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- Human cancer cell antiproliferative and antioxidant activities of Juglans regia L.Publication . Carvalho, Márcia; Ferreira, Pedro J.; Mendes, Vanda S.; Silva, Renata; Pereira, José A.; Jerónimo, Carmen; Silva, Branca M.Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. Walnuts contain several phenolic compounds which are thought to contribute to their biological properties. The present study reports the total phenolic contents and antioxidant properties of methanolic and petroleum ether extracts obtained from walnut (Juglans regia L.) seed, green husk and leaf. The total phenolic contents were determined by the Folin-Ciocalteu method and the antioxidant activities assessed 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. Methanolic seed extract presented the highest total phenolic content (116 mg GAE/g of extract) and DPPH scavenging activity (EC(50) of 0.143 mg/mL), followed by leaf and green husk. In petroleum ether extracts, antioxidant action was much lower or absent. Under the oxidative action of AAPH, all methanolic extracts significantly protected the erythrocyte membrane from hemolysis in a time- and concentration-dependent manner, although leaf extract inhibitory efficiency was much stronger (IC(50) of 0.060 mg/mL) than that observed for green husks and seeds (IC(50) of 0.127 and 0.121 mg/mL, respectively). Walnut methanolic extracts were also assayed for their antiproliferative effectiveness using human renal cancer cell lines A-498 and 769-P and the colon cancer cell line Caco-2. All extracts showed concentration-dependent growth inhibition toward human kidney and colon cancer cells. Concerning A-498 renal cancer cells, all extracts exhibited similar growth inhibition activity (IC(50) values between 0.226 and 0.291 mg/mL), while for both 769-P renal and Caco-2 colon cancer cells, walnut leaf extract showed a higher antiproliferative efficiency (IC(50) values of 0.352 and 0.229 mg/mL, respectively) than green husk or seed extracts. The results obtained herein strongly indicate that walnut tree constitute an excellent source of effective natural antioxidants and chemopreventive agents.
- First report on Cydonia oblonga Miller anticancer potential: differential antiproliferative effect against human kidney and colon cancer cellsPublication . Carvalho, Márcia; Silva, Branca M.; Silva, Renata; Valentão, Patrícia; Andrade, Paula B.; Bastos, Maria L.The present study reports the phenolic profile and antiproliferative properties of quince (Cydonia oblonga Miller) leaf and fruit (pulp, peel, and seed) against human kidney and colon cancer cells. The phenolic profiles of quince methanolic extracts were determined by high-performance liquid chromatography (HPLC)/diode array detector (DAD). 5-O-Caffeoylquinic acid was always one of the two major phenolic compounds present in all extracts, except for seed. Our results revealed that quince leaf and fruit extracts exhibited distinctive antiproliferative activities. The extracts from quince leaf showed concentration-dependent growth inhibitory activity toward human colon cancer cells (IC(50) = 239.7 +/- 43.2 microg/mL), while no effect was observed in renal adenocarcinoma cells. Concerning the fruit, seed extracts exhibited no effect on colon cancer cell growth, whereas strong antiproliferative efficiency against renal cancer cells was observed for the highest concentration assayed (500 microg/mL). The antiproliferative activity of pulp and peel extracts was low or absent in the selected range of extract concentrations. This is the first report showing that C. oblonga may be useful as a cancer chemopreventive and/or chemotherapeutic agent.
- 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.
- Green tea: a promising anticancer agent for renal cell carcinomaPublication . Carvalho, Márcia; Jerónimo, Carmen; Valentão, Patrícia; Andrade, Paula B.; Silva, Branca M.Renal cell carcinoma (RCC) is one of the most lethal amongst the urologic malignancies, comprising three percent of all human neoplasms, and its incidence appears to be rising. RCC is refractory to both chemotherapy and radiotherapy. Therefore, the discovery of new strategies for therapeutic intervention remains a priority. Green tea (Camellia sinensis) and tea polyphenols have been proposed to exert protective effects against several types of cancer, based on preclinical and clinical trial data; however, the anticarcinogenic activity of green tea towards RCC is unknown. In this study, a targeted metabolite analysis on a green tea leaves methanolic extract was performed by HPLC/DAD and the antiproliferative activity of the extract was assayed using human renal cancer cell lines A-498 and 769-P. The total phenolic content was very high (31.8% of methanolic extract), and the main compounds were flavan-3-ols (94.3% of the total phenolic content), and especially (−)-epigallocatechin-3-gallate (35.9% of the total phenolic content). In addition, two methylxanthines – theophylline and caffeine – were also present in the extract, caffeine being the most abundant. Green tea extract strongly inhibited the growth of both RCC cell lines in a concentration-dependent manner, with IC50 values of 54 ± 10 and 129 ± 28 μg/ml for A-498 and 769-P cells, respectively. This is the first report showing that green tea is likely to be an effective anticancer agent for renal cell carcinoma.