Edible nuts deliver polyphenols and their transformation products to the large intestine: An in vitro fermentation model combining targeted/untargeted metabolomics.
The fate of polyphenols from edible tree nuts was investigated using a simulated in vitro intestinal fermentation system. The digested food matrix was fermented for 48 h and the changes in the phenolic profiles were evaluated by both untargeted UHPLC-QTOF and targeted UHPLC-Orbitrap mass spectrometry. The untargeted metabolomics approach allowed us to monitor the comprehensive changes in phenolic profiles from 0 up to 48 h of in vitro fermentation. Multivariate statistics (i.e., orthogonal projection to latent structures discriminant analysis) applied to this untargeted data allowed us to identify the most discriminating phenolic metabolites and to further understand the colonic transformation pathways involved. In particular, 13 putatively identified compounds derived from flavonoids, lignans and phenolic acids were found to have the highest discrimination potential. Six phenolic metabolites were then quantified by means of targeted metabolomics (using a UHPLC-Orbitrap). These metabolites included 3,4-dihydroxyphenylacetic acid, 4-hydroxybenzoic acid, hippuric acid, caffeic acid, protocatechuic acid and protocatechuic aldehyde. Using the targeted data, a clear matrix effect was observed over time, with an increase of some phenolic metabolites moving from 8 to 48 h of in vitro fermentation. Based on these data, catabolic pathways for colonic microbial degradation of flavonoids, hydroxycinnamic acids, tyrosols and lignans are proposed. Our findings show that edible tree nuts deliver polyphenols to the colon, where several microbial transformations occur that lead to smaller phenolic metabolites being observed. Furthermore, we found that the combined use of targeted and untargeted metabolomics can be particularly effective for investigating the fate of polyphenols in the large intestine.
['Rocchetti|Gabriele|G|', 'Bhumireddy|Sudarshana Reddy|SR|', 'Giuberti|Gianluca|G|', 'Mandal|Rupasri|R|', 'Lucini|Luigi|L|', 'Wishart|David S|DS|']
D000818:Animals D001419:Bacteria D001711:Biotransformation D002851:Chromatography, High Pressure Liquid D003106:Colon D031211:Corylus D004032:Diet D004063:Digestion D005243:Feces D005285:Fermentation D031324:Juglans D055432:Metabolomics D009754:Nuts D027927:Pistacia D059808:Polyphenols D000068181:Prunus dulcis D021241:Spectrometry, Mass, Electrospray Ionization D034421:Sus scrofa D013997:Time Factors
Nuts Polyphenols In vitro fermentation UHPLC-QTOF UHPLC-Orbitrap Food metabolomics