Interaction between extra virgin olive oil phenolic compounds and mucin

Abstract

Extra virgin olive oil (EVOO) phenolic compounds provide nutritional benefits because of their antioxidant capacity. The interaction between phenolic compounds and proteins may reduce their bioavailability and antioxidant capacity. The objective of this project was to evaluate the interaction between phenolic compounds from EVOO and mucin (protein produced by epithelial tissues). EVOO phenolic extract and a number of commercially available pure phenolics present in EVOO were also used in this study: cinnamic, p‐coumaric, caffeic, vanillic and protocatechuic acids, tyrosol, hydroxytyrosol and oleuropein. The interaction between polyphenols and proteins was measured by monitoring the increasing turbidity of the reaction mixture and expressed in nephelometric turbidity units. Polyphenol solutions at different concentrations were mixed with mucin solutions. Reaction mixtures were measured after 1, 30, 60, 90 and 180 min at 37°C. The results suggest that EVOO polyphenols interact with the mucin solution forming an insoluble complex after 1 min of reaction. The highest interaction between polyphenols and proteins was observed for the EVOO phenolic extract and cinnamic, p‐coumaric and caffeic acids. The interaction between polyphenols and mucin varied depending on the phenol concentration and chemical structure. The importance of the results is to evaluate the possible consequences of EVOO phenolic–protein interactions in the bioavailability and antioxidant capacity of the polyphenols present in the EVOO.Practical applications: Nephelometry is a simple method for the evaluation of the interaction between phenolic extract from EVOO and mucin. Phenolic compounds interact with mucin and this could provide information about possible negative consequences for the bioavailability of polyphenols and finally for the health benefits of EVOO. Additionally, this method could complement sensorial analysis for evaluation of the astringency of EVOOs, according to their polyphenol profiles.Schematic representation of the stages occurring in binding and precipitation of polyphenol by mucin. Adapted from [30, 45].