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  • Effect of in vitro gastrointestinal digestion on the total phenolic contents and antioxidant activity of wild Mediterranean edible plant extracts
    Publication . Gonçalves, Sandra; Moreira, E.; Andrade, Paula B.; Valentao, Patricia; Romano, Anabela
    The recent interest in wild edible plants is associated with their health benefits, which are mainly due to their richness in antioxidant compounds, particularly phenolics. Nevertheless, some of these compounds are metabolized after ingestion, being transformed into metabolites frequently with lower antioxidant activity. The aim of the present study was to evaluate the influence of the digestive process on the total phenolic contents and antioxidant activity of extracts from four wild edible plants used in the Mediterranean diet (Beta maritima L., Plantago major L., Oxalis pes-caprae L. and Scolymus hispanicus L.). HPLC-DAD analysis revealed that S. hispanicus is characterized by the presence of caffeoylquinic acids, dicaffeoylquinic acids and flavonol derivatives, P. major by high amounts of verbascoside, B. maritima possesses 2,4-dihydroxybenzoic acid, 5-O-caffeoylquinic acid, quercetin derivatives and kaempferol-3-O-rutinoside, and O. pes-caprae extract contains hydroxycinnamic acids and flavone derivatives. Total phenolic contents were determined by Folin-Ciocalteu assay, and antioxidant activity by the ABTS, DPPH, ORAC and FRAP assays. Phenolic contents of P. major and S. hispanicus extracts were not affected by digestion, but they significantly decreased in B. maritima after both phases of digestion process and in O. pes-caprae after the gastric phase. The antioxidant activity results varied with the extract and the method used to evaluate the activity. Results showed that P. major extract has the highest total phenolic contents and antioxidant activity, with considerable values even after digestion, reinforcing the health benefits of this species.
  • Phenolic profile, antioxidant activity and enzyme inhibitory activities of extracts from aromatic plants used in Mediterranean diet
    Publication . Goncalves, Sandra; Moreira, Elsa; Grosso, C.; Andrade, Paula B.; Valentao, Patricia; Romano, Anabela
    The antioxidant and enzyme inhibitory properties of methanolic extracts from four aromatic plants used in traditional medicine and food [Calamintha nepeta (L.) Savi subsp. nepeta, Helichrysum italicum subsp. picardii Franco, Mentha spicata L. and Origanum vulgare subsp. virens (Hoffmanns. & Link) Bonnier & Layens] were evaluated. The extract from O. vulgare exhibited the strongest DPPH (IC50 of 4.65 +/- 0.12 mu g/ml) and ABTS (1479.56 +/- 12.29 mu mol(TE)/g(extract)) scavenging capacities, as well as the largest ferric reducing ability (1746.76 +/- 45.11 mu mol(AAE)/g(extract)). This extract also showed the highest total phenolic content (1597.20 +/- 24.10 mu mol(GAE)/g(extract)) and although HPLC-DAD analysis revealed rosmarinic acid as the main compound of the extract, other compounds seem to be involved in the antioxidant activity. Furthermore, the extract from H. italicum, which was found to be rich in caffeoylquinic and dicaffeoylquinic acids and in pinocembrin, showed the highest inhibitory potential against acetylcholinesterase, tyrosinase and alpha-glucosidase. Overall, the results obtained validate the usefulness of the studied plants as valuable sources of natural agents beneficial for human health.