Browsing by Author "Costa, Rossana M."
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- Evaluation of free radical-scavenging and antihemolytic activities of quince (Cydonia oblonga) leaf: a comparative study with green tea (Camellia sinensis)Publication . Costa, Rossana M.; Magalhães, Ana S.; Pereira, José A.; Andrade, Paula B.; Valentão, Patrícia; Carvalho, Márcia; Silva, Branca M.This study aimed to determine the phenolic profile and to investigate the antioxidant potential of quince (Cydonia oblonga) leaf, comparing it with green tea (Camellia sinensis). For these purposes, methanolic extracts were prepared and phenolics content of quince leaf was determined by HPLC/UV. The antioxidant properties were assessed by Folin-Ciocalteu reducing capacity assay and by the ability to quench the stable free radical 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and to inhibit the 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of human erythrocytes.5-O-Caffeoylquinic acid was found to be the major phenolic compound in quince leaf extract. Quince leaf exhibited a significantly higher reducing power than green tea (mean value of 227.8 +/- 34.9 and 112.5 +/- 1.5 g/kg dry leaf, respectively). Quince leaf extracts showed similar DPPH radical-scavenging activities (EC50 mean value of 21.6 +/- 3.5 microg/ml) but significantly lower than that presented by green tea extract (EC50 mean value of 12.7 +/- 0.1 microg/ml). Under the oxidative action of AAPH, quince leaf methanolic extract significantly protected the erythrocyte membrane from hemolysis in a similar manner to that found for green tea (IC50 mean value of 30.7 +/- 6.7 and 24.3 +/- 9.6 microg/ml, respectively, P > 0.05). These results point that quince leaf may have application as preventive or therapeutic agent in diseases in which free radicals are involved.
- Targeted metabolites and biological activities of Cydonia oblonga Miller leavesPublication . Oliveira, Andreia P.; Costa, Rossana M.; Magalhães, Ana S.; Pereira, José A.; Carvalho, Márcia; Valentão, Patrícia; Andrade, Paula B.; Silva, Branca M.Natural products continue to play a significant role in drug discovery and development processes, and many plants have already provided valuable clues for potentially bioactive compounds. Additionally, in recent years it has become evident that significant health risks and benefits are associated with dietary food choice. Nutritional studies recommend the regular consumption of fruits and vegetables, which constitute an essential part of the Mediterranean diet, to favor a healthy life. Several works have showed that quince tree (Cydonia oblonga Miller) is a good and low cost natural source of metabolites with interesting biological properties. Extensive research has been performed on the metabolic profile and biological potential of this species. In particular, quince leaves revealed to constitute a promising natural source of bioactive phytochemicals, suitable for application in nutritional/pharmaceutical fields. In this review phenolics and organic acids composition of quince leaf is overviewed, as well as its antioxidant and antiproliferative properties, in chemical and cellular in vitro systems. Comparisons with green tea, considered by the scientific community as an effective natural antioxidant, were established.