DCFQE - Comunicações a Conferências / ConferenceItem
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Todo o tipo de documentos relacionados com uma conferência; ex.: artigos de conferências, relatórios de conferências, palestras em conferências, artigos publicados em proceedings de conferências, relatórios de abstracts de artigos de conferência e posters de conferências.
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Browsing DCFQE - Comunicações a Conferências / ConferenceItem by Subject "Antioxidant"
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- Antioxidant and anticholinesterasic activities of Morella faya (Aiton) Wilbur extractsPublication . Silva, Bruno J. C.; Seca, Ana M. L.; Moreno-Rodriguez, L.; Barreto, Maria do CarmoMorella faya (Aiton) Wilbur (Myricaceae), formerly Myrica faya, is a shrub or small tree native to Macaronesia, Spain and Portugal and invasive in Hawai'i [1]. In the present study, bioactivities of extracts from leaves and bark collected in S. Miguel, Azores, were determined. Extracts were prepared by sequentially extracting the dry material with dichloromethane and acetone at room temperature. The antioxidant activity of the extracts was determined by the DPPH radical scavenging and FeCl3 reduction assays, total phenolics by the Folin-Ciocalteau method and in vitro anticholinesterasic (anti-AChE) activity by a modification of the Ellman method [2]. The dichloromethane extracts did not present any of these activities between 4.9 and 1250 µg/mL. Both acetone extracts presented a high antioxidant activity. For the DPPH scavenging activity, EC50= 17.7 ± 0.13 and 16.9 ± 0.36 µg/mL for leaves and bark, respectively and 4.5 ± 1.1 µg/mL for quercetin (positive control). In the FeCl3reduction assay, EC50 values were 3.8 ± 0.40 and 3.9 ± 0.16 µg/mL for leaves and bark respectively, and 0.995 ± 0.06 µg/mL for gallic acid (positive control). The acetone extracts also showed anti-AChE activity, stronger for the bark, with IC50= 82.9 ± 6.16 µg/mL and weaker for the leaves, with IC50= 333.0 ± 27.3 µg/mL, which are interesting values for whole extracts. Anti-AChE activity was inversely proportional to the amount of phenolic compounds, 639.3 ± 17.8 mg GAE/g of leaf extract and 95.3 ± 6.55 mg GAE/g of bark extract, therefore the compounds responsible for this effect do not belong to this group. The antioxidant activity cannot be explained by the amount of these compounds alone, since it was quite similar for both acetone extracts and did not therefore reflect the differences in polyphenol content.
- Cytotoxic, antibacterial, antioxidant, and anticholinesterasic activity of Juniperus brevifolia extractsPublication . Oliveira, Nemésia; Medeiros, Sofia; Barreto, Maria do Carmo; Seca, Ana M. L.; Rosa, José S.The cytotoxic, antibacterial, antioxidant and anticholinesterasic (anti-AChE) activities of the methanol and acetone extracts of Juniperus brevifolia wood and bark were determined. The present study demonstrates that bark extracts of J. brevifolia are the most active and showed good antioxidant activity, lower anti-AChE activity except for the acetone extract, poor cytotoxic and antibacterial activities and absence of activity for Gram (-) bacteria.
- New xanthenodione: synthesis and antioxidant activity evaluationPublication . Leal, Stephanie B.; Pinto, Diana C. G. A.; Seca, Ana M. L.; Silva, Artur M. S.; Cavaleiro, José A. S.Due to the continuing interest of the research group in the synthesis of novel oxygen heterocycles we have recently developed a unique synthetic route towards new xanthenodiones 5 (scheme 1).[6] The application of this methodology in the cyclization of chromone derivatives 4b,c bearing methoxyl groups not only promote the cyclization to xanthenedione derivatives but also promote the demethylation leading to the 4-(benzylidene)-8-hydroxy-3-phenyl-3,4-dihydro-1H-xanthene-1,9(2H)-diones 5b,c . This interesting result prompted us to investigate the antioxidant potential of 4-(benzylidene)-8-hydroxy-3-phenyl-3,4-dihydro-1H-xanthene-1,9(2H)-diones 5a-c .
- Synthesis and antioxidant activity of new xanthone-type compoundsPublication . Leal, Stephanie B.; Pinto, Diana C. G. A.; Seca, Ana M. L.; Silva, Artur M. S.; Cavaleiro, José A. S.Owing to our continuing interest in the synthesis of novel oxygen heterocycles we have recently developed a unique synthetic procedure towards the synthesis of new xanthenodiones (2)[5] and extend the work to their aromatization into xanthones (3). Our aim was also to obtain new derivatives with potential biological activities, therefore their ability to scavenge the DPPH radical and to reduce iron(III) were also evaluated. In the present communication we will present and discussed our last results on the synthetic and potential application of xanthones (3).