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1.
The interaction between ilaprazole and bovine serum albumin (BSA) has been investigated in the absence and presence of four popular flavonoids with different C-ring structures, quercetin, luteolin, taxifolin, and (+)-catechin, by means of fluorescence spectroscopy. The results indicated that ilaprazole had a strong ability to quench the intrinsic fluorescence of BSA, and site marker competitive experiments indicated that the binding of ilaprazole to BSA primarily took place in subdomain IIA. The quenching process of ilaprazole with BSA was easily affected by flavonoids,; however, they did not change the quchenching mechanism of ilaprazole with BSA, whereas all of the fluorescence quenching was initiated by a static quenching procedure combining with nonradiative energy transfer. The presence of flavonoids decreased the quenching constants of ilaprazole with BSA from 2.2 to 23.7% and decreased the binding constants from 73.7 to 98.3%, which depended on the different flavonoids' structures. The decreased binding constants and unchangeable spatial distance of ilaprazole with BSA by the introduction of quercetin, luteolin, and taxifolin may result from the competition of flavonoids and ilaprazole binding to BSA, whereas in the presence of (+)-catichin, decreased binding constants and increased spatial distance possibly resulted from the formation of a ternary ilaprazole-BSA-(+)-catechin complex. All of these results may have relevant consequences in rationalizing the interferences of common food to gastric ulcer treatments.  相似文献   

2.
Antioxidant activities of seven phenolic agents against Fe(2+)-induced lipid oxidation were compared with alpha-tocopherol, beta-carotene, and vitamin C in human erythrocyte membrane ghosts and liposome systems. The antioxidant activity of five test flavonoids followed the order catechin > epicatechin > rutin > quercetin > myricetin in both systems (p < 0.05), which was negatively correlated with their partition coefficients. The antioxidant interaction of these phenolic agents with alpha-tocopherol, beta-carotene, or vitamin C in inhibiting Fe(2+)-induced lipid oxidation was examined. Synergistic effects were present in the combinations of alpha-tocopherol plus caffeic acid, catechin, or epicatechin as well as in all combinations of vitamin C plus phenolic antioxidants. On the basis of the stronger individual and combined effects present in caffeic acid, catechin, and epicatechin, the application of these three phenolic agents with or without alpha-tocopherol, beta-carotene, and vitamin C may provide stronger protective benefits against lipid oxidation, which may be helpful for oxidation-related diseases prevention.  相似文献   

3.
为筛选出欧李叶片类黄酮和9种类黄酮物质中单一物质含量较高的品种,并分析确定具有抗氧化和抑制酪氨酸酶活性的物质,本研究以38份欧李种质基生枝成熟期叶片为试材,利用超高效液相色谱法(UHPLC)测定儿茶素、表儿茶素、甘草素、芦丁、槲皮素、槲皮素-7-O-葡萄糖苷、杨梅素、光甘草定、根皮素活性物质含量,对其抗氧化及抑制酪氨酸...  相似文献   

4.
The aqueous extract of Eucommia ulmoides leaves has been commonly known as Du-zhong tea as a functional health food for the treatment of hypertension, hypercholesterolemia, and fatty liver. This study developed a centrifugal ultrafiltration-high-performance liquid chromatography (HPLC) method for screening and identification of bioactive compounds in E. ulmoides leaves binding with bovine serum albumin (BSA). Six active compounds were screened, isolated, and elucidated by their ultraviolet (UV), electrospray ionization-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR) data as geniposidic acid (1), caffeic acid (2), chlorogenic acid (3), quercetin-3-O-sambubioside (4), rutin (5), and isoquercitrin (6). The interaction between active compounds and BSA was investigated in the absence and presence of other compounds by quenching the intrinsic BSA fluorescence. The results indicated that the structures significantly affected the binding process. The values of binding constants for compounds 2-6 were in the range of 10(5)-10(6) mol L(-1), while geniposidic acid (1) hardly quenching the BSA intrinsic fluorescence. However, the quenching process of geniposidic acid was easily affected in the presence of other active compounds. The formation of the geniposidic acid-phenylpropanoid (flavonoid) complex could increase the binding affinity of geniposidic acid with BSA; however, the increased steric hindrance of the complex may make phenylpropanoid or flavonoid dissociate from BSA and then decrease their affinities.  相似文献   

5.
The optical sensor for "tea catechins" was built by immobilizing 2,2'-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline (PBHQ) on TiO? nanoparticles (NPs). The sensor worked by "indophenol blue" dye formation on PBHQ-immobilized TiO? NPs as a result of p-aminophenol (PAP) autoxidation with dissolved O? at pH 10. Among quercetin, rutin, naringenin, naringin, gallic acid, caffeic acid, ferulic acid, p-coumaric acid, catechin, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, and trolox, only catechin group antioxidants delayed the color formation on NPs, as measured by the reflectance signal at 710 nm. For quantitative analysis, reflectance signal versus time was recorded, and the difference between the areas under curve (ΔAUC) in the presence and absence of catechin was correlated (r = 0.98) to catechin concentration. The selectivity of the sensor for catechins was shown in tea infusions compared to other plant extracts and was ascribed to the nonplanar structure of catechin interfering with the formation of perfectly conjugated indophenol blue on TiO? surface.  相似文献   

6.
A high-performance capillary electrophoresis with amperometric detection (CE-AD) method has been developed for the simultaneous determination of the pharmacologically active ingredients in Cynomorium songaricum in this work. Under the optimum conditions, phloridzin, epicatechin, catechin, naringenin, rutin, luteolin, quercetin, gallic acid, and protocatechuic acid can be well separated or nearly baseline separated (epicatechin and catechin peaks) within 31 min at the separation voltage of 14 kV in a 50 mmol L(-1) Borax running buffer (pH 9.0). Detection limits (S/N=3) ranged from 5.7 x 10(-8) to 8.5 x 10(-9) g mL(-1) for all nine analytes. This procedure was successfully used for the analysis and comparison of the content difference of C. songaricum samples collected from different places based on their electrophorograms or "electromigration profiles".  相似文献   

7.
The effects of 1:1 flavonoid-Cu(2+) complexes of four flavonoids with different C-ring substituents, quercetin (QU), luteolin (LU), taxifolin (TA), and (+)-catechin (CA), on bovine serum albumin (BSA) were investigated and compared with corresponding free flavonoids by spectroscopic analysis in an attempt to characterize the chemical association taking place. The results indicated that all of the quenching mechanisms were based on static quenching combined with nonradiative energy transfer. Cu(2+) chelation changed the binding constants for BSA depending on the structures of flavonoids and the detected concentrations. The reduced hydroxyl groups, increased steric hindrance, and hydrophilicity of Cu(2+) chelation may be the main reasons for the reduced binding constants, whereas the formation of stable flavonoid-Cu(2+) complexes and synergistic action could increase the binding constants. The changed trends of critical energy transfer distance (R(0)) for Cu(2+) chelation were contrary to those of binding constants.  相似文献   

8.
The B-ring substitution pattern of flavonols is a significant structural feature for their function as free radical scavengers and antioxidants. In this paper, four differently substituted B-ring hydroxylation flavonols (galangin, kaempferol, quercetin, and myricetin) and a flavonol glycoside (quercitrin) were studied for their ability to bind BSA by quenching the protein intrinsic fluorescence. From the spectra obtained, the biomolecular quenching constants, the apparent static binding constants, and the binding site values were calculated. The B-ring hydroxylation of flavonols significantly affected the binding/quenching process; in general, the binding affinity increased with the number of hydroxyl groups on the B-ring. The binding constants ( Ka) were determined as myricetin (4.90 x 10(8) L/mol) > quercetin (3.65 x 10(7) L/mol) > kaempferol (2.57 x 10(6) L/mol) > galangin (6.43 x 10(5) L/mol). The glycoside substitute at the C-ring position decreased the binding affinity. The chromatographic retention factor ( K') and logarithms of apparent partition coefficient (log Kow) were linear to the logarithms of apparent binding constants (log Ka) for flavonols with increasing hydroxyl groups on the B-ring. These results showed that the hydrogen bond force play an important role in binding flavonols to BSA. These results are also in agreement with the generally accepted structure-dependent free radical scavenger and antioxidant abilities of flavonols.  相似文献   

9.
以苦荞(F.tataricum(L.)Gaertn)麸皮为试材,采用HPLC-UV和HPLC-ESI-MSn测定技术研究了麸皮中黄酮类化合物用微波辅助提取工艺的最佳条件及其提取过程中黄酮类化合物各化学组分的动态变化。结果表明,苦荞麸皮黄酮类化合物的最佳提取工艺条件为微波加热时间15min,乙醇体积分数40%,压力400kPa。在此条件下总黄酮提取产率达20.6μmol/g,其组分芦丁、槲皮素、表儿茶素分别达11.2、5.6和3.8μmol/g。在提取压力超过400kPa时,芦丁开始失去一个芸香糖转化为槲皮素;随着微波照射时间的延长,芦丁、表儿茶素和槲皮素提取产率先增加,而后下降。提取压力越大,提取速率越快,分解速度也越快,达到最高提取产率的时间越短。  相似文献   

10.
A simple and sensitive method has been developed for determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat (Fagopyrum esculentum Moench) flour and seeds by micro-high-performance liquid chromatography with electrochemical detection. Chromatography was performed using an octadecylsilica column, acetonitrile-water-formic acid (13:87:1, v/v/v) as a mobile phase, and an applied potential at +0.5 V vs Ag/AgCl. We found that Japanese buckwheat flour contains rutin (12.7 mg/100 g), catechin (3.30 mg/100 g), epicatechin (20.5 mg/100 g), and epicatechin gallate (1.27 mg/100 g). The relative standard deviations for rutin, catechin, epicatechin, and epicatechin gallate peak heights were less than 0.86% (n = 5). The detection limit of rutin was 0.86 ng/mL. Moreover, the present method was applied to the distribution analysis of these compounds in buckwheat seed. The embryo proper and cotyledons of a mature buckwheat seed contained rutin with the highest concentration as compared to other parts. This method is useful in determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat with a small amount of sample for quality control in the food industry.  相似文献   

11.
Cochineal Red A is a negatively charged synthetic azo food colorant and a potential carcinogen. We present here the study of binding of Cochineal Red A with two homologous serum albumins, human (HSA) and bovine (BSA), in aqueous pH 7.4 buffer by optical spectroscopic techniques. Protein intrinsic fluorescence quenching by Cochineal Red A occurs through ground-state static interaction and its binding with BSA is stronger than with HSA. The magnitudes of thermodynamic parameters suggest that dye binding occurs principally via electrostatic complexation. Site-marker competitive binding shows that Cochineal Red A binds primarily to site I of serum albumins. Circular dichroic spectra indicate that dye binding results in some conformational modification of serum albumins. Increased ionic strength of the medium results in lowering of binding. This study provides an important insight into possible means of removal of dye toxicity.  相似文献   

12.
Phenolic compounds are responsible for major organoleptic characteristics of plant-derived food and beverages; these substances have received much attention, given that the major function of these compounds is their antioxidant ability. In the context of this study, our major aim was study the binding of several phenolic compounds such as (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, malvidin-3-glucoside, tannic acid, procyanidin B4, procyanidin B2 gallate, and procyanidin oligomers to different proteins (bovine serum albumin and human alpha-amylase) by fluorescence quenching of protein intrinsic fluorescence. From the spectra obtained, the Stern-Volmer, the apparent static, and the bimolecular quenching constants were calculated. The structure of polyphenols revealed to significantly affect the binding/quenching process; in general, the binding affinity increased with the molecular weight of polyphenol compounds and in the presence of galloyl groups. For catechin monomer and procyanidin dimer B4, the K(SV) was 14,100 and 13,800 M(-1), respectively, and for galloyl derivatives, the K(SV) was 19,500 and 21,900 M(-1), respectively. Tannic acid was shown to be the major quenching molecule for both proteins. However, comparing different proteins, the same polyphenol showed different quenching effects, which are suggested to be related to the three-dimensional structure of the proteins studied. For (+)-catechin and BSA, the K(SV) was 8700 M(-1), and with alpha-amylase, it was 14,100 M(-1); for tannic acid, the K(SV) was 10,0548 and 11,0674 M(-1), respectively. From the results obtained, besides the main binding analysis performed, we conclude that this technique is more sensitive than thought because we can detect several interactions that have not been proven by other methods, namely, nephelometry. Overall, fluorescence quenching has proven to be a very sensitive technique with many potentialities to analyze the interaction between polyphenols and proteins.  相似文献   

13.
为提高木薯嫩茎叶黄酮资源利用水平,以木薯品种SC09与SC205为研究对象,分析不同干燥温度(40~120℃)对黄酮提取率及干燥后其贮存稳定性的影响,探讨木薯嫩茎叶采后干燥收贮方法。结果表明,随干燥温度增大,总黄酮提取率先升后降再升,黄酮成分芦丁、穗花杉双黄酮或儿茶素、山奈酚、二氢黄酮甙、槲皮素提取程度依次减小。120℃与110℃分别干燥的SC09、SC205嫩茎叶,总黄酮达提取峰值,并120 d贮存期内稳定性最好。干燥嫩茎叶贮存后,二氢黄酮甙提取程度增大,其他5种成分随品种、温度增减不一;山奈酚提取率变异系数(CV)最小,其值为1.03%~6.86%,稳定性最好;110℃干燥后SC205中芦丁和山奈酚的提取程度增加最大,增加率分别为44.89%和7.27%,变异程度小(CV为6.94%、4.59%),提取率稳定性好;儿茶素、穗花杉双黄酮、槲皮素、二氢黄酮甙提取率的最大提升率分别为211.60%、17.60%、186.39%、538.08%,但贮存期内变异程度大(CV=18.47%~50.03%),不稳定。本研究还进一步提出了基于黄酮利用的木薯茎叶干燥贮存预处理方案。  相似文献   

14.
Vitamin C equivalent antioxidant capacity (VCEAC) of phenolic phytochemicals   总被引:11,自引:0,他引:11  
To express the antioxidant capacity of plant foods in a more familiar and easily understood manner (equivalent to vitamin C mg/100 g), two stable radical species, ABTS(*)(-) and DPPH(*), commonly used for antioxidant activity measurements, were employed independently to evaluate their efficacies using apple polyphenolic extracts and seven polyphenolic standards including synthetic Trolox. Their antioxidant activities were expressed as vitamin C equivalent antioxidant capacity (VCEAC) in mg/100 g apple or mg/100 mL of the reference chemical compounds in 10 and 30 min using the ABTS(*)(-) and DPPH(*) scavenging assays, respectively. The antioxidant capacity of Gala apples and seven phenolic standards, determined by both ABTS(*)(-) and DPPH(*) scavenging assays, showed a dose-response of the first-order. Fresh Gala apples had a VCEAC of 205.4 +/- 5.6 mg/100 g using the ABTS assay, and the relative VCEACs of phenolic standards were as follows: gallic acid > quercetin > epicatechin > catechin > vitamin C > rutin > chlorogenic acid > Trolox. With the DPPH radical assay, the VCEAC of fresh Gala apples was 136.0 +/- 6.6 mg/100 g, and the relative VCEACs of seven phenolic standards were, in decreasing order, as follows: gallic acid > quercetin > epicatechin > catechin > or = vitamin C > Trolox > rutin > chlorogenic acid. Because the ABTS assay can be used in both organic and aqueous solvent systems, employs a specific absorbance at a wavelength remote from the visible region, and requires a short reaction time, it is a more desirable method than the DPPH assay. Therefore, it is recommended that antioxidant capacity be expressed as vitamin C mg/100 g equivalent (VCEAC) using the ABTS assay.  相似文献   

15.
Limited information is available concerning the qualitative and quantitative composition of polyphenolic compounds, especially flavonoids, in almonds. We determined total phenols, flavonoids, and phenolic acids in California almond (Prunus dulcis) skins and kernels among the principal almond varieties (Butte, Carmel, Fritz, Mission, Monterey, Nonpareil, Padre, and Price) with high-performance liquid chromatography (HPLC)/electrochemical detection and UV detection. Liquid chromatography/tandem mass spectrometry under identical HPLC conditions was utilized to verify identities of the predominant flavonoids and phenolic acids. Total phenols ranged from 127 (Fritz) to 241 (Padre) mg gallic acid equivalents/100 g of fresh weight. The analyses were compiled to produce a data set of 18 flavonoids and three phenolic acids. The predominant flavonoids were isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-glucoside (in combination), catechin, kaempferol-3-O-rutinoside, epicatechin, quercetin-3-O-galactoside, and isorhamnetin-3-O-galactoside at 16.81, 1.93, 1.17, 0.85, 0.83, and 0.50 mg/100 g of fresh weight almonds, respectively. Using the existing approach of calculating only the aglycone form of flavonoids for use in the U.S. Department of Agriculture nutrient database, whole almonds would provide the most prevalent aglycones of isorhamnetin at 11.70 (3.32), kaempferol at 0.60 (0.17), catechin at 1.93 (0.55), quercetin at 0.72 (0.20), and epicatechin at 0.85 (0.24) mg/100 g of fresh weight (mg/oz serving), respectively. These data can lead to a better understanding of the mechanisms of action underlying the relationship between almond consumption and health-related outcomes and provide values for whole and blanched almonds suitable for inclusion in nutrient databases.  相似文献   

16.
Quercetin and rutin are popular flavonoids in plant foods, herbs, and dietary supplements. Cyclosporine (CSP), an immunosuppressant with a narrow therapeutic window, is a substrate of P-glycoprotein (P-gp) and cytochrome P-450 3A4 (CYP3A4). This study investigated the effects of quercetin and rutin on CSP pharmacokinetics from Neoral and relevant mechanisms. Rats were orally administered Neoral with and without quercetin or rutin. The blood CSP concentration was assayed by a specific monoclonal fluorescence polarization immunoassay. The results showed that quercetin and rutin significantly decreased the C(max) of CSP by 67.8 and 63.2% and reduced the AUC(0-540) by 43.3 and 57.2%, respectively. The in vitro studies indicated that the quercetin and rutin induced the functions of P-gp and CYP3A4. In conclusion, quercetin and rutin decreased the bioavailability of CSP through activating P-gp and CYP3A. Transplant patients treated with Neoral should avoid concurrent consumption of quercetin or rutin to minimize the risk of allograft rejection.  相似文献   

17.
The binding mechanism of molecular interaction between diosmetin and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using atomic force microscopy (AFM) and various spectroscopic techniques including fluorescence, resonance light scattering (RLS), UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by diosmetin was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The RLS spectra and AFM images showed that the dimension of the individual HSA molecules were larger after interaction with diosmetin. The thermodynamic parameters, ΔH° and ΔS° were calculated to be -24.56 kJ mol(-1) and 14.67 J mol(-1) K(-1), respectively, suggesting that the binding of diosmtin to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies and denaturation experiments in the presence of urea indicated site I as the main binding site for diosmetin on HSA. The binding distance between diosmetin and HSA was determined to be 3.54 nm based on the F?rster theory. Analysis of CD and FT-IR spectra demonstrated that HSA conformation was slightly altered in the presence of diosmetin.  相似文献   

18.
The interaction of antiperoxidative flavonoids artocarpin (AR), cycloartocarpin (CAR), dalspinin (DP), dalspinosin (DPO), and dalspinin-7-O-galactoside (DPG) with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(.+)) and O2(-.) was studied in phosphate buffer (pH 7.4). The ability of these compounds to inhibit lipid peroxidation and DNA scission was also investigated. The radical scavenging efficiency of flavonoids is demonstrated by the reduction of nitrogen-centered radical cation (ABTS(.+)). The reduction of ABTS(.+) follows the order quercetin > morin > Trolox > AR > DPO > CAR > DP. Inhibition of lipid peroxidation was studied by following Mb(IV) reduction, induced by lipid, arachidonic acid. These results are compared with those obtained for well-known antioxidants such as quercetin, morin, and Trolox. The structure-activity relationships between chemical structures of the flavonoids and their radical scavenging activities are anlayzed. The scavenging of O2(-.), inhibition of lipid peroxidation, and DNA damage depend on the oxidation potential of the flavonoids. The possible mechanism for radical scavenging activities of flavonoids in relation to their structure is also outlined.  相似文献   

19.
Analytical data are reported for 20 flavonoids (as aglycones) determined for more than 60 fresh fruits, vegetables, and nuts collected from four regions across the United States at two times of the year. Sample collection was designed and implemented by the Nutrient Data Laboratory (USDA). Analyses of eight flavan-3-ols (catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, gallocatechin, and gallocatechin gallate), six anthocyanins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin), two flavanones (hesperetin and naringenin), two flavones (apigenin and luteolin), and two flavonols (myricetin and quercetin) were performed by the Food Composition Laboratory (USDA) using a hydrolysis method for the anthocyanidins, flavones, and flavonols and a direct extraction method for the flavan-3-ols and flavanones. Experimental results compare favorably (few statistically significant differences) to literature values in the flavonoid and proanthocyanidin database previously compiled by the Nutrient Data Laboratory. The results of this study showed a seasonal variation only for blueberries. This study also showed that the variation in the flavonoid content of foods, as purchased by the U.S. consumer, is very large. The relative standard deviation, averaged for each flavonoid in each food, was 168%.  相似文献   

20.
In the context of this study, the noncovalent binding of selected phenolic compounds (chlorogenic, ferulic, and gallic acids, quercetin, rutin, and isoquercetin) to different proteins (human serum albumin, bovine serum albumin, soy glycinin, and lysozyme) was studied with direct (Hummel-Dreyer/size exclusion chromatography) and/or indirect methods (fluorescence absorbance properties of the binding components). In the latter case, the measurement of the phenol binding was achieved by exploiting the intrinsic fluorescence emission properties of quercetin as a probe. From the data obtained, the binding constants and the number of binding sites were calculated. The binding parameters were influenced by different factors, where, e.g., increasing temperature and ionic strength as well as decreasing pH cause a diminished binding. The structures of the proteins as determined by circular dichroism indicate changes in the tertiary structure with the secondary structure remaining intact.  相似文献   

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