[show abstract][hide abstract] ABSTRACT: The present work was reported on investigation of saponin profiles in nine different legume seeds, including soybean, adzuki bean, cowpea, common bean, scarlet runner bean, lentil, chick pea, hyacinth bean, and broad bean using ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass spectrometry (UPLC-PDA-ESI/MS) technique. A total of twenty saponins were characterised under rapid and simple conditions within 15min by the 80% methanol extracts of all species. Their chemical structures were elucidated as soyasaponin Ab (1), soyasaponin Ba (2), soyasaponin Bb (3), soyasaponin Bc (4), soyasaponin Bd (5), soyasaponin αg (6), soyasaponin βg (7), soyasaponin βa (8), soyasaponin γg (9), soyasaponin γa (10), azukisaponin VI (11), azukisaponin IV (12), azukisaponin II (13), AzII (14), AzIV (15), lablaboside E (16), lablaboside F (17), lablaboside D (18), chikusetusaponin IVa (19), and lablab saponin I (20). The individual and total saponin compositions exhibited remarkable differences in all legume seeds. In particular, soyasaponin βa (8) was detected the predominant composition in soybean, cowpea, and lentil with various concentrations. Interestingly, soybean, adzuki bean, common bean, and scarlet runner bean had high saponin contents, while chick pea and broad bean showed low contents.
[show abstract][hide abstract] ABSTRACT: Enzyme binding affinity has been recently introduced as a selective screening method to identify bioactive substances within complex mixtures. We used an assay which identified small molecule binders of acetylcholinesterase (AChE) using the following series of steps: incubation of enzyme with extract; centrifugation and filtration; identification of small molecule content in the flow through. The crude extract contained 10 peaks in the UPLC chromatogram. However after incubation the enzyme, six peaks were reduced, indicating these compounds bound AChE. All these isolated compounds (2, 3, and 5-8) significantly inhibited human AChE with IC50s = 5.4-15.0 υM and butyrylcholinsterase (IC50s = 0.7-11.0 υM). All compounds exhibited reversible mixed kinetics. Consistent with the binding screen and fluorescence quenching, gamma-mangostin 6 had a much higher affinity for AChE than 9-hydroxycalabaxanthone 9. This validates this screening protocol as a rapid method to identify inhibitors of AChE.
Journal of Agricultural and Food Chemistry 01/2014; · 2.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Stilbene urea derivatives as a novel and competitive class of non-glycosidic α-glucosidase inhibitors are effective for the treatment of type II diabetes and obesity. The main purposes of our molecular modeling study are to explore the most suitable binding poses of stilbene derivatives with analyzing the binding affinity differences and finally to develop a pharmacophore model which would represents critical features responsible for α-glucosidase inhibitory activity. Three-dimensional structure of S. cerevisiae α-glucosidase was built by homology modeling method and the structure was used for the molecular docking study to find out the initial binding mode of compound 12, which is the most highly active one. The initial structure was subjected to molecular dynamics (MD) simulations for protein structure adjustment at compound 12-bound state. Based on the adjusted conformation, the more reasonable binding modes of the stilbene urea derivatives were obtained from molecular docking and MD simulations. The binding mode of the derivatives was validated by correlation analysis between experimental Ki value and interaction energy. Our results revealed that the binding modes of the potent inhibitors were engaged with important hydrogen bond, hydrophobic, and π-interactions. With the validated compound 12-bound structure obtained from combining approach of docking and MD simulation, a proper four featured pharmacophore model was generated. It was also validated by comparison of fit values with the Ki values. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from stilbene derivatives.
PLoS ONE 01/2014; 9(1):e85827. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: Bacterial neuraminidase (NA) is one of the key enzymes involved in pathogenesis of inflammation during infection. The organic extract of the roots of Flemingia philippinensis showed high bacterial NA inhibitory activity with an IC50 of around 5μg/mL. Activity-guided separation of the methanol extract yielded nine prenylated isoflavones together with the novel species isoflavone (2) which was given the name flemingsin. Isolated prenylated isoflavones (1-9) were evaluated for NA inhibition and their IC50 values were determined to range between 0.30 and 56.8μM. The most potent inhibitor 4 (IC50=300nM, Ki=130nM) features a catechol motif in the B-ring and a furan in the A-ring. Structure-activity analysis also showed a 4-hydroxyl group within the B-ring was essential for NA inhibitory activity, because isoflavone (9) having protected 4-hydroxyl group was much less potent than its hydroxylated counterpart. All neuraminidase compounds screened were found to be reversible noncompetitive inhibitors. Furthermore, the most active NA inhibitors (1-9) were proven to be present in the native roots in high quantities by HPLC and LC-DAD-ESI/MS.
[show abstract][hide abstract] ABSTRACT: This paper describes a comparison of the properties of the three versions of the QuEChERS method (quick, easy, cheap, effective, rugged and safe) - the original (unbuffered), acetate-buffered, and citrate-buffered methods - for the determination of fenobucarb residues in beef muscles via liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI(+)-MS/MS). The recovery results were good for all the versions; however, the acetate-buffered version gave higher and more consistent recoveries for fenobucarb than the other versions. Performance characteristics, such as linearity, accuracy, and precision were determined. Matrix-matched standard calibration was used for quantification, obtaining recoveries in the range of 83.7-93.4% with relative standard deviations of <5%, at two spiking levels: 10 and 40μg/kg. The limits of detection (LOD) and quantification (LOQ) were estimated to be 1.5 and 5μg/kg, respectively. Finally, the method was applied to the analysis of 15 market samples, and no residues were found over the limit of quantification. The method developed was found able to determine the analyte with satisfactory intensity and accuracy.
[show abstract][hide abstract] ABSTRACT: The pre-harvest residue limit (PHRL) of abamectin (abamectin B1a and B1b) in Perilla frutescens leaves grown under greenhouse conditions were investigated using high-performance liquid chromatography with a fluorescence detector. Samples were extracted with acetonitrile. The extract was purified through a solid phase extraction procedure. Then the purified extract was derivatized with trifluoroacetic anhydride and N-methylimidazole to form a strong stable fluorescent derivative of abamectin. Finally, derivatized abamectins were conveyed to the detector via an Atlantis C18 column, with water and methanol as a mobile phase. Calibration curves were linear over the calibration ranges with coefficients of determinants r (2) ≥ 0.999. The limits of detection and quantification were 0.0033 and 0.01 mg kg(-1) for abamectin B1a and B1b, respectively. Recovery was assessed in a control matrix at two different fortification concentrations, with three replicates for each concentration. Good recoveries were obtained for the target analytes and ranged from 82.11 to 93.03 %, with relative standard deviations of less than 8 %. The rate of disappearance of total abamectin on perilla leaves for recommended and double the recommended doses was described as first-order kinetics with a half-life of 0.7 days. Using the PHRL curve, we could predict the residue level of total abamectin to be 0.92 mg kg(-1) at 7 days before harvest or 0.26 mg kg(-1) at 4 days before harvest, which would be below the provisional MRL designed by the Korea Food and Drug Administration.
Environmental Monitoring and Assessment 06/2013; · 1.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Chelidonium majus L. is an herbal plant that is commonly used in Western phytotherapy and traditional Chinese medicine for diuretic, antitussive, eye-regenerative, anti-osteoporotic, and radioprotective purposes. In this study, we purified 6-acetonyl-5,6-dihydrosanguinarine (ADS) from C. majus and investigated its immune-stimulatory effect. We found that ADS has the potential to induce the inflammatory cytokines TNF-α, IL-6, and IL-8 in macrophages and dendritic cells (DCs), that NFκB activation is a critical mediator of ADS-induced cytokine production, and that the activation of NFκB was dependent on reactive oxygen species (ROS). ADS induced phosphorylation of ERK and JNK, which was also associated with NFκB activation; phosphorylarion and cytokine production were inhibited by ROS scavenger and by specific MAPK inhibitors. Taken together, the results suggest that ADS from C. majus, as a positive immune modulator, induces inflammatory cytokines that might improve immunity, via the ROS-ERK/JNK-NFκB pathway.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 05/2013; · 2.99 Impact Factor
[show abstract][hide abstract] ABSTRACT: Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the most abundant plant leaf protein, hampering deep analysis of the leaf proteome. Here, we describe a novel protamine sulfate precipitation (PSP) method for the depletion of RuBisCO. For this purpose, soybean leaf total proteins were extracted using Tris-Mg/NP-40 extraction buffer. Obtained clear supernatant was subjected to the PSP method, followed by 13% SDS-PAGE analysis of total, PS-supernatant and -precipitation derived protein samples. In a dose-dependent experiment, 0.1% (w/v) PS was found to be sufficient for precipitating RuBisCO large and small subunits (LSU and SSU). Western-blot analysis confirmed no detection of RuBisCO LSU in the PS-supernatant proteins. Application of this method to Arabidopsis, rice, and maize leaf proteins revealed results similar to soybean. Furthermore, 2-DE analyses of PS-treated soybean leaf displayed enriched protein profile for the protein sample derived from the PS-supernatant than total proteins. Some enriched 2-D spots were subjected to MALDI-TOF-TOF analysis and were successfully assigned for their protein identity. Hence, the PSP method is: (i) simple, fast, economical, and reproducible for RuBisCO precipitation from the plant leaf sample; (ii) applicable to both dicot and monocot plants; and (iii) suitable for down-stream proteomics analysis.
[show abstract][hide abstract] ABSTRACT: 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 14.4μM. 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.
[show abstract][hide abstract] ABSTRACT: A simple multiresidue analytical method is developed for the simultaneous determination of carbendazim (CB), thiabendazole (TB), and 6-benzyl aminopurine (6-BA) in bean sprouts. The samples were extracted with acetonitrile followed by partitioning at -80°C for 5-10min. A YMC C(8) column was used to separate the analytes before being qualitatively and quantitatively determined by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). The matrix-matched calibration curves showed good linearity in the range 0.01-1.0mg/kg with correlation coefficients in excess of 0.998. The mean recoveries were in the range of 80.4-96.3% at 0.1 and 0.5 spiked levels, and the relative standard deviations (RSDs) were in the range of 0.5-7.6%. The limits of quantifications (LOQ) were in the range of 0.005-0.01mg/kg. The method was successfully applied to 90 samples (among which 45 were organic) collected from a commercial bean sprout production house throughout the city. Except for 6-BA, the rest of the analytes had values lower than their LOQs. In sum, carbendazim, thiabendazole, and 6-BA were extracted in a single step, and no steps for clean-up or concentration of the extracts were needed. The current method can be used for sensitive and accurate determination and confirmation of residues in bean sprout samples.
[show abstract][hide abstract] ABSTRACT: Abstract Severe acute respiratory syndrome coronavirus (SARS-CoV) papain-like protease (PLpro) is a key enzyme that plays an important role in SARS virus replication. The ethanol extract of the seeds of Psoralea corylifolia showed high activity against the SARS-CoV PLpro with an IC(50) of value of 15 µg/ml. Due to its potency, subsequent bioactivity-guided fractionation of the ethanol extract led to six aromatic compounds (1-6), which were identified as bavachinin (1), neobavaisoflavone (2), isobavachalcone (3), 4'-O-methylbavachalcone (4), psoralidin (5) and corylifol A (6). All isolated flavonoids (1-6) inhibited PLpro in a dose-dependent manner with IC(50) ranging between 4.2 and 38.4 µM. Lineweaver-Burk and Dixon plots and their secondary replots indicated that inhibitors (1-6) were mixed inhibitors of PLpro. The analysis of K(I) and K(IS) values proved that the two most promising compounds (3 and 5) had reversible mixed type I mechanisms.
Journal of Enzyme Inhibition and Medicinal Chemistry 01/2013; · 1.50 Impact Factor
[show abstract][hide abstract] ABSTRACT: The present research was the first to investigate phenolic compound profiles and antioxidant properties in the seeds of various perilla (Perilla frutescens) cultivars. The 80% methanol extract (50μg/ml) of this species showed potent antioxidant activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals. Phenolic compounds were characterised by nuclear magnetic resonance (NMR) spectroscopy, and ultra performance liquid chromatography with photodiode array detector and electrospray ionisation/mass (UPLC-PDA-ESI/MS) analysis. Nine compounds were elucidated as caffeic acid-3-O-glucoside (1), caffeic acid (2), luteolin-7-O-glucoside (3), apigenin-7-O-glucoside (4), rosmarinic acid-3-O-glucoside (5), rosmarinic acid (6), luteolin (7), apigenin (8), and chrysoeriol (9). The individual and total phenolic contents were remarkably different, especially rosmarinic acid-3-O-glucoside (5) and rosmarinic acid (6) which were the predominant compounds (>95%) in all perilla cultivars. Additionally, Yeupsil cultivar exhibited the highest phenolic content (5029.0μg/g) and antioxidant activity, whereas the lowest was shown by Dasil (2138.7μg/g). Therefore, these results suggest that antioxidant effects of perilla seeds are correlated with phenolic contents.
[show abstract][hide abstract] ABSTRACT: A new analytical method was developed for dinotefuran and its metabolites, MNG, UF, and DN, in melon using high-performance liquid chromatography (HPLC) coupled with an ultraviolet detector (UVD). Due to shorter wavelength, lower sensitivity to UV detection, and high water miscibility of some metabolites, QuEChERs acetate-buffered version was modified for extraction and purification. Mobile phases with different ion pairing or ionisation agents were tested in different reverse phase columns, and ammonium bicarbonate buffer was found as the best choice to increase the sensitivity of target analytes to the UV detector. After failure of dispersive SPE clean-up with primary secondary amine, different solid phase extraction cartridges (SPE) were used to check the protecting capability of analytes against matrix interference. Finally, samples were extracted with a simple and rapid method using acetonitrile and salts, and purified through C(18)SPE. The method was validated at two spiking levels (three replicates for each) in the matrix. Good recoveries were observed for all of the analytes and ranged between 70.6% and 93.5%, with relative standard deviations of less than 10%. Calibration curves were linear over the calibration ranges for all the analytes with r(2)⩾0.998. Limits of detection ranged from 0.02 to 0.05mgkg(-1), whereas limits of quantitation ranged from 0.06 to 0.16mgkg(-1) for dinotefuran and its metabolites. The method was successfully applied to real samples, where dinotefuran and UF residues were found in the field-incurred melon samples. Residues were confirmed via LC-tandem mass spectrometry (LC-MS/MS) in positive-ion electrospray ionisation (ESI(+)) mode.
[show abstract][hide abstract] ABSTRACT: AMPK is an intracellular sensor that modulates the energy balance within the cell. 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 (three times above the initial stages) 10 days after seeding. After this time, the activation decreased between 13 days to 20 days post sprouting. Analysis of the hexane extracts by GC-MS, showed the amounts of policosanols (C20-30) in the plant dramatically increased between 5 days (109.7 mg/100g) to 10 days (343.7 mg/100g) post sprouting, and then levels fell back down, reaching 76.4 mg/100g 20 days post sprouting. This trend is consistent with policosanols 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 Daejin cultivar. Cultivars had a significant effect on total PC content (113.2 to 183.5 mg/100g) within the plant up to 5 days post sprouting. However this dependence on cultivar was not so apparent at peak stages of PC production (10 days post sprouting). The most abundant policosanol 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 ensure that policosanols from barley sprouts are within the required limits.
Journal of Agricultural and Food Chemistry 01/2013; · 2.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bacterial neuraminidase (NA) is a lynch pin enzyme in the formation of biofilms. Thus NA continues to be one of the key enzymes targeted by bacterial infection. The purpose of this manuscript is to communicate four new naturally derived inhibitors of neuraminidase (IC50s 3.7-24.4 μM). All these active species (1-4) contained a resveratrol chemotype, however resveratrol itself was inactive (IC50 > 100 μM). 1-4 were isolated from the 60% aqueous ethanol extract of seeds of paeonia lactiflora, which exhibited potent neuraminidase inhibition. Purification of the extracts yielded four chiral polyphenols, suffruticosol A (1), suffruticosol B (2), trans-ε-viniferin (3), and trans-gnetin H (4). Mechanistic analysis of 1-4's inhibition showed that they were all reversible, noncompetitive inhibitors. Trans-ε-viniferin (3) underwent trans-cis isomerization, which led to a reduction in inhibition potency. This correlates with the fact that the cis-isomer is a weaker inhibitor of neuraminidase than the trans-isomer. Importantly, significantly different optical rotations ([α]D) compared to previous reports were found for suffruticosols A (+95 vs -34) and B (+136 vs +13). These two species are the most important standard metabolites in the whole paeoniaceae family and therefore correction of this error is important.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 01/2013; · 2.99 Impact Factor
[show abstract][hide abstract] ABSTRACT: TSAHC [4'-(p-toluenesulfonylamido)-4-hydroxychalcone] is a promising antitumorigenic chalcone compound, especially against TM4SF5 (four-transmembrane L6 family member 5)-mediated hepatocarcinoma. We evaluated the potential of TSAHC to inhibit the catalytic activities of nine cytochrome P450 isoforms and of P-glycoprotein (Pgp). The abilities of TSAHC to inhibit phenacetin Odeethylation (CYP1A2), coumarin 6-hydroxylation (CYP2A6), bupropion hydroxylation (CYP2B6), amodiaquine Ndeethylation (CYP2C8), diclofenac 4-hydroxylation (CYP2C9), omeprazole 5-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and midazolam 1'-hydroxylation (CYP3A) were tested using human liver microsomes. The P-gp inhibitory effect of TSAHC was assessed by [3H]digoxin accumulation in the LLCPK1-MDR1 cell system. TSAHC strongly inhibited CYP2C8, CYP2C9, and CYP2C19 isoform activities with Ki values of 0.81, 0.076, and 3.45 microM, respectively. It also enhanced digoxin accumulation in a dose-dependent manner in the LLCPK1-MDR1 cells. These findings indicate that TSAHC has the potential to inhibit CYP2C isoforms and P-gp activities in vitro. TSAHC might be used as a nonspecific inhibitor of CYP2C isoforms based on its negligible inhibitory effect on other P450 isoforms such as CYP1A2, CYP2A6, CYP2B6, CYP2D6, CYP2E1, and CYP3A.
Journal of Microbiology and Biotechnology 12/2012; 22(12):1659-1664. · 1.40 Impact Factor
[show abstract][hide abstract] ABSTRACT: A new method was developed for kresoxim-methyl (parent compound) and its two thermolabile metabolites, BF 490-2 and BF 490-9, in Korean plum, introducing pepper leaf matrix as a natural analyte protectant for GC-amenable metabolites using a GC-electron capture detector. Samples were extracted with a simple and rapid method using a mixture of ethyl acetate-n-hexane (1:1) and salts, and purified via SPE. Due to the elution gap between parent compound and metabolites in the SPE cartridge and matrix interference, kresoxim-methyl was isolated separately from its metabolites. An optimized amount of pepper leaf matrix (0.25 g/mL) was added to the metabolites prior to each injection. Calibration curves were linear over the concentration ranges with coefficient of determination (r(2) ) ≥ 0.999. The method was validated in triplicate at two fortification levels, giving recoveries ranging between 74.3 and 101.4%, and RSDs less than 5%. The LOD and LOQ were 0.015 and 0.05 mg/kg, respectively. The method was successfully applied to real samples where kresoxim-methyl residues were detected in field-incurred plum samples. Residues were confirmed using GC-MS.
Journal of Separation Science 11/2012; · 2.59 Impact Factor