A mechanistic investigation of H/D scrambling processes in flavonoids

Abstract

Several classes of flavonoids, such as anthocyanins, flavonols, flavanols and flavones, undergo a slow H/D exchange on aromatic ring A, leading to full deuteration at positions C(6) and C(8). Within the flavanol class, H-C(6) and H-C(8) of catechin and epicatechin are slowly exchanged in D2O to the corresponding deuterated analogues; even quercetin, a relevant flavonol representative, shows the same behaviour in a D2O/DMSOd6 1:1 solution. Detailed kinetic measurements of these H/D scrambling processes are here reported by exploiting the time-dependent changes of their peak areas in the 1H-NMR spectra taken at different temperatures. A unifying reaction mechanism is also proposed based on our detailed kinetic observations, even taking into account pH and solvent effects. Molecular modelling and QM calculations were also carried out to shed more light on several molecular details of the proposed mechanism.

DOI:

Publication date: September 16, 2021

Issue: Macrowine 2021

Type: Article

Authors

Graziano Guella

Biorganic Chemistry Lab/Dept. of Physics/University of Trento,Federico Bonaldo1, Fulvio Mattivi2, Daniele Catorci*, &, Panagiotis Arapitsas3, Graziano Guella1, * 1  Bioorganic Chemistry Laboratory, Department of Physics, University of Trento, Trento, Italy; 2 Department of Cellular, Computational and Integrative Biology – CIBIO and C3A, University of Trento, Trento, Italy; 3 Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all’Adige, Italy; * D. Catorci passed away on June 27th, 2020

Contact the author

Keywords

flavonoids; chemistry of polyphenols; h/d isotopic scrambling; reaction mechanism

Citation

Related articles…

Impact of environmental conditions in vscs production during wine fermentation by Saccharomyces cerevisiae

The aroma of wine is one of the most important determinants of quality as it strongly influences the consumer’s acceptance or rejection. Among the thousands of molecules comprising the wine aroma, sulfur-containing compounds can be considered as a “double-edged sword”: some of them, deriving from varietal precursors provide fruity pleasant aromas, while other ones, produced by yeast metabolism are related to “unpleasant” aromas

Modeling the suitability of Pinot Noir in Oregon’s Willamette Valley in a changing climate

Air temperature is the key driver of grapevine phenology and a significant environmental factor impacting yield and quality for a winegrape growing region. In this study the optimal downscaled CMIP5 ensemble for computing thegrowing season average temperature (GST) viticulture climate classification index was determined to spatially compute on a decadal basis predictions of the GST climate index and the grapevine sugar ripeness (GSR) model for Pinot Noir throughout the Willamette Valley (WV) American Viticultural Area (AVA). Forecasts for average temperature and a 220 g/L target sugar concentration level were computed using daily Localized Constructed Analogs (LOCA) downscaled CMIP5 historic and Representative Concentration Pathways (RCP) future climate projections of minimum and maximum daily temperature. We explore spatiotemporal trends of the GST climate classification index and Pinot Noir specific applications of the GSR phenology model for the WV AVA. Spatiotemporal computations of the GST climate index and Pinot Noir specific applications of the GSR model enable the opportunity to explore relationships between their computed values with one intent being to provide updated GST ranges that better align with current temperature-based modeling understanding of Pinot Noir grapevine phenology and the viticultural application of LOCA CMIP5 climate projections for the WV AVA. The Pinot Noir specific applications of the GSR model or the GST index with updated bounds indicate that the percent of the WV AVA area suitable for Pinot Noir production is currently at or near its peak value in the upper 80s to lower 90s of this century.

Use of fumaric acid to control pH and inhibit malolactic fermentation in wines

In this audio recording of the IVES science meeting 2022, Antonio Morata (Universidad Politécnica de Madrid, Madrid, Spain) speaks about the use of fumaric acid to control pH and inhibit malolactic fermentation in wines.

Influence of nitrogen source on expression of genes involved in aroma production in Saccharomyces uvarum

Saccharomyces uvarum has interesting properties that can be exploited for the production of fermented beverages. Particularly, the cryotolerance and capacity to produce high amounts of volatile compounds offers new opportunities for the wine industry.

Staying hydrated – not easy when it’s hot!

Heat and drought episodes during the growing season are becoming more frequent and more severe in many of the world’s grape‐growing regions