Title : Antioxidant activity of phenolic extracts from wild Mediterranean edible plants before and after in vitro digestion
Wild edible plants have represented an important food source for the communities of the Mediterranean basin providing a relevant role in Mediterranean diet. The recent interest in wild edible plants is largely associated to their potential health benefits related with the richness in antioxidant compounds mainly phenolics. Nevertheless, these compounds, particularly flavonoids and phenolic acids, are metabolized after ingestion and gastrointestinal absorption, usually being transformed into plasma metabolites with lower antioxidant activity than the precursor molecules. The knowledge about the bioactive properties of underutilized plants could provide feedback about their value and agro-industrial potential and could also be used by gastronomic companies interested in the exploitation of these plants as additives or natural ingredients. The aim of the present study was to evaluate the total phenolic contents and antioxidant activity of extracts from four wild edible plants (Beta maritima L., Plantago major L., Oxalis pes-caprae L. and Scolymus hispanicus L.) used in Mediterranean diet before and after in vitro digestion. The in vitro digestion consisted of a gastric phase and an intestinal phase using simulated gastric and intestinal fluids (Ryan et al. 2008). Total phenolic contents (TPC) were determined by Folin-Ciocalteu assay and antioxidant activity by the ABTS, DPPH and FRAP assays (Gonçalves et al. 2018). The TPCs of P. major and S. hispanicus extracts were not affected by in vitro digestion. On the other hand, TPCs significantly decreased in B. maritima after both phases of in vitro digestion process and in O. pes-caprae after the gastric phase only. The radical scavenging capacity of the four extracts was mainly affect by the acid conditions of the gastric phase and the ferric reducing power was not significantly affected by the digestion conditions. Results showed that P. major extract has the highest TPC and antioxidant activity in all the assays, with considerable values even after digestion, reinforcing the health benefits of this species.