Preparation of grape pomace extracts by using deep eutectic solvents, isolation of anthocyanins and their in vitro biological activity

Eutektična otapala (DES), kao nova zelena otapala, posljednjih se godina istražuju kao alternativa za zelenu ekstrakciju i separaciju antocijana iz komine grožđa. U ovom radu pripremljeno je 5 različitih DES-ova s ciljem pronalaženja najboljeg otapala za ekstrakciju antocijana. Najveći učinak ekstrakcije postignut je s eutektičnim otapalom kolin klorid:prolin:jabučna kiselina. Iz pripravljenih ekstrakata antocijani su izolirani na makroporoznoj smoli Amberlite XAD-16 i eluirani 96%-tnim etanolom. Učinak etanolnih eluata ispitan je u in vitro uvjetima na tri stanične linije (HeLa, MCF-7 i HEK293T), a najizraženiji citotoksični učinak je vidljiv kod etanolnog eluata betain:jabučna kiselina. Određen je i antioksidacijski kapacitet etanolnih eluata i najvišu vrijednost ima etanolni eluat betain:jabučna kiselina. Razvijen postupak ekstrakcije i izolacije na makroporoznoj smoli pokazao se kao alternativna i zelena metoda za ekstrakciju i koncentriranje antocijana iz komine grožđa.Deep eutectic solvents (DES), as new extraction solvents, have attracted increasing attention for the green and efficient extraction and separation of anthocyanins from grape pomace. In this study, five different DESs were prepared and observed to determine which of them possess the predominant extraction performance for anthocyanins. The best extraction efficiency was obtained with choline chloride:proline:malic acid. Anthocyanins were separated using macroporous resin Amberlite XAD-16 and were eluted with 96% ethanol. Ethanol eluents were valorised by testing their biological activity in in vitro assay using three cell lines (HeLa, MCF-7, and HEK293T), and the most evident toxic effect was caused by betaine:malic acid. Antioxidant activity of the ethanol eluents was also determined, and the highest value obtained for the betaine:malic acid. The developed procedures based on extraction and direct macroporous resin enrichment processes could be an alternative and environmental method for the extraction and enrichment of anthocyanins from grape pomace