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Authors = Tomas Pekarek

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13 pages, 3406 KiB  
Article
Synthesis and Characterization of New 3-(4-Arylpiperazin-1-yl)-2-hydroxypropyl 4-Propoxybenzoates and Their Hydrochloride Salts
by Pavlina Marvanova, Tereza Padrtova, Tomas Pekarek, Jiri Brus, Jiri Czernek, Petr Mokry, Otakar Humpa, Michal Oravec and Josef Jampilek
Molecules 2016, 21(6), 707; https://doi.org/10.3390/molecules21060707 - 1 Jun 2016
Cited by 8 | Viewed by 6095
Abstract
Five new 3-(4-arylpiperazin-1-yl)-2-hydroxypropyl 4-propoxybenzoates were designed and synthesized as potential dual antihypertensive agents. The compounds were prepared as free bases and subsequently transformed to hydrochloride salts. The position of protonation of nitrogen atoms in the piperazine ring of hydrochloride salts was determined by [...] Read more.
Five new 3-(4-arylpiperazin-1-yl)-2-hydroxypropyl 4-propoxybenzoates were designed and synthesized as potential dual antihypertensive agents. The compounds were prepared as free bases and subsequently transformed to hydrochloride salts. The position of protonation of nitrogen atoms in the piperazine ring of hydrochloride salts was determined by means of 13C-CP/MAS and 15N-CP/MAS NMR and IR spectroscopy. Using these solid-state analytical techniques, it was found that both nitrogen atoms were protonated when excess hydrogen chloride was used for preparation of salts. On the other hand, when the equimolar amount of hydrogen chloride was used, piperazine nitrogen substituted by aryl was protonated. Full article
(This article belongs to the Collection Heterocyclic Compounds)
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21 pages, 978 KiB  
Article
Crystallization Products of Risedronate with Carbohydrates and Their Substituted Derivatives
by Jiri Kos, Monika Pentakova, Zbynek Oktabec, Lukas Krejcik, Zuzana Mandelova, Pavla Harokova, Jana Hruskova, Tomas Pekarek, Ondrej Dammer, Marcela Tkadlecova, Jaroslav Havlicek, Jarmila Vinsova, Vladimir Kral, Jiri Dohnal and Josef Jampílek
Molecules 2011, 16(5), 3740-3760; https://doi.org/10.3390/molecules16053740 - 4 May 2011
Cited by 8 | Viewed by 8909
Abstract
The gastrointestinal absorption of bisphosphonates is in general only about 1%. To address this problem mixtures of risedronate monosodium salt with twelve varied sugar alcohols, furanoses, pyranoses and eight gluco-, manno- and galactopyranoside derivatives as counterions were designed in an effort to prepare [...] Read more.
The gastrointestinal absorption of bisphosphonates is in general only about 1%. To address this problem mixtures of risedronate monosodium salt with twelve varied sugar alcohols, furanoses, pyranoses and eight gluco-, manno- and galactopyranoside derivatives as counterions were designed in an effort to prepare co-crystals/new entities with improved intestinal absorption. Crystalline forms were generated by means of kinetically and/or thermodynamically controlled crystallization processes. One hundred and fifty-two prepared samples were screened by means of FT-NIR and FT-Raman spectroscopy. No co-crystal was prepared, but noteworthy results were obtained. A new solid phase of risedronate monosodium salt generated in the presence of phenyl-β-d-galactopyranoside under thermodynamically controlled crystallization conditions was found and also characterized using solid state NMR spectroscopy, X-ray powder diffraction and differential scanning calorimetry. This new polymorph was named as form P. Interactions between risedronate monosodium salt and both carbohydrates were confirmed by means of molecular dynamics simulation. In the present study the relationships between the chemical structures of the studied compounds required for crystalline form change are discussed. Full article
(This article belongs to the Special Issue ECSOC-14)
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15 pages, 412 KiB  
Article
Preparation and Properties of New Co-Crystals of Ibandronate with Gluco- or Galactopyranoside Derivatives
by Zbynek Oktabec, Jiri Kos, Zuzana Mandelova, Lenka Havelkova, Tomas Pekarek, Anna Rezacova, Lukas Placek, Marcela Tkadlecova, Jaroslav Havlicek, Jiri Dohnal and Josef Jampílek
Molecules 2010, 15(12), 8973-8987; https://doi.org/10.3390/molecules15128973 - 8 Dec 2010
Cited by 10 | Viewed by 7646
Abstract
Mixtures of ibandronate monosodium salt with eleven gluco- and/or galacto-pyranoside derivatives as counterions were designed to prepare co-crystals with improved intestinal absorption. In general, gastrointestinal absorption of bisphosphonates after oral administration is approximately 1%. Co-crystals were generated by means of thermodynamically and/or kinetically [...] Read more.
Mixtures of ibandronate monosodium salt with eleven gluco- and/or galacto-pyranoside derivatives as counterions were designed to prepare co-crystals with improved intestinal absorption. In general, gastrointestinal absorption of bisphosphonates after oral administration is approximately 1%. Co-crystals were generated by means of thermodynamically and/or kinetically controlled crystallization processes. Seventy-seven prepared samples were analyzed by means of FT-NIR, FT-Raman spectrometry and solid state NMR spectroscopy. New entities of ibandronate monosodium salt with phenyl-β-d-galactopyranoside were found and characterized. The absorption of these potential new co-crystals was investigated by means of PAMPA experiments. In the present study the relationships between the chemical structures of the studied compounds required for co-crystal generation are discussed. Full article
(This article belongs to the Special Issue ECSOC-13)
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