首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 796 毫秒
1.
Liquorice (root of Glycyrrhiza uralensis FISCH) is an ingredient of candies and used as a popular medicine in Europe and oriental countries. Cyclosporine (CsA), an immunosuppressant with narrow therapeutic window, is widely used in transplant patients. The absorption and disposition of CsA were associated with P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4). This study investigated the effects of liquorice extract (LE) and its major ingredient, glycyrrhizin (GZ), on CsA pharmacokinetics in rats. The results indicated that LE and GZ significantly decreased the peak blood concentration and the areas under the curves of CsA in rats. Mechanism studies revealed that glycyrrhetic acid (GA), the major metabolite of GZ, significantly activated the functions of P-gp and CYP3A4. In conclusion, liquorice significantly reduced the oral bioavailability of CsA through activating P-gp and CYP3A4.  相似文献   

2.
Little is known about the content and development of pyranoanthocyanins, pigments mainly formed during red wine ageing, in commercial wines. Some of the major pyranoanthocyanins in a wide selection of 1–10 years-old Spanish Tempranillo wines and also in a 29 years wide-vertical series of Tempranillo wines from an individual cellar have been determined. Great variability in pyranoanthocyanin concentrations was found (range, mg/l): vitisin A, 0–10.76; pinotin A, 0–4.26; and malvidin 3-glucoside-4-vinylphenol, 0.03–1.37. Vitisin A and malvidin 3-glucoside-4-vinylphenol were already present in 1–2 years-old wines, whereas pinotin A was only detectable in a few of the 1 and 2 years-old wines. Vitisin A tended to decrease with wine age, while hydroxyphenyl-pyranoanthocyanins showed the reverse trend. However, the aforementioned trends were interrupted by various temporary maxima, most likely due to some “refreshment” of the oldest wines (i.e., addition of young wine), as suggested by unexpected high concentrations of malvidin 3-glucoside, in contrast to the results found in the wine vertical series. The effects of addition of young wine on aged wine pyranoanthocyanin concentrations were confirmed by wine refreshment experiments.  相似文献   

3.
For the reliability of analytical Quality Control Materials (QCMs), stability studies are essential. In spite of the importance of the stability studies, there is no article relating to QCMs of olive oil. This paper describes an intralaboratory stability study aimed for assuring olive oil QCMs concerning to the physical–chemical characteristics defined in Commission Regulation (EC) No. 1989/2003. The study concluded that, in storage conditions of darkness and low controlled temperature (0–8 °C), critical physical–chemical parameters of the olive oil QCMs, such as acidity level, peroxide value, K-values and total waxes, are stable at least during 24 months (2 years) with, in general, light variability and up trends. Theoretically, according to this study a homogeneous sample olive oil could be used as a QCM during two years if this material were stored in the dark and low temperature. Then, olive oil quality control testing laboratories have an alternative to dispose stable in-house QCMs for the control of their measurements.  相似文献   

4.
The scientific basis of the adverse, or at times lethal, effect of ingesting durian (Durio zibethinus Murray) while imbibing alcohol has not been established. Symptoms are reminiscent of the disulfiram–ethanol reaction (DER) arising from the inhibition of aldehyde dehydrogenase (ALDH). Cognizant of the inhibitory effect of sulphur compounds like disulfiram on ALDH and the rich sulphur content of durian, the influence of durian fruit extract on the ALDH-mediated oxidative metabolism of acetaldehyde was investigated. We report a dose-dependent inhibition of yeast ALDH (yALDH), at most 70% at 0.33 ppm (mg extract/l assay mix), by dichloromethane:pentane extracts. Sulphur-rich TLC fruit extract fractions that eluted farthest from the origin effected the greatest inhibitory action. yALDH assay using diethyl disulfide as internal standard further supports the role of durian’s sulfury constituents in the fruit’s ALDH-inhibiting property. Insight into the etiology of DER-like symptoms felt upon simultaneous durian and alcohol consumption is hereby presented.  相似文献   

5.
The extraction of Salvia macrosiphon seed hydrocolloid was performed successfully and the optimum hydration time and temperature were found to be 30 min and 25 °C for 12% extraction yield. The effect of solution pH (3–9) and addition of NaCl (0.5–3%), CaCl2 (0.5–3%) and Na2HPO4 (0.2–0.6%) on rheological properties of the hydrocolloid solutions were investigated. Rheologcal data were fitted with the Power law model with regression coefficient of greater than 0.95. Strong shear thinning behavior with the n value of less than 0.53 was recorded. All variables had significant impacts on rheological parameters. The minimum and maximum consistencies were found at pH 3 and the 9, respectively. This was explained with the presence of carboxylic groups on the biopolymer backbone as indicated by FTIR. NaCl, CaCl2 and Na2HPO4 had significant effects on rheological properties. Moreover, at similar salt concentration of 0.5%, Na2HPO4 had the greatest and NaCl had the lowest effect.  相似文献   

6.
A simply and sensitively electroanalytical method for determination of bisphenol A (BPA) using poly(amidoamine) (PAMAM) and Fe3O4 magnetic nanoparticles modified glassy carbon electrode (GCE) was presented. Compared with bare electrode, PAMAM–Fe3O4 modified electrode not only significantly enhanced the oxidation peak current of BPA, but also lowered the oxidation overpotential, suggesting that the modified electrode can remarkably improve the determining sensitivity of BPA. Factors influencing the detection processes were optimised and kinetic parameters were calculated. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 1 × 10−8–3.07 × 10−6 M with the correlation coefficient of 0.9996 and the detection limit of 5 × 10−9 M. The current reached 95% of the steady-state current within about 6 s. The proposed method was successfully applied to determine BPA in milk samples and satisfactory results were obtained.  相似文献   

7.
The amino acid (AA) composition and physicochemical and conformational properties of protein isolate (SNPI), globulin (SNG) and albumin (SNA) fractions from soapnut seeds were evaluated. The essential AA of SNG, SNA and SNPI (except sulfur-containing AA) are sufficient for the FAO/WHO suggested requirements for 2–5 year old infants. SNG and SNPI showed similar electrophoresis patterns and AA compositions, the subunit of those proteins consisted of two polypeptides linked by disulfide bonds. In contrast, SNA showed a different AA compositions and SDS–PAGE pattern. Both SNG and SNPI presented a typical U-shape protein solubility (PS)–pH profile, SNA showed a completely different PS–pH profile, especially at pH 2.0–4.0. The near-UV circular dichroism (CD), differential scanning calorimetry (DSC) and tryptophan fluorescence spectra analyses indicated that the flexibility in tertiary conformations decreased in the order: SNA > SNPI > SNG, while soapnut proteins had a similar secondary conformation, with a highly ordered structure (the β-types), as evidenced by far-UV CD spectra.  相似文献   

8.
The heat and pH stability of prebiotic non-digestible wheat bran-derived arabinoxylooligosaccharides (AXOS), xylooligosaccharides (XOS)-and chicory root inulin-derived fructooligosaccharides (FOS) were compared. Heat stability (at 100 and 121 °C) and shelf-life measurements (at 4 and 37 °C) revealed decomposition at alkaline pH (pH 11.0) for all three preparations tested. The short chain oligosaccharides, XOS and FOS (apparent peak molecular mass of 400 and 800 Da, respectively), were more sensitive to alkaline decomposition than were the longer chain AXOS (apparent peak molecular mass of 1500 Da), the latter being the result of the higher abundancy of reducing ends in short chain oligosaccharide preparations. At pH 2.0 and 3.0, hydrolysis of oligosaccharide linkages took place, with FOS being the most acid-sensitive component.  相似文献   

9.
Kaempferia parviflora and Boesenbergia pandurata are perennial herbs in the Zingiberaceae family. The rhizomes of these two plants have been used as food ingredients and in Thai traditional medicine for treatment of several inflammatory-related diseases, such as gout, allergy, apthous ulcer and peptic ulcer. The compounds isolated from the rhizomes of K. parviflora and B. pandurata were, therefore, examined for their inhibitory activities against nitric oxide (NO) production. For K. parviflora, compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) exhibited the highest activity against the NO inhibitory effect, with an IC50 value of 16.1 μM, followed by 4 (IC50 = 24.5 μM) and 3 (IC50 = 30.6 μM). Regarding the NO inhibitory activity of B. pandurata, compound 2 (panduratin A) displayed the most potent effect with an IC50 value of 5.3 μM, followed by 3 (hydroxypanduratin A, IC50 = 13.3 μM) and 7 (cardamonin, IC50 = 24.7 μM), respectively. The 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (5), panduratin A (2) and hydroxypanduratin A (3), were also tested on prostaglandin E2 (PGE2) and tumour necrosis factor-alpha (TNF-α) production. 5-Hydroxy-3,7,3′,4′-tetramethoxyflavone (5) exhibited a potent inhibitory effect on PGE2 production (IC50 = 16.3 μM), but a mild effect on TNF-α (IC50 > 100 μM). Panduratin A and hydroxypanduratin A showed strong activity against PGE2 with IC50 values of 10.5 and 12.3 μM, respectively, and a moderate effect on TNF-α (IC50 = 60.3 and 57.3 μM, respectively). This study indicated that compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) is responsible for anti-inflammatory activity of K. parviflora, while 2 (panduratin A) and 3 (hydroxypanduratin A), the prenylated chalcones, are responsible for that of B. pandurata.  相似文献   

10.
The pharmacokinetics of resveratrol in 11 healthy male volunteers has been assessed in a randomized, crossover, controlled clinical trial after the administration of three grape products: red wine (250 mL), grape juice (1/L), or tablets (red wine extracts enriched with trans-resveratrol). Doses of trans-resveratrol independently of the product administered, were about 14 μg/kg. Biological samples were collected and analysed by capillary gas chromatography–mass spectrometry. cis-Resveratrol, trans-resveratrol and dihydroresveratrol were determined in plasma and urine. Plasma concentration of trans-resveratrol after hydrolysis increased as a response to all grape products and that of cis-resveratrol after wine and grape juice. Free forms of these phenolic compounds were deemed undetectable in plasma. Despite similar trans-resveratrol doses being administered, its bioavailability from wine and grape juice was 6-fold higher, than that from tablets. Resveratrol was better absorbed from natural grape products than from tablets, pointing out the importance of the matrix in its bioavailability.  相似文献   

11.
One of the major concerns in the meat processing industry is the loss of emulsion stability resulting in cooking losses. An optical sensor technology to control the emulsification process would minimize this problem. The normalized light intensity (IN) as a function of fat/lean ratio (RFL; 0.075, 0.25, 0.33) and chopping time (CT; 2, 5, 8 min) were measured at three radial distances (2, 2.5, 3 mm) from the light source to calculate the optical density (OD) and the loss of intensity (ILoss), using a fiber optic spectrometer. ANOVA results were highly significant for IN, ILoss. Normalized intensity decreased with increased chopping time as a result of emulsion homogenization, and with increased distance. Chopping time had a positive correlation with fat losses during cooking, which in turn had a negative correlation with IN and ILoss. These results suggest that light extinction spectroscopy could provide information about emulsion stability.  相似文献   

12.
The electrochemical behaviour and the antioxidant effectiveness of ascorbic acid (AA), caffeic acid (CA), quercetin (Q), catechin (Cat), hesperetin (H) and their equimolar binary mixtures were evaluated by means of cyclic voltammetry and luminol Co(II)–EDTA chemiluminescence, respectively, with a view to the prediction of a potential prooxidant or synergistic behaviour of mixtures of antioxidants. An important synergistic oxidation between Q and Cat was observed. The mixture CA/AA manifested the most prooxidant tendency among all the tested compounds and their mixtures. AA increased the antioxidant activity of Q and decreased that of Cat. Q and Cat regenerated CA, the prooxidant effect of the mixtures increasing with less e-delocalisation. Cat and CA have an antagonistic effect. H has the closest oxidation potential to CA and a slight increase of its antioxidant activity was registered when mixed with CA, which was not the case when it was combined with the other compounds or measured alone.  相似文献   

13.
The aim of this study was to investigate the effect of including thyme leaves (TL) in the diet of pregnant sheep on the sensorial characteristics, bacterial spoilage and oxidative stability of lamb meat stored in modified atmosphere (70% O2:30% CO2). For this, thirty-six sheep were randomly assigned to three groups: control (basal diet), T1 (3.7% thyme leaves), T2 (7.5% thyme leaves). Meat spoilage (TV, PSY, MY, ENT, and LA), TBARS, CIELAB coordinates, metmyoglobin and the sensory characteristics of fresh lamb meat were analyzed on days 0, 7, 14 and 21. The presence of antioxidant compounds in the diet containing TL delayed (< 0.05) colour deterioration, lipid oxidation and bacterial counts, while at the same time imparting a better appearance to the fresh lamb meat. In general, this effect was more pronounced at the higher level of TL (7.5%). High Pearson’s correlation coefficients were found between the sensory attributes, CIELAB coordinates and TBARS.  相似文献   

14.
In this work, a robust brefeldin A-synthesizing fungus, Eupenicillium brefeldianum ZJB082702, was bred from a Murraya paniculata endophytic fungus E. brefeldianum A1163. Using one-factor-at-a-time experimental design, optimization of media composition for E. brefeldianum ZJB082702 fermenting brefeldin A was conducted. Outcomes indicated that mixed carbon source and mixed nitrogen source were of c ritical importance to brefeldin A fermentation. After 6d culture in the optimized fermentation media, composed of (gl(-1)) 13.33 starch, 26.67 glucose, 1.0 yeast extract powder, 1.0 corn steep liquor, 0.5 soybean meal, 0.75 NaNO(3), 2.5 malt extract, 6.0 CaCO(3), 3.0 MgSO(4), 4.0 KH(2)PO(4), 1.0 × 10(-2) CuSO(4), brefeldin A yield peaked at 1304.7 mgl(-1), 648.2 mgl(-1) in 500 ml baffled flask and 15 l stirred fermentor respectively, formed as a growth associated type of secondary metabolite based on fermentation profile analysis.  相似文献   

15.
In order to prevent potato from browning during preservation and processing, the effects of p-alkylbenzoic acids (p-propylbenzoic acid, p-butylbenzoic acid, p-pentylbenzoic acid, p-hexylbenzoic acid, p-heptylbenzoic acid, p-octylbenzoic acid) on the activity of potato polyphenol oxidase (PPO) have been studied. The PPO was extracted with PBS (pH 6.8), fractionated with ammonium sulphate, concentrated, and purified with Sephadex G-100 (1.8 × 100 cm) filtration chromatography. The active fractions were pooled and the PPO activity was determined to be 79.83 U/mg. The results showed that p-alkylbenzoic acids could strongly inhibit the activity of potato PPO. The values of IC50 of these six inhibitors were determined to be 0.213, 0.180, 0.152, 0.106, 0.075 and 0.047 mM, respectively. Kinetic analyses showed that p-alkylbenzoic acids used in this experiment were reversible and noncompetitive inhibitors to the enzyme. The inhibitory effects were potentiated with increasing lengths of the hydrocarbon chains, indicating that the inhibitory efficiency on the enzyme was influenced by the steric effect of the substituted groups.  相似文献   

16.
Two baking times (9 and 24 min) and storage temperatures (4 and 25 °C) were used to explore the impact of heat exposure during bread baking and subsequent storage on amylopectin retrogradation, water mobility, and bread crumb firming. Shorter baking resulted in less retrogradation, a less extended starch network and smaller changes in crumb firmness and elasticity. A lower storage temperature resulted in faster retrogradation, a more rigid starch network with more water inclusion and larger changes in crumb firmness and elasticity. Crumb to crust moisture migration was lower for breads baked shorter and stored at lower temperature, resulting in better plasticized biopolymer networks in crumb. Network stiffening, therefore, contributed less to crumb firmness. A negative relation was found between proton mobilities of water and biopolymers in the crumb gel network and crumb firmness. The slope of this linear function was indicative for the strength of the starch network.  相似文献   

17.
This paper describes the microwave characterization and wettability of a uniform and light magnetic nanofibers web. Iron oxide nanoparticles/recycled poly (ethylene terephthalate) nanofibers web (Fe3O4 NPs/RPET NFs web) were fabricated from bath-sonication solution via electrospinning method. For environmental conservation and economic reasons, RPET instead of virgin material was used. After synthesizing magnetic Fe3O4 NPs with an average diameter of 35?nm by precipitation method using iron sulfate and sodium hydroxide, Fe3O4 NPs/RPET NFs web was made. The main objective of this work is to show how Fe3O4 NPs are able to significantly modify electromagnetic properties at X-band frequencies. Microwave characterization is based on the microwave scattering parameters measured in the X-band (8–12?GHz). Various characterization methods, including field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), have been used to study morphologies, crystalline structure, magnetic, and wettability properties of NFs web. The saturation magnetization of the Fe3O4 NPs/RPET NFs web at a concentration of 5% was 2.79?emu/g. The mathematical model was estimated for magnetization, diameter and concentration by MathWorks Model Predictive Control Toolbax Software. The wettability, reflection coefficient, absorption coefficient, and EMI shielding of Fe3O4 NPs/RPET NFs web have been improved compared to RPET NFs web.  相似文献   

18.
The aim of this study was the detailed qualitative and quantitative analysis of the phenolic content of several extracts and fractions of Sorbus domestica fruits. The analysis was realized by LC–DAD–MS (ESI+). Twenty-four different extracts and fractions of five different maturity stages of the fruit were analyzed for comparison reasons in order to determine the most beneficial for health type of consuming. Sixty-two different phenolics were identified. There were significant qualitative and quantitative differentiations in the phenolic content among the different types of the fruits. All categories were rich in benzoic, phenylpropanoic and cinnamoylquinic acids and derivatives. Unripe fruit categories were also rich in flavonoids, while well matured fruit categories had a low content of flavonoids. Fruit pulp, which was proved to be a strong antioxidant according to previous research work, contained very low amounts of both acids and flavonoids, but its phenolic content was highly qualitatively differentiated from the other categories.  相似文献   

19.
The agglomeration phenomenon of amorphous particulate material is a major problem in the food industry. Currently, the glass transition temperature (Tg) is used as a fundamental parameter to describe and control agglomeration. Models are available that describe the kinetics of the agglomeration process as a function of the distance of the material from Tg (i.e. T − Tg). In practice these models are often not applied because they assume that the powder material is instantly in equilibrium with the humidity conditions of the environment and that solid mobility only occurs at Tg. Insights in the kinetics and mechanisms of water transport in powder material can help to better understand and control powder agglomeration. For this purpose, gravimetric step-change water sorption experiments were performed on maltodextrins as a function of the water activity aw. The maltodextrins vary in dextrose equivalents (DE), particle size and morphology. The experimental results were compared with a Fickian diffusion model in order to understand the dependency of the transport mechanism on water concentration gradient and material relaxation. The water transport kinetics in the maltodextrins with low DE (i.e. 6) were well described by Fickian diffusion for low aw, independently of particle size and morphology, until relaxation phenomena started to occur at an aw corresponding to T − Tg = −20 °C. The importance of the matrix relaxation phenomena on the water transport mechanism increased with increasing DE (i.e. 29 and 32), not showing any relationship with the Tg. The results of this study indicate that the water migration mechanism is controlled by relaxation phenomena when the amorphous material is still far from the glass–rubber transition. The T − Tg at which the relaxation phenomena occur depends on the material. On the contrary, the T − Tg parameter could well describe the onset of agglomeration, independently from the material properties. Therefore, it can be concluded that within the conditions of this study, matrix relaxation occurring far below Tg did not affect the onset of agglomeration.  相似文献   

20.
The quality assessment of wild European eel (Anguilla anguilla) stored in ice and in boxes without ice (3 ± 1 °C) was investigated by the sensory analysis, levels of nucleotide breakdown products and biogenic amines for up to 19 days. Sensory analysis was assessed using the Tasmanian Food Research Unit Scheme. K and related values (Ki, G, P, H and Fr) were used as freshness indicators. Linear regressions (r2) obtained from K, Ki, G, P, H and Fr were 0.95, 0.96, 0.83, 0.96, 0.99 and 0.96, respectively, for eel stored in ice whereas, for eel kept in boxes without ice, the values were 0.86, 0.86, 0.96, 0.91, 0.98 and 0.86, respectively. When eel stored in ice and in boxes without ice were considered at the limit of acceptability by assessors at ∼12–14 days and ∼5–7 days, respectively, the average K, Ki and P values were ∼70–85%, H values were ∼60% and Fr values were ∼10% for both storage conditions. The level of histamine exceeded the legal limit (5 mg/100 g fish) in eel stored without ice after 6–7 days and, in ice, after 13–14 days of storage, at which time eels were rejected by the sensory panel. The concentrations of biogenic amines were higher in eel stored in boxes without ice than in eel kept in ice. The levels of histamine in the muscle of eel kept in boxes without ice and in ice increased to the maximum levels of 17.9 mg/100 g on day 12 and 12.6 mg/100 g on day 19, respectively.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号