Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
J Mass Spectrom ; 58(8): e4964, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37464563

RESUMO

Phlorizin (PRZ) is a natural product that belongs to a class of dihydrochalcones. The unique pharmacological property of PRZ is to block glucose absorption or reabsorption through specific and competitive inhibitors of the sodium/glucose cotransporters (SGLTs) in the intestine (SGLT1) and kidney (SGLT2). This results in glycosuria by inhibiting renal reabsorption of glucose and can be used as an adjuvant treatment for type 2 diabetes. The pharmacokinetic profile, metabolites of the PRZ, and efficacy of metabolites towards SGLTs are unknown. Therefore, the present study on the characterization of hitherto unknown in vivo metabolites of PRZ and pharmacokinetic profiling using liquid chromatography-electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) and accurate mass measurements is undertaken. Plasma, urine, and feces samples were collected after oral administration of PRZ to Sprague-Dawley rats to identify in vivo metabolites. Furthermore, in silico efficacy of the identified metabolites was evaluated by docking study. PRZ at an intraperitoneal dose of 400 mg/kg showed maximum concentration in the blood to 439.32 ± 8.84 ng/mL at 1 h, while phloretin showed 14.38 ± 0.33 ng/mL at 6 h. The pharmacokinetic profile of PRZ showed that the maximum concentration lies between 1 and 2 h after dosing. Decreased blood glucose levels and maximum excretion of glucose in the urine were observed when the PRZ and metabolites were observed in plasma. The identification and characterization of PRZ metabolites by LC/ESI/MS/MS further revealed that the phase I metabolites of PRZ are hydroxy (mono-, di-, and tri-) and reduction. Phase II metabolites are O-methylated, O-acetylated, O-sulfated, and glucuronide metabolites of PRZ. Further docking study revealed that the metabolites diglucuronide metabolite of mono-hydroxylated PRZ and mono-glucuronidation of PRZ could be considered novel inhibitors of SGLT1 and SGLT2, respectively, which show better binding affinities than their parent compound PRZ and the known inhibitors.


Assuntos
Diabetes Mellitus Tipo 2 , Hipoglicemiantes , Ratos , Animais , Ratos Sprague-Dawley , Hipoglicemiantes/farmacologia , Espectrometria de Massas em Tandem/métodos , Transportador 2 de Glucose-Sódio , Florizina/farmacologia , Espectrometria de Massas por Ionização por Electrospray/métodos , Glucose/metabolismo , Sódio , Cromatografia Líquida de Alta Pressão/métodos
2.
Chem Asian J ; 18(2): e202201136, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36482874

RESUMO

Paclitaxel (PTX) is a widely used chemotherapeutic agent in the clinic. However, its clinical benefit is limited due to its low water solubility, off-target toxicity, and for being a multidrug-resistant (MDR) substrate. To overcome these limitations in this study, a tumor-targeting peptide (CRGDK peptide, a ligand for NRP-1 receptor) conjugate of α-tocopheryl succinate (α-TOS) was synthesized and modified on PTX-loaded lipid aggregate (TL-PTX) to leverage the benefits of α-TOS, which include a) anti-cancer activity, b) increased PTX loading, and c) inhibition of MDR activity. Use of peptide conjugate of α-TOS (α-TOS-CRGDK) in lipid aggregate increased PTX entrapment efficiency by 20%, helped in NRP-1 specific cellular uptake and significantly enhanced apoptotic and cell killing activity (p <0.01) of PTX compared to control formulation (CL-PTX) by inhibiting MDR-activity in melanoma resulting in ∼70% increment in overall survival of melanoma tumor-bearing mice. In conclusion, CRGDK- α-TOS conjugate in association with PTX-loaded liposome provided a unique NRP-1 targeted, drug-resistant reversing anticancer regimen for treating aggressive melanoma.


Assuntos
Melanoma , Paclitaxel , Camundongos , Animais , Paclitaxel/farmacologia , Paclitaxel/uso terapêutico , alfa-Tocoferol/farmacologia , Sistemas de Liberação de Medicamentos/métodos , Peptídeos/farmacologia , Lipídeos , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos
3.
Rapid Commun Mass Spectrom ; 34(22): e8915, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32761944

RESUMO

RATIONALE: Nintedanib, an oral, triple angiokinase inhibitor, is used alongside docetaxel in the management of locally recurrent non-small-cell lung cancer and idiopathic pulmonary fibrosis. The present study deals with the identification and characterization of in vitro and in vivo stable and reactive (if any) metabolites of nintedanib and sheds light on some novel metabolites of the drug which have not been reported previously. METHODS: The study involved an oral administration of the drug to male Wistar rats, followed by collection of the biological matrices (urine, plasma and feces) at specific intervals for determination of in vivo metabolites. In addition, in vitro studies were performed on human and rat liver microsomes in the presence of appropriate co-factors. The samples were subjected to protein precipitation and nitrogen evaporation prior to ultra-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry analysis. The toxicities of all the metabolites were assessed in silico, employing ADMET Predictor™. RESULTS: A total of 18 metabolites of nintedanib were identified in all the matrices, of which nine were found to be novel and unreported previously. The unreported metabolites were elucidated as oxidative, demethylated and glucuronide conjugates of nintedanib. Interestingly, acetonitrile adducts of a few metabolites (low concentration) were also observed. No reactive metabolites were observed in this study. CONCLUSIONS: Characterization of hitherto unknown in vitro and in vivo metabolites of nintedanib adds to the existing knowledge on the metabolism of the drug. Identification on the basis of the solvated adducts can be a useful approach for characterization of minor metabolites, which remain undetected owing to sensitivity issues.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Indóis , Microssomos Hepáticos , Espectrometria de Massas em Tandem/métodos , Administração Oral , Animais , Simulação por Computador , Humanos , Indóis/administração & dosagem , Indóis/análise , Indóis/metabolismo , Indóis/toxicidade , Masculino , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Ratos , Ratos Wistar
4.
J Mater Chem B ; 8(19): 4318-4330, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32330214

RESUMO

Combating brain tumors (glioblastoma multiforme or GBM) is a formidable challenge because of the existence of blood-brain barrier (BBB), a tight cellular junction that separates the central nervous system (CNS) and systemic circulation. Such a selectively permeable barrier prevents the entry of therapeutic molecules from blood circulation to brain parenchyma. Towards enhancing the efficacy of brain tumor-selective drug delivery without perturbing the BBB integrity, nanometric drug carriers are increasingly becoming an efficient therapeutic modality in preclinical studies. Psychostimulant drugs such as amphetamine and methylated amphetamine (METH) are known to penetrate the BBB. Still, little effort has been made to exploit them in nano-drug delivery, largely due to their toxicities. Herein, for the first time, we design, synthesize, and formulate three different ß-amphetaminylated cationic lipid nanoparticles. We show that the ß-amphetaminylated cationic lipid nanoparticles are nontoxic and can cross the BBB presumably through active transcytosis. The BBB penetrating ability also depends on the hydrophilic-hydrophobic balance of the lipids, with hexadecyl lipid (16-BACL) nanoparticle showing maximum accumulation in the brain. The lipid nanoparticle of 16-BACL can simultaneously encapsulate paclitaxel and PDL1-siRNA. The dual drug-loaded lipid nanoparticles showed apoptosis driven cellular cytotoxicity against GL261 cells and improved the overall survivability of orthotopic glioblastoma bearing mice compared to their non-targeting counterpart. The present work describes a new class of BBB-crossing lipid nanoparticles and delineates their therapeutic promise against glioblastoma.


Assuntos
Anfetamina/química , Antineoplásicos/farmacologia , Barreira Hematoencefálica/efeitos dos fármacos , Neoplasias Encefálicas/tratamento farmacológico , Glioblastoma/tratamento farmacológico , Lipídeos/química , Nanopartículas/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Barreira Hematoencefálica/patologia , Neoplasias Encefálicas/patologia , Cátions/química , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Glioblastoma/patologia , Camundongos , Camundongos Endogâmicos C57BL , Estrutura Molecular , Paclitaxel/química , Paclitaxel/farmacologia , Tamanho da Partícula , RNA Interferente Pequeno/química , RNA Interferente Pequeno/farmacologia , Propriedades de Superfície , Células Tumorais Cultivadas
5.
J Mass Spectrom ; 53(10): 963-975, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29987857

RESUMO

Sumatriptan succinate, a selective 5-HT1B receptor agonist, was subjected to forced degradation studies as per to International Conference on Harmonization-specified conditions. The drug exclusively showed its degradation under basic, photolytic, and oxidative stress conditions, whereas it was found to be stable under acidic, thermal, and neutral conditions. Eight (DP-1 to DP-8) degradation products were identified and characterized by UPLC-ESI/MS/MS experiments combined with accurate mass measurements. The effective chromatographic separation was achieved on Hibar Purospher STAR, C18 (250 × 4.6 mm, 5 µm) column using mobile phase consisting of 0.1% formic acid and methanol at a flow rate of 0.6 mL/minute in gradient elution method. It is noteworthy that 2 major degradation products DP-3 and DP-7 were isolated using preparative HPLC and characterized by advanced NMR experiments. The degradation pathway of the sumatriptan was established, which was duly justified by mechanistic explanation. In vitro cytotoxicity of isolated DPs was tested on normal human cells such as HEK 293 (embryonic kidney cells) and RWPE-1 (normal prostate epithelial cells). This study revealed that they were nontoxic up to 100 µm concentration. Further, in silico toxicity of the drug and its degradation products was determined using ProTox-II prediction tool. This study revealed that DP-4 and DP-8 are predicted for immune toxicity. Amine oxidase A and prostaglandin G/H synthase 1 are predicted as toxicity targets for DP-3, DP-4, and DP-6 whereas DP-1 and DP-2 are predicted for amine oxidase A target.


Assuntos
Cromatografia Líquida/métodos , Espectroscopia de Ressonância Magnética/métodos , Sumatriptana/análise , Sumatriptana/química , Espectrometria de Massas em Tandem/métodos , Sobrevivência Celular/efeitos dos fármacos , Estabilidade de Medicamentos , Células HEK293 , Humanos , Espectrometria de Massas por Ionização por Electrospray/métodos , Sumatriptana/toxicidade
6.
Biochemistry ; 56(33): 4392-4404, 2017 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-28737386

RESUMO

Guanine rich regions in DNA, which can form highly stable secondary structures, namely, G-quadruplex or G4 DNA structures, affect DNA replication and transcription. Molecules that stabilize G4 DNA have become important in recent years. In this study, G4 DNA stabilization, inhibition of telomerase, and anticancer activity of synthetic ß-carboline-benzimidazole derivatives (5a, 5d, 5h, and 5r) were studied. Among them, derivatives containing a 4-methoxyphenyl ring at C1 and a 6-methoxy-substituted benzimidazole at C3 (5a) were found to stabilize telomeric G-quadruplex DNA efficiently. The stoichiometry and interaction of a synthetic, ß-carboline-benzimidazole derivative, namely, 3-(6-methoxy-1H-benzo[d]imidazol-2-yl)-1-(4-methoxyphenyl)-9H-pyrido[3,4-b]indole (5a), with human intermolecular G-quadruplex DNA at low concentrations were examined using electrospray ionization mass spectrometry. Spectroscopy techniques indicate that 5a may intercalate between the two stacks of G-quadruplex DNA. This model is supported by docking studies. When cancer cells are treated with 5a, the cell cycle arrest occurs at the sub-G1 phase. In addition, an apoptosis assay and fluorescence microscopy studies using cancer cells indicate that 5a can induce apoptosis. Results of biochemical assays such as the polymerase chain reaction stop assay and telomerase activity assay indicate that 5a has the potential to stabilize G-quadruplex DNA, and thereby, it may interfere with in vitro DNA synthesis and decrease telomerase activity. The results of this study reveal that the ß-carboline-benzimidazole derivative (5a) is efficient in G-quadruplex DNA stabilization over double-stranded DNA, inhibits telomerase activity, and induces apoptosis in cancer cells.


Assuntos
Apoptose/efeitos dos fármacos , Benzimidazóis , Quadruplex G , Fase G1/efeitos dos fármacos , Telomerase , Telômero , Benzimidazóis/farmacologia , DNA/metabolismo , Células HeLa , Humanos , Espectrometria de Massas por Ionização por Electrospray , Telomerase/antagonistas & inibidores , Telomerase/química , Telomerase/metabolismo , Telômero/química , Telômero/metabolismo
7.
Rapid Commun Mass Spectrom ; 29(4): 343-8, 2015 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-26406346

RESUMO

RATIONALE: McLafferty rearrangements occur in radical cations of molecules containing a carbonyl group and a γ hydrogen atom but are not common in the [M+H](+) ions of carbonyl compounds. We propose to investigate the collision-induced dissociation (CID) of the [M+H](+) ions of nicotinoyl and picolinoyl amides of 1- and 2-phenylethylamines to explore the possibility of McLafferty-type rearrangement. METHODS: The compounds for study were synthesized by the reaction of methyl nicotinate or methyl picolinate with 1- and 2-phenylethylamines. The CID mass spectra of electrospray ionization (ESI)-generated protonated molecules were obtained using a QSTAR XL quadrupole time-of-flight (QTOF) mass spectrometer, and density functional theory (DFT) calculations using the B3LYP method were employed to elucidate the fragmentation mechanisms. The total electronic and thermal energies of intermediate transition states (TSs) and product ions are reported relative to those of the [M+H](+) ions. RESULTS: CID of the [M+H](+) ions of N-[nicotinoyl]-2-phenylethylamine (1) yielded product ions of m/z 105 (1-phenylethyl cation) and 123 ([M+H-styrene](+) cation). The competitive formation of the ions of m/z 123 and 105 is proposed to involve a McLafferty-type rearrangement. Similarly, the [M+H](+) ions of the isomeric compound 2 and the N-[picolinoyl] phenylethyl amines (3 and 4) dissociate to yield ions of m/z 123 and 105. CONCLUSIONS: A molecule of styrene was eliminated from the ESI-generated [M+H](+) ions of N-[nicotinoyl]phenylethylamines and the isomeric N-[picolinoyl]phenylethylamines, through a mechanism involving a McLafferty-type 1,5-H shift. The transition state energy for the 1,5-H shift is less for the amides of 1-phenylethylamine than for the amides of 2-phenylethylamine. The process occurs as a charge remote process and the presence of the pyridine ring is essential for the process.

8.
J Sep Sci ; 38(10): 1625-32, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25727389

RESUMO

Ondansetron hydrochloride was subjected to forced degradation studies under various conditions of hydrolysis (acidic, basic, and neutral), oxidation, photolysis, and thermal as prescribed by International Conference on Harmonisation guideline Q1A (R2). A simple, selective, precise, and accurate high-performance liquid chromatography method was developed on a Waters Xterra C18 (150 × 4.6 mm id, 3.5 µm) column using 10 mM ammonium formate (pH 3.0)/methanol as a mobile phase in gradient elution mode at a flow rate of 0.6 mL/min. The method was extended to liquid chromatography quadrupole time-of-flight tandem mass spectrometry for identification and structural characterization of stress degradation products of ondansetron. The drug showed significant degradation in base hydrolytic and photolytic stress conditions in the liquid state, while it was found to be stable in neutral, acidic, thermal, and oxidative stress conditions. A total of five degradation products were characterized and most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation of the [M + H](+) ions of the drug and its degradation products. Finally, the developed method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonisation guideline Q2 (R1).


Assuntos
Cromatografia Líquida/métodos , Ondansetron/isolamento & purificação , Antagonistas da Serotonina/isolamento & purificação , Espectrometria de Massas em Tandem/métodos , Ondansetron/química , Oxirredução , Antagonistas da Serotonina/química
9.
Rapid Commun Mass Spectrom ; 29(17): 1577-1584, 2015 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28339153

RESUMO

RATIONALE: The collisional-induced dissociations (CID) of the [M+H]+ ions of molecules having benzyl groups attached to N-atoms have been proposed to involve migration of the benzyl group through the intermediacy of ion/neutral complexes (INCs). We report the investigation of the mechanism of dissociation of protonated N-benzyl- and N-(1-phenylethyl)tyrosine amides by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) and density functional theory (DFT) calculations. METHODS: The amides were synthesized from the corresponding amino acids and amines. The ESI-MS/MS spectra were recorded using an Agilent QTOF 6540 mass spectrometer. The DFT calculations were performed by using Gaussian 09 software. The structures of the [M+H]+ ions, intermediates, products and transition states (TS) were optimized at the B3LYP/6-31G(d,p) level of theory. RESULTS: CID of the [M+H]+ ions of N-benzyltyrosine amide yields two product ions due to rearrangements: (i) the [M+H-74]+ ion (m/z 197) due to benzyl migration to the hydroxyphenyl ring and (ii) the [M+H-45]+ ion (m/z 226) due to benzyl migration to the NH2 group. DFT calculations suggest that the rearrangements occur through an INC in which the benzyl cation is the cation partner. The [M+H]+ ion of N-(1-phenylethyl)tyrosine amide rearranges to an INC of the 1-phenylethyl cation. Subsequent elimination of styrene occurs by transfer of a proton from the 1-phenylethyl cation to the neutral partner. CONCLUSIONS: The [M+H]+ ions of both N-benzyl (1) and N-(1-phenylethyl) (2) tyrosine amide rearrange into INCs. The dissociation of [M+H]+ ion of 1 yields the benzyl cation and [M+H-74]+ and [M+H-45]+ due to benzyl migration to the hydroxyphenyl ring and NH2 group, respectively. However, the formation of the [M+H-74]+ ion is not observed when the aromatic ring is deactivated. The [M+H]+ ion of 2 either dissociates to form the 1-phenylethyl cation or [M+H-styrene]+ . Copyright © 2015 John Wiley & Sons, Ltd.

10.
J Sep Sci ; 37(16): 2160-71, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24913516

RESUMO

The present work describes the systematic development of a robust, precise, and rapid reversed-phase liquid chromatography method for the simultaneous determination of eprosartan mesylate and its six impurities using quality-by-design principles. The method was developed in two phases, screening and optimization. During the screening phase, the most suitable stationary phase, organic modifier, and pH were identified. The optimization was performed for secondary influential parameters--column temperature, gradient time, and flow rate using eight experiments--to examine multifactorial effects of parameters on the critical resolution and generated design space representing the robust region. A verification experiment was performed within the working design space and the model was found to be accurate. This study also describes other operating features of the column packed with superficially porous particles that allow very fast separations at pressures available in most liquid chromatography instruments. Successful chromatographic separation was achieved in less than 7 min using a fused-core C18 (100 mm × 2.1 mm, 2.6 µm) column with linear gradient elution of 10 mM ammonium formate (pH 3.0) and acetonitrile as the mobile phase. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance with the International Conference on Harmonization Q2 (R1) guidelines. The impurities were identified by liquid chromatography with mass spectrometry.


Assuntos
Acrilatos/análise , Química Farmacêutica/métodos , Cromatografia Líquida/métodos , Imidazóis/análise , Espectrometria de Massas/métodos , Tiofenos/análise , Acetonitrilas/química , Compostos de Amônio/química , Cromatografia de Fase Reversa/métodos , Espectroscopia de Ressonância de Spin Eletrônica , Concentração de Íons de Hidrogênio , Porosidade , Reprodutibilidade dos Testes , Software , Temperatura
11.
J Am Soc Mass Spectrom ; 25(3): 398-409, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24415061

RESUMO

ESI-protonated 1,5-bis-(2-methoxyphenyl)-1,4-pentadien-3-one (1) undergoes a gas-phase Nazarov cyclization and dissociates via expulsions of ketene and anisole. The dissociations of the [M + D](+) ions are accompanied by limited HD scrambling that supports the proposed cyclization. Solution cyclization of 1 was effected to yield the cyclic ketone, 2,3-bis-(2-methoxyphenyl)-cyclopent-2-ene-1-one, (2) on a time scale that is significantly shorter than the time for cyclization of dibenzalacetone. The dissociation characteristics of the ESI-generated [M + H](+) ion of the synthetic cyclic ketone closely resemble those of 1, suggesting that gas-phase and solution cyclization products are the same. Additional mechanistic studies by density functional theory (DFT) methods of the gas-phase reaction reveals that the initial cyclization is followed by two sequential 1,2-aryl migrations that account for the observed structure of the cyclic product in the gas phase and solution. Furthermore, the DFT calculations show that the methoxy group serves as a catalyst for the proton migrations necessary for both cyclization and fragmentation after aryl migration. An isomer formed by moving the 2-methoxy to the 4-position requires relatively higher collision energy for the elimination of anisole, as is consistent with DFT calculations. Replacement of the 2-methoxy group with an OH shows that the cyclization followed by aryl migration and elimination of phenol occurs from the [M + H](+) ion at low energy similar to that for 1.


Assuntos
Gases/química , Cetonas/química , Ciclização , Íons , Modelos Moleculares , Espectrometria de Massas em Tandem
12.
J Pharm Anal ; 4(2): 107-116, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29403872

RESUMO

A simple, precise, accurate stability-indicating gradient reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the quantitative determination of zotepine (ZTP) in bulk and pharmaceutical dosage forms in the presence of its degradation products (DPs). The method was developed using Phenomenex C18 column (250 mm×4.6 mm i.d., 5 µm) with a mobile phase containing a gradient mixture of solvents, A (0.05% trifluoroacetic acid (TFA), pH=3.0) and B (acetonitrile). The eluted compounds were monitored at 254 nm; the run time was within 20.0 min, in which ZTP and its DPs were well separated, with a resolution of >1.5. The stress testing of ZTP was carried out under acidic, alkaline, neutral hydrolysis, oxidative, photolytic and thermal stress conditions. ZTP was found to degrade significantly in acidic, photolytic, thermal and oxidative stress conditions and remain stable in basic and neutral conditions. The developed method was validated with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness as per ICH guidelines. This method was also suitable for the assay determination of ZTP in pharmaceutical dosage forms. The DPs were characterized by LC-MS/MS and their fragmentation pathways were proposed.

13.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-672135

RESUMO

A simple, precise, accurate stability-indicating gradient reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the quantitative determination of zotepine (ZTP) in bulk and pharmaceutical dosage forms in the presence of its degradation products (DPs). The method was developed using Phenomenex C18 column (250 mm ~ 4.6 mm i.d., 5 mm) with a mobile phase containing a gradient mixture of solvents, A (0.05%trifluoroacetic acid (TFA), pH ? 3.0) and B (acetonitrile). The eluted compounds were monitored at 254 nm;the run time was within 20.0 min, in which ZTP and its DPs were well separated, with a resolution of 41.5. The stress testing of ZTP was carried out under acidic, alkaline, neutral hydrolysis, oxidative, photolytic and thermal stress conditions. ZTP was found to degrade significantly in acidic, photolytic, thermal and oxidative stress conditions and remain stable in basic and neutral conditions. The developed method was validated with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness as per ICH guidelines. This method was also suitable for the assay determination of ZTP in pharmaceutical dosage forms. The DPs were characterized by LC-MS/MS and their fragmentation pathways were proposed.

14.
PLoS One ; 7(4): e35920, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22558271

RESUMO

Studies on ligand interaction with quadruplex DNA, and their role in stabilizing the complex at concentration prevailing under physiological condition, has attained high interest. Electrospray ionization mass spectrometry (ESI-MS) and spectroscopic studies in solution were used to evaluate the interaction of PBD and TMPyP4 ligands, stoichiometry and selectivity to G-quadruplex DNA. Two synthetic ligands from PBD family, namely pyrene-linked pyrrolo[2,1-c][1,4]benzodiazepine hybrid (PBD1), mixed imine-amide pyrrolobenzodiazepine dimer (PBD2) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP4) were studied. G-rich single-stranded oligonucleotide d(5'GGGGTTGGGG3') designated as d(T(2)G(8)), from the telomeric region of Tetrahymena Glaucoma, was considered for the interaction with ligands. ESI-MS and spectroscopic methods viz., circular dichroism (CD), UV-Visible, and fluorescence were employed to investigate the G-quadruplex structures formed by d(T(2)G(8)) sequence and its interaction with PBD and TMPyP4 ligands. From ESI-MS spectra, it is evident that the majority of quadruplexes exist as d(T(2)G(8))(2) and d(T(2)G(8))(4) forms possessing two to ten cations in the centre, thereby stabilizing the complex. CD band of PBD1 and PBD2 showed hypo and hyperchromicity, on interaction with quadruplex DNA, indicating unfolding and stabilization of quadruplex DNA complex, respectively. UV-Visible and fluorescence experiments suggest that PBD1 bind externally where as PBD2 intercalate moderately and bind externally to G-quadruplex DNA. Further, melting experiments using SYBR Green indicate that PBD1 unfolds and PBD2 stabilizes the G-quadruplex complex. ITC experiments using d(T(2)G(8)) quadruplex with PBD ligands reveal that PBD1 and PBD2 prefer external/loop binding and external/intercalative binding to quadruplex DNA, respectively. From experimental results it is clear that the interaction of PBD2 and TMPyP4 impart higher stability to the quadruplex complex.


Assuntos
Benzodiazepinas/metabolismo , Quadruplex G , Pirróis/metabolismo , Espectrometria de Massas por Ionização por Electrospray/métodos , Benzodiazepinas/química , Ligantes , Desnaturação de Ácido Nucleico , Pirróis/química , Análise Espectral , Temperatura , Tetrahymena/metabolismo
15.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-472272

RESUMO

A new rapid and sensitive high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of atorvastatin-an antihyperlipidemic drug along with most commonly prescribed drugs (antihyperlipidemic,antihypertensive,antidiabetic,antithrombotic) in bulk and marketed combined formulations.The chromatographic separation was carried out by gradient elution mode with acetonitrile as organic modifier and 0.1% triethylamine acetate (TEAA) buffer pH 5 at a flow rate of 1 mL/min and a diode array detector at wavelength 230 nm was employed for detection of the analytcs.Calibration curves were linear in the range of 5 -150 μg/mL for all the drugs with correlation coefficients of determination (r2 values) ≥ 0.999.Limits of detection (LODs) and Limits of quantification (LOQs) ranged from 0.1 to 0.27 μg/mL and 0.3 to 0.89 μg/mL respectively.Intra-day and inter-day precision was studied at three concentration levels (20,60 and 100 μg/mL).The intra-day and inter-day RSD for all compounds was less than 2.0%.The accuracy for all compounds was found to be between 98% and 102%.Thus,the performance of the method described allows its use in quantification of atorvastatin along with 9 most commonly prescribed drugs available in market as atorvastatin combined dosage forms.

16.
J Org Chem ; 75(4): 1087-94, 2010 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-20095586

RESUMO

A cyclic tetrapeptide is prepared from alternating (S)-beta-Caa (C-linked carbo-beta-amino acid) and (R)-Ama (alpha-aminoxy acid). Extensive NMR (in CDCl(3) solution) and mass spectral (MS) studies show its halide binding capacity, with a special affinity to the chloride ion. At higher concentration it was found to form molecular aggregates as evidenced from transmission electron microscopic and atomic force microscopic analysis, confirming the formation of nanorods.


Assuntos
Aminoácidos/química , Cloretos/química , Íons/química , Oligopeptídeos/química , Oligopeptídeos/síntese química , Peptídeos Cíclicos/química , Peptídeos Cíclicos/síntese química , Sítios de Ligação , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Nanoestruturas/química , Conformação Proteica , Estereoisomerismo , Espectrometria de Massas em Tandem
17.
J Sep Sci ; 32(9): 1312-22, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19399862

RESUMO

Modafinil, adrafinil and their related substances were synthesized and analyzed by RP-LC with ESI-MS/MS. The ionization mode, polarity, cone voltage, and chromatographic conditions were evaluated. The optimum LC-MS conditions to obtain fragment ions indispensable for identification of the structures were described. The bulk drugs purity of modafinil and adrafinil was evaluated on Kromasil C(18) column with ACN/0.02 M ammonium acetate as mobile phase in gradient elution mode at 30 degrees C. The method was found to be suitable not only for monitoring the reactions during the process development but also for quality assurance of modafinil and adrafinil.


Assuntos
Estimulantes do Sistema Nervoso Central/análise , Espectrometria de Massas em Tandem/métodos , Compostos Benzidrílicos/análise , Compostos Benzidrílicos/química , Estimulantes do Sistema Nervoso Central/química , Cromatografia Líquida , Ácidos Hidroxâmicos/análise , Ácidos Hidroxâmicos/química , Modafinila , Estrutura Molecular , Reprodutibilidade dos Testes , Espectrometria de Massas por Ionização por Electrospray
18.
J Am Soc Mass Spectrom ; 20(5): 805-18, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19230703

RESUMO

Upon CA, ESI generated [M + H](+) ions of chalcone (benzalacetophenone) and 3-phenyl-indanone both undergo losses of H(2)O, CO, and the elements of benzene. CA of the [M + H](+) ions of 2-methoxy and 2-hydroxychalcone, however, prompts instead a dominant loss of ketene. In addition, CA of the [M + H](+) ions of 2-methoxy-beta-methylchalcone produces an analogous loss of methylketene instead. Furthermore, the [M + D](+) ion of 2-methoxychalcone upon CA eliminates only unlabeled ketene, and the resultant product, the [M + D - ketene](+) ion, yields only the benzyl-d(1) cation upon CA. We propose that the 2-methoxy and 2-hydroxy (ortho) substituents facilitate a Nazarov cyclization to the corresponding protonated 3-aryl-indanones by mediating a critical proton transfer. The resultant protonated indanones then undergo a second proton transport catalysis facilitated by the same ortho substituents producing intermediates that eliminate ketene to yield 2-methoxy- or 2-hydroxyphenyl-phenyl-methylcarbocations, respectively. The basicity of the ortho substituent is important; for example, replacement of the ortho function with a chloro substituent does not provide an efficient catalyst for the proton transports. The Nazarov cyclization must compete with an alternate cyclization, driven by the protonated carbonyl group of the chalcone that results in losses of H(2)O and CO. The assisted proton transfer mediated by the ortho substituent shifts the competition in favor of the Nazarov cyclization. The proposed mechanisms for cyclization and fragmentation are supported by high-mass resolving power data, tandem mass spectra, deuterium labeling, and molecular orbital calculations.


Assuntos
Chalconas/química , Modelos Químicos , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Deutério/química , Etilenos/química , Indanos/química , Cetonas/química , Termodinâmica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...