Logo do repositório

Percorrer por autor "de Carvalho, Isabel Saraiva"

A mostrar 1 - 2 de 2
  • Chemical composition, antioxidant and alpha-Glucosidase-Inhibiting activities of the aqueous and hydroethanolic extracts of Vaccinium myrtillus Leaves
    Publication . Bljajic, Kristina; Petlevski, Roberta; Vujic, Lovorka; Cacic, Ana; Sostaric, Nina; Jablan, Jasna; de Carvalho, Isabel Saraiva; Koncic, Marijana Zovko
    Vaccinium myrtillus (bilberry) leaf is traditionally used in southeastern Europe for the treatment of diabetes. In the present study, the ability of bilberry leaf extracts to inhibit carbohydrate-hydrolyzing enzymes and restore glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress was investigated. A comprehensive analysis of the antioxidant activity of two bilberry leaf extracts was performed. The aqueous extract showed excellent total antioxidant and chelating activity. Its antioxidant activity in the beta-carotene-linoleic acid assay was very good, reaching the activity of the antioxidant standard BHA (93.4 +/- 2.3% vs. 95.1 +/- 2.4%, respectively). The hydroethanolic extract (ethanol/H2O, 8:2, v/v), on the other hand, was a better radical scavenger and Fe2+ reducing agent. Furthermore, the aqueous extract was able to efficiently increase glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress and restore it to the levels observed in non-hyperglycaemic cells. The hydroethanolic extract strongly inhibited alpha-glucosidase, with the IC50 statistically equal to the antidiabetic drug acarbose (0.29 +/- 0.02 mg/mL vs. 0.50 +/- 0.01 mg/mL, respectively). Phytochemical analysis revealed the presence of quercetin and kaemferol derivatives, as well as chlorogenic and p-coumaric acid. The study results indicate that V. myrtillus leaf may have promising properties as a supporting therapy for diabetes.
    2017-05Artigo científico Acesso aberto Ver mais
  • Development of a beverage benchtop prototype based on sweet potato peels: optimization of antioxidant activity by a mixture design
    Publication . Anastácio, Ana; de Carvalho, Isabel Saraiva
    A beverage benchtop prototype related to oxidative stress protection was developed based on sweet potato peels phenolics. Formula components were sweet potato peel (Ipomoeas batatas L.) aqueous extract (SPPE), sweet potato leaves water extract (SPLE) and honey solution (HonS). According to linear squares regression (LSR) models, SPLE presented higher additive effect on total phenolic content (TPC), FRAP and DPPH than the other components. All antagonist interactions were not significant. The optimum formula obtained by artificial neural networks (ANN) analysis was 50.0% of SPPE, 21.5% of SPLE and 28.5% of HonS. Predicted responses of TPC, FRAP, DPPH and soluble solids were 309mg GAE/L, 476mg TE/L, 1098mg TE/L and 12.3 degrees Brix, respectively. Optimization with LSR models was similar to ANN. Beverage prototype results positioned next to commercial vegetable and fruit beverages, thus it has an interesting potential to the market of health and wellness.
    2016-08Artigo científico Acesso restrito Ver mais