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…

Metabolomic profiling of botrytized grape berries: unravelling the dynamic chemical transformations during noble rot

Botrytis cinerea, a fungal pathogen commonly known as grey mold, which under specific climatic conditions can develop into a desirable form known as noble rot. In this process the fungus penetrates the grape skin, allowing water evaporation and concentration of sugars and flavors, while profoundly affects the metabolite composition of grapes, leading to the production of unique and desirable compounds in the resulting wines. The result is a unique and complex wine with a luscious sweetness, heightened aromatics, and a distinct character.

Variability in intrinsic water use efficiency (WUEi) of eight red varieties grown in the center of the Iberian Peninsula during an atypical vintage year

The study was performed in the summer of 2007, the point of confluence of a rather atypical vintage year in the area with abnormally low temperatures after a very humid spring

Influence of protein stabilization with aspergillopepsin I on wine aroma composition

The protein haze formation in white and rosé wines during storage, shipping and commercialization has always been an important issue for winemakers. Among the various solutions industrially proposed, the use of bentonite is certainly the most widespread. However, the harmful effects of this treatment are known either in terms of wine volume loss and wine flavour and aroma.

Unveiling the viticultural heritage of Rachaya, Lebanon: genetic, ampelographic and chemical profiling of local grape varieties

Located in the western bekaa region of lebanon, rachaya is known for its extensive history of viticulture and ideal mediterranean conditions for grapevine cultivation. Despite the area’s importance in grapevine production, there is limited knowledge about the local grape varieties grown there. In this work, we conducted a detailed analysis of five local grapevine varieties in the area, obeidy, kassoufi, foddeh, aswadi, and maryami, of which little is currently known, in comparison to a set of international varieties.

The selection of Vitis vinifera L. cultivars based on berry texture, iPBS genetic markers, and noble rot susceptibility analysis

The selection of a suitable grape variety (Vitis vinifera L.) for specific viticulture and oenology objectives is a considerable challenge in the context of climate change.