RESUMEN
Auditory attention detection (AAD) is the tracking of a sound source to which a listener is attending based on neural signals. Despite expectation for the applicability of AAD in real-life, most AAD research has been conducted on recorded electroencephalograms (EEGs), which is far from online implementation. In the present study, we attempted to propose an online AAD model and to implement it on a streaming EEG. The proposed model was devised by introducing a sliding window into the linear decoder model and was simulated using two datasets obtained from separate experiments to evaluate the feasibility. After simulation, the online model was constructed and evaluated based on the streaming EEG of an individual, acquired during a dichotomous listening experiment. Our model was able to detect the transient direction of a participant's attention on the order of one second during the experiment and showed up to 70% average detection accuracy. We expect that the proposed online model could be applied to develop adaptive hearing aids or neurofeedback training for auditory attention and speech perception.
Asunto(s)
Atención , Percepción Auditiva , Electroencefalografía , Audífonos , Humanos , Percepción del HablaRESUMEN
The antidepressant activities of hispidol and decursin (both potent monoamine oxidase A (MAO-A) inhibitors) were evaluated using the forced swimming test (FST) and the tail suspension test (TST) in mice, and thereafter, levels of neurotransmitter monoamines and metabolites in brain tissues were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hispidol (15 mg/kg) caused less or comparable immobility than fluoxetine (15 mg/kg; the positive control) in immobility time, as determined by FST (9.6 vs 32.0 s) and TST (53.1 vs 48.7 s), respectively, and its effects were dose-dependent and significant. Decursin (15 mg/kg) also produced immobility comparable to that of fluoxetine as determined by FST (47.0 vs 43.4 s) and TST (55.6 vs 63.4 s), and its effects were also dose-dependent and significant. LC-MS/MS analysis after FST showed that hispidol (15 mg/kg) greatly increased dopamine (DA) and serotonin levels dose-dependently in brain tissues as compared with the positive control. Decursin (15 mg/kg) dose-dependently increased DA level after TST. Slight changes in norepinephrine and 3,4-dihydroxyphenylacetic acid levels were observed after FST and TST in hispidol- or decursin-treated animals. It was observed that hispidol and decursin were effective and comparable to fluoxetine in immobility tests. These immobility and monoamine level results suggest that hispidol and decursin are potential antidepressant agents for the treatment of depression, and that they act mainly through serotonergic and/or dopaminergic systems.
Asunto(s)
Antidepresivos/uso terapéutico , Benzofuranos/uso terapéutico , Benzopiranos/uso terapéutico , Compuestos de Bencilideno/uso terapéutico , Butiratos/uso terapéutico , Depresión/tratamiento farmacológico , Dopamina/metabolismo , Serotonina/metabolismo , Animales , Conducta Animal/efectos de los fármacos , Encéfalo/metabolismo , Suspensión Trasera , Masculino , Ratones Endogámicos ICR , Inhibidores de la Monoaminooxidasa/uso terapéutico , NataciónRESUMEN
Osthenol (6), a prenylated coumarin isolated from the dried roots of Angelica pubescens, potently and selectively inhibited recombinant human monoamine oxidase-A (hMAO-A) with an IC50 value of 0.74⯵M and showed a high selectivity index (SIâ¯>â¯81.1) for hMAO-A versus hMAO-B. Compound 6 was a reversible competitive hMAO-A inhibitor (Kiâ¯=â¯0.26⯵M) with a potency greater than toloxatone (IC50â¯=â¯0.93⯵M), a marketed drug. Isopsoralen (3) and bakuchicin (1), furanocoumarin derivatives isolated from Psoralea corylifolia L., showed slightly higher IC50 values (0.88 and 1.78⯵M, respectively) for hMAO-A than 6, but had low SI values (3.1 for both). Other coumarins tested did not effectively inhibit hMAO-A or hMAO-B. A structural comparison suggested that the 8-(3,3-dimethylallyl) group of 6 increased its inhibitory activity against hMAO-A compared with the 6-methoxy group of scopoletin (4). Molecular docking simulations revealed that the binding affinity of 6 for hMAO-A (-8.5â¯kcal/mol) was greater than that for hMAO-B (-5.6â¯kcal/mol) and that of 4 for hMAO-A (-7.3â¯kcal/mol). Docking simulations also implied that 6 interacted with hMAO-A at Phe208 and with hMAO-B at Ile199 by carbon hydrogen bondings. Our findings suggest that osthenol, derived from natural products, is a selective and potent reversible inhibitor of MAO-A, and can be regarded a potential lead compound for the design of novel reversible MAO-A inhibitors.
Asunto(s)
Cumarinas/química , Inhibidores de la Monoaminooxidasa/química , Monoaminooxidasa/química , Acetilcolinesterasa/química , Dominio Catalítico , Inhibidores de la Colinesterasa/química , Cumarinas/metabolismo , Pruebas de Enzimas , Humanos , Cinética , Simulación del Acoplamiento Molecular , Estructura Molecular , Monoaminooxidasa/metabolismo , Inhibidores de la Monoaminooxidasa/metabolismo , Unión Proteica , Relación Estructura-ActividadRESUMEN
Three flavanones and two flavones were isolated from the leaves of Prunus padus var. seoulensis by the activity-guided screening for new monoamine oxidase (MAO) inhibitors. Among the compounds isolated, rhamnocitrin (5) was found to potently and selectively inhibit human MAO-A (hMAO-A, IC50â¯=â¯0.051⯵M) and effectively inhibit hMAO-B (IC50â¯=â¯2.97⯵M). The IC50 value of 5 for hMAO-A was the lowest amongst all natural flavonoids reported to date, and the potency was 20.2 times higher than that of toloxatone (1.03⯵M), a marketed drug. In addition, 5 reversibly and competitively inhibited hMAO-A and hMAO-B with Ki values of 0.030 and 0.91⯵M, respectively. Genkwanin (4) was also observed to strongly inhibit hMAO-A and hMAO-B (IC50â¯=â¯0.14 and 0.35⯵M, respectively), and competitively inhibit hMAO-A and hMAO-B (Kiâ¯=â¯0.097 and 0.12⯵M, respectively). Molecular docking simulation reveals that the binding affinity of 5 with hMAO-A (-18.49â¯kcal/mol) is higher than that observed with hMAO-B (0.19â¯kcal/mol). Compound 5 interacts with hMAO-A at four possible residues (Asn181, Gln215, Thr336, and Tyr444), while hMAO-B forms a single hydrogen bond at Glu84. These findings suggest that compound 5 as well as 4 can be considered as novel potent and reversible hMAO-A and/or hMAO-B inhibitors or useful lead compounds for future development of hMAO inhibitors in neurological disorder therapies.
Asunto(s)
Quempferoles/química , Inhibidores de la Monoaminooxidasa/química , Prunus/química , Dominio Catalítico , Flavonas/química , Flavonas/aislamiento & purificación , Flavonas/metabolismo , Humanos , Quempferoles/aislamiento & purificación , Quempferoles/metabolismo , Simulación del Acoplamiento Molecular , Monoaminooxidasa/química , Monoaminooxidasa/metabolismo , Inhibidores de la Monoaminooxidasa/aislamiento & purificación , Inhibidores de la Monoaminooxidasa/metabolismo , Hojas de la Planta/química , Unión ProteicaRESUMEN
Six hundred forty natural compounds were tested for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Of those, sargachromanol I (SCI) and G (SCG) isolated from the brown alga Sargassum siliquastrum, dihydroberberine (DB) isolated from Coptis chinensis, and macelignan (ML) isolated from Myristica fragrans, potently and effectively inhibited AChE with IC50 values of 0.79, 1.81, 1.18, and 4.16⯵M, respectively. SCI, DB, and ML reversibly inhibited AChE and showed mixed, competitive, and noncompetitive inhibition, respectively, with Ki values of 0.63, 0.77, and 4.46⯵M, respectively. Broussonin A most potently inhibited BChE (IC50â¯=â¯4.16⯵M), followed by ML, SCG, and SCI (9.69, 10.79, and 13.69⯵M, respectively). In dual-targeting experiments, ML effectively inhibited monoamine oxidase B with the greatest potency (IC50â¯=â¯7.42⯵M). Molecular docking simulation suggested the binding affinity of SCI (-8.6â¯kcal/mol) with AChE was greater than those of SCG (-7.9â¯kcal/mol) and DB (-8.2â¯kcal/mol). Docking simulation indicated SCI interacts with AChE at Trp81, and that SCG interacts at Ser119. No hydrogen bond was predicted for the interaction between AChE and DB. This study suggests SCI, SCG, DB, and ML be viewed as new reversible AChE inhibitors and useful lead compounds for the development for the treatment of Alzheimer's disease.
Asunto(s)
Acetilcolinesterasa/metabolismo , Benzopiranos/farmacología , Productos Biológicos/farmacología , Inhibidores de la Colinesterasa/farmacología , Alcoholes Grasos/farmacología , Sargassum/química , Anemarrhena/química , Animales , Benzopiranos/química , Benzopiranos/aislamiento & purificación , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Butirilcolinesterasa/metabolismo , Inhibidores de la Colinesterasa/química , Inhibidores de la Colinesterasa/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Electrophorus , Alcoholes Grasos/química , Alcoholes Grasos/aislamiento & purificación , Caballos , Humanos , Cinética , Simulación del Acoplamiento Molecular , Estructura Molecular , Monoaminooxidasa/metabolismo , Myristica/química , Relación Estructura-ActividadRESUMEN
The present study documents the synthesis of oxygenated chalcone (O1-O26) derivatives and their abilities to inhibit monoamine oxidases. All 26 derivatives examined showed potent inhibitory activity against MAO-B. Compound O23 showed the greatest inhibitory activity against MAO-B with an IC50 value of 0.0021⯵M, followed by compounds O10 and O17 (IC50â¯=â¯0.0030 and 0.0034⯵M, respectively). In addition, most of the derivatives potently inhibited MAO-A and O6 was the most potent inhibitor with an IC50 value of 0.029⯵M, followed by O3, O4, O9, and O2 (IC50â¯=â¯0.035, 0.053, 0.072, and 0.082⯵M, respectively). O23 had a high selectivity index (SI) value for MAO-B of 138.1, and O20 (IC50 value for MAO-Bâ¯=â¯0.010⯵M) had an extremely high SI of >4000. In dialysis experiments, inhibitions of MAO-A and MAO-B by O6 and O23, respectively, were recovered to their respective reversible reference levels, demonstrating both are reversible inhibitors. Kinetic studies revealed that O6 and O23 competitively inhibited MAO-A and MAO-B, respectively, with respective Ki values of 0.016⯱â¯0.0007 and 0.00050⯱â¯0.00003⯵M. Lead compound are also non-toxic at 200⯵g/mL in normal rat spleen cells. Molecular docking simulations and subsequent Molecular Mechanics/Generalized Born Surface Area calculations provided a rationale that explained experimental data.
Asunto(s)
Chalconas/química , Diseño de Fármacos , Inhibidores de la Monoaminooxidasa/química , Inhibidores de la Monoaminooxidasa/farmacología , Monoaminooxidasa/efectos de los fármacos , Oxígeno/química , Animales , Cinética , Simulación del Acoplamiento Molecular , Inhibidores de la Monoaminooxidasa/síntesis química , Ratas , Bazo/citología , Bazo/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Chelerythrine, an isoquinoline alkaloid isolated from the herbaceous perennial Chelidonium majus, was found to potently and selectively inhibit an isoform of recombinant human monoamine oxidase-A (MAO-A) with an IC50 value of 0.55⯵M. Chelerythrine was a reversible competitive MAO-A inhibitor (Kiâ¯=â¯0.22⯵M) with a potency much greater than toloxatone (IC50â¯=â¯1.10⯵M), a marketed drug. Other isoquinoline alkaloids tested did not effectively inhibit MAO-A or MAO-B. A structural comparison with corynoline suggested the 1- and/or 2-methoxy groups of chelerythrine increase its inhibitory activity against MAO-A. Molecular docking simulations revealed that the binding affinity of chelerythrine for MAO-A (-9.7â¯kcal/mol) was greater than that for MAO-B (-4.6â¯kcal/mol). Docking simulation implied that Cys323 and Tyr444 of MAO-A are key residues for hydrogen-bond interaction with chelerythrine. Our findings suggest chelerythrine is one of the most reversible selective and potent natural inhibitor of MAO-A, and that it be regarded a potential lead compound for the design of novel reversible MAO-A inhibitors.
Asunto(s)
Benzofenantridinas/farmacología , Inhibidores de la Monoaminooxidasa/farmacología , Monoaminooxidasa/metabolismo , Benzofenantridinas/síntesis química , Benzofenantridinas/química , Relación Dosis-Respuesta a Droga , Humanos , Simulación del Acoplamiento Molecular , Estructura Molecular , Inhibidores de la Monoaminooxidasa/síntesis química , Inhibidores de la Monoaminooxidasa/química , Relación Estructura-ActividadRESUMEN
Hispidol, an aurone, isolated from Glycine max Merrill, was found to potently and selectively inhibit an isoform of recombinant human monoamine oxidase-A (MAO-A), with an IC50 value of 0.26⯵M, and to inhibit MAO-B, but with lower potency (IC50â¯=â¯2.45⯵M). Hispidol reversibly and competitively inhibited MAO-A with a Ki value of 0.10⯵M with a potency much greater than toloxatone (IC50â¯=â¯1.10⯵M), a marketed drug. It also reversibly and competitively inhibited MAO-B (Kiâ¯= 0.51⯵M). Sulfuretin, an analog of hispidol, effectively inhibited MAO-A (IC50â¯=â¯4.16⯵M) but not MAO-B (IC50â¯>â¯80⯵M). A comparison of their chemical structures showed that the 3'-hydroxyl group of sulfuretin might reduce its inhibitory activities against MAO-A and MAO-B. Flexible docking simulation revealed that the binding affinity of hispidol for MAO-A (-9.1â¯kcal/mol) was greater than its affinity for MAO-B (-8.7â¯kcal/mol). The docking simulation showed hispidol binds to the major pocket of MAO-A or MAO-B. The findings suggest hispidol is a potent, selective, reversible inhibitor of MAO-A, and that it be considered a novel lead compound for development of novel reversible inhibitors of MAO-A.
Asunto(s)
Benzofuranos/química , Inhibidores de la Monoaminooxidasa/química , Sitios de Unión , Clorgilina/química , Flavonoides/química , Humanos , Concentración 50 Inhibidora , Cinética , Simulación del Acoplamiento Molecular , Monoaminooxidasa/química , Oxazolidinonas/química , Ácidos Picolínicos/químicaRESUMEN
ß-1,3-1,4-Glucanase (BGlc8H) from Paenibacillus sp. X4 was mutated by error-prone PCR or truncated using termination primers to improve its enzyme properties. The crystal structure of BGlc8H was determined at a resolution of 1.8 Å to study the possible roles of mutated residues and truncated regions of the enzyme. In mutation experiments, three clones of EP 2-6, 2-10, and 5-28 were finally selected that exhibited higher specific activities than the wild type when measured using their crude extracts. Enzyme variants of BG2-6, BG2-10, and BG5-28 were mutated at two, two, and six amino acid residues, respectively. These enzymes were purified homogeneously by Hi-Trap Q and CHT-II chromatography. Specific activity of BG5-28 was 2.11-fold higher than that of wild-type BGwt, whereas those of BG2-6 and BG2-10 were 0.93- and 1.19-fold that of the wild type, respectively. The optimum pH values and temperatures of the variants were nearly the same as those of BGwt (pH 5.0 and 40 °C, respectively). However, the half-life of the enzyme activity and catalytic efficiency (k cat/K m) of BG5-28 were 1.92- and 2.12-fold greater than those of BGwt at 40 °C, respectively. The catalytic efficiency of BG5-28 increased to 3.09-fold that of BGwt at 60 °C. These increases in the thermostability and catalytic efficiency of BG5-28 might be useful for the hydrolysis of ß-glucans to produce fermentable sugars. Of the six mutated residues of BG5-28, five residues were present in mature BGlc8H protein, and two of them were located in the core scaffold of BGlc8H and the remaining three residues were in the substrate-binding pocket forming loop regions. In truncation experiments, three forms of C-terminal truncated BGlc8H were made, which comprised 360, 286, and 215 amino acid residues instead of the 409 residues of the wild type. No enzyme activity was observed for these truncated enzymes, suggesting the complete scaffold of the α6/α6-double-barrel structure is essential for enzyme activity.
Asunto(s)
Glicósido Hidrolasas/genética , Glicósido Hidrolasas/metabolismo , Mutagénesis Sitio-Dirigida , Paenibacillus/enzimología , Catálisis , Clonación Molecular , Cristalización , Cartilla de ADN , Expresión Génica , Semivida , Concentración de Iones de Hidrógeno , Cinética , Paenibacillus/genética , Reacción en Cadena de la Polimerasa/métodos , Conformación Proteica , Especificidad por Sustrato , Temperatura , beta-Glucanos/metabolismoRESUMEN
When individuals listen to speech, their neural activity phase-locks to the slow temporal rhythm, which is commonly referred to as "neural tracking". The neural tracking mechanism allows for the detection of an attended sound source in a multi-talker situation by decoding neural signals obtained by electroencephalography (EEG), known as auditory attention decoding (AAD). Neural tracking with AAD can be utilized as an objective measurement tool for diverse clinical contexts, and it has potential to be applied to neuro-steered hearing devices. To effectively utilize this technology, it is essential to enhance the accessibility of EEG experimental setup and analysis. The aim of the study was to develop a cost-efficient neural tracking system and validate the feasibility of neural tracking measurement by conducting an AAD task using an offline and real-time decoder model outside the soundproof environment. We devised a neural tracking system capable of conducting AAD experiments using an OpenBCI and Arduino board. Nine participants were recruited to assess the performance of the AAD using the developed system, which involved presenting competing speech signals in an experiment setting without soundproofing. As a result, the offline decoder model demonstrated an average performance of 90%, and real-time decoder model exhibited a performance of 78%. The present study demonstrates the feasibility of implementing neural tracking and AAD using cost-effective devices in a practical environment.
Asunto(s)
Percepción del Habla , Humanos , Estimulación Acústica , Electroencefalografía , Habla , AtenciónRESUMEN
Selective auditory attention has been shown to modulate the cortical representation of speech. This effect has been well documented in acoustically more challenging environments. However, the influence of top-down factors, in particular topic familiarity, on this process remains unclear, despite evidence that semantic information can promote speech-in-noise perception. Apart from individual features forming a static listening condition, dynamic and irregular changes of auditory scenes-volatile listening environments-have been less studied. To address these gaps, we explored the influence of topic familiarity and volatile listening on the selective auditory attention process during dichotic listening using electroencephalography. When stories with unfamiliar topics were presented, participants' comprehension was severely degraded. However, their cortical activity selectively tracked the speech of the target story well. This implies that topic familiarity hardly influences the speech tracking neural index, possibly when the bottom-up information is sufficient. However, when the listening environment was volatile and the listeners had to re-engage in new speech whenever auditory scenes altered, the neural correlates of the attended speech were degraded. In particular, the cortical response to the attended speech and the spatial asymmetry of the response to the left and right attention were significantly attenuated around 100-200 ms after the speech onset. These findings suggest that volatile listening environments could adversely affect the modulation effect of selective attention, possibly by hampering proper attention due to increased perceptual load.
Asunto(s)
Percepción Auditiva , Percepción del Habla , Humanos , Percepción del Habla/fisiología , Audición , Electroencefalografía , Atención/fisiologíaRESUMEN
Nineteen compounds were isolated from the stems of Maackia amurensis by activity-guided screening for new human monoamine oxidase-B (hMAO-B) inhibitors. Among the compounds isolated, flavonoids calycosin (5) and 8-O-methylretusin (6) were found to potently and selectively inhibit hMAO-B (IC50 = 0.24 and 0.23 µM, respectively) but not hMAO-A with high selectivity index (SI) values (SI = 293.8 and 81.3, respectively). In addition, 5 and 6 reversibly and competitively inhibited hMAO-B with Ki values of 0.057 and 0.054 µM, respectively. A pterocarpan (-)-medicarpin (18) was also observed to strongly inhibit hMAO-B (IC50 = 0.30 µM). Most of the compounds weakly inhibited AChE, except isolupalbigenin (13) (IC50 = 20.6 µM), which suggested 13 be considered a potential dual function inhibitor of MAO-B and AChE. Molecular docking simulation revealed that the binding affinities of 5 and 6 for hMAO-B (both -9.3 kcal/mol) were higher than those for hMAO-A (-7.4 and -7.2 kcal/mol, respectively). Compound 5 was found to interact by hydrogen bonding with hMAO-B at Cys172 residue (distance: 3.250 Å); no hydrogen bonding was predicted between 5 and hMAO-A. These findings suggest that compounds 5 and 6 be considered novel potent, selective, and reversible hMAO-B inhibitors and candidates for the treatment of neurological disorders.
Asunto(s)
Isoflavonas/química , Isoflavonas/farmacología , Maackia/química , Inhibidores de la Monoaminooxidasa/química , Inhibidores de la Monoaminooxidasa/farmacología , Extractos Vegetales/farmacología , Relación Dosis-Respuesta a Droga , Activación Enzimática/efectos de los fármacos , Humanos , Isoflavonas/aislamiento & purificación , Cinética , Conformación Molecular , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Estructura Molecular , Inhibidores de la Monoaminooxidasa/aislamiento & purificación , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Relación Estructura-ActividadRESUMEN
Six synthetic (1-6) and six natural (7-12) chalcones were tested for human monoamine oxidases (hMAOs) and acetylcholinesterase (AChE) inhibitory activities. Compounds 4-dimethylaminochalcone (2), 4'-chloro-4-dimethylaminochalcone (5), and 2,4'-dichloro-4-dimethylaminochalcone (1) potently inhibited hMAO-B with IC50 values of 0.029, 0.061, and 0.075⯵M, respectively. 4-Nitrochalcone (4) and 4-chlorochalcone (3) also potently inhibited hMAO-B with IC50 values of 0.066 and 0.082⯵M, respectively (2.3- and 2.6-fold less than compound 2). Compound 2 had a high selectivity index (113.1) for hMAO-B over hMAO-A (IC50â¯=â¯3.28⯵M). Compounds 1 and 2,2'-dihydroxy-4',6'-dimethoxychalcone (12) potently inhibited hMAO-A with IC50 values of 0.18 and 0.39⯵M, respectively. In addition, compounds 4 and 2 also effectively inhibited AChE with IC50 values of 1.25 and 6.07⯵M, respectively, and thus, exhibited dual-targeting. Compound 2 reversibly and competitively inhibited hMAO-B with a Ki value of 0.0066⯵M. Docking simulations showed binding affinities of compounds 1 to 5 for hMAO-B were higher than those for hMAO-A or AChE and suggested these five chalcones form hydrogen bonds with MAO-B at Cys172 but that they do not form hydrogen bonds with hMAO-A or AChE. These findings suggest compound 2 be considered a promising and dual-targeting lead compound for the treatment of Alzheimer's disease.
Asunto(s)
Chalconas/química , Chalconas/farmacología , Inhibidores de la Monoaminooxidasa/química , Inhibidores de la Monoaminooxidasa/farmacología , Monoaminooxidasa/metabolismo , Chalconas/metabolismo , Humanos , Simulación del Acoplamiento Molecular , Monoaminooxidasa/química , Inhibidores de la Monoaminooxidasa/metabolismo , Conformación ProteicaRESUMEN
BACKGROUND: Chalcones are considered as the selective scaffold for the inhibition of MAO-B. OBJECTIVES: A previously synthesized ethyl acetohydroxamate-chalcones (L1-L22) were studied for their inhibitory activities against human recombinant monoamine oxidase A and B (hMAO-A and hMAO-B, respectively) and acetylcholinesterase (AChE) as multi-target directed ligands for the treatment of Alzheimer's Disease (AD). METHODS: Enzyme inhibition studies of MAO-A, MAO-B and AChE is carried out. Computational studies such as Molecular docking, Molecular Mechanics/Generalized Born Surface Area calculations, ADMET prediction, and protein target prediction are also performed. RESULTS: Among the screened compounds, compound L3 has most potent hMAO-B inhibition with an IC50 value of 0.028 ± 0.0016 µM, and other compounds, L1, L2, L4, L8, L12, and L21 showed significant potent hMAO-B inhibition with IC50 values of 0.051 ± 0.0014, 0.086 ± 0.0035, 0.036 ± 0.0011, 0.096 ± 0.0061, 0.083 ± 0.0016, and 0.038 ± 0.0021 µM, respectively. On the other hand, among the tested compounds, compound L13 showed highest hMAO-A inhibition with an IC50 value of 0.51± 0.051 µM and L9 has a significant value of 1.85 ± 0.045 µM. However, the compounds L3 and L4 only showed high selectivities for hMAO-B with Selectivity Index (SI) values of 621.4 and 416.7, respectively. Among the substituents in ring A of ethyl acetohydroxamate-chalcones (L1-L9), F atom at p-position (L3) showed highest inhibitory effect against hMAO-B. This result supports the uniqness and bizarre behavior of fluorine. Moreover, chalcones L3, L4, L9, L11, and L12 showed potential AChE inhibitory effect with IC50 values of 0.67, 0.85, 0.39, 0.30, and 0.45 µM, respectively. Inhibitions of hMAO-B by L3 or L4 were recovered to the level of the reversible reference (lazabemide), and were competitive with Ki values of 0.0030 ± 0.0002 and 0.0046 ± 0.0005 µM, respectively. Inhibitions of AChE by L3 and L11 were of the competitive and mixed types with Ki values of 0.30 ± 0.044 and 0.14 ± 0.0054 µM, respectively. CONCLUSION: The studies indicated that L3 and L4 are considered to be promising multitarget drug molecules with potent, selective, and reversible competitive inhibitors of hMAO-B and with highly potent AChE inhibitory effect.
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Enfermedad de Alzheimer/tratamiento farmacológico , Chalconas/uso terapéutico , Inhibidores de la Monoaminooxidasa/uso terapéutico , Acetilcolinesterasa/metabolismo , Enfermedad de Alzheimer/metabolismo , Diseño de Fármacos , Humanos , Simulación del Acoplamiento Molecular , Monoaminooxidasa/metabolismo , Relación Estructura-ActividadRESUMEN
A new intracellular serine protease gene of Bacillus megaterium, ispK, encoding a protein composed of 332 amino acid residues with a predicted pI of 4.7 was cloned into Escherichia coli. The deduced amino acid sequence of IspK showed 49-56% similarity with the other microbial intracellular serine proteases described in the literature. The enzyme was effectively purified by one-step chromatography after heat-treatment, and showed a homogeneous band corresponding to 35kDa by SDS-PAGE analysis. Amino acid analysis showed that 16 amino acids of the N-terminus of IspK were removed by post-translational protease activity. The optimum pH and temperature of IspK were 6.0-7.0 and 50°C, respectively. In the presence of 2mM of Ca2+ ion, the optimum temperature was increased to 65°C and thermostability (t1/2) increased 32.9-fold from 3.3min to 108.5min at 60°C. The enzyme was activated by Ca2+ and Mg2+, almost completely inhibited by phenylmethanesulfonyl fluoride (PMSF) and EDTA, but tolerant to nonionic surfactants, such as, Triton X-100 or Tween 80. IspK efficiently hydrolyzed natural proteins, such as, casein and hemoglobin, and improved blood stain removal. These results suggest IspK can be used as a useful additive for detergent formulations and for deproteinizations.
Asunto(s)
Bacillus megaterium/enzimología , Bacillus megaterium/genética , Clonación Molecular , Serina Proteasas/genética , Serina Proteasas/metabolismo , Secuencia de Aminoácidos , Carbono/metabolismo , Detergentes/química , Detergentes/farmacología , Activación Enzimática , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , Cinética , Metales/química , Peso Molecular , Nitrógeno/metabolismo , Proteolisis , Serina Proteasas/química , Serina Proteasas/aislamiento & purificación , Especificidad por Sustrato , TemperaturaRESUMEN
A series of twelve furanochalcones (F1-F12) was synthesized and investigated for their human monoamine oxidase inhibitory activities. Among the series, compound (2E, 4E)-1-(furan-2-yl)-5-phenylpenta-2, 4-dien-1-one (F1), which was analyzed by single-crystal X-ray diffraction, showed potent and selective MAO-B inhibitory activity with an inhibition constant (Ki) value of 0.0041⯵M and selectivity index of (SI) 172.4, and exhibited competitive inhibition. Introduction of a cinnamyl group to the furanochalcone significantly increased the inhibitory activity. In the dilution-recovery experiments, the residual activities of MAO-A and MAO-B by F1 under the diluted condition fully recovered as compared with the undiluted condition, indicating F1 is a reversible inhibitor. The Ki value of F1 is the lowest among the values of chalcone derivatives and furthermore lower than that (0.0079⯵M) of the reversible MAO-B inhibitor, lazabemide, a marketed drug. Molecular docking study against hMAO-B provided the binding site interactions of the lead compound, including strong π-π stacking between the phenyl system and FAD nucleus.
Asunto(s)
Chalconas/química , Chalconas/farmacología , Descubrimiento de Drogas , Inhibidores de la Monoaminooxidasa/química , Inhibidores de la Monoaminooxidasa/farmacología , Sitios de Unión , Humanos , Cinética , Conformación Molecular , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Monoaminooxidasa/química , Unión Proteica , Relación Estructura-ActividadRESUMEN
In the present study, series of eleven (2E)-1-[4-(1H-imidazol-1-yl)substituted phenyl]-3-phenylprop-2-en-1-one (IM1-IM11) derivatives were synthesized and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The results indicate that (2E)-3-[4-(dimethylamino) phenyl]-1-[4-(1H-imidazol-1-yl) phenyl] prop-2-en-1-one (IM5) is a nonselective and reversible competitive inhibitor of MAO-A and MAO-B with IC50 values of 0.30⯱â¯0.010 and 0.40⯱â¯0.017 µM, respectively ; those of (2E)-1-[4-(1H-imidazol-1-yl) phenyl]-3-(4-methylphenyl) prop-2-en-1-one (IM4) were 1.06⯱â¯0.090 and 0.32⯱â¯0.021 µM, respectively. Kinetic studies document that both IM5 and IM4 are competitive inhibitors of MAO-A and MAO-B with Ki value of 0.11⯱â¯0.0085 and 0.085⯱â¯0.0064 µM, respectively. Molecular docking studies of lead compounds further explained the binding modes in the inhibitor binding cavity of both MAO-A and MAO-B.
Asunto(s)
Chalconas/farmacología , Imidazoles/farmacología , Inhibidores de la Monoaminooxidasa/farmacología , Monoaminooxidasa/metabolismo , Sitios de Unión , Chalconas/síntesis química , Chalconas/metabolismo , Humanos , Imidazoles/síntesis química , Imidazoles/metabolismo , Cinética , Simulación del Acoplamiento Molecular , Estructura Molecular , Inhibidores de la Monoaminooxidasa/síntesis química , Unión Proteica , Relación Estructura-ActividadRESUMEN
A cellulolytic fungus, YDJ14, was isolated from compost and identified as an Aspergillus sp. strain. Three extracellular ß-glucosidases, BGL-A1, BGL-A2, and BGL-A3, were separated using ultrafiltration, ammonium sulfate fractionation, and High-Q chromatography. The molecular masses of the three enzymes were estimated to be 100, 45, and 40 kDa, respectively, by SDS-PAGE. The optimum pH and temperature of BGL-A3 were 5.0 and 50°C, respectively, whereas the optimum pH and temperature of BGL-A1 and BGL-A2 were identical (4.0 and 60°C, respectively). The half-life of BGL-A3 at 70°C (2.8 min) was shorter than that of BGL-A1 and BGL-A2 (12.1 and 8.8 min, respectively). All three enzymes preferred p-nitrophenyl-ß-D-glucopyranoside (pNPG) and hardly hydrolyzed cellobiose, suggesting that these enzymes were aryl ß-glucosidases. The Km of BGL-A3 (1.26 mM) for pNPG was much higher than that of BGL-A1 and BGL-A2 (0.25 and 0.27 mM, respectively). These results suggested that BGL-A1 and BGL-A2 were similar in their enzymatic properties, whereas BGL-A3 differed from the two enzymes. When tilianin (a flavone glycoside of acacetin) was reacted with the three enzymes, the inhibitory activity for monoamine oxidase, a target in the treatment of neurological disorders, was similar to that shown by acacetin. We conclude that these enzymes may be useful in the hydrolysis of flavone glycosides to improve their inhibitory activities.
Asunto(s)
Aspergillus/enzimología , Flavonoides/metabolismo , Proteínas Fúngicas/metabolismo , Glicósidos/metabolismo , beta-Glucosidasa/metabolismo , Celobiosa/química , Celobiosa/metabolismo , Espacio Extracelular/enzimología , Flavonoides/química , Proteínas Fúngicas/química , Proteínas Fúngicas/aislamiento & purificación , Glicósidos/química , Concentración de Iones de Hidrógeno , Hidrólisis , Filogenia , Temperatura , beta-Glucosidasa/química , beta-Glucosidasa/aislamiento & purificaciónRESUMEN
A cellulolytic fungus YDJ216 was isolated from a compost and identified as an Aspergillus sp. strain. Two extracellular ß-glucosidases, BGL1 and BGL2, were purified using ultrafiltration, ammonium sulfate fractionation, and High-Q chromatography. Molecular masses of BGL1 and BGL2 were estimated to be 97 and 45â¯kDa, respectively, by SDS-PAGE. The two enzymes eluted as one peak at 87â¯kDa by Sephacryl S-200 chromatography, and located at similar positions in a zymogram after intact gel electrophoresis, suggesting BGL1 and BGL2 might be monomeric and dimeric, respectively. Both enzymes showed similar enzymatic properties; they were optimally active at pHâ¯4.0-4.5 and 60⯰C, and had similar half-lives at 70⯰C. Two enzymes also preferred p-nitrophenyl glucose (pNPG) with the same Km and hardly hydrolyzed cellobiose, suggesting both enzymes are aryl ß-glucosidases. However, Vmax for pNPG of BGL1 (953.2â¯U/mg) was much higher than those of BGL2 (66.5U/mg) and other ß-glucosidases reported. When tilianin (a flavone glycoside of acacetin) was reacted with both enzymes, inhibitory activity for monoamine oxidase, relating to oxidation of neurotransmitter amines, was increased closely to the degree obtained by acacetin. These results suggest that BGL1 and BGL2 could be used to hydrolyze flavone glycosides to improve their inhibitory activities.
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Aspergillus/enzimología , Celulasas/química , Flavonas/química , Glicósidos/química , Aspergillus/química , Celobiosa/química , Celulasas/farmacología , Flavonas/farmacología , Flavonoides/química , Glucosa/química , Glicósidos/farmacología , Hidrólisis , CinéticaRESUMEN
A series of 13 phenyl substituted thiosemicarbazones (SB1-SB13) were synthesized and evaluated for their inhibitory potential towards human recombinant monoamine oxidase A and B (MAO-A and MAO-B, respectively) and acetylcholinesterase. The solid state structure of SB4 was ascertained by the single X-ray diffraction technique. Compounds SB5 and SB11 were potent for MAO-A (IC50 1.82 ± 0.14) and MAO-B (IC50 0.27 ± 0.015 µM), respectively. Furthermore, SB11 showed a high selectivity index (SI > 37.0) for MAO-B. The effects of fluorine orientation revealed that SB11 (m-fluorine) showed 28.2 times higher inhibitory activity than SB12 (o-fluorine) against MAO-B. Furthermore, inhibitions by SB5 and SB11 against MAO-A and MAO-B, respectively, were recovered to near reference levels in reversibility experiments. Both SB5 and SB11 showed competitive inhibition modes, with K i values of 0.97 ± 0.042 and 0.12 ± 0.006 µM, respectively. These results indicate that SB5 and SB11 are selective, reversible and competitive inhibitors of MAO-A and MAO-B, respectively. Compounds SB5, SB7 and SB11 showed moderate inhibition against acetylcholinesterase with IC50 values of 35.35 ± 0.47, 15.61 ± 0.057 and 26.61 ± 0.338 µM, respectively. Blood-brain barrier (BBB) permeation was studied using the parallel artificial membrane permeation assay (PAMPA) method. Molecular docking studies were carried out using AutoDock 4.2.