An automatic optosensing device for the simultaneous determination of resveratrol and piceid in wines

For the first time, a spectrofluorimetric method is reported for the simultaneous determination of resveratrol (RVT) and piceid (PCD), two stilbenes showing diverse interesting physiological and biochemical attributes, as well as a wide range of health benefits ranging from cardioprotection to chemoprevention. The method makes use of a multicommutated flow-through optosensor in which the resolution of RVT and PCD is accomplished by means the sequential arrival of their photoproducts, on-line generated by UV-irradiation, to the detection area. This is possible due to the different kinetic behaviour of these latter on a solid support (C₁₈ silica gel) filling a minicolumn placed before the detector. The measurement in solid-phase of the photochemically induced fluorescence of the photoproducts (λ_ex: 257 nm/λ_em: 382 nm) is used as analytical signal for monitoring both compounds. The method has been applied to the analysis of RVT and PCD in wines and requires a previous solid-phase extraction (SPE) using Bakerbond C₁₈ cartridges. This pretreatment and the use of a solid-support in both the minicolumn and the flow-cell of the detector allow the determination of RVT and PCD by external calibration. Detection limits (DLs) are 9.3 and 12.6 ng mL⁻¹ for RVT and PCD, respectively. Commercial red and white wine samples have been analysed and the results obtained have been satisfactorily validated by high-performance liquid chromatography (HPLC).     

Simple and rapid method for cis- and trans-resveratrol and piceid isomers determination in wine by high-performance liquid chromatography using chromolith columns

A simple and rapid HPLC method has been developed for simultaneous determination of the four resveratrol forms (aglycon and glycosidic) in a Grenache wine from Chateauneuf du Pape (Vaucluse). These analyses were achieved by using two commercial monolith HPLC columns and diode array detection. The method provided reliable separations at low pressure with a short analysis time. The limit of detection (LD) and limit of quantification (LQ) were calculated for each standard. The molecules were separated and quantified in a single run without any purification of the sample.     

RSM and ANN modeling-based optimization approach for the development of ultrasound-assisted liposome encapsulation of piceid

Piceid, a naturally occurring derivative of resveratrol found in many plants, has recently been considered as a potential nutraceutical. However, its poorly water-soluble property could cause a coupled problem of biological activities concerning drug dispersion and absorption in human body, which is still unsolved now. Liposome, a well-known aqueous carrier for water-insoluble ingredients, is commonly applied in drug delivery systems. In this study, a feasible approach for solving the problem is that the targeted piceid was encapsulated into a liposomal formula as aqueous substrate to overcome its poor water-solubility. The encapsulation process was assisted by ultrasound, with investigation of lipid content, ultrasound power and ultrasound time, for controlling encapsulation efficiency (E.E%), absolute loading (A.L%) and particle size (PS). Moreover, both RSM and ANN methodologies were further applied to optimize the ultrasound-assisted encapsulation process. The data indicated that the most important effects on the encapsulation performance were found to be of lipid content followed by ultrasound time and ultrasound power. The maximum E.E% (75.82%) and A.L% (2.37%) were exhibited by ultrasound assistance with the parameters of 160 mg lipid content, ultrasound time for 24 min and ultrasound power of 90 W. By methodological aspects of processing, the predicted E.E% and A.L% were respectively in good agreement with the experimental results for both RSM and ANN. Moreover, RMSE, R² and AAD statistics were further used to compare the prediction abilities of RSM and ANN based on the validation data set. The results indicated that the prediction accuracy of ANN was better than that of RSM. In conclusion, ultrasound-assisted liposome encapsulation can be an efficient strategy for producing well-soluble/dispersed piceid, which could be further applied to promote human health by increased efficiency of biological absorption, and the process of ultrasound-mediated liposome encapsulation can be well established by a methodological approach using either RSM or ANN, but it is worth mentioning that the ANN model used here showed the superiority over RSM for predicting and optimizing encapsulation.     

Rapid separation of three glucosylated resveratrol analogues from the invasive plant Polygonum cuspidatum by high‐speed countercurrent chromatography

Three glucosylated resveratrol analogues (piceid, piceatannol glucoside, resveratroloside) were successfully isolated from the crude MeOH extract of the invasive plant species Polygonum cuspidatum by semi‐preparative high‐speed countercurrent chromatography with a two‐phase solvent system composed of cyclohexane‐ethyl acetate‐methanol‐water (1:5:1:5, v/v/v/v). Piceid (23 mg), resveratroloside (17 mg), piceatannol glucoside (15 mg) of purities over 80% were isolated from 500 mg crude MeOH extract in one step. Subsequent passage over a SPE column was used to quickly bring their purities to over 90%. The purities were determined by HPLC analysis and their structures were elucidated by proton nuclear magnetic resonance (¹H‐NMR), HMBC, ESI‐MS and HR‐MS.     

Simultaneous analysis of serotonin, melatonin, piceid and resveratrol in fruits using liquid chromatography tandem mass spectrometry

An analytical method was developed for the simultaneous quantification of serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol using reversed-phase high performance liquid chromatography coupled to mass spectrometry (HPLC-MS) with electrospray ionization (ESI) in both positive and negative ionization modes. HPLC optimal analytical separation was achieved using a mixture of acetonitrile and water with 0.1% formic acid as the mobile phase in linear gradient elution. The mass spectrometry parameters were optimized for reliable quantification and the enhanced selectivity and sensitivity selected reaction monitoring mode (SRM) was applied. For extraction, the direct analysis of initial methanol extracts was compared with further ethyl acetate extraction. In order to demonstrate the applicability of this analytical method, serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol from 24 kinds of commonly consumed fruits were quantified. The highest serotonin content was found in plantain, while orange bell peppers had the highest melatonin content. Grape samples possessed higher trans- and cis-piceid, and trans- and cis-resveratrol contents than the other fruits. The results indicate that the combination of HPLC-MS detection and simple sample preparation allows the rapid and accurate quantification of serotonin, melatonin, trans- and cis-piceid, and trans- and cis-resveratrol in fruits.     

Peroxynitrite Scavenging Activities of Resveratrol and Piceid

In vitro antioxidant activities of resveratrol and piceid against peroxynitrite(ONOO^-) were examined by the inhibition of 3-nitrotyrosine formation. Trolox was used as a positive control. Resveratrol and piceid exhibited high ONOO^--scavenging activities in a concentration dependent manner. The antioxidant activities(the concentration of test compound required to yield a 50% inhibition of tyrosine nitration, IC₅₀) of resveratrol and piceid against ONOO^- were (48.34±0.97) and (74.69±1.49) μmol/L, respectively. Compared with that of trolox[(105.40±1.16) μmol/L], their scavenging activities were 2.2- and 1.5-fold higher for resveratrol and piceid. Formation of nitro-resveratrol as shown by UV-Vis spectroscopy and liquid chromatography-tandom mass spectrometry(LC-MS/MS) analysis indicates that resveratrol could directly scavenge ONOO^- via nitration reaction. Our results demonstrate that foods and medicinal herbs with resveratrol and piceid as stronger ONOO^- scavengers are valuable ingredients and have healthy application in preventing humans from peroxynitrite-mediated oxidative damage by scavenging peroxynitrite efficiently.     

虎杖中白藜芦醇和白藜芦醇甙的高速逆流色谱分离提纯及其分析

采用高速逆流色谱技术分离提纯中药虎杖中的活性多酚成分白藜芦醇和白藜芦醇甙。确定了样品前处理方法,选择了逆流色谱流动相体系,经高效液相色谱检验纯度,＾１ＨＮＭＲ及质谱判定结构,证实所得样品为白藜芦醇和白藜芦甙,得率分别为２．１８％和１．０７％。     

Isocratic chromatography of resveratrol and piceid after previous generation of fluorescent photoproducts: wine analysis without sample preparation

Resveratrol and its 3-glucoside (piceid), are stilbene-like molecules produced by plants. Both of them are weakly fluorescent, but highly fluorescent compounds are obtained when their hydroethanolic solutions are UV-irradiated, which implies a substantial improvement in the sensitivity of analytical methods. Experimental design (central composite design) together with the response surface methodology have been used to find optimum conditions for the fast, sensitive, and precise chromatographic analysis (with isocratic elution) of resveratrol and piceid in wine samples. These compounds have been UV-transformed into their respective photoproducts, which have been separated in a C18 column (Novapack C(18) 150x3.9 mm, 4 microm) by isocratic elution, using a mobile phase made up of acetonitrile and 4.1 vol% aqueous acetic acid, 19:81 v/v, at a flow rate of 0.8 mL/min, and fluorimetrically detected at 364 nm (lambda(exc) = 260 nm). Detection limits (S/N = 3) are 0.29 and 0.28 microg/L for resveratrol and piceid, respectively. The method has been applied to the analysis of these compounds in wine samples without a clean-up step. The analysis is completed in only 20 min. The standard addition method has been applied to the analysis of a commercial red wine and average recoveries near 100% were obtained for resveratrol and piceid. Three wine pools were satisfactorily analysed by external calibration.     

Development and validation of a liquid chromatography with mass spectrometry method to determine resveratrol and piceid isomers in beeswax

This paper represents the first report of a liquid chromatography coupled to electrospray ionization mass spectrometry method for simultaneously analyzing resveratrol and piceid isomers (cis and trans) in beeswax. An efficient extraction procedure has been proposed (average analyte recoveries were between 89 and 95%); this involved a solid–liquid extraction using a mixture of ethanol and water (80:20, v/v) and a concentration step in a rotary evaporator. The separation of all the compounds was achieved using a C₁₈ column and a mobile phase composed of ammonium formate 0.03 M in water and acetonitrile in gradient elution mode at a flow rate of 1 mL/min. The method was fully validated in terms of selectivity, limits of detection and quantification, linearity, precision, and accuracy. The limits of detection and quantification ranged from 1.0 to 1.7 and 3.5 to 5.5 μg/kg, respectively. Finally, the proposed method was applied to analyze beeswax samples collected from experimental and organic apiaries.     

Sensitized synchronous fluorimetric determination of trans-resveratrol and trans-piceid in red wine based on their immobilization on nylon membranes

It has been carried out the determination of trans-resveratrol and trans-piceid in red wine samples by using room temperature synchronous fluorescence, sensitized through their retention on nylon membranes, in front-face mode. These compounds are weakly fluorescent in solution but their retention allows using the native fluorescence of these compounds as analytical signal, due to the increase in the medium rigidity. To determine these compounds in red wine, a previous liquid-liquid extraction is necessary and in the case of trans-resveratrol it is also necessary a previous cleanup stage using C18 cartridges. Diethylether and ethyl acetate are the selected extractant solvents for trans-resvertarol and trans-piceid, respectively. The retention on nylon membranes was carried out by immersion of the membranes in solutions of these compounds. Variables involved in the retention and measurement processes were optimized, and the analytical figures of merit were obtained under optimal conditions. Ethanol:water 10:90 v:v and ethyl acetate were the solvents used for the retention of trans-resveratrol and trans-piceid, respectively and, for each case a immersion time of 300 and 600 s was selected. Satisfactory linear relation between fluorescence intensity and concentration was found in the intervals 0.040 and 0.242 mg L⁻¹ of trans-resvertarol and 0.009 and 0.288 mg L⁻¹ of trans-piceid. Concentration of 1.08 ± 0.21 mg L⁻¹ for trans-resveratrol and 1.49 ± 0.36 mg L⁻¹ for trans-piceid were found in a wine sample obtained from a pool of commercial red wines.