-3,5-diiodobenzene and each of electron rich pyrimidines 2- and 5-(4-N,N-dimethyl-aminophenylethynyl)pyrimidine. The X-ray single crystal structures of these cocrystals are described in terms of halogen bonding and electron donor-acceptor π-complexation. Computations confirm that the donor-acceptor π-stacking interactions are consistently stronger than the halogen bonding interactions and that there is cooperativity between π-stacking and halogen bonding in the crystals.

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Asha, R. Nandini, V. Vel Murugan, P. Pon Matheswari, S. Kumaresan, N. Bhuvanesh i B. Ravindran Durai Nayagam. "Cocrystallization of 2,4-Diamino-6-phenyl-1,3,5-triazine with β-(phenylthio)propionic acid: Crystal structure, Hirshfeld surface, DFT studies and molecular docking". Chemical Data Collections 29 (październik 2020): 100520. http://dx.doi.org/10.1016/j.cdc.2020.100520.

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Ravaud, Stephanie, Patrice Gouet, Richard Haser i Nushin Aghajari. "Probing the Role of Divalent Metal Ions in a Bacterial Psychrophilic Metalloprotease: Binding Studies of an Enzyme in the Crystalline State by X-Ray Crystallography". Journal of Bacteriology 185, nr 14 (15.07.2003): 4195–203. http://dx.doi.org/10.1128/jb.185.14.4195-4203.2003.

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ABSTRACT The psychrophilic alkaline metalloprotease (PAP) produced by a Pseudomonas bacterium isolated in Antarctica belongs to the clan of metzincins, for which a zinc ion is essential for catalytic activity. Binding studies in the crystalline state have been performed by X-ray crystallography in order to improve the understanding of the role of the zinc and calcium ions bound to this protease. Cocrystallization and soaking experiments with EDTA in a concentration range from 1 to 85 mM have resulted in five three-dimensional structures with a distinct number of metal ions occupying the ion-binding sites. Evolution of the structural changes observed in the vicinity of each cation-binding site has been studied as a function of the concentration of EDTA, as well as of time, in the presence of the chelator. Among others, we have found that the catalytic zinc ion was the first ion to be chelated, ahead of a weakly bound calcium ion (Ca 700) exclusive to the psychrophilic enzyme. Upon removal of the catalytic zinc ion, the side chains of the active-site residues His-173, His-179 and Tyr-209 shifted ∼4, 1.0, and 1.6 Å, respectively. Our studies confirm and also explain the sensitivity of PAP toward moderate EDTA concentrations and propose distinct roles for the calcium ions. A new crystal form of native PAP validates our previous predictions regarding the adaptation of this enzyme to cold environments as well as the proteolytic domain calcium ion being exclusive for PAP independent of crystallization conditions.

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Wasim, Muhammad, Abdul Mannan, Muhammad Hassham Hassan Bin Asad, Muhammad Imran Amirzada, Muhammad Shafique i Izhar Hussain. "Fabrication of Carbamazepine Cocrystals: Characterization, In Vitro and Comparative In Vivo Evaluation". BioMed Research International 2021 (15.03.2021): 1–9. http://dx.doi.org/10.1155/2021/6685806.

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Carbamazepine (CBZ) is an antiepileptic drug having low bioavailability due to its hydrophobic nature. In the current study, efforts are made to investigate the effect of dicarboxylic acid coformer spacer groups (aliphatic chain length) on physicochemical properties, relative humidity (RH) stability, and oral bioavailability of CBZ cocrystals. Slurry crystallization technique was employed for the preparation of CBZ cocrystals with the following coformers: adipic (AA), glutaric (GA), succinic (SA), and malonic acid (MA). Powder X-ray diffractometry and Fourier-transform infrared spectroscopy confirmed cocrystal preparation. Physicochemical properties, RH stability, and oral bioavailability of cocrystals were investigated. Among the prepared cocrystals, CBZ-GA showed maximum solubility as well as improved dissolution profile (CBZ-GA > CBZ-MA > CBZ-AA > pure CBZ > CBZ-SA) in ethanol. Maximum RH stability was shown by CBZ-AA, CBZ-SA, and CBZ-MA. In vivo studies confirmed boosted oral bioavailability of cocrystals compared to pure CBZ. Furthermore, in vivo studies depicted the oral bioavailability order of cocrystals as CBZ-GA > CBZ-MA > Tegral® > CBZ-AA > CBZ-SA > pure CBZ. Thus, pharmaceutical scientists can effectively employ cocrystallization technique for tuning physicochemical properties of hydrophobic drugs to achieve the desired oral bioavailability. Overall, results reflect no consistent effect of spacer group on physicochemical properties, RH stability, and oral bioavailability of cocrystals.

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Reddy, B. K. Kishore, Sudhir Landge, Sudha Ravishankar, Vikas Patil, Vikas Shinde, Subramanyam Tantry, Manoj Kale i in. "Assessment of Mycobacterium tuberculosis Pantothenate Kinase Vulnerability through Target Knockdown and Mechanistically Diverse Inhibitors". Antimicrobial Agents and Chemotherapy 58, nr 6 (31.03.2014): 3312–26. http://dx.doi.org/10.1128/aac.00140-14.

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ABSTRACTPantothenate kinase (PanK) catalyzes the phosphorylation of pantothenate, the first committed and rate-limiting step toward coenzyme A (CoA) biosynthesis. In our earlier reports, we had established that the type I isoform encoded by thecoaAgene is an essential pantothenate kinase inMycobacterium tuberculosis, and this vital information was then exploited to screen large libraries for identification of mechanistically different classes of PanK inhibitors. The present report summarizes the synthesis and expansion efforts to understand the structure-activity relationships leading to the optimization of enzyme inhibition along with antimycobacterial activity. Additionally, we report the progression of two distinct classes of inhibitors, the triazoles, which are ATP competitors, and the biaryl acetic acids, with a mixed mode of inhibition. Cocrystallization studies provided evidence of these inhibitors binding to the enzyme. This was further substantiated with the biaryl acids having MIC against the wild-typeM. tuberculosisstrain and the subsequent establishment of a target link with an upshift in MIC in a strain overexpressing PanK. On the other hand, the ATP competitors had cellular activity only in aM. tuberculosisknockdown strain with reduced PanK expression levels. Additionally,in vitroandin vivosurvival kinetic studies performed with aM. tuberculosisPanK (MtPanK) knockdown strain indicated that the target levels have to be significantly reduced to bring in growth inhibition. The dual approaches employed here thus established the poor vulnerability of PanK inM. tuberculosis.

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Buysschaert, Geraldine, Kenneth Verstraete, Savvas N. Savvides i Bjorn Vergauwen. "Crystallization of an atypical short-chain dehydrogenase fromVibrio vulnificuslacking the conserved catalytic tetrad". Acta Crystallographica Section F Structural Biology and Crystallization Communications 68, nr 7 (27.06.2012): 771–74. http://dx.doi.org/10.1107/s1744309112018672.

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Short-chain dehydrogenases/reductases (SDRs) are a rapidly expanding superfamily of enzymes that are found in all kingdoms of life. Hallmarked by a highly conserved Asn-Ser-Tyr-Lys catalytic tetrad, SDRs have a broad substrate spectrum and play diverse roles in key metabolic processes. Locus tag VVA1599 inVibrio vulnificusencodes a short-chain dehydrogenase (hereafter referred to as SDRvv) which lacks the signature catalytic tetrad of SDR members. Structure-based protein sequence alignments have suggested that SDRvv may harbour a unique binding site for its nicotinamide cofactor. To date, structural studies of SDRs with altered catalytic centres are underrepresented in the scientific literature, thus limiting understanding of their spectrum of substrate and cofactor preferences. Here, the expression, purification and crystallization of recombinant SDRvv are presented. Two well diffracting crystal forms could be obtained by cocrystallization in the presence of the reduced form of the phosphorylated nicotinamide cofactor NADPH. The collected data were of sufficient quality for successful structure determination by molecular replacement and subsequent refinement. This work sets the stage for deriving the identity of the natural substrate of SDRvv and the structure–function landscape of typical and atypical SDRs.

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Bala, Madhu, Manoj Kumar Gautam i Renu Chadha. "What if Cocrystallization Fails for Neutral Molecules? Screening Offered Eutectics as Alternate Pharmaceutical Materials: Leflunomide-a Case Study". Pharmaceutical Sciences 25, nr 3 (30.09.2019): 235–43. http://dx.doi.org/10.15171/ps.2019.46.

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Background: The manuscript is aimed to optimize the biopharmaceutical parameters of a poorly soluble, neutral anti-rheumatic drug ‘leflunomide’ by preparing its non-covalent derivatives (NCDs). For this various monocarboxylic acids- (adipic acid, picolinic acid) and dicarboxylic acids (maleic acid, malonic acid, sorbic acid), as well as pyridine carboxamide derivatives (nicotinamide, isonicotinamide), are used as coformers. Methods: The novel solid forms were rationally prepared and systematically characterized. Further, these solid forms were subjected to equilibrium solubility and intrinsic dissolution rate (IDR) analysis in three aqueous media (pH 1.2, pH 4.5 and pH 6.8). In vivo plasma studies in male Wistar rats were done to assess the effect on area under the curve (AUC) and the maximum concentration (Cmax) of leflunomide in prepared solid forms. Results: These NCD were primarily characterized to be eutectics rather than cocrystals as expected. The stoichiometry was established by phase diagrams. The negative value of heat of mixing indicated them to be of cluster type. In addition, leflunomide in eutectics showed approximately 9 folds increase in solubility up to 4 hours. Besides this, approximately 4 folds enhancement in the in IDR was also observed. Maximum increase in bioavailability indicated by enhanced values of AUC and Cmax (490.29 μg h-1 mL-1 and 31.42 μg mL-1, respectively) for leflunomide-maleic acid eutectic in comparison to pure LEF (AUC: 193.20 μg h-1 mL-1 and Cmax: 12.09 μg mL-1). Conclusion: The unsuccessful cocrystallization experiments were found be the latent eutectics. The evaluation of these novel eutectics of poorly soluble drug exhibited possibility to further amplify the scope of accessible material phase options other than pure active pharmaceutical ingredient (API) without disturbing the structural integrity.

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Srivastava, Dipti, Zeeshan Fatima, Chanchal D. Kaur, Sachin L. Tulsankar, Sanap S. Nashik i Dilshad A. Rizvi. "Pharmaceutical Cocrystal: A Novel Approach to Tailor the Biopharmaceutical Properties of a Poorly Water Soluble Drug". Recent Patents on Drug Delivery & Formulation 13, nr 1 (8.07.2019): 62–69. http://dx.doi.org/10.2174/1872211313666190306160116.

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Background: The present study reports the formation of a cocrystal of candesartan with the coformer methyl paraben, its characterization and determination of its bioavailability. Candesartan is a poorly water-soluble drug having an anti-hypertensive activity. The recent patents on the cocrystals of the drugs Progesterone (US9982007B2), Epalrestat (EP2326632B1), Gefitinib (WO2015170345A1), and Valsartan (CN102702118B) for enhancement of solubility, helped in selection of the drug for this work. Methods: Candesartan cocrystal was prepared by solution crystallization method. The formation of a new crystalline phase was characterized by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) and Powder X-ray Diffraction (PXRD) studies. Saturation solubility studies were carried out in ethanol: water (50:50 % v/v) mixture. The dissolution studies were conducted in 900 ml of phosphate buffer at pH 7.4(I.P.) with 0.7% w/w of Tween 20 at 50 rpm, maintained at a temperature of 37±0.5°C in a USP type II dissolution apparatus. The pharmacokinetic behavior of candesartan and its cocrystal was thereof investigated in male Wistar rats. Results: There was 6.94 fold enhancement in the solubility of candesartan after its cocrystallization. The dissolution profile of the cocrystal exhibited significant improvement in solubility at 60 and 120 minutes and it remained stable in ethanol: water (50:50%v/v) mixture for 48 h as confirmed by PXRD studies. The AUC0-24of the cocrystal was found to be increased by 2.9 fold in terms of bioavailability as compared to the pure drug. Conclusion: The prepared cocrystal was found to be relatively more soluble than the pure drug and also showed an enhanced oral bioavailability as compared to the pure drug.

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Li, Congwei, Pengfei Du, Meilin Zhou, Liuxin Yang, Haoyue Zhang, Jing Wang i Caiqin Yang. "Spectroscopic Methodology and Molecular Docking Studies on Changes in Binding Interaction of Felodipine with Bovine Serum Albumin Induced by Cocrystallization with β-Resorcylic Acid". Chemical and Pharmaceutical Bulletin 68, nr 10 (1.10.2020): 946–53. http://dx.doi.org/10.1248/cpb.c20-00212.

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Pramanik, Titas, Mysore S. Pavan i Tayur N. Guru Row. "Do halogen bonds dictate the packing preferences in solid solutions?" Faraday Discussions 203 (2017): 201–12. http://dx.doi.org/10.1039/c7fd00084g.

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The isomeric compounds, 4-bromo-2-chloro benzoic acid (4Br) and 2-bromo-4-chlorobenzoic acid (2Br), crystallize in entirely different space groups, P2₁/n and P1̄ respectively. Both structures are stabilized by a strong O–H⋯O hydrogen bonds generating a carboxylic acid dimer along with an unusual triangular halogen bonded motif in the former and a well-defined halogen bond in the latter. Charge density analysis establishes the nature of halogen bonds by bringing out significant changes in the packing features of the two structures as well as the quantification of the interaction energies involved in the formation of the motifs. Cocrystallization efforts lead to the formation of solid solutions of varied stoichiometric ratios among the two entirely different crystalline forms, a feature which is observed for the first time, and depends on the nature of the halogen bonds. Despite the significant variations in the charge density distribution in intermolecular space, the triangular motif, with two type II Br⋯Cl and Cl⋯Br and one type I Br⋯Br contact in the structure of 4Br dictates the packing preferences in the solid solution as established by accurate single crystal diffraction studies supported by cognate powder diffraction analysis (PXRD) and differential scanning calorimetric (DSC) studies. A systematic study of the solid solution by varying the stoichiometric ratios establishes the hierarchy in halogen bonded motifs and consequently its directional influence to form the resultant supramolecular assembly.

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González-González, Juan Saulo, Raquel Jiménez-López, David Ortegón-Reyna, Gabino Gonzalez-Carrillo i Francisco Javier Martínez-Martínez. "Mechanochemical Synthesis of the Catechol-Theophylline Cocrystal: Spectroscopic Characterization and Molecular Structure". Applied Sciences 11, nr 9 (23.04.2021): 3810. http://dx.doi.org/10.3390/app11093810.

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Pharmaceutical cocrystallization offers the possibility to modify the physicochemical and biopharmaceutical properties of active pharmaceutical ingredients. The mechanochemical synthesis and spectroscopic characterization of the catechol-theophylline (CAT-TEO) cocrystal is reported. The cocrystal was prepared by the solvent-assisted grinding method. The ATR-IR spectroscopy study allowed to determine the formation of the cocrystal because the O-H and C=O stretching bands in the CAT-TEO cocrystal were shifted with respect to the starting materials, suggesting the formation of the C=O···H-O hydrogen bond interaction. Infrared spectroscopy also allowed to discard hydration of the cocrystal, and polymorphic transitions of the starting products as a consequence of the mechanochemical grinding. The X-ray powder diffraction and thermal studies confirmed the formation of a new solid phase. In the solid state 13C NMR spectra of the cocrystal, the signals were shifted with respect to the starting products. The 13C NMR chemical shifts of the CAT-TEO cocrystal were simulated by using the gauge including the atomic orbital (GIAO) method. These results showed a good correlation between the experimental and calculated 13C NMR results. Theoretical calculations and natural bonding orbital analysis (NBO) at a B3LYP/6-31G(d,p) level of theory were performed to obtain structural information of the cocrystal.

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Biscaia, Isabela Fanelli Barreto, Samantha Nascimento Gomes, Larissa Sakis Bernardi i Paulo Renato Oliveira. "Obtaining Cocrystals by Reaction Crystallization Method: Pharmaceutical Applications". Pharmaceutics 13, nr 6 (17.06.2021): 898. http://dx.doi.org/10.3390/pharmaceutics13060898.

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Cocrystals have gained attention in the pharmaceutical industry due to their ability to improve solubility, stability, in vitro dissolution rate, and bioavailability of poorly soluble drugs. Conceptually, cocrystals are multicomponent solids that contain two or more neutral molecules in stoichiometric amounts within the same crystal lattice. There are several techniques for obtaining cocrystals described in the literature; however, the focus of this article is the Reaction Crystallization Method (RCM). This method is based on the generation of a supersaturated solution with respect to the cocrystal, while this same solution is saturated or unsaturated with respect to the components of the cocrystal individually. The advantages of the RCM compared with other cocrystallization techniques include the ability to form cocrystals without crystallization of individual components, applicability to the development of in situ techniques for the screening of high quality cocrystals, possibility of large-scale production, and lower cost in both time and materials. An increasing number of scientific studies have demonstrated the use of RCM to synthesize cocrystals, mainly for drugs belonging to class II of the Biopharmaceutics Classification System. The promising results obtained by RCM have demonstrated the applicability of the method for obtaining pharmaceutical cocrystals that improve the biopharmaceutical characteristics of drugs.

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Doores, Katie J., i Dennis R. Burton. "Variable Loop Glycan Dependency of the Broad and Potent HIV-1-Neutralizing Antibodies PG9 and PG16". Journal of Virology 84, nr 20 (4.08.2010): 10510–21. http://dx.doi.org/10.1128/jvi.00552-10.

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ABSTRACT The HIV-1-specific antibodies PG9 and PG16 show marked cross-isolate neutralization breadth and potency. Antibody neutralization has been shown to be dependent on the presence of N-linked glycosylation at position 160 in gp120. We show here that (i) the loss of several key glycosylation sites in the V1, V2, and V3 loops; (ii) the generation of pseudoviruses in the presence of various glycosidase inhibitors; and (iii) the growth of pseudoviruses in a mutant cell line (GnT1−/−) that alters envelope glycosylation patterns all have significant effects on the sensitivity of virus to neutralization by PG9 and PG16. However, the interaction of antibody is not inhibited by sugar monosaccharides corresponding to those found in glycans on the HIV surface. We show that some of the glycosylation effects described are isolate dependent and others are universal and can be used as diagnostic for the presence of PG9 and PG16-like antibodies in the sera of HIV-1-infected patients. The results suggest that PG9 and PG16 recognize a conformational epitope that is dependent on glycosylation at specific variable loop N-linked sites. This information may be valuable for the design of immunogens to elicit PG9 and PG16-like antibodies, as well as constructs for cocrystallization studies.

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Vandebroek, Laurens, Luc Van Meervelt i Tatjana N. Parac-Vogt. "Direct observation of the ZrIV interaction with the carboxamide bond in a noncovalent complex between Hen Egg White Lysozyme and a Zr-substituted Keggin polyoxometalate". Acta Crystallographica Section C Structural Chemistry 74, nr 11 (19.10.2018): 1348–54. http://dx.doi.org/10.1107/s2053229618010690.

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The successful cocrystallization of the noncovalent complex formed between (Et2NH2)8[{α-PW11O39Zr-(μ-OH)(H2O)}2]·7H2O Keggin polyoxometalate (2) and Hen Egg White Lysozyme (HEWL) protein is reported. The resulting structural model revealed interaction between monomeric [Zr(PW11O39)]4−(1), which is a postulated catalytically active species, and the protein in two positions in the asymmetric unit. The first position (occupancy 36%) confirms the previously observed binding sites on the protein surface, whereas the second position (occupancy 14%) provides novel insights into the hydrolytic mechanisms of ZrIV-substituted polyoxometalates. The new interaction site occurs at the Asn65 residue, which is directly next to the Asp66–Gly67 peptide bond that was identified recently as a cleavage site in the polyoxometalate-catalysed hydrolysis of HEWL. Furthermore, in this newly discovered binding site, the monomeric polyoxometalate 1 is observed to bind directly to the side chain of the Asn65 residue. This binding of ZrIV as a Lewis-acid metal to the carbonyl O atom of the Asn65 side chain is very similar to the intermediate state proposed in density functional theory (DFT) studies in which ZrIV activates the peptide bond via interaction with its carbonyl O atom, and can be thus regarded as a model for interaction between ZrIV and a peptide bond.

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Dhibar, Manami, Santanu Chakraborty, Souvik Basak, Paramita Pattanayak, Tanmay Chatterjee, Balaram Ghosh, Mohamed Raafat i Mohammed A. S. Abourehab. "Critical Analysis and Optimization of Stoichiometric Ratio of Drug-Coformer on Cocrystal Design: Molecular Docking, In Vitro and In Vivo Assessment". Pharmaceuticals 16, nr 2 (13.02.2023): 284. http://dx.doi.org/10.3390/ph16020284.

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In this present research, an attempt has been made to address the influence of drug-coformer stoichiometric ratio on cocrystal design and its impact on improvement of solubility and dissolution, as well as bioavailability of poorly soluble telmisartan. The chemistry behind cocrystallization and the optimization of drug-coformer molar ratio were explored by the molecular docking approach, and theoretical were implemented practically to solve the solubility as well as bioavailability related issues of telmisartan. A new multicomponent solid form, i.e., cocrystal, was fabricated using different molar ratios of telmisartan and maleic acid, and characterized by SEM, DSC and XRD studies. The molecular docking study suggested that specific molar ratios of drug-coformer can successfully cluster with each other and form a specific geometry with favourable energy conformation to form cocrystals. Synthesized telmisartan-maleic acid cocrystals showed remarkable improvement in solubility and dissolution of telmisartan by 9.08-fold and 3.11-fold, respectively. A SEM study revealed the formation of cocrystals of telmisartan when treated with maleic acid. DSC and XRD studies also confirmed the conversion of crystalline telmisartan into its cocrystal state upon treating with maleic acid. Preclinical investigation revealed significant improvement in the efficacy of optimized cocrystals in terms of plasma drug concentration, indicating enhanced bioavailability through improved solubility as well as dissolution of telmisartan cocrystals. The present research concluded that molecular docking is an important path in selecting an appropriate stoichiometric ratio of telmisartan: maleic acid to form cocrystals and improve the solubility, dissolution, and bioavailability of poorly soluble telmisartan.

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Sgourakis, Nikolaos, Kannan Natarajan, David Margulies i Ad Bax. "A structural approach to the study of viral immune evasion mechanisms (TECH1P.850)". Journal of Immunology 192, nr 1_Supplement (1.05.2014): 69.18. http://dx.doi.org/10.4049/jimmunol.192.supp.69.18.

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Abstract Mouse cytomegalovirus encodes immunoevasin proteins that interfere with MHC-I antigen presentation to CD8+ T cells and natural killer (NK) cells. Members of the m02-m16 family contribute to viral survival and infectivity. One member of this family, m04/gp34, binds MHC-I molecules in the endoplasmic reticulum and accompanies them to the cell surface, while the related m06 binds and directs MHC-I to endosomes. Biochemical evidence suggests that m04 counters MHC-retaining functions of other viral proteins. Despite many genetic and functional studies, the structural basis of immunoevasin specificities and functions is poorly understood, due largely to difficulty in cocrystallization of these proteins with their ligands. There is no identifiable amino acid homology of any member of this family to any protein structure available. To bypass this structural bottleneck, we have developed a new technology that combines sparse datasets recorded from Nuclear Magnetic Resonance spectroscopy with sophisticated Rosetta macromolecular modeling methods. We apply this approach to determine the structure of the m04 core domain and its interactions with the H2-Dd MHC-I molecule. m04 has a novel Ig-like fold, with long loops providing a flexible scaffold for MHC-I binding. This study provides insight into a key site on MHC-I “discovered” by the virus and helps us to understand the function of m04 with respect to T and NK cell MHC recognition.

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Guzei, Ilia A., i Kelsey C. Miles. "Ab initioX-ray structural characterization of an inclusion compound with a compositionally disordered chiral guest: no prior knowledge of the crystal composition". Acta Crystallographica Section C Structural Chemistry 72, nr 3 (10.02.2016): 179–83. http://dx.doi.org/10.1107/s2053229616001972.

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The crystal structure and absolute configuration of a molecular host/guest/impurity inclusion complex were established unequivocally in spite of our having no prior knowledge of its chemical composition. The host (4R,5R)-4,5-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane, (I), displays expected conformational features. The crystal-disordered chiral guest 4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, (II), is present in the crystal 85.1 (4)% of the time. It shares a common site with 4a-hydroperoxymethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, (III), present 14.9 (4)% of the time, which is the product of autoxidation of (II). This minor peroxide impurity was isolated, and the results of nuclear magnetic resonance, mass spectrometry, and X-ray fluorescence studies are consistent with the proposed structure of (III). The complete structure was therefore determined to be (4R,5R)-4,5-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane–4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one–4a-hydroperoxymethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one (1/0.85/0.15), C31H30O4·0.85C10H14O·0.15C10H14O3, (IV). There are host–host, host–guest, and host–impurity hydrogen-bonding interactions of typesSandDin the solid state. We believe that the crystals of (IV) were originally prepared to establish the chirality of the guest (II) by means of X-ray diffraction analysis of host/guest crystals obtained in the course of chiral resolution during cocrystallization of (II) with (I). In spite of the absence of `heavy' elements, the absolute configurations of all anomeric centres in the structure are assigned asRbased on resonant scattering effects.

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Sjuts, Hanno, Attilio V. Vargiu, Steven M. Kwasny, Son T. Nguyen, Hong-Suk Kim, Xiaoyuan Ding, Alina R. Ornik i in. "Molecular basis for inhibition of AcrB multidrug efflux pump by novel and powerful pyranopyridine derivatives". Proceedings of the National Academy of Sciences 113, nr 13 (14.03.2016): 3509–14. http://dx.doi.org/10.1073/pnas.1602472113.

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The Escherichia coli AcrAB-TolC efflux pump is the archetype of the resistance nodulation cell division (RND) exporters from Gram-negative bacteria. Overexpression of RND-type efflux pumps is a major factor in multidrug resistance (MDR), which makes these pumps important antibacterial drug discovery targets. We have recently developed novel pyranopyridine-based inhibitors of AcrB, which are orders of magnitude more powerful than the previously known inhibitors. However, further development of such inhibitors has been hindered by the lack of structural information for rational drug design. Although only the soluble, periplasmic part of AcrB binds and exports the ligands, the presence of the membrane-embedded domain in AcrB and its polyspecific binding behavior have made cocrystallization with drugs challenging. To overcome this obstacle, we have engineered and produced a soluble version of AcrB [AcrB periplasmic domain (AcrBper)], which is highly congruent in structure with the periplasmic part of the full-length protein, and is capable of binding substrates and potent inhibitors. Here, we describe the molecular basis for pyranopyridine-based inhibition of AcrB using a combination of cellular, X-ray crystallographic, and molecular dynamics (MD) simulations studies. The pyranopyridines bind within a phenylalanine-rich cage that branches from the deep binding pocket of AcrB, where they form extensive hydrophobic interactions. Moreover, the increasing potency of improved inhibitors correlates with the formation of a delicate protein- and water-mediated hydrogen bond network. These detailed insights provide a molecular platform for the development of novel combinational therapies using efflux pump inhibitors for combating multidrug resistant Gram-negative pathogens.

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Xiang, Yong, Khanita Karaveg i Kelley W. Moremen. "Substrate recognition and catalysis by GH47 α-mannosidases involved in Asn-linked glycan maturation in the mammalian secretory pathway". Proceedings of the National Academy of Sciences 113, nr 49 (17.11.2016): E7890—E7899. http://dx.doi.org/10.1073/pnas.1611213113.

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Maturation of Asn-linked oligosaccharides in the eukaryotic secretory pathway requires the trimming of nascent glycan chains to remove all glucose and several mannose residues before extension into complex-type structures on the cell surface and secreted glycoproteins. Multiple glycoside hydrolase family 47 (GH47) α-mannosidases, including endoplasmic reticulum (ER) α-mannosidase I (ERManI) and Golgi α-mannosidase IA (GMIA), are responsible for cleavage of terminal α1,2-linked mannose residues to produce uniquely trimmed oligomannose isomers that are necessary for ER glycoprotein quality control and glycan maturation. ERManI and GMIA have similar catalytic domain structures, but each enzyme cleaves distinct residues from tribranched oligomannose glycan substrates. The structural basis for branch-specific cleavage by ERManI and GMIA was explored by replacing an essential enzyme-bound Ca2+ ion with a lanthanum (La3+) ion. This ion swap led to enzyme inactivation while retaining high-affinity substrate interactions. Cocrystallization of La3+-bound enzymes with Man9GlcNAc2 substrate analogs revealed enzyme–substrate complexes with distinct modes of glycan branch insertion into the respective enzyme active-site clefts. Both enzymes had glycan interactions that extended across the entire glycan structure, but each enzyme engaged a different glycan branch and used different sets of glycan interactions. Additional mutagenesis and time-course studies of glycan cleavage probed the structural basis of enzyme specificity. The results provide insights into the enzyme catalytic mechanisms and reveal structural snapshots of the sequential glycan cleavage events. The data also indicate that full steric access to glycan substrates determines the efficiency of mannose-trimming reactions that control the conversion to complex-type structures in mammalian cells.

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