The Experts below are selected from a list of 5196 Experts worldwide ranked by ideXlab platform
Francisco Veiga - One of the best experts on this subject based on the ideXlab platform.
-
physicochemical investigation of the effects of water soluble polymers on vinpocetine complexation with β cyclodextrin and its sulfobutyl Ether Derivative in solution and solid state
European Journal of Pharmaceutical Sciences, 2003Co-Authors: Laura Ribeiro, Domingos Ferreira, Francisco VeigaAbstract:Abstract The studies reported in this work aimed to elucidate the inclusion complex formation of vinpocetine (VP), a poorly water-soluble base type drug, with β-cyclodextrin (βCD) and its sulfobutyl Ether Derivative (sulfobutyl Ether β-cyclodextrin (SBEβCD)), with or without water-soluble polymers (PVP and HPMC), by thoroughly investigating their interactions in solution and solid state. Phase solubility studies were carried out to evaluate the solubilizing power of both cyclodextrins (CDs), in association with water-soluble polymers, towards VP and to determine the apparent stability constants (Kc) of the complexes. SBEβCD showed higher solubilizing efficacy toward VP than the parent βCD due to its greater solubility and complexing abilities, what was reflected in higher Kc values. Improvement in Kc values for ternary complexes clearly proves the benefit on the addition of water-soluble polymers to promote higher complexation efficiency. VP–CDs (1:1) binary and ternary systems were prepared by physical mixing, kneading, co-evaporation, and lyophilization methods. In the solid state, drug-carrier interactions were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy. The results of these analysis suggested the formation of new solid phases, some of them in amorphous state, allowing to the conclusion of strong evidences of binary and ternary inclusion complex formation between VP, CD and water-soluble polymers, particularly for co-evaporated and lyophilized binary and ternary products.
-
physicochemical investigation of the effects of water soluble polymers on vinpocetine complexation with β cyclodextrin and its sulfobutyl Ether Derivative in solution and solid state
European Journal of Pharmaceutical Sciences, 2003Co-Authors: Laura Ribeiro, Domingos Ferreira, Francisco VeigaAbstract:The studies reported in this work aimed to elucidate the inclusion complex formation of vinpocetine (VP), a poorly water-soluble base type drug, with beta-cyclodextrin (betaCD) and its sulfobutyl Ether Derivative (sulfobutyl Ether beta-cyclodextrin (SBEbetaCD)), with or without water-soluble polymers (PVP and HPMC), by thoroughly investigating their interactions in solution and solid state. Phase solubility studies were carried out to evaluate the solubilizing power of both cyclodextrins (CDs), in association with water-soluble polymers, towards VP and to determine the apparent stability constants (Kc) of the complexes. SBEbetaCD showed higher solubilizing efficacy toward VP than the parent betaCD due to its greater solubility and complexing abilities, what was reflected in higher Kc values. Improvement in Kc values for ternary complexes clearly proves the benefit on the addition of water-soluble polymers to promote higher complexation efficiency. VP-CDs (1:1) binary and ternary systems were prepared by physical mixing, kneading, co-evaporation, and lyophilization methods. In the solid state, drug-carrier interactions were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy. The results of these analysis suggested the formation of new solid phases, some of them in amorphous state, allowing to the conclusion of strong evidences of binary and ternary inclusion complex formation between VP, CD and water-soluble polymers, particularly for co-evaporated and lyophilized binary and ternary products.
Erqiang Chen - One of the best experts on this subject based on the ideXlab platform.
-
novel optical anisotropy of a liquid crystalline cubic phase in a discotic crown Ether Derivative
Journal of Materials Chemistry C, 2014Co-Authors: Ben Zhang, Shuang Yang, Jun Wang, Anchang Shi, Erqiang ChenAbstract:To obtain a columnar structure with nucleophilic channels embedded in the column centres, we synthesized a series of new crown Ether Derivatives (compounds 1, 2, and 3) which are composed of a core of dibenzo-24-crown-8 symmetrically surrounded by four identical substituents. Experimental results indicate that compounds 2 and 3 with smaller substituents around the dibenzo-24-crown-8 core form only crystalline phases, while compound 1 bearing larger dendron substituents on the molecular periphery shows multiple liquid crystalline phase transitions. X-ray diffraction demonstrates that 1 can stack parallel to form a hexagonal columnar liquid crystalline (Colh) phase. A stable phase, which renders the diffraction features of a body-centred cubic (BCC) structure and shows unexpected optical anisotropy, is observed in between the Colh and the isotropic state. On the basis of further support from model calculations, we propose that the optically anisotropic “BCC” structure is an array of ellipsoidal domains placed in the BCC lattice with their long axis along the [111] direction, which results from the periodic density fluctuation of the columns.
-
a reproducible mechano responsive luminescent system based on a discotic crown Ether Derivative doped with fluorophores taking advantage of the phase transition of a matrix
Chemical Communications, 2013Co-Authors: Ben Zhang, Chihhao Hsu, Shuang Yang, Erqiang ChenAbstract:A reproducible mechano-responsive luminescent system based on a discotic crown Ether Derivative (1) doped with a small amount of fluorophore has been prepared. The emission intensity was enhanced when the material was subjected to mechanical shear with localized response.
María P. Portillo - One of the best experts on this subject based on the ideXlab platform.
-
pterostilbene a dimethyl Ether Derivative of resveratrol reduces fat accumulation in rats fed an obesogenic diet
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Saioa Gomezzorita, Alfredo Fernandezquintela, Leixuri Aguirre, Arrate Lasa, Agnes M. Rimando, María P. PortilloAbstract:The current study aimed to demonstrate the effects of pterostilbene in rats fed an obesogenic diet. For this purpose, pterostilbene was administered at doses of 15 mg/kg body weight/day (PT15 group) or 30 mg/kg body weight/day (PT30 group) for 6 weeks. Pterostilbene reduced adipose tissue mass −15.1% (PT15) and −22.9% (PT30). In this tissue, it decreased malic enzyme (−39.4 and −49.5% for PT15 and PT30 groups, respectively) and fatty acid synthase (−45 and −53.4% for PT15 and PT30) activities. Acetyl-CoA carboxylase activity was reduced and AMPK activity was increased only in the PT30 group. In the liver, pterostilbene (PT30) reduced malic enzyme (−29.5%) and glucose-6-P dehydrogenase (−43.2%) activities and increased carnitine palmitoyltransferase-1a (37.5%) and acyl-coenzyme A oxidase (42.5%) activities. This increased oxidative capacity was not associated with increased mitochondriogenesis. Among biochemical serum parameters, only insulin was modified by pterostilbene (−31.6%) in the PT15 group. The am...
-
pterostilbene a dimethyl Ether Derivative of resveratrol reduces fat accumulation in rats fed an obesogenic diet
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Saioa Gomezzorita, Alfredo Fernandezquintela, Leixuri Aguirre, Arrate Lasa, Agnes M. Rimando, María P. PortilloAbstract:The current study aimed to demonstrate the effects of pterostilbene in rats fed an obesogenic diet. For this purpose, pterostilbene was administered at doses of 15 mg/kg body weight/day (PT15 group) or 30 mg/kg body weight/day (PT30 group) for 6 weeks. Pterostilbene reduced adipose tissue mass -15.1% (PT15) and -22.9% (PT30). In this tissue, it decreased malic enzyme (-39.4 and -49.5% for PT15 and PT30 groups, respectively) and fatty acid synthase (-45 and -53.4% for PT15 and PT30) activities. Acetyl-CoA carboxylase activity was reduced and AMPK activity was increased only in the PT30 group. In the liver, pterostilbene (PT30) reduced malic enzyme (-29.5%) and glucose-6-P dehydrogenase (-43.2%) activities and increased carnitine palmitoyltransferase-1a (37.5%) and acyl-coenzyme A oxidase (42.5%) activities. This increased oxidative capacity was not associated with increased mitochondriogenesis. Among biochemical serum parameters, only insulin was modified by pterostilbene (-31.6%) in the PT15 group. The amounts of pterostilbene in serum and tissues from rats in the PT30 group were in not all cases 2-fold greater than those found in the PT15 group. In conclusion, pterostilbene shows antiobesity properties due, at least in part, to reduced lipogenesis in adipose tissue and increased fatty acid oxidation in liver.
Gilles Gasser - One of the best experts on this subject based on the ideXlab platform.
-
a solid phase assisted approach for the facile synthesis of a highly water soluble zirconium 89 chelator for radiopharmaceutical development
Dalton Transactions, 2017Co-Authors: Manon Briand, Margaret L. Aulsebrook, Thomas L. Mindt, Gilles GasserAbstract:Nuclear medicine has seen impressive growth in recent years. An important development in this field occurred through the application of new radionuclides, e.g., 89Zr (t1/2 = 78.4 h, β+ 0.396 MeV), the physical properties of which allow the use of antibodies as biological vectors for specific cancer targeting in combination with high resolution imaging by positron emission tomography (PET). The most commonly used chelator for 89Zr-based PET imaging is the hexadentate desferrioxamine (DFO) chelator. However, due to the instability of this complex, there has been a strong push towards the development of octadentate chelators. We report an Ether Derivative, oxoDFO*, resembling the motif of DFO with four hydroxamic acid groups for the binding of the radiometal and four Ether linkages to increase the water solubility. Very importantly, the synthesis of this chelator follows a solid phase-assisted approach allowing for the development of an attractive synthetic methodology and widening the scope for the access to DFO-like chelators in highly efficient synthetic sequences.
Won Lee - One of the best experts on this subject based on the ideXlab platform.
-
determination of the metabolites of gestrinone in human urine by high performance liquid chromatography liquid chromatography mass spectrometry and gas chromatography mass spectrometry
Rapid Communications in Mass Spectrometry, 2000Co-Authors: Yunje Kim, Yongkwan Lee, Myungsoo Kim, Yonghyeon Yim, Won LeeAbstract:Gestrinone was studied by high performance liquid chromatography (HPLC) for screening and by gas chromatography/mass spectrometry (GC/MS) for confirmation. When the chromatograms of blank, spiked urine and dosed urine were compared by HPLC, two unknown metabolites were found and these were excreted as the conjugated forms. Metabolites 1 and 2 were tested by LC/MS and LC/MS/MS and both had parent ions at m/z 325. The fragment ion of metabolite 1 was at m/z 263 and ions for metabolite 2 were m/z 307 [MH − H2O]+, 289, 279 and 241. LC/MS/MS of m/z 263 as the parent ion of metabolite 1 gave fragment ions at m/z 245 and 217, which were assumed to be [263 − H2O]+ and [235 − H2O]+, respectively. The trimethylsilyl (TMS)-enol-TMS Ether Derivative of gestrinone displayed three peaks in its GC/MS chromatogram, formed by tautomerism. Copyright © 2000 John Wiley & Sons, Ltd.
-
determination and excretion study of gestrinone in human urine by high performance liquid chromatography and gas chromatography mass spectrometry
Rapid Communications in Mass Spectrometry, 2000Co-Authors: Yunje Kim, Yongkwan Lee, Myungsoo Kim, Yonghyeon Yim, Won LeeAbstract:Gestrinone was studied by HPLC for screening and by GC/MS for confirmation. Three unknown peaks were found by HPLC which are probably the metabolites of gestrinone, and conjugated gestrinone in dosed human urine. The metabolites and gestrinone were excreted as the conjugated forms. The total amounts of metabolite 1 and conjugated gestrinone, recovered after 48 h, were 0.20 and 0.32 mg, respectively. When metabolite 1 was tested by LC/MS and LC/MS/MS, the parent ion was m/z 327, [MH]+, and fragment ions were seen at m/z 309 [MH − H2O]+, 291 [MH − 2H2O]+, 283, 263 and 239. The TMS-enol-TMS Ether Derivative of gestrinone has three peaks in the GC/MS chromatogram formed by tautomerism. The reproducibility of the derivatization method was stable and recoveries were over 87% when spiked into blank urine. Copyright © 2000 John Wiley & Sons, Ltd.