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Percorrer por autor "Costa, P."

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  • Inclusion complexes of rosmarinic acid and cyclodextrins: stoichiometry, association constants, and antioxidant potential
    Publication . Medronho, B.; Valente, A. J. M.; Costa, P.; Romano, Anabela
    The interaction between beta-cyclodextrin (beta-CD) and the polyphenol rosmarinic acid (RA) is here reported by H-1 NMR titration experiments. The formation of an aqueous soluble inclusion complex is confirmed and valuable information regarding mode of penetration of guest into beta-CD, stoichiometry, and stability of the complex is obtained. The analysis by the continuous variation method shows the undoubted formation of 1:1 beta-CD/RA complex. Additionally, the estimated apparent association constants reveal the importance of the asymmetry of the RA in the complexation; the incorporation of the catechol moiety closer to the carboxylic group is more favorable (K = 2,028 M-1) than from the other end of the RA molecule (K = 1,184 M-1). Finally, we have also investigated the antioxidant activity and storage stability of the beta-CD/RA complexed system; the presence of beta-CD was found to produce a remarkable enhancement on the antioxidant activity.
    2014Artigo científico Acesso restrito Ver mais
  • Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts
    Publication . Costa, P.; Gonçalves, Sandra; Valentão, Patrícia; Andrade, Paula B.; Almeida, C.; Nogueira, J. M. F.; Romano, Anabela
    We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC-DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe2+ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health. © 2013 Elsevier Ltd. All rights reserved.
    2013Artigo científico Acesso restrito Ver mais