RESUMO
Depression is one of the most common psychiatric disorders. Nanotechnology has emerged to optimize the pharmacological response. Therefore, the aim of this work was to develop and characterize liposomes and nanocapsules containing paroxetine hydrochloride and evaluate their antidepressant-like effect using the open field and tail suspension tests in mice. Liposomes and nanocapsules were prepared using the reverse-phase evaporation and nanoprecipitation methods, respectively. The particle size of the formulation ranged from 121.81 to 310.73 nm, the polydispersity index from 0.096 to 0.303, the zeta potential from -11.94 to -34.50 mV, the pH from 5.31 to 7.38, the drug content from 80.82 to 94.36 %, and the association efficiency was 98 %. Paroxetine hydrochloride showed slower release when associated with liposomes (43.82 %) compared to nanocapsules (95.59 %) after 10 h. In Vero cells, in vitro toxicity showed a concentration-dependent effect for paroxetine hydrochloride nanostructures. Both nanostructures decreased the immobility time in the TST at 2.5 mg/kg without affecting the number of crossings in the open field test, suggesting the antidepressant-like effect of paroxetine. In addition, the nanocapsules decreased the number of groomings, reinforcing the anxiolytic effect of this drug. These results suggest that the nanostructures were effective in preserving the antidepressant-like effect of paroxetine hydrochloride even at low doses.
Assuntos
Lipossomos , Nanocápsulas , Paroxetina , Animais , Paroxetina/administração & dosagem , Paroxetina/farmacologia , Paroxetina/química , Nanocápsulas/química , Camundongos , Chlorocebus aethiops , Masculino , Células Vero , Tamanho da Partícula , Liberação Controlada de Fármacos , Depressão/tratamento farmacológico , Elevação dos Membros Posteriores , Antidepressivos/administração & dosagem , Antidepressivos/química , Antidepressivos/farmacologia , Antidepressivos de Segunda Geração/administração & dosagem , Antidepressivos de Segunda Geração/química , Antidepressivos de Segunda Geração/farmacologia , Comportamento Animal/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacosRESUMO
Thus far, many hypotheses have been proposed explaining the cause of depression. Among the most popular of these are: monoamine, neurogenesis, neurobiology, inflammation and stress hypotheses. Many studies have proven that neurogenesis in the brains of adult mammals occurs throughout life. The generation of new neurons persists throughout adulthood in the mammalian brain due to the proliferation and differentiation of adult neural stem cells. For this reason, the search for drugs acting in this mechanism seems to be a priority for modern pharmacotherapy. Paroxetine is one of the most commonly used antidepressants. However, the exact mechanism of its action is not fully understood. The fact that the therapeutic effect after the administration of paroxetine occurs after a few weeks, even if the levels of monoamine are rapidly increased (within a few minutes), allows us to assume a neurogenic mechanism of action. Due to the confirmed dependence of depression on serotonin, norepinephrine, dopamine and γ-aminobutyric acid levels, studies have been undertaken into paroxetine interactions with these primary neurotransmitters using in silico and in vitro methods. We confirmed that paroxetine interacts most strongly with monoamine transporters and shows some interaction with γ-aminobutyric acid transporters. However, studies of the potency inhibitors and binding affinity values indicate that the neurogenic mechanism of paroxetine's action may be determined mainly by its interactions with serotonin transporters.
Assuntos
Proteínas da Membrana Plasmática de Transporte de GABA/metabolismo , Paroxetina/metabolismo , Proteínas Vesiculares de Transporte de Monoamina/metabolismo , Animais , Sítios de Ligação , Células CHO , Cricetulus , Humanos , Simulação de Acoplamento Molecular , Neurotransmissores/química , Neurotransmissores/metabolismo , Paroxetina/químicaRESUMO
A simple and green high-performance liquid chromatography method for the separation of paroxetine from its enantiomeric and diastereomeric impurities has been developed. The simultaneous chromatographic resolution was carried out on the amylose-based Chiralpak IA-3 chiral stationary phase using the mixture ethanol-water-diethylamine 80:20:0.1 (v/v/v) as a mobile phase. The effects of substitution of ethanol with methanol or acetonitrile and changes in column temperature on selectivity have been carefully investigated. The optimized single-run HPLC protocol allows the baseline separation of the enantiomers of paroxetine without suffering from interference from five other chiral and achiral impurities reported in the monograph of the European Pharmacopoeia.
Assuntos
Amilose , Cromatografia Líquida de Alta Pressão , Química Verde , Paroxetina , Amilose/química , Química Verde/métodos , Metanol/química , Paroxetina/química , Paroxetina/isolamento & purificação , EstereoisomerismoRESUMO
The design, stereoselective synthesis and inâ vivo antiallodynic activity of four novel paroxetine analogs, named 3-hydroxy paroxetines (3HPXs), is reported herein. Among the novel synthesized compounds, three showed an antiallodynic effect, while (R,R)-3HPX was found to be 2.5 times more bioactive than (-)-paroxetine itself in neuropathic rats. Consequently, the current investigation not only discloses a novel promising analgesic drug, but also reveals that functionalization at the C3 position of paroxetine could be as effective as the common functionalization at either C4 or within the sesamol group.
Assuntos
Analgésicos/farmacologia , Dor/tratamento farmacológico , Paroxetina/farmacologia , Analgésicos/síntese química , Analgésicos/química , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Hidroxilação , Estrutura Molecular , Paroxetina/síntese química , Paroxetina/química , Ratos , Ratos Wistar , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Antidepressants target the serotonin transporter (SERT) by inhibiting serotonin reuptake. Structural and biochemical studies aiming to understand binding of small-molecules to conformationally dynamic transporters like SERT often require thermostabilizing mutations and antibodies to stabilize a specific conformation, leading to questions about relationships of these structures to the bonafide conformation and inhibitor binding poses of wild-type transporter. To address these concerns, we determined the structures of ∆N72/∆C13 and ts2-inactive SERT bound to paroxetine analogues using single-particle cryo-EM and x-ray crystallography, respectively. We synthesized enantiopure analogues of paroxetine containing either bromine or iodine instead of fluorine. We exploited the anomalous scattering of bromine and iodine to define the pose of these inhibitors and investigated inhibitor binding to Asn177 mutants of ts2-active SERT. These studies provide mutually consistent insights into how paroxetine and its analogues bind to the central substrate-binding site of SERT, stabilize the outward-open conformation, and inhibit serotonin transport.
Assuntos
Paroxetina/química , Inibidores Seletivos de Recaptação de Serotonina/química , Proteínas da Membrana Plasmática de Transporte de Serotonina/química , Microscopia Crioeletrônica , Cristalografia por Raios X , Humanos , Estrutura Molecular , Paroxetina/metabolismo , Estrutura Terciária de Proteína , Serotonina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/metabolismoRESUMO
The mechanism-based inactivation (MBI) of P450 by paroxetine was investigated by computational analysis. The drug-enzyme interactions were figured out through studying energy profiles of three competing mechanisms. The potency of paroxetine as P450's inhibitor was estimated based on the availability of two active sites for the MBI in the paroxetine structure. The inactivation by the amino site of paroxetine mainly proceeds via the hydrogen atom transfer pathway because of the lower energy demand of its rate determining step. In addition, the low-spin state is the predominant route in the MBI at the methylenedioxo active site as a result of being rebound barrier-free mechanism. Our comparative investigation showed that inactivation at the secondary amine is thermodynamically more favorable because of the lower energy barrier of the dehydration mechanism of the hydroxylated paroxetine complex than its methylenedioxo counterpart. The results of docking analysis coincided with the outputs of DFT calculations since the docking pose with the lowest binding affinity is that for conformation with polar interaction between the amino group of paroxetine and the oxo moiety of P450's active site. Assessment of the molecular dynamics simulations trajectories revealed the favorable interaction of paroxetine with P450.
Assuntos
Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/metabolismo , Ativação Enzimática/efeitos dos fármacos , Paroxetina/química , Paroxetina/metabolismo , Aminas/química , Catálise , Domínio Catalítico , Desidratação , Hidroxilação , Conformação Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , TermodinâmicaRESUMO
G protein-coupled receptor (GPCR) kinases (GRKs) play a key role in terminating signals initiated by agonist-bound GPCRs. However, chronic stimulation of GPCRs, such as that which occurs during heart failure, leads to the overexpression of GRKs and maladaptive downregulation of GPCRs on the cell surface. We previously reported the discovery of potent and selective families of GRK inhibitors based on either the paroxetine or GSK180736A scaffold. A new inhibitor, CCG258747, which is based on paroxetine, demonstrates increased potency against the GRK2 subfamily and favorable pharmacokinetic parameters in mice. CCG258747 and the closely related compound CCG258208 also showed high selectivity for the GRK2 subfamily in a kinome panel of 104 kinases. We developed a cell-based assay to screen the ability of CCG258747 and 10 other inhibitors with different GRK subfamily selectivities and with either the paroxetine or GSK180736A scaffold to block internalization of the µ-opioid receptor (MOR). CCG258747 showed the best efficacy in blocking MOR internalization among the compounds tested. Furthermore, we show that compounds based on paroxetine had much better cell permeability than those based on GSK180736A, which explains why GSK180736A-based inhibitors, although being potent in vitro, do not always show efficacy in cell-based assays. This study validates the paroxetine scaffold as the most effective for GRK inhibition in living cells, confirming that GRK2 predominantly drives internalization of MOR in the cell lines we tested and underscores the utility of high-resolution cell-based assays for assessment of compound efficacy. SIGNIFICANCE STATEMENT: G protein-coupled receptor kinases (GRKs) are attractive targets for developing therapeutics for heart failure. We have synthesized a new GRK2 subfamily-selective inhibitor, CCG258747, which has nanomolar potency against GRK2 and excellent selectivity over other kinases. A live-cell receptor internalization assay was used to test the ability of GRK2 inhibitors to impart efficacy on a GRK-dependent process in cells. Our data indicate that CCG258747 blocked the internalization of the µ-opioid receptor most efficaciously because it has the ability to cross cell membranes.
Assuntos
Indazóis/química , Paroxetina/química , Pirimidinas/química , Receptores Opioides mu/antagonistas & inibidores , Receptores Opioides mu/metabolismo , Animais , Western Blotting , Permeabilidade da Membrana Celular , Cristalografia por Raios X , Feminino , Células HEK293 , Humanos , Indazóis/farmacologia , Camundongos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Pirimidinas/farmacologiaRESUMO
Paroxetine is an effective drug for the treatment of depression and stress which has been commonly used in recent years. Because of the widespread use and therapeutic effects of paroxetine, a rapid and sensitive method is needed to determine the trace concentration of paroxetine. Herein, an electrochemical sensor was constructed for the measurement of paroxetine using a modified pencil graphite electrode (PGE). Modification of the PGE was carried out by the reduced graphene oxide/phosphotungstic acid (rGO/PWA) by potentiostatic procedure at -1.2â¯V for 5â¯min in phosphate buffer solution with pHâ¯=â¯7.0. Surface morphology analyzing of the modified PGE was performed by scanning electron microscopy (SEM), Raman, XRD, FTIR and electrochemical impedance spectroscopy (EIS) techniques. The kinetic parameter of electron transfer coefficient (α) was calculated for the oxidation process of paroxetine at the modified PGE. Differential pulse voltammetry (DPV) was performed for the determination of PRX. The calibration graph exhibited linear characteristics in the range of 8.0â¯×â¯10-9-1.0â¯×â¯10-6â¯M of PRX concentration (R2â¯=â¯0.998). The relevant limit of detection was found to be 9.0â¯×â¯10-10â¯M. The modified PGE was successfully performed for the determination of PRX in paroxetine tablets and real samples such as human serum and urine.
Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Paroxetina/química , Compostos de Tungstênio/química , Técnicas Biossensoriais/métodos , OxirreduçãoRESUMO
PURPOSE: The effects of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and paroxetine on dopamine formation from p-tyramine, mediated by cytochrome P450 (CYP) 2D6.2 (Arg296Cys, Ser486Thr) and CYP2D6.10 (Pro34Ser, Ser486Thr), were compared with their effects on CYP2D6.1 (wild type)-mediated dopamine formation, to investigate the influence of a CYP2D6 polymorphism on neuroactive amine metabolism in the brain. METHODS: The Michaelis constants (Km) and maximal velocity (Vmax) values of dopamine formation mediated by CYP2D6.1, CYP2D6.2, and CYP2D6.10 (expressed in recombinant Escherichia coli), and inhibition constants (Ki) of the SSRIs toward dopamine formation catalyzed by the CYP2D6 variants were estimated. RESULTS: The Km values for CYP2D6.2 and CYP2D6.10 decreased at lower fluoxetine concentrations, while the Vmax values for all CYP2D6 variants increased, indicating that fluoxetine stimulated dopamine formation. Conversely, paroxetine competitively inhibited dopamine formation mediated by CYP2D6.1, CYP2D6.2, and CYP2D6.10 with Ki values of 0.47, 1.33, and 31.3 µM, respectively. CONCLUSIONS: These results suggest that the inhibition/stimulation of CYP2D6-mediated dopamine formation by these SSRIs would be affected by CYP2D6 polymorphisms in the brain.
Assuntos
Citocromo P-450 CYP2D6/metabolismo , Dopamina/biossíntese , Fluoxetina/farmacologia , Paroxetina/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Tiramina/metabolismo , Dopamina/análise , Fluoxetina/química , Humanos , Estrutura Molecular , Paroxetina/química , Inibidores Seletivos de Recaptação de Serotonina/químicaRESUMO
The G-protein coupled receptor kinase 2 (GRK2) regulates the desensitization of beta-adrenergic receptors (ß-AR), and its overexpression has been implicated in heart failure. Hence, the inhibition of GRK2 is considered to be an important drug target for the treatment of heart failure. Due to the high sequence similarity of GRK2 with the A, G, and C family (AGC family) of kinases, the inhibition of GRK2 also leads to the inhibition of AGC kinases such as Rho-associated coiled-coil kinase 1 (ROCK1). Therefore, unraveling the mechanisms to selectively inhibit GRK2 poses an important challenge. We have performed molecular docking, three dimensional quantitative structure activity relationship (3D-QSAR), molecular dynamics (MD) simulation, and free energy calculations techniques on a series of 53 paroxetine-like compounds to understand the structural properties desirable for enhancing the inhibitory activity for GRK2 with selectivity over ROCK1. The formation of stable hydrogen bond interactions with the residues Phe202 and Lys220 of GRK2 seems to be important for selective inhibition of GRK2. Electropositive substituents at the piperidine ring and electronegative substituents near the amide linker between the benzene ring and pyrazole ring showed a higher inhibitory preference for GRK2 over ROCK1. This study may be used in designing more potent and selective GRK2 inhibitors for therapeutic intervention of heart failure.
Assuntos
Quinase 2 de Receptor Acoplado a Proteína G/química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Paroxetina/química , Inibidores de Proteínas Quinases/química , Quinases Associadas a rho/química , Algoritmos , Sítios de Ligação , Domínio Catalítico , Desenho de Fármacos , Ativação Enzimática/efeitos dos fármacos , Quinase 2 de Receptor Acoplado a Proteína G/antagonistas & inibidores , Humanos , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Molecular , Paroxetina/farmacologia , Ligação Proteica , Inibidores de Proteínas Quinases/farmacologia , Relação Quantitativa Estrutura-Atividade , Quinases Associadas a rho/antagonistas & inibidoresRESUMO
The main mechanistic function of most chemotherapeutic drugs is mediated by inducing mitochondria-dependent apoptosis. Tumor cells usually respond to upregulate autophagy to eliminate impaired mitochondria for survival. Hypothetically, inhibiting autophagy might promote mitochondria-dependent apoptosis, thus enhancing the efficacy of chemotherapeutic therapies. We previously identified N-methylparoxetine (NMP) as an inducer of mitochondrial fragmentation with subsequent apoptosis in non-small cell lung cancer (NSCLC) cells. We discovered that ROS was accumulated in NMP-treated NSCLC cells, followed by c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38) activation. This was reversed by the application of a reactive oxygen species (ROS) scavenger, N-acetylcysteine (NAC), leading to a reduction in apoptosis. Our data suggested that NMP induced apoptosis in NSCLC cells by activating mitogen-activated protein kinase (MAPK) pathway. We further speculated that the remarkable increase of ROS in NMP-treated NSCLC cells might result from an inhibition of autophagy. Our current data confirmed that NMP blocked autophagy flux at late stage wherein lysosomal acidification was inhibited. Taken together, this study demonstrated that NMP could exert dual apoptotic functions-mitochondria impairment and, concomitantly, autophagy inhibition. NMP-related excessive ROS accumulation induced apoptosis by activating the MAPK pathway in NSCLC cells.
Assuntos
Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Neoplasias Pulmonares/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Paroxetina/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Lisossomos/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Estrutura Molecular , Paroxetina/análogos & derivados , Paroxetina/química , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The wide occurrence of pharmaceuticals in aquatic environments urges the development of cost-effective solutions for their removal from water. In a circular economy context, primary paper mill sludge (PS) was used to produce activated carbon (AC) aiming the adsorptive removal of these contaminants. The use of low-cost precursors for the preparation of ACs capable of competing with commercial ACs continues to be a challenge. A full factorial design of four factors (pyrolysis temperature, residence time, precursor/activating agent ratio, and type of activating agent) at two levels was applied to the production of AC using PS as precursor. The responses analysed were the yield of production, percentage of adsorption for three pharmaceuticals (sulfamethoxazole, carbamazepine, and paroxetine), specific surface area (SBET), and total organic carbon (TOC). Statistical analysis was performed to evaluate influencing factors in the responses and to determine the most favourable production conditions. Four ACs presented very good responses, namely on the adsorption of the pharmaceuticals under study (average adsorption percentage around 78%, which is above that of commercial AC), and SBET between 1389 and 1627â¯m2â¯g-1. A desirability analysis pointed out 800⯰C for 60â¯min and a precursor/KOH ratio of 1:1 (w/w) as the optimal production conditions.
Assuntos
Carbamazepina/química , Carvão Vegetal/química , Paroxetina/química , Sulfametoxazol/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Resíduos Industriais , PapelRESUMO
Racemic trans-paroxol, trans-N-methylparoxetine and trans-paroxetine containing two chiral centres were stereoselectively separated using countercurrent chromatography with hydroxypropyl-ß-cyclodextrin as the chiral selector. A two-phase solvent system composed of n-butyl acetate and 0.1 mol L-1 sodium carbonate-sodium bicarbonate buffer at pH 9.2 (1:1, v/v) was selected, and 0.10 mol L-1 hydroxypropyl-ß-cyclodextrin was added to the aqueous phase as the chiral selector. Racemic trans-N-methylparoxetine and racemic trans-paroxol (20 mg of each) were stereoselectively separated by countercurrent chromatography in an individual run, yielding 7.1-8.3 mg of enantiomers with a purity of 95-98%, where the recovery of each separated isomer reached approximately 70-83%. Racemic trans-paroxetine (20 mg) was stereoselectively separated by countercurrent chromatography using a recycling elution mode with a biphasic solvent system composed of n-hexane: n-butyl acetate: 0.1 mol L-1 sodium carbonate-sodium bicarbonate buffer at pH 9.2 (9:1:10, v/v/v), and 0.10 mol L-1 hydroxypropyl-ß-cyclodextrin was added to the aqueous phase as the chiral selector, yielding 5.0-5.6 mg of enantiomer with a high purity of over 98-99%.
Assuntos
Distribuição Contracorrente/métodos , Paroxetina/química , Paroxetina/isolamento & purificação , Inibidores Seletivos de Recaptação de Serotonina/química , Inibidores Seletivos de Recaptação de Serotonina/isolamento & purificação , Solventes/química , EstereoisomerismoRESUMO
The interactions of the drugs amlodipine and paroxetine, which are prescribed respectively for treatment of hypertension and depression, with the metabolizing enzyme cytochrome CYP2B4 as the drug target, have been studied by molecular dynamics (MD) simulation. Poly ethylene glycol was used to control the drugs' interactions with each other and with the target CYP2B4. Thirteen simulation systems were carefully designed, and the results obtained from MD simulations indicated that amlodipine in the PEGylated form prescribed with paroxetine in the nonPEGylated form promotes higher cytochrome stability and causes fewer fluctuations as the drugs approach the target CYP2B4 and interact with it. The simulation results led us to hypothesize that the combination of the drugs with a specific drug ratio, as proposed in this work, manifests more effective diffusivity and less instability while metabolizing with enzyme CYP2B4. Also, the active residues in the CYP2B4 enzyme that interact with the drugs were determined by MD simulation, which were consistent with the reported experimental results. Graphical Abstract Efficient drug-enzyme interactions, as a result of PEGylation.
Assuntos
Anlodipino/química , Antidepressivos de Segunda Geração/química , Anti-Hipertensivos/química , Hidrocarboneto de Aril Hidroxilases/química , Paroxetina/química , Anlodipino/metabolismo , Antidepressivos de Segunda Geração/metabolismo , Anti-Hipertensivos/metabolismo , Hidrocarboneto de Aril Hidroxilases/metabolismo , Família 2 do Citocromo P450/química , Família 2 do Citocromo P450/metabolismo , Difusão , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Paroxetina/metabolismoRESUMO
Selective serotonin reuptake inhibitors are clinically prescribed antidepressants that act by increasing the local concentrations of neurotransmitters at synapses and in extracellular spaces via blockade of the serotonin transporter. Here we report X-ray structures of engineered thermostable variants of the human serotonin transporter bound to the antidepressants sertraline, fluvoxamine, and paroxetine. The drugs prevent serotonin binding by occupying the central substrate-binding site and stabilizing the transporter in an outward-open conformation. These structures explain how residues within the central site orchestrate binding of chemically diverse inhibitors and mediate transporter drug selectivity.
Assuntos
Antidepressivos/química , Fluvoxamina/química , Paroxetina/química , Inibidores Seletivos de Recaptação de Serotonina/química , Proteínas da Membrana Plasmática de Transporte de Serotonina/química , Sertralina/química , Sítios de Ligação , Química Farmacêutica , Cristalografia por Raios X , Humanos , Cinética , Mutação , Ligação ProteicaRESUMO
The enantiomers of trans-paroxetine (the selectand) were separated on four chiral stationary phases incorporating either quinine [ZWIX(+), ZWIX(+A)] or quinidine [ZWIX(-), ZWIX(-A)] and (R,R)-aminocyclohexanesulfonic acid [in ZWIX(-), and ZWIX(+A)] or (S,S)-aminocyclohexanesulfonic acid [in ZWIX(+), and ZWIX(-A)] chiral selectors. The zwitterion nature of the phases is due to the presence of either (R,R)- or (S,S)-aminocyclohexanesulfonic acid in the selector structure bearing the quinuclidine moiety. ZWIX(+) and ZWIX(-) phases are available on the market with the commercial names CHIRALPAK ZWIX(+) and CHIRALPAK ZWIX(-), respectively. With the aim of rationalizing the enantiomer elution order with the above chiral stationary phases, a molecular dynamic protocol was applied and two energetic parameters were initially measured: selectand conformational energy and selectand interaction energy. In the search for other descriptors allowing a better fitting with the experimental evidences, in the present work we consider an energetic parameter, defined as the selector conformational energy, which resulted to be relevant in the explanation of the experimental elution order in most of the cases. Very importantly, the computational data produced by the present study strongly support the outstanding role of the conformational energy of the chiral selector as it interacts with the analytes.
Assuntos
Alcaloides de Cinchona/química , Paroxetina/isolamento & purificação , Modelos Moleculares , Conformação Molecular , Paroxetina/química , EstereoisomerismoRESUMO
In spite of the important role of the human serotonin transporter (hSERT) in depression treatment, the molecular details of how antidepressant drugs bind are still not completely understood, in particular those related to potential high- and low-affinity binding sites in hSERT. Here, we utilize amber codon suppression in hSERT to encode the photo-cross-linking unnatural amino acid p-azido-l-phenylalanine into the suggested high- and low-affinity binding sites. We then employ UV-induced cross-linking with azF to map the binding site of escitalopram and paroxetine, two prototypical selective serotonin reuptake inhibitors (SSRIs). We find that the two antidepressant drugs exclusively cross-link to azF incorporated at the high-affinity binding site of hSERT, while cross-linking is not observed at the low-affinity binding site. Combined with previous homology models and recent structural data on hSERT, our results provide important information to understand the molecular details of these clinical relevant binding sites.
Assuntos
Citalopram/química , Paroxetina/química , Inibidores Seletivos de Recaptação de Serotonina/química , Proteínas da Membrana Plasmática de Transporte de Serotonina/química , Sítios de Ligação , Citalopram/farmacologia , Cristalografia por Raios X , Humanos , Modelos Moleculares , Paroxetina/farmacologia , Ligação Proteica , Conformação Proteica , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacologiaRESUMO
A high dietary intake of phosphorus is considered to be a significant health threat for hemodialysis (HD) patients. Prescription medications, which might be a major source of phosphorus, is largely unrecognized in Japan. However, the amount of phosphorus indicated on the package label, is not quantified. In this study, the phosphorus content of 22 of the most widely prescribed medications that are used in conjunction with HD therapy were examined and differences between branded and generic prescription medications were compared. All samples were selected from medications that are typically prescribed for HD patients. The samples were ground prior to analysis. Phosphorus was measured using the Wako L-Type Phosphate method. All instruments used in the study were calibrated according to the manufacturers' specifications. Amlodipine (15 mg/tablet) and paroxetine (30.0 mg/tablet) were found to contain higher contents of phosphorus than the medications tested. Differences in phosphorus content between branded and generic drugs was also determined. The phosphorus content of all generic paroxetine preparations was significantly lower than the values for identical branded medications. On the other hand, the phosphorus content of several generic amlodipine preparations were significantly different from those of similar, branded preparations. Specific information regarding the phosphorus content of prescribed medications used by HD patient needs to be made available to the dialysis community.
Assuntos
Fósforo/efeitos adversos , Fósforo/análise , Medicamentos sob Prescrição/química , Diálise Renal , Anlodipino/química , Medicamentos Genéricos/química , Humanos , Japão , Paroxetina/química , Fósforo na Dieta/efeitos adversos , Fósforo na Dieta/análiseRESUMO
A highly enantioselective tandem Michael/ring-closure reaction of α,ß-unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N'-dioxide-Yb(OTf)3 complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo- and enantioselectivities. Moreover, this methodology could be used for gram-scale manipulation and was successfully applied to the synthesis of (-)-paroxetine. Further nonlinear and HRMS studies revealed that the real catalytically active species was a monomeric L-PMe2 -Yb3+ complex. A plausible transition state was proposed to explain the origin of the asymmetric induction.
Assuntos
Paroxetina/síntese química , Pirazóis/química , Catálise , Paroxetina/química , EstereoisomerismoRESUMO
The serotonin transporter (SERT) terminates serotonergic signalling through the sodium- and chloride-dependent reuptake of neurotransmitter into presynaptic neurons. SERT is a target for antidepressant and psychostimulant drugs, which block reuptake and prolong neurotransmitter signalling. Here we report X-ray crystallographic structures of human SERT at 3.15 Å resolution bound to the antidepressants (S)-citalopram or paroxetine. Antidepressants lock SERT in an outward-open conformation by lodging in the central binding site, located between transmembrane helices 1, 3, 6, 8 and 10, directly blocking serotonin binding. We further identify the location of an allosteric site in the complex as residing at the periphery of the extracellular vestibule, interposed between extracellular loops 4 and 6 and transmembrane helices 1, 6, 10 and 11. Occupancy of the allosteric site sterically hinders ligand unbinding from the central site, providing an explanation for the action of (S)-citalopram as an allosteric ligand. These structures define the mechanism of antidepressant action in SERT, and provide blueprints for future drug design.