Suchergebnisse

Natural matrices represent a rich source of biologically active compounds and are an example of molecular diversity, with recognized potential in drug discovery and development. Many plants frequently used in folk medicine have antioxidant and pharmacological properties connected with the presence of phenolic compounds, especially flavonoids [1]. The biological, pharmacological and medicinal properties of this group of compounds have been extensively reviewed (2]. Ethnobotanical surveys conducted in the Northeast of Portugal highlighted the decoction of Helichrysum stoechas (L.) Moench (shrubby everl asting; port. douradinha) for cold, bronchitis and fever [3]. In the present study, the phenolic composition of H. stoechas (inflorescences and leafy flowering stems) was analyzed by reversed-phase high performance liquid chromatography coupled to diode array detection and mass spectrometry with electron spray ionization (HPLC-DAD-ESI/MS), after extraction with methanol:water (80:20 v/v). Seventeen different phenolic compounds were identified, in which eight were characterized as phenolic acids, being 5-0-caffeoylquinic and 3,5-0-dicaffeoylquinic acids the most abundant compounds. Furthermore, nine flavonols were also identified, mostly derivatives of quercetin and myricetin, being myricetin 0 -acylhexoside the most abundant flavonoid. Overall, the analytical screening by HPLC-MS represents a valid and rapid approach in the search of new bioactive phenolic compounds. ; FCT for financial support to CIMO (strategic project PEstOE/ AGR/UI0690/2011 ). L. Barros also thanks to FCT, POPH-QREN and FSE for her grant (SFRH/BPD/4609/2008). The GIP-USAL is financially supported by the Spanish Government through the Conso/ider-lngenio 2010 Programme (FUN-C-FOOD, CSD2007-00063). M. Duenas thanks to the Programa Ram6n y Cajal for a contract.

The present study aims to assess the effect of different nitrogen (N) rates on the chemical composition and antioxidant properties of stevia frozen fresh and dried leaves, and to define the best growing conditions to maximize the levels of bioactive compounds. In general, processing affects more significantly the tocopherol and sugar contents than N fertilization. The most abundant sugars were xylose, arabinose + fructose and sucrose, presenting dried samples with higher contents than frozen fresh ones, while the latter better retained tocopherols than dry samples. Regarding phenolic compounds, greater levels were found in dried samples and in those fertilized with 25 kg N ha −1 . Leaves from plants fertilized with 25 and 50 kg N ha −1 also evidenced higher antioxidant activity, which seemed to be influenced by the phenolic composition. In general, N fertilization provides an improvement in the chemical composition and bioactive potential of stevia leaves. ; The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013) and to L. Barros contract. The authors are also grateful to the Interreg España-Portugal for financial support through the project 0377_Iberphenol_6_E. The GIP-USAL is financially supported by the Spanish Government through the project AGL2015-64522-C2-2-R. ; info:eu-repo/semantics/publishedVersion