CAVALCANTE, Kelma Maria dos Santos Pires. Avaliação do potencial antioxidante de macroalgas marinhas do litoral cearense. 2012. 122 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Fortaleza-CE, 2012 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-27T13:00:44Z
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Previous issue date: 2012 / Seaweeds are sources of a wide variety of beneficial compounds for human. Many of these compounds have antioxidant activity, such as phenolic compounds, carotenoids, and vitamin E. The aim of this research was to evaluate the in vitro antioxidant activity of 50% methanolic extracts from seaweed collected in the coastline of Ceará State, Brazil. The methods used were: DPPH radical scavenging, ferrous ion chelation (FIC), ferric reducing antioxidant power (FRAP), and β-carotene bleaching. In addition to in vitro antioxidant activity, the total phenolic content (TPC) was measured by the Folin-Ciocalteu method, followed by a phytochemical prospecting to point out which are the main classes of compounds present in the algal extracts. The quantification of carotenoids (α- and β-carotene, and lutein) and vitamin E (α- and -tocopherol) was carried out by HPLC. In general, the extracts of brown algae showed the highest ability to scavenger the DPPH radical, the largest FRAP and the highest TPC, followed by extracts of green and red algae. The greatest FIC was observed in red alga extracts, followed by brown and green alga extracts. The high antioxidant activity in β-carotene/linoleic acid model system of green and red alga extracts ranged from 65% to 95%, however it represented less than 40% in brown alga extracts, exception to Padina gymnospora extract which presented activity up to 92%. The majority of the algal extracts analyzed in this study presented activity similar to or even greater than those observed in positive controls (quercetin, BHA, BHT, ascorbic acid, α-tocopherol, β-carotene and EDTA). Fenols were detected in brown algae only; anthocyanins, anthocyanidins, chacons, aurons and leucoanthocyanins were observed in some species of Rhodophyta Phylum. All the other classes of phenolic compounds were found in at least one species within each Phylum, exception to flavononols which have not been detected in green alga extracts. TPC was the main responsible for the ability to scavenger the DPPH radical, FIC and FRAP in green and red algae. On the other hand, in brown algae TCP was influenced only by FRAP. All extracts of green, red and brown algae exhibited the presence of β-carotene and lutein. The latter was the major carotenoid within Chlorophyta and Rhodophyta. Naturally absent in brown algae, α-carotene was not detected in five species of Chlorophyta and Rhodophyta algae. α-Tocopherol was determined in all species, except Ulva fasciata and U. lactuca extracts. The isomer δ-tocopherol was quantified in eleven out of twenty-three alga species. Antioxidant activity and levels of compounds in the algal extracts were different, but all of them showed antioxidant potential. / As macroalgas marinhas são fontes de compostos com atividade antioxidante como compostos fenólicos, pigmentos carotenóides e vitamina E. O objetivo deste trabalho foi avaliar a atividade antioxidante in vitro de extratos metanólicos (50%) de macroalgas cearenses, através da capacidade de sequestrar o DPPH, habilidade de quelação do íon ferroso (FIC), poder de redução do ferro (FRAP) e degradação do β-caroteno. Além disso, também foi determinado o conteúdo de compostos fenólicos pelo método de Folin-Ciocalteu, seguido de uma prospecção fitoquímica para indicar possivelmente as principais classes de compostos. Os teores de α- e β-caroteno, luteína e α- e -tocoferol foram quantificados por cromatografia líquida de alta eficiência. De um modo geral, capacidade de sequestrar o DPPH, FRAP e conteúdo de compostos fenólicos foram maiores nos extratos das algas pardas, seguidos dos das algas verdes e vermelhas. FIC mais elevada foi observada nos extratos das algas vermelhas, seguidas das pardas e verdes. No sistema modelo β-caroteno/ácido linoléico as maiores atividades foram determinadas nas clorófitas e rodófitas, tendo variado de 64,8% a 95,3%, nas ocrófitas, inferiores a 40,5%, com exceção de Padina gymnospora com cerca de 92%. Os extratos algáceos analisados apresentaram atividades antioxidantes semelhantes ou superiores aos controles positivos (quercetina, BHA, BHT, ácido ascórbico, α-tocoferol, β-caroteno e EDTA). Fenóis foram detectados apenas em algas pardas; antocianinas, antocianidinas, chaconas, auronas e leucoantocianidinas foram observadas apenas em algumas espécies do Filo Rhodophyta; as demais classes de compostos fenólicos investigadas foram observadas em pelo menos uma espécie dentro de cada Filo, com exceção de flavanonóis que não foram encontrados nos extratos de algas verdes. O conteúdo de compostos fenólicos foi o principal responsável pelas atividades de sequestro do DPPH, FRAP e FIC nas algas verdes e vermelhas. Nas pardas esses compostos só influenciaram no FRAP. β-Caroteno e luteína foram quantificados em todos os extratos de algas verdes, vermelhas e pardas, sendo a luteína o carotenóide majoritário nas clorófitas e rodófitas. Com exceção das algas pardas que naturalmente não possuem α-caroteno, apenas os extratos de cinco espécies de clorófitas e rodófitas não apresentaram esse composto. Todos os extratos analisados apresentaram α-tocoferol, menos Ulva fasciata e U. lactuca. Extratos de onze espécies apresentaram δ-tocoferol. As atividades antioxidantes e os teores de compostos detectados nos extratos algáceos foram distintos, mas todos eles apresentaram potencial antioxidante.
| Identifer | oai:union.ndltd.org:IBICT/oai:www.repositorio.ufc.br:riufc/18729 |
| Date | January 2012 |
| Creators | Cavalcante, Kelma Maria dos Santos Pires |
| Contributors | Sampaio , Silvana Saker |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFC, instname:Universidade Federal do Ceará, instacron:UFC |
| Rights | info:eu-repo/semantics/openAccess |
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