- Evaluation of the chiral recognition properties and the column performances of three chiral stationary phases based on cellulose for the enantioseparation of six dihydropyridines by high-performance liquid chromatography
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Separations of six dihydropyridine enantiomers on three commercially available cellulose-based chiral stationary phases (Chiralcel OD-RH, Chiralpak IB, and Chiralpak IC) were evaluated with high-performance liquid chromatography (HPLC). The best enantioseparation of the six chiral drugs was obtained with a Chiralpak IC (250?×?4.6?mm i.d., 5?μm) column. Then the influence of the mobile phase including an alcohol-modifying agent and alkaline additive on the enantioseparation were investigated and optimized. The optimal mobile phase conditions and maximum resolution for every analyte were as follows respectively: n-hexane/isopropanol (85:15, v/v) for nimodipine (R?=?5.80) and cinildilpine (R?=?5.65); n-hexane/isopropanol (92:8, v/v) for nicardipine (R?=?1.76) and nisoldipine (R?=?1.92); and n-hexane/isopropanol/ethanol (97:2:1, v/v/v) for felodipine (R?=?1.84) and lercanidipine (R?=?1.47). Relative separation mechanisms are discussed based on the separation results, and indicate that the achiral parts in the analytes' structure showed an important influence on the separation of the chiral column.
- Yu, Jia,Tang, Jing,Yuan, Xiaowei,Guo, Xingjie,Zhao, Longshan
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- Chiral separation of calcium channel antagonists by SFC and HPLC using different immobilized chiral stationary phases
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Supercritical fluid chromatography and high-performance liquid chromatography techniques are popular for the chiral separations of different drugs and pharmaceuticals. Therefore, this article describes a comparative study of the chiral separation of some calcium channel antagonists such as verapamil, gallopamil, and nisoldipine. The columns used were Chiralpak IG and Chiralpak ID (250 mm × 4.6?mm, 5.0?μm). The separation was achieved by using a variety of mobile phases in both techniques. The retention, separation, and resolution factors in SFC were in the range of 1.36–7.30, 1.09–1.72, and 1.16–3.47, while these values in the case of HPLC were 1.03–2.42, 1.12–1.35, and 0.49–2.46. The complete resolution of gallopamil and verapamil was achieved successfully. The chiral recognition was controlled by hydrogen bondings, π-π interactions, dipole induced dipole interactions, van der Waal forces, and steric effects. SFC was found to be a better technique than HPLC because of quick separation, good separation power, economic, environment-friendly, and green technology.
- Raja, Rupak,Alam, Syed Dilshad,Mukhopadhyay, Dipanjan,Shirsath, Vikas,Jain, Arvind K.,ALOthman, Zeid A.,Locatelli, Marcello,Ali, Imran
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p. 514 - 520
(2022/01/11)
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- METHODS FOR TREATING CHRONIC FATIGUE SYNDROME AND MYALGIC ENCEPHALOMYELITIS
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In one aspect the invention relates to a method of treatment selected from the group consisting of: (a) treating a symptom such as pain in a subject identified or diagnosed as having Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS); (b) treating a symptom such as pain in a subject having dysfunctional TRPM3 ion channel activity; (c) restoring NK cell function in a subject having dysfunctional TRPM3 ion channel activity; and (d) restoring calcium homeostasis in a subject having dysfunctional TRPM3 ion channel activity. The method comprises the step of administering to the subject a therapeutically effective amount of at least one therapeutic compound selected from the group consisting of: (i) an opioid receptor antagonist; (ii) an opioid antagonist; and (iii) a therapeutic compound that restores TRPM3 ion channel activity. In some embodiments the therapeutic compound is naltrexone hydrochloride.
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- Enantioselective potential of polysaccharide-based chiral stationary phases in supercritical fluid chromatography
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The enantioselective potential of two polysaccharide-based chiral stationary phases for analysis of chiral structurally diverse biologically active compounds was evaluated in supercritical fluid chromatography using a set of 52 analytes. The chiral selectors immobilized on 2.5?μm silica particles were tris-(3,5-dimethylphenylcarmabate) derivatives of cellulose or amylose. The influence of the polysaccharide backbone, different organic modifiers, and different mobile phase additives on retention and enantioseparation was monitored. Conditions for fast baseline enantioseparation were found for the majority of the compounds. The success rate of baseline and partial enantioseparation with cellulose-based chiral stationary phase was 51.9% and 15.4%, respectively. Using amylose-based chiral stationary phase we obtained 76.9% of baseline enantioseparations and 9.6% of partial enantioseparations of the tested compounds. The best results on cellulose-based chiral stationary phase were achieved particularly with propane-2-ol and a mixture of isopropylamine and trifluoroacetic acid as organic modifier and additive to CO2, respectively. Methanol and basic additive isopropylamine were preferred on amylose-based chiral stationary phase. The complementary enantioselectivity of the cellulose- and amylose-based chiral stationary phases allows separation of the majority of the tested structurally different compounds. Separation systems were found to be directly applicable for analyses of biologically active compounds of interest.
- Kucerova, Gabriela,Kalikova, Kveta,Tesarova, Eva
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supporting information
p. 239 - 246
(2017/05/29)
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- An efficient and recyclable 3D printed α-Al2O3 catalyst for the multicomponent assembly of bioactive heterocycles
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A catalytic methodology is reported that enables the efficient, operationally simple and environmentally friendly synthesis of diverse 1,4-dihydropyridines and 3,4-dihydropyrimidin-2(1H)-ones, including some relevant drugs and pharmacologically active derivatives. This strategy is based on the use of a 3D printed Al2O3 woodpile material that was sintered to generate a rigid structure with controlled porosity and noteworthy catalytic performance. The 3D printed Al2O3 catalyst exhibits remarkable efficacy as a Lewis acid in Biginelli and Hantzsch reactions and it can be recovered and reused ten times without any decrease in the activity. Remarkable E factors, excellent recyclability and scalability, broad substrate scope, short reaction times, excellent yields, solvent-free conditions and easy isolation procedures are key features of this methodology.
- Azuaje, Jhonny,Tubío, Carmen R.,Escalante, Luz,Gómez, Mónica,Guitián, Francisco,Coelho, Alberto,Caama?o, Olga,Gil, Alvaro,Sotelo, Eddy
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p. 203 - 210
(2016/12/09)
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- THERAPY FOR COMPLICATIONS OF DIABETES
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A method for enhancing glycemic control and/or insulin sensitivity in a human subject having diabetic nephropathy and/or metabolic syndrome comprises administering to the subject a selective endothelin A (ETA) receptor antagonist in a glycemic control and/or insulin sensitivity enhancing effective amount. A method for treating a complex of comorbidities in an elderly diabetic human subject comprises administering to the subject a selective ETA receptor antagonist in combination or as adjunctive therapy with at least one additional agent that is (i) other than a selective ETA receptor antagonist and (ii) effective in treatment of diabetes and/or at least one of said comorbidities other than hypertension. A therapeutic combination useful in such a method comprises a selective ETA receptor antagonist and at least one antidiabetic, anti-obesity or antidyslipidemic agent other than a selective ETA receptor antagonist.
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- ANTIHYPERTENSIVE THERAPY
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A new use of darusentan is provided in preparation of a pharmaceutical composition for lowering blood pressure in a patient exhibiting resistance to a baseline antihypertensive therapy with one or more drugs. The composition comprises darusentan in an amount providing a therapeutically effective daily dose; wherein (a) the composition is orally deliverable and/or (b) the daily dose of darusentan is effective to provide a reduction of at least about 3 mmHg in one or more blood pressure parameters selected from trough sitting systolic, trough sitting diastolic, 24-hour ambulatory systolic, 24-hour ambulatory diastolic, maximum diurnal systolic and maximum diurnal diastolic blood pressures. Further provided is a new use of darusentan in preparation of a pharmaceutical composition for lowering blood pressure in a patient exhibiting resistance to a baseline antihypertensive therapy, wherein the composition is administered adjunctively with at least one diuretic and at least one antihypertensive drug selected from ACE inhibitors, angiotensin II receptor blockers, beta-adrenergic receptor blockers and calcium channel blockers.
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- Method for treating resistant hypertension
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A method is provided for lowering blood pressure in a patient having clinically diagnosed resistant hypertension. The method comprises administering darusentan to the patient adjunctively with a baseline antihypertensive regimen that comprises administration of at least one diuretic and at least two antihypertensive drugs selected from at least two of (a) ACE inhibitors and angiotensin II receptor blockers, (b) beta-adrenergic receptor blockers and (c) calcium channel blockers. The darusentan is orally administered at a dose and frequency effective, in combination with the baseline regimen, to provide a reduction of at least about 3 mmHg in one or more blood pressure parameters selected from trough sitting systolic, trough sitting diastolic, 24-hour ambulatory systolic, 24-hour ambulatory diastolic, maximum diurnal systolic and maximum diurnal diastolic blood pressures.
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- AN IMPROVED PROCESS FOR THE PREPARATION OF PURE NISOLDIPINE
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Nisoldipine is prepared by the process according to this invention by cyclocondensing 3-Aminocrotonoic acid isobutyl ester with 2-(2-nitrobenzylidene)-3-oxo-butyric acid methyl ester in the presence of a water immiscible organic solvent such as toluene and an aprotic organic solvent. The reaction product is recovered after refluxing with diisopropyl ether. Water miscible aprotic solvent may be selected from ethers and glycol ethers.
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Page/Page column 4; 7
(2008/06/13)
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- INDUSTRIAL PROCESS FOR THE SYNTHESIS OF ISOBUTYL METHYL 1,4-DIHYDRO-2,6-DIMETHYL-4-(2-NITROPHENYL)-3,5-PYRIDINE DICARBOXYLATE (NISOLDIPINE)
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Synthetic process of isobutyl methyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)3,5-pyridine dicarboxylate (Nisoldipine) comprising on the reaction of isobutyl 2-(2-nitrobenzylidene)acetoacetate with methyl 3-aminocrotonate in an apolar solvent.
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- Enantioselective retention of 4-aryl-1,4-dihydropyridine calcium-channel blockers on human serum albumin and α1-acid glycoprotein HPLC columns: Relationships with different scales of lipophilicity
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The enantioselective retention of eight 4-aryl-1,4-dihydropyridine (DHP) calcium-channel blockers on HPLC stationary phases supporting human serum albumin (HSA) or α1-acid glycoprotein (AGP) was investigated. All chiral neutral DHPs were resolved on the AGP column, whereas, on the HSA column, only isradipine showed a split chromatographic peak. Analyses performed on AGP with eluents containing dimethyloctylamine (DMOA) as thc displacer demonstrated that the protein has at least two binding sites for DHPs. The first family of binding sites is enantioselective, binds exclusively to the (R)-forms, and presumably interacts competitively with DMOA. The second family of binding sites appears to be non-enantioselective and is affected by a cooperative interaction with DMOA. For the selected set of DHPs, the lipophilicity scale in octan-1-ol/H2O (log P) was not collinear with log k(w)(IAM) values obtained with immobilized artificial membranes (IAM-HPLC) due to the inclusion of both neutral and basic congeners. Only for the neutral DHPs did log k(w)(IAM) behave as a better descriptor than log P for retention date on HSA and AGP. In fact, the behavior of the basic DHPs amlodipine and nicardipine on both proteins correlated better with the octan- 1-ol/H2O log P values. We, therefore, infer that the amphipathic nature of the IAM phase only mimics the interaction of non-ionizable compounds with serum proteins. In contrast, the IAM-HPLC retention data of protonated bases encode additional interaction mechanisms that are specific for phospholipids and not involved in ligand-protein interactions.
- Barbato, Francesco,Quaglia, Fabiana,Quercia, Maria Tiziana,La Rotonda, Maria Immacolata
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p. 767 - 776
(2007/10/03)
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- Camptothecin drug combinations and methods with reduced side effects
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This invention provides methods and combination formulations and kits to reduce the toxicity of camptothecin drugs, such as irinotecan (CPT-11). Disclosed are therapeutics and treatment methods employing such drugs in combination with agents that increase conjugative enzyme activity or glucuronosyltransferase activity, and agents that decrease biliary transport protein activity, such as cyclosporine A, the resultant effects of which are to decrease the significant side effects previously associated with treatment using these drugs.
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- Intermediates of optically active 1,4-dihydropyridines
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STR1 in which optically pure products are obtained. The process is novel, as is II. I is known as being active on the blood circulation system.
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