Characterization of white wine pomace content and its bioactivity by HPTLC

Résumé

White wine pomace is the main by-product of the winery industry with a high polyphenol and dietary fiber content. Recently, it has garnered interest for its potential health benefits against hypertension, hyperglycemia, endothelial dysfunction, infection... Since its functions depend on its composition, the characterization of bioactive molecules is fundamental to determine its potential healthy properties. High-performance thin-layer chromatography (HPTLC) allows the separation of components from an extract on silica gel plates. Subsequently, these separated components can undergo different chemical derivatization and effect-direct analysis, allowing not only the characterization of groups of molecules but also the determination of their bioactivities. This approach was employed to evaluate methanol: water extracts of white wine pomace as well as the bioaccesible fractions obtained after gastrointestinal digestion and colonic fermentation of the pomace. Further characterization was achieved by HPTLC–MS. The use of various –chemical reagents in the layers provided the deter-mination of the chemical structure of the separated compounds present in the zones of interest. The results revealed that most of the bioactive compounds separated were lipophilic. However, zones exhibiting antioxidant activity were observed when highly polar mobile phases were used for separation. HPTLC combined with antibacterial and enzyme inhibition assays were performed to determine the bioactivity of the compounds separated. Several zones showed anti-lipase activity, as well as antibacterial effect against Gram positive bacteria (Bacillus subtilis). These results contribute to the further characterization of white wine pomace, highlighting the bioactivity of its components and potential health properties. The authors thank the financial support of Ministry of Science, Innovation and Universities, Spanish State Research Agency and European Regional Development Fund (Project PGC2018-097113-B-I00), the collaboration of Á.M. Móricz’s research group in the Plant Protection Institute in Budapest, Hungary, and the Junta de Castilla y León for the pre-doctoral scholarship ORDEN EDU/875/2021 received by the student Víctor Gutiérrez González.