Analysis of trans-resveratrol by laser ionization mass spectrometry and HPLC with fluorescence detection. Comparison between both techniques

Development and Validation of a Stability-Indicating HPLC Method for the Simultaneous Determination of trans-Resveratrol and cis-Resveratrol in an Injectable Solution

trans-Resveratrol, a phytochemical compound with antioxidant power and various therapeutic effects, such as cardioprotective, chemopreventive, and neuroprotective, among others, has disadvantages of poor solubility and limited stability, creating difficulties for the development of new strategies for its quantification. This study developed and validated an analytical stability method for trans-resveratrol by high-pressure liquid chromatography with photodiode-array detection (HPLC-PDA), which allowed its quantification in the presence of its degradation products. The quantification of trans-resveratrol occurred at a retention time of 2.6 min, with ammonium formate (10 mM, pH = 4)/acetonitrile, 70/30 v/v, as mobile phase. The validation met the ICH Q2 criteria of specificity, method linearity (2.8-4.2 μg/ml), precision and accuracy, robustness, quantification limit (0.176 μg/ml), and detection (0.058 μg/ml). As degradation products, cis-resveratrol was observed at 3.9 min, which could be resveratrone in 3.2 min and five unidentified products in 0.7, 1.0, 1.4, 1.8, and 5 min. Some solutions subjected to temperature stress of 40 and 60°C, UV light, and acidic and basic hydrolysis exhibited colour changes. An analytical method was obtained by HPLC-PDA, which allowed quantifying the stability of trans-resveratrol in a fast and specific manner in the presence of its degradation products.

Detection of Biomedically Relevant Stilbenes from Wines by Mass Spectrometry

Stilbenes represent a class of compounds with a common 1,2-diphenylethylene backbone that have shown extraordinary potential in the biomedical field. As the most well-known example, resveratrol proved to have anti-aging effects and significant potential in the fight against cardiovascular diseases and some types of cancer. Mass spectrometry is an analytical method of critical importance in all studies related to stilbenes that are important in the biomedical field. From the discovery of new natural compounds and mapping the grape metabolome up to advanced investigations of stilbenes' potential for the protection of human health in clinical studies, mass spectrometry has provided critical analytical information. In this review we focus on various approaches related to mass spectrometry for the detection of stilbenes-such as coupling with chromatographic separation methods and direct infusion-with presentation of some illustrative applications. Clearly, the potential of mass spectrometry for assisting in the discovery of new stilbenes of biomedical importance, elucidating their mechanisms of action and quantifying minute quantities in complex matrices is far from being exhausted.

Ultrasound-Assisted Extraction of Stilbenes from Grape Canes

An analytical ultrasound-assisted extraction (UAE) method has been optimized and validated for the rapid extraction of stilbenes from grape canes. The influence of sample pre-treatment (oven or freeze-drying) and several extraction variables (solvent, sample-solvent ratio and extraction time between others) on the extraction process were analyzed. The new method allowed the main stilbenes in grape canes to be extracted in just 10 min, with an extraction temperature of 75 °C and 60% ethanol in water as the extraction solvent. Validation of the extraction method was based on analytical properties. The resulting RSDs (n = 5) for interday/intraday precision were less than 10%. Furthermore, the method was successfully applied in the analysis of 20 different grape cane samples. The result showed that grape cane byproducts are potentially sources of bioactive compounds of interest for pharmaceutical and food industries.

Development and validation of a HPLC method using a monolithic column for quantification of trans-resveratrol in lipid nanoparticles for intestinal permeability studies

The development of nanodelivery systems that protect trans-resveratrol is extremely important to preserve its bioactive properties in the development of further applications as nutraceuticals to supplement foods and beverages. In this work, a validated HPLC method was developed for the quantification of trans-resveratrol in lipid nanoparticles for application in studies of in vitro intestinal permeability. The chromatographic separation was achieved in a C18 monolithic column connected to a fluorometric detector (330/374 nm), by isocratic elution consisting of 2% acetic acid/acetonitrile (80:20). Two calibration ranges were established (0.020-0.200 and 0.200-2.00 μmol L(-1)), and low quantification limits (2-6 nmol L(-1), 23-69 pg) were achieved. Stability studies showed that trans-resveratrol is stable for 24 h at 4 °C, and storage at room temperature and freeze-thaw cycles are not recommended. The proposed method was applied to in vitro intestinal permeability studies, in which values between 0.05 ± 0.01 and 1.8 ± 0.3 μmol L(-1) were found.

Resveratrol ameliorates high glucose and high-fat/sucrose diet-induced vascular hyperpermeability involving Cav-1/eNOS regulation

Vascular endothelial hyperpermeability is one of the manifestations of endothelial dysfunction. Resveratrol (Res) is considered to be beneficial in protecting endothelial function. However, currently, the exact protective effect and involved mechanisms of Res on endothelial dysfunction-hyperpermeability have not been completely clarified. The aim of present study is to investigate the effects of Res on amelioration of endothelial hyperpermeability and the role of caveolin-1 (Cav-1)/endothelial nitric oxide synthase (eNOS) pathway. Adult male Wistar rats were treated with a normal or high-fat/sucrose diet (HFS) with or without Res for 13 weeks. HFS and in vitro treatment with high glucose increased hyperpermeability in rat aorta, heart, liver and kidney and cultured bovine aortic endothelial cells (BAECs), respectively, which was attenuated by Res treatment. Application of Res reversed the changes in eNOS and Cav-1 expressions in aorta and heart of rats fed HFS and in BAECs incubated with high glucose. Res stimulated the formation of NO inhibited by high glucose in BAECs. Beta-Cyclodextrin (β-CD), caveolae inhibitor, showed the better beneficial effect than Res alone to up-regulate eNOS phosphorylative levels, while NG-Nitro-77 L-arginine methyl ester (L-NAME), eNOS inhibitor, had no effect on Cav-1 expression. Our studies suggested that HFS and in vitro treatment with high glucose caused endothelial hyperpermeability, which were ameliorated by Res at least involving Cav-1/eNOS regulation.

Ultrasound-assisted extraction of stilbenoids from grape stems

A new method for fast determination of stilbenoids from grape stems was developed. Ultrasound-assisted extraction was applied prior to chromatographic determination of stilbenoids in the extracts, and the stability of stilbenoids under extraction conditions was checked. A fractional experimental design was developed to analyze the influence on the extraction process of seven different extraction variables: temperature, ultrasound amplitude, ultrasonic cycle duration, ultrasonic probe type, time, sample-solvent ratio, and solvent (mixtures of ethanol and water). The most important variables for the recovery of major stilbenoids were studied and the final conditions optimized. With this new method, the main stilbenoids found in grape stems can be extracted in 15 min, using 75 °C as the extraction temperature and 80% ethanol as the extraction solvent, and no cleaning step with organic solvent is needed. The optimized method allowed for the analysis of stilbenoid content from 22 grape stem samples, many of them analyzed for the first time.

Development and validation of an analytical method for the determination of trans- and cis-resveratrol in wine: analysis of its contents in 186 Portuguese red wines

A simple procedure based on solid-phase extraction and high performance liquid chromatography coupled to diode array detector has been developed and validated for the qualitative and quantitative analysis of cis- and trans-resveratrol in wines. The method was linear from 0.025 (lower limit of quantitation, LLOQ) to 15 μg/mL for trans-resveratrol and from 0.023 (LLOQ) to 0.92 μg/mL for cis-resveratrol, with correlation coefficients higher than 0.99 for both isomers. Intra- and interday precision and accuracy were in conformity with the criteria normally accepted in method validation, that is, CVs inferior to 15% and mean relative errors within a ±14% interval. The extraction presented mean efficiencies close to 100% for both analytes. The validated methodology was applied to 186 Portuguese red wines from different regions, grape varieties and vintage. The results obtained showed that the content of trans-resveratrol in red wines ranged from 0.05 to 10.9 μg/mL, while the concentrations of cis-resveratrol ranged from 0.04 to 8.71 μg/mL.

Multiwalled carbon nanotubes as sorbent for online solid-phase extraction of resveratrol in red wines prior to fused-core C18-based ultrahigh-performance liquid chromatography-tandem mass spectrometry quantification

An ultrafast analytical protocol based on online solid-phase extraction (SPE)/high-performance liquid chromatography-tandem mass spectrometry for the determination of resveratrol in red wines has been developed. In the present work, multiwalled carbon nanotubes (MWCNTs) were used as SPE sorbents for the analytes' online extraction and cleanup. The target analytes were separated on a fused-core C18-silica column (Halo, 50 mm × 2.1 mm i.d., 2.7 μm) and quantified by triple-quadrupole linear ion trap mass spectrometry in negative ion multiple-reaction monitoring (MRM) mode. The proposed analytical procedures were carefully optimized and validated. The calibration function is linear from 0.37 to 370 ng mL(-1) and from 0.13 to 130 ng mL(-1) for trans- and cis-resveratrol, respectively. The limits of quantification (LOQs) of trans- and cis-resveratrol obtained were 0.05 and 0.06 ng mL(-1), which means that the proposed method is suitable for trace analysis of resveratrol at low-level concentration. At the three fortified levels (low, medium, and high), recoveries of resveratrol ranging from 76.9 to 108.3% were obtained. Eight red wine samples from different regions of China were analyzed. The results indicated that the present online SPE-LC-MS/MS system significantly increased sample throughput and decreased solvent consumption, exhibiting great potential to be applied for analyzing resveratrol in red wines.

Analysis of selected stilbenes in Polygonum cuspidatum by HPLC coupled with CoulArray detection

The roots of three varieties of Polygonum cuspidatum were analyzed for resveratrol and its analogs. The powder of the dried roots was extracted with aqueous ethanol (60% v/v) and the extracts obtained were analyzed using RP HPLC with coulometric detection. A simple HPLC method with a multichannel CoulArray detector was developed for the determination of four stilbenes: resveratrol, its glucoside piceid, piceatannol, and its glucoside astringin. Analyses were carried out on a LiChrospher C18 (125 x 4.6 mm id, particle size 5 microm) column with a mobile phase of ammonium acetate (pH 3) and ACN in gradient mode. Four compounds were monitored by a CoulArray electrochemical detector. Potentials of eight electrochemical cells in series were set in the range of 200-900 mV. Optimization of the mobile phase pH was performed. Calibration curves showed good linearity with correlation coefficients (r(2))--more than 0.9975.

Analysis of non-anthocyanin phenolic compounds in wine samples using high performance liquid chromatography with ultraviolet and fluorescence detection

A simple and rapid HPLC method with UV and fluorescence detection (FLD) for the separation of ten phenolic compounds including gallic acid, catechin, epicatechin, caffeic acid, coumaric, trans-piceid, cis-piceid, trans-resveratrol, cis-resveratrol and quercetin is reported. The UV and fluorescence detector in series provided a high selectivity for the determination of these compounds. Precisions, recoveries and LODs achieved for all the analytes were satisfactory. The proposed method was applied to the determination of these compounds in commercially available red wines.

Molecular imprinted polymer-based chemiluminescence imaging sensor for the detection of trans-resveratrol

Sensitive, rapid and inexpensive chemiluminescence (CL) imaging has been developed based on molecular imprinted polymer (MIP) sensing elements. Imprinted uniform microspheres were synthesized by precipitation polymerization. Microtiter plates (96 wells) were coated with polymer microspheres imprinted with trans-resveratrol, which were fixed in place using poly(vinyl alcohol) (PVA) as glue. The amount of polymer-bound trans-resveratrol was quantified using imidazole (IMZ)-catalyzed peroxyoxalate chemiluminescence (PO-CL) reaction. The light produced was then measured with a high-resolution CCD camera. Calibration curve corresponding to analyte concentration ranging from 0.3 to 25 microg mL(-1) was obtained with a limit of detection 0.1 microg mL(-1). These results showed that the MIP-based CL imaging sensor can become a useful analytical tool for quick simultaneous detection of trans-resveratrol in a large number of real samples.