Use of solid-supported liquid-liquid extraction in the analysis of polyphenols in wine

Trace-level quantification of N-nitrosopiperazine in treated wastewater using supported liquid extraction and hydrophilic interaction chromatography mass spectrometry

Regenerable amine-based solvents used for post-combustion CO2 capture, primarily monoethanolamine and piperazine, are known to undergo degradation and secondary reactions over time forming, amongst other species, N-nitrosamines. These carcinogenic species can eventually make their way from treated wastewater into environmental waters. The United States Environmental Protection Agency (US EPA) recommends that the concentration of N-nitrosamines in surface water not exceed 1.24 μg/L. We have developed a straightforward method to quantify N-nitrosopiperazine in treated wastewater by hydrophilic interaction liquid chromatography – mass spectrometry (HILIC–MS) after sample preparation by supported liquid extraction (SLE). To achieve the best extraction recovery and method limits of quantification (MLOQ), standards were prepared in a high-salt synthetic matrix to mimic the treated wastewater effluent. To further improve the MLOQ, the drying steps after extraction were optimized. HILIC separation of the highly polar analytes was achieved using an ethylene-bridged hybrid amide stationary phase. Detection was achieved using a triple quadrupole mass spectrometer operated in positive electrospray ionisation and multiple reaction monitoring mode, providing a final MLOQ of 0.25 μg/L for N-nitrosopiperazine. Validation of the method was carried out to ensure good confidence in the data obtained for a treated wastewater sample from a post-combustion CO2 capture facility. In addition, N-nitrosopiperazine was quantified with the developed SLE-HILIC–MS method in eight degraded carbon capture samples that had not yet undergone wastewater treatment.

Development and Validation of a Simultaneous RP-HPLCUV/DAD Method for Determination of Polyphenols in Gels Containing S. terebinthifolius Raddi (Anacardiaceae)

Topical gels containing extracts of Schinus terebinthifolius have been used to treat bacterial vaginosis. It has been reported that this species has antimicrobial, anti-inflammatory and anti-ulcerogenic properties, which can be attributed to the presence of phenolic compounds. In this work, a sensitive and selective reversed-phase HPLC-UV/DAD method for the simultaneous assay of six polyphenols that could be present in S. terebinthifolius was developed. The method was shown to be accurate and precise. Peak purity and similarity index both exceeded 0.99. Calibration curves were linear over the concentration range studied, with correlation coefficients between 0.9931 and 0.9974. This method was used to determine the polyphenol content of a hydroalcoholic extract and pharmacy-compounded vaginal gel. Although the method is useful to assess the 6 phenolic compounds, some compounds could not be detected in the products.

Optimization of Purification, Identification and Evaluation of the in Vitro Antitumor Activity of Polyphenols from Pinus Koraiensis Pinecones

In this study, an efficient purification method for the polyphenols of Pinus koraiensis pinecone (PPP) has been developed. AB-8 resin was verified to offer good adsorption and desorption ratio for PPP. Response surface methodology (RSM) indicated that the optimized purification parameters for PPP were 1.70 mg GAE/mL phenolic sample concentration, 22.00 mL sample volume, and 63.00% ethanol concentration. Under these conditions, the experimental purity of PPP was 27.93 ± 0.14% (n = 3), which matched well with the predicted purity of 28.17%. Next, the antiproliferative effects of PPP on seven cancer cell lines, including A375 (human skin melanoma cancer cell line), A549 (human lung cancer cell line), SH-SY5Y (human neuroblastoma cell line), LOVO (human colon cancer stem cell line), MCF-7 (human breast cancer cell line), HeLa (human cervical cancer line), and HT29 (human colon cancer line), were examined by MTT assays. The results indicated that PPP had the highest capacity for inhibiting LOVO cells growth with an EC50 value of 0.317 ± 0.0476 mg/mL. Finally, Ultra-high performance liquid chromatography- tandem mass spectrometry (UPLC-MS) was used to tentatively identify twenty-four peaks in the purified PPP, of which five representative peaks were identified as catechin, methyl quercetin, o-vanillin, luteolin and coronaric acid. Our results demonstrate that Pinus koraiensis pinecone is a readily available source of polyphenols, and the purified PPP could be a promising natural antitumor agent for applications in functional foods.

Antioxidant activities and antiproliferative activity of Thai purple rice cooked by various methods on human colon cancer cells

The changes in anthocyanins, phenolic compounds, and antioxidant activities of Thai purple rice cooked by various cooking devices, including an electric rice cooker, an autoclave and a microwave oven, were investigated. In raw rice, cyanidin-3-glucoside (cy-3-glu) and peonidin-3-glucoside (pn-3-glu) are predominant anthocyanins, whereas protocatechuic acid (PCA) and vanillic acid (VA) are major free phenolic acids, and ferulic acid (FA) and VA are major bound phenolic acids. The microwave cooking method resulted in a marked loss of phenolics, anthocyanins and antioxidant activities (p<0.05). A decrease of cy-3-glu occurred concomitantly with an increase of PCA upon any cooking methods applied. A methanolic extract of rice cooked under sterilization exhibited the highest content of PCA and the highest inhibition of Caco-2 cell proliferation with an IC50 (16.11 μg/mL) comparable to that of raw rice. Thai purple rice cooked under sterilization could be a potential source of PCA exerting high antiproliferative activity.

Extraction methods for the removal of phospholipids and other endogenous material from a biological fluid

Background: A comparison of three different sample preparation techniques for the analysis of plasma samples has been investigated to highlight the effect that these approaches have on the removal of endogenous material. The three techniques under investigation are: SPE, support assisted liquid–liquid extraction and nonspecific solvent-based protein precipitation. Results: Comparisons are made on the practicalities of each approach and to allow a semiquantitative assessment between the effectiveness of these different techniques the relative amounts of phospholipids present within the sample are analyzed. Total ion chromatograms are also obtained to further study the effects of different extraction techniques in the removal of endogenous components from a biological matrix. Both of these approaches provide a very coarse measure of the cleanliness of the extracts and demonstrate that support assisted liquid–liquid extraction and an optimized SPE approach remove a greater amount of endogenous material. Conclusion: This study highlights the importance of sample preparation in removing endogenous material, which may have a detrimental effect on the performance of a bioanalytical assay.

Cloud-point extraction and reversed-phase high performance liquid chromatography for analysis of phenolic compounds and their antioxidant activity in Thai local wines

A cloud-point extraction (CPE) was developed for the determination of 12 phenolic compounds (i.e. gallic acid, procatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, guaiacol, p-cresol, o-cresol and 3,5-xylenol) using reversed-phase high performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detection. The optimum CPE conditions were 2.0% (w/v) Triton X-114, 3.0% (w/v) Na2SO4 and 20-min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by HPLC using a Symmetry C18 column, gradient mobile phase of acetonitrile and 1% (v/v) acetic acid, and PDA detection at 280 nm. Under the optimum condition, the target phenolic compounds were separated within 25 min. CPE gave higher enrichment factor up to 15-fold compared to that of direct analysis. The proposed method showed good analytical performances with limits of detection in the range 0.01-0.1 mg L(-1) and precisions with relative standard deviation (RSD) lower than 5% for retention time and 10% for peak area. The method was successfully applied to the analysis of phenolic compounds in Thai local wine samples. Gallic acid, procatechuic acid, and vanillic acid were the highest phenolics found in the studied wines with the contents up to 172.4, 99.1, and 26.6 mg L(-1), respectively. The recovery of the spiked wine samples (0.5, 1.0, and 2.0 mg L(-1)) were obtained in the range of 90.4-110%. High total phenolic content, total flavonoids, and antioxidant activity (DPPH method) in the studied wines were also observed.

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.