RESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: P. cuspidatum is a popular Chinese medicinal herb, having a long history of usage in traditional Chinese medicine for the treatment of several inflammatory diseases in the form of powders and decoctions. Similarly there are many reports that P. cuspidatum has antibacterial and anti-inflammatory effects, both of which are properties associated with compounds having activity against bacterial neuraminidase (BNA). AIM OF THE STUDY: We investigated whether P. cuspidatum's metabolites exhibited BNA inhibition. Consistent with our hypothesis, we found several inhibitors from the methanol extract of this plant, and then fully characterized their inhibitory mechanisms. MATERIALS AND METHODS: Activity guided separation of methanol extract led to isolation of individual constituents, and subsequently their structures were elucidated by spectroscopic analysis. Detailed kinetic behaviors of BNA inhibitors were explored by showing the changes of Km and Vmax, the ratios of KI/KIS and Kik/Kiv, and fluorescence quenching effect. RESULTS AND CONCLUSION: This study attempted to isolate the responsible metabolites and elucidate the BNA inhibitory mechanism. The principal BNA inhibitory compounds (2-6) were identified as emodin (2), physcion-8-O-ß-D-glucopyranoside (3), emodin-8-O-ß-D-glucopyranoside (4), emodin-1-O-ß-D-glucopyranoside (5), and 2-methoxy-6-acetyl-7-methyljuglone (6). Unexpectedly, anthraquinone glucosides (3-5) were much more potent than their corresponding aglycones (1 and 2). For example, emodin (2) had an IC50=5.4µM, whereas its glucosides (4 and 5) had IC50=0.85µM and 0.43µM respectively. A similar trend was observed with physcion (1, IC50>200µM) and its glucoside (3, IC50=6.2µM). The anthraquinone (2) was mixed type I inhibitor, whereas its glucosides (4 and 5) were noncompetitive. In addition, the fluorescence quenching study showed that the affinity constants (KSV) of inhibitors increased in proportion to their inhibitory potencies. Furthermore, we quantified the major and minor metabolites through UPLC-PDA-Q-TOF/MS, and revealed that the most potent inhibitors were the major constituents. This result contributes to our understanding of P. cuspidatum utility as functional food stuff and widely used herbal medicine.
Asunto(s)
Bacterias/química , Inhibidores Enzimáticos/farmacología , Fallopia japonica/química , Glucósidos/química , Neuraminidasa/administración & dosificación , Quinonas/farmacología , Cinética , Quinonas/química , Espectrometría de FluorescenciaRESUMEN
Angelica keiskei is used as popular functional food stuff. However, quantitative analysis of this plant's metabolites has not yet been disclosed. The principal phenolic compounds (1-16) within A. keiskei were isolated, enabling us to quantify the metabolites within different parts of the plant. The specific quantification of metabolites (1-16) was accomplished by multiple reaction monitoring (MRM) using a quadruple tandem mass spectrometer. The limit of detection and limit of quantitation were calculated as 0.4-44 µg/kg and 1.5-148 µg/kg, respectively. Abundance and composition of these metabolites varied significantly across different parts of plant. For example, the abundance of chalcones (12-16) decreased as follows: root bark (10.51 mg/g)>stems (8.52 mg/g)>leaves (2.63 mg/g)>root cores (1.44 mg/g). The chalcones were found to be responsible for the xanthine oxidase (XO) inhibition shown by this plant. The most potent inhibitor, xanthoangelol inhibited XO with an IC50 of 8.5 µM. Chalcones (12-16) exhibited mixed-type inhibition characteristics.
Asunto(s)
Angelica/química , Cromatografía Líquida de Alta Presión/métodos , Inhibidores Enzimáticos/análisis , Fenoles/análisis , Extractos Vegetales/análisis , Espectrometría de Masas en Tándem/métodos , Xantina Oxidasa/antagonistas & inhibidores , Angelica/metabolismo , Inhibidores Enzimáticos/metabolismo , Humanos , Fenoles/metabolismo , Extractos Vegetales/metabolismo , Xantina Oxidasa/análisis , Xantina Oxidasa/metabolismoRESUMEN
Flemingia philippinensis is used as a foodstuff or medicinal plant in the tropical regions of China. The methanol (95%) extract of the roots of this plant showed potent tyrosinase inhibition (80% inhibition at 30µg/ml). Activity-guided isolation yielded six polyphenols that inhibited both the monophenolase (IC50=1.01-18.4µM) and diphenolase (IC50=5.22-84.1µM) actions of tyrosinase. Compounds 1-6 emerged to be three new polyphenols and three known flavanones, flemichin D, lupinifolin and khonklonginol H. The new compounds (1-3) were identified as dihydrochalcones which we named fleminchalcones (A-C), respectively. The most potent inhibitor, dihydrochalcone (3) showed significant inhibitions against both the monophenolase (IC50=1.28µM) and diphenolase (IC50=5.22µM) activities of tyrosinase. Flavanone (4) possessing a resorcinol group also inhibited monophenolase (IC50=1.79µM) and diphenolase (IC50=7.48µM) significantly. In kinetic studies, all isolated compounds behaved as competitive inhibitors. Fleminchalcone A was found to have simple reversible slow-binding inhibition against monophenolase.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Fabaceae/química , Monofenol Monooxigenasa/antagonistas & inhibidores , Polifenoles/farmacología , Benzopiranos/aislamiento & purificación , Benzopiranos/farmacología , Chalconas/aislamiento & purificación , Chalconas/farmacología , China , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/aislamiento & purificación , Flavonas/química , Flavonas/aislamiento & purificación , Flavonas/farmacología , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Concentración 50 Inhibidora , Cinética , Estructura Molecular , Oxidorreductasas/antagonistas & inhibidores , Raíces de Plantas/química , Plantas Medicinales/química , Polifenoles/química , Polifenoles/aislamiento & purificación , Terpenos/aislamiento & purificación , Terpenos/farmacologíaRESUMEN
SARS-CoV papain-like protease (PLpro) is an important antiviral target due to its key roles in SARS virus replication. The MeOH extracts of the fruits of the Paulownia tree yielded many small molecules capable of targeting PLpro. Five of these compounds were new geranylated flavonoids, tomentin A, tomentin B, tomentin C, tomentin D, tomentin E (1-5). Structure analysis of new compounds (1-5) by NMR showed that they all contain a 3,4-dihydro-2H-pyran moiety. This chemotype is very rare and is derived from cyclization of a geranyl group with a phenol functionality. Most compounds (1-12) inhibited PLpro in a dose dependent manner with IC50's raging between 5.0 and 14.4 µM. All new compounds having the dihydro-2H-pyran group showed better inhibition than their parent compounds (1 vs 11, 2 vs 9, 4 vs 12, 5 vs 6). In kinetic studies, 1-12 emerged to be reversible, mixed inhibitors.
Asunto(s)
Antivirales/química , Flavonoides/química , Magnoliopsida/química , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/enzimología , Proteínas Virales/antagonistas & inhibidores , Antivirales/aislamiento & purificación , Proteasas 3C de Coronavirus , Cisteína Endopeptidasas/química , Escherichia coli/genética , Flavonoides/aislamiento & purificación , Frutas/química , Cinética , Extractos Vegetales/química , Proteínas Recombinantes/química , Proteínas Virales/químicaRESUMEN
Adenosine 5'-monophosphate-activated protein kinase (AMPK) is an intracellular sensor that can regulate glucose levels within the cell. For this reason, it is well-known to be a target for drugs against diabetes and obesity. AMPK was activated significantly by the hexane extract of barley sprouts. This AMPK activation emerges across the growth stages of the sprout, becoming most significant (3 times above the initial stages) 10 days after sprouting. After this time, the activation decreased between 13 and 20 days post-sprouting. Analysis of the hexane extracts by gas chromatography-mass spectrometry showed that the amounts of policosanols (PCs, which are linear, primary aliphatic alcohols with 20-30 carbons) in the plant dramatically increased between 5 days (109.7 mg/100 g) and 10 days (343.7 mg/100 g) post-sprouting and then levels fell back down, reaching 76.4 mg/100 g at 20 days post-sprouting. This trend is consistent with PCs being the active ingredient in the barley plants. We validate this by showing that hexacosanol is an activator of AMPK. The richest cultivar for PCs was found to be the Daejin cultivar. Cultivars had a significant effect on the total PC content (113.2-183.5 mg/100 g) within the plant up to 5 days post-sprouting. However this dependence upon the cultivar was not so apparent at peak stages of PC production (10 days post-sprouting). The most abundant PC in barley sprout, hexacosanol, contributed 62-80% of the total PC content at every stage. These results are valuable to determine the optimal times of harvest to obtain the highest yield of PCs.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Alcoholes Grasos/química , Hordeum/química , Extractos Vegetales/química , Supervivencia Celular/efectos de los fármacos , Alcoholes Grasos/farmacología , Cromatografía de Gases y Espectrometría de Masas , Células Hep G2 , Humanos , Immunoblotting , Fosforilación , Extractos Vegetales/farmacología , Hojas de la Planta/químicaRESUMEN
Alzheimer's disease is rapidly becoming one of the most prevalent human diseases. Inhibition of human acetylcholinestrase (hAChE) and butyrylcholinestrase (BChE) has been linked to amelioration of Alzheimer's symptoms and research into inhibitors is of critical importance. Purification of the methanol extract of Paulownia tomentosa fruits yielded potent hAChE and BChE inhibitory flavonoids (1-9). A comparative activity screen indicated that a geranyl group at C6 is crucial for both hAChE and BChE. For example, diplacone (8) showed 250-fold higher efficacy than its parent eriodictyol (12). IC(50)s of diplacone (8) were 7.2 µM for hAChE and 1.4 µM for BChE. Similar trends were also observed for 4'-O-methyldiplacone (4) (vs its parent, hesperetin 10) and mimulone (7) (vs its parent, naringenin 11). Representative inhibitors (1-8) showed mixed inhibition kinetics as well as time-dependent, reversible inhibition toward hAChE. The binding affinities of these compounds to hAChE were investigated by monitoring quenching of inherent enzyme fluorescence. The affinity constants (K(SA)) increased in proportion to inhibitory potencies.
Asunto(s)
Colinesterasas/metabolismo , Inhibidores Enzimáticos/farmacología , Flavonoides/farmacología , Frutas/química , Extractos Vegetales/farmacología , Scrophulariaceae/química , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/aislamiento & purificación , Flavonoides/química , Flavonoides/aislamiento & purificación , Humanos , Estructura Molecular , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Relación Estructura-ActividadRESUMEN
It is necessary to develop food additives to help treat chronic disorders like neurodegenerative diseases from medicinal plants. Ethanol extracts of paper mulberry were found to display significant inhibition against cholinesterases, enzymes that are strongly linked with Alzheimer's disease (AD). The active components were identified as prenylated flavonols (2-4) that inhibited two related human cholinesterases in a dose-dependent manner, with IC50's ranging between 0.8 and 3.1µM and between 0.5 and 24.7µM against human acetylcholinesterase (hAChE) and butylcholinesterase (BChE), respectively. Prenyl groups within these flavonols were found to play a critical role for inhibition because the parent compound 1, quercetin, was inactive (IC50>500µM) towards the target enzymes. Flavonols (2-4) showed mixed inhibition kinetics as well as slow and time-dependent reversible inhibition toward hAChE. The affinity between protein and inhibitors was investigated using fluorescence quenching. The affinity constants (KSA) of inhibitors increased in proportion to their inhibitory potencies.
RESUMEN
An ethanol extract of the fruit case of Garcinia mangostan, whose most abundant chemical species are xanthones, showed potent α-glucosidase inhibitory activity (IC(50)=3.2 µg/ml). A series of isolated xanthones (1-16) demonstrated modest to high inhibition of α-glucosidase with IC(50) values of 1.5-63.5 µM. In particular, one hitherto unknown xanthone 16 has a very rare 2-oxoethyl group on C-8. Kinetic enzymatic assays with a p-nitrophenyl glucopyranoside indicated that one of them, compound (9) exhibited the highest activity (K(i)=1.4 µM) and mixed inhibition. Using, a physiologically relevant substrate, maltose, as substrate, many compounds (6, 9, 14, and 15) also showed potent inhibition which ranged between 17.5 and 53.5 µM and thus compared favorably with deoxynojirimycin (IC(50)=68.8 µM). Finally, the actual pharmacological potential of the ethanol extract was demonstrated by showing that it could elicit reduction of postprandial blood glucose levels. Furthermore, the most active α-glucosidase inhibitors (6, 9, and 14) were proven to be present in high quantities in the native seedcase by a HPLC chromatogram.
Asunto(s)
Glucemia/metabolismo , Garcinia mangostana/química , Inhibidores de Glicósido Hidrolasas , Hiperglucemia/tratamiento farmacológico , Hipoglucemiantes/farmacología , Fitoterapia , Xantonas/farmacología , 1-Desoxinojirimicina/farmacología , Animales , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/aislamiento & purificación , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/uso terapéutico , Frutas , Hiperglucemia/sangre , Hiperglucemia/inducido químicamente , Hipoglucemiantes/aislamiento & purificación , Hipoglucemiantes/uso terapéutico , Concentración 50 Inhibidora , Masculino , Maltosa/metabolismo , Extractos Vegetales/química , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Periodo Posprandial , Ratas , Ratas Sprague-Dawley , Semillas , Xantonas/aislamiento & purificación , Xantonas/uso terapéuticoRESUMEN
Neuraminidase is a proven target in anti-viral drug development. It also appears to be important for infection by certain pathogenic bacteria and has been implicated in biofilm formation. Based on activity-guided fractionation, the acetone extract of Amorpha fruticosa roots gave four flavanones 1-4 and three rotenoids 5-7 which were identified as amoradicin (1), amorisin (2), isoamoritin (3), amoricin (4), amorphigeni (5), dalbinol (6), and 6-ketodehydroamorphigenin (7), respectively. All isolated inhibitors showed strong neuraminidase inhibition with IC50s between 0.12 and 22.03 µM. In particular, amorisin 2 exhibited 120 nM IC(50, which is 30-fold more potent than the positive control, quercetin. In addition, this is the first report detailing rotenoids (IC50 = 8.34-16.74 µM) exhibiting neuraminidase inhibition. Kinetic analysis revealed that all inhibitors were noncompetitive. The most active neuraminidase inhibitors (2, 3, 5, 6) were proven to be present in the native root in high quantities by HPLC. Finally, at concentrations where no toxicity was observed, 3 and 6 inhibited Pseudomonas aeruginosa biofilm production. 29.7% and 21.0% inhibition respectively was observed at 25 µΜ.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Fabaceae/química , Flavanonas/farmacología , Neuraminidasa/antagonistas & inhibidores , Extractos Vegetales/farmacología , Raíces de Plantas/química , Rotenona/farmacología , Antivirales/farmacología , Biopelículas/efectos de los fármacos , Concentración 50 Inhibidora , Cinética , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/enzimologíaRESUMEN
Cholinesterases are key enzymes that play important roles in cholinergic transmission. Nine flavonoids displaying cholinesterase inhibitory activity were isolated from the root bark of Morus lhou L., a cultivated edible plant. The isolated compounds were identified as a new flavone (1), 5'-geranyl-5,7,2',4'-tetrahydroxyflavone (2), kuwanon U (3), kuwanon E (4), morusin (5), morusinol (6), cyclomorusin (7), neocyclomorusin (8), and kuwanon C (9). All compounds apart from compound 6 inhibited cholinesterase enzyme in a dose-dependent manner with K(i) values ranging between 3.1 and 37.5 µM and between 1.7 and 19.1 µM against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes, respectively. The new compound was charactierized as 5'-geranyl-4'-methoxy-5,7,2'-trihydroxyflavone (1). It showed the most potent inhibitory activity (K(i) = 3.1 µM for AChE, K(i) = 1.74 µM for BChE). Lineweaver-Burk and Dixon plots and their secondary replots indicated that flavones (5-9) with prenyl substitution on C-3 were noncompetitive inhibitors, whereas those unsubstituted (1-4) at C-3 were mixed inhibitors of both AChE and BChE. In conclusion, this is the first study to demonstrate that alkylated flavonoids of M. lhou have potent inhibitory activities against AChE and BChE.
Asunto(s)
Inhibidores de la Colinesterasa/aislamiento & purificación , Inhibidores de la Colinesterasa/farmacología , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Morus/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Inhibidores de la Colinesterasa/química , Colinesterasas/química , Flavonoides/química , Cinética , Extractos Vegetales/química , Raíces de Plantas/químicaRESUMEN
This study was designed to gain deeper insights into the molecular properties of natural xanthones as neuraminidase inhibitors. A series of xanthones 1-12 was isolated from the seedcases of Garcinia mangostana and evaluated for bacteria neuraminidase inhibitory activity. Compounds 11 and 12 emerged to be new xanthones (mangostenone F, mangostenone G) which we fully spectroscopically characterized. The IC(50) values of compounds 1-12 were determined to range between 0.27-65.7 microM. The most potent neuraminidase inhibitor 10 which has an IC(50) of 270 nM features a 5,8-diol moiety on the B ring. Interestingly, structure-activity studies reveal that these xanthones show different kinetic inhibition mechanisms depending upon the arrangement of hydroxyl groups in the B ring. Compound 6 possessing a 6,7-diol motif on the B-ring operated under the enzyme isomerization model (k(5)=0.1144 microM(-1) s(-1), k(6)=0.001105 s(-1), and K(i)(app)=7.41 microM), whereas compound 10 possessing a 5,8-diol unit displayed simple reversible slow-binding inhibition (k(3)=0.02294 microM(-1) s(-1), k(4)=0.001025 s(-1), and K(i)(app)=0.04468 microM).
Asunto(s)
Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Garcinia mangostana/química , Neuraminidasa/antagonistas & inhibidores , Xantonas/química , Xantonas/farmacología , Inhibidores Enzimáticos/aislamiento & purificación , Humanos , Cinética , Neuraminidasa/análisis , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Semillas/química , Relación Estructura-Actividad , Xantonas/aislamiento & purificaciónRESUMEN
The organic extract of the roots of Broussonetia papyrifera showed extremely high alpha-glucosidase inhibitory activity with an IC50 of around 10 microg/mL. Due to its potency, subsequent bioactivity-guided fractionation of the chloroform extract led to 12 polyphenols, 1-12, 4 of which were identified as chalcones (1-4), another 4 as flavans (5-8), 2 as flavonols (9 and 10), and 2 others as the novel species benzofluorenones (11 and 12). Broussofluorenone A (11) and broussofluorenone B (12) emerged as new compounds possessing the very rare 5,11-dioxabenzo[b]fluoren-10-one skeleton. These compounds (1-12) were evaluated for alpha-glucosidase inhibitory activity to identify their inhibitory potencies and kinetic behavior. The most potent inhibitor, 10 (IC50=2.1 microM, Ki=2.3 microM), has an inhibitory activity slightly higher than that of the potent alpha-glucosidase inhibitor deoxynojirimycin (IC50=3.5 microM). The novel alpha-glucosidase inhibitors 11 (IC50=27.6 microM) and 12 (IC50=33.3 microM) are similar in activity to sugar-derived alpha-glucosidase inhibitors such as voglibose (IC50=23.4 microM). Interestingly, major constituents (1, 2, 6, 7, 9, and 10) of B. papyrifera displayed significant inhibitory activity with IC50 values of 5.3, 11.1, 12.0, 26.3, 3.6, and 2.1 microM, respectively. In kinetic studies, chalcones (1-4) exhibited noncompetitive inhibition characteristics, whereas the others (5-12) showed mixed behavior.
Asunto(s)
Broussonetia/química , Inhibidores Enzimáticos/química , Flavonoides/química , Inhibidores de Glicósido Hidrolasas , Fenoles/química , Extractos Vegetales/química , Cinética , Polifenoles , alfa-Glucosidasas/análisisRESUMEN
Six 1,3-diphenylpropanes exhibiting inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase were isolated from the methanol (95%) extract of Broussonetia kazinoki. These compounds, 1-6, were identified as kazinol C (1), D (2), F (3), broussonin C (4), kazinol S (5) and kazinol T (6). The latter two species (5 and 6) emerged to be new 1,3-diphenylpropanes which we fully spectroscopically characterized. The IC(50) values of compounds (1, 3-5) for monophenolase inhibition were determined to range between 0.43 and 17.9 microM. Compounds 1 and 3-5 also inhibited diphenolase significantly with IC(50) values of 22.8, 1.7, 0.57, and 26.9 microM, respectively. All four active tyrosinase inhibitors (1, 3-5) were competitive inhibitors. Interestigly they all mainfested simple reversible slow-binding inhibition against diphenolase. The most potent inhibitor, compound 4 diplayed the following kinetic parameters k(3)=0.0993 microM(-1)min(-1), k(4)=0.0048 min(-1), and K(i)(app)=0.0485 microM.
Asunto(s)
Derivados del Benceno/farmacología , Broussonetia/química , Hemiterpenos/farmacología , Monofenol Monooxigenasa/antagonistas & inhibidores , Propano/farmacología , Resorcinoles/farmacología , Unión Competitiva , Concentración 50 Inhibidora , Cinética , Extractos VegetalesRESUMEN
Pterocarpans (1-3) and flavanones (4-10) were isolated from Sophora flavescens and screened for their ability to inhibit neuraminidase (an enzyme crucial in the proliferation of the influenza virus). The majority of inhibitors were shown to have IC(50) values of 20 microM or below. Interestingly, pterocarpan 1 emerged as the best inhibitor with an IC(50) of 1.4 microM. We were thus able to prove that the pterocarpan skeleton is a new class of lead structure for neuraminidase inhibitors. Our studies reveal that the IC(50) has a marked dependence upon structure in the case of the pterocarpans but much less so for the flavanones. Kinetic analysis disclosed that all inhibitors are noncompetitive. Our molecular docking experiment resulted that the most potent pterocarpan-derived inhibitor 1 may bind to another binding pocket adjacent to the active site.
Asunto(s)
Antivirales/aislamiento & purificación , Antivirales/farmacología , Clostridium/enzimología , Flavanonas/aislamiento & purificación , Flavanonas/farmacología , Neuraminidasa/antagonistas & inhibidores , Orthomyxoviridae/efectos de los fármacos , Plantas Medicinales/química , Pterocarpanos/aislamiento & purificación , Pterocarpanos/farmacología , Sophora/química , Antivirales/química , Relación Dosis-Respuesta a Droga , Flavanonas/química , Modelos Moleculares , Estructura Molecular , Pterocarpanos/química , Relación Estructura-ActividadRESUMEN
We have proven that xanthones 1-8 isolated from the root of C. tricuspidata possess highly potent alphaalpha-glucosidase inhibition properties. Compound 1 was identified as a new isoprenylated tetrahydroxy xanthone, 1,3,6,7-tetrahydroxy-2-(3-methylbut-2-enyl)-8-(2-methylbut-3-en-2-yl)-9H-xanthen-9-one (1). These are the first natural xanthones documented to exhibit such inhibition. The IC(50) values of compounds 1-8 inhibiting alpha-glucosidase activity were determined to be up to 16.2microM. Mechanistic analysis showed the xanthones 1-8 exhibited full mixed inhibition.