Agrimoniin the most important ellagitannin in human diet: elucidation of its identity in strawberry fruits and the influence of fruit ripening on its concentration

Of the most commonly consumed berries, strawberries (Fragaria ananassa Duch.) are the most popular choice with consumers, being eaten both fresh and frozen, as well as in different processed products. Although the composition of strawberry fruit has been extensively studied, especially for the most abundant phenolic compounds, agrimoniin has been only recently univocally identified as one of the most abundant phenolic compounds in the fruit (Vrhovsek et al. 2012). In this study agrimoniin was isolated in the fruit of Fragaria vesca and its structure fully characterized, reporting for the first time the full NMR assignments for this dimeric ellagitannin. Agrimoniin is a known bioactive compound, which has been used for treatment of diarrhea and haemorrhaging and reported to have antitumor properties. Its presence as the main ellagitannin in both F. vesca and Fragaria ananassa D. fruit is therefore noticeable. The establishment of a new HPLC protocol for the separation of the strawberry ellagitannins, and the isolation and characterisation of other ellagic acid derivatives, allowed us to produce an accurate quantification of the main ellagitannins and ellagic acid conjugates in 6 different varieties of strawberry and in 2 woodland strawberry at four different ripening stages from the green stage up to overripe fruit. Of fruit containing ellagitannins, strawberries are the most widely consumed, and agrimoniin is suggested to be one of the most widely present ellagitannins in the human diet. Agrimoniin, together with the other strawberry ellagitannins and ellagic acid derivatives characterised in this study, deserve further attention since they are expected to play an important, yet still largely unexplored, role in the beneficial health effects associated with the consumption of strawberries by humans.