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Development and validation of methods for the investigation of wine stilbenoids

University of British Columbia

Stilbenoids are secondary plant metabolites responsible for the protection of grape vine from bacterial and fungal infection. Red wine has been shown to be a major source of these compounds in the human diet, where they display an array of health benefits. The first goal of our study was to develop and validate a robust and selective method for quantification of the major stilbenoids in red and white wine using ultra-high-performance liquid chromatography coupled with electrospray ionization/quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF). Both isomers of resveratrol and piceid were quantified externally using authentic standards, while piceatannol was quantified in trans-piceid equivalents. Due to the minimal amount of sample preparation and the short method runtime, results were obtained rapidly and with low expenditure of energy, chemicals, and labor. The method was validated with respect to linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, intra- and inter-day precision and stability. All six stilbene monomers were quantified in 44 British Columbian wines; the highest total stilbene concentration in an individual wine was 28.81 mg/L in Pinot Noir, while the average across all wines was 8.49 ± 6.25 mg/L.. Another method was developed for separation, identification and semi-quantification of all derivatives of resveratrol that are present in wine. A total of 41 (both known and novel) stilbenoids were detected in extracted red wine. In addition to the well-known monomeric stilbenes, several resveratrol-resveratrol homodimers (m/z 453.1344), resveratrol-piceatannol heterodimers (m/z 469.1293) and piceatannolpiceatannol homodimers (m/z 485.1236) were detected. Modified dimers of resveratrol were also detected. Multiple trimers of resveratrol (m/z 679.1978) were detected for the first time in red wine, as well as some known and some novel stilbenoid tetramers (m/z 905.2604). A solid-phase extraction (SPE) method was developed for quantification of the stilbenoid oligomers in red wines. The monomers and oligomers in red wine from the Okanagan Valley (Cabernet Sauvignon, Merlot and Pinot Noir) and Québec (Maréchal Foch, Marquette, Sabrevois, St.Croix, and Frontenac) wines were semi-quantified as using this method. The highest concentration of total stilbenoids was 10.67 mg/L in Pinot Noir with an overall average of 3.32 ± 2.86 mg/L in all wines.

Text

2014-10-21

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/50808

Chemistry

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/