Abstract
Antioxidants play an important role as Reactive Oxygen Species (ROS) chelating agents and, therefore, the screening for potent antioxidants from natural sources as potential protective agents is of great relevance. The main aim of this study was to obtain antioxidant-enriched fractions from the common seaweed Fucus spiralis and evaluate their activity and efficiency in protecting human cells (MCF-7 cells) on an oxidative stress condition induced by H2O2. Five fractions, F1–F5, were obtained by reversed-phase vacuum liquid chromatography. F3, F4 and F5 revealed the highest phlorotannin content, also showing the strongest antioxidant effects. The cell death induced by H2O2 was reduced by all fractions following the potency order F4 > F2 > F3 > F5 > F1. Only fraction F4 completely inhibited the H2O2 effect. To understand the possible mechanisms of action of these fractions, the cellular production of H2O2, the mitochondrial membrane potential and the caspase 9 activity were studied. Fractions F3 and F4 presented the highest reduction on H2O2 cell production. All fractions decreased both caspase-9 activity and cell membrane depolarization (except F1). Taken all together, the edible F. spiralis reveal that they provide protection against oxidative stress induced by H2O2 on the human MCF-7 cellular model, probably acting as upstream blockers of apoptosis.
Highlights
IntroductionEdible seaweeds have been highly valued and widely consumed as a direct human food by Oriental communities [1]
For thousands of years, edible seaweeds have been highly valued and widely consumed as a direct human food by Oriental communities [1]
In order to describe the antioxidant potential of each fraction, the total phenolic content (TPC) was assessed as well as the evaluation of the Oxygen Radical Absorbance Capacity (ORAC), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and evaluation of the hydroxyl radical scavenging activity (OH)
Summary
Edible seaweeds have been highly valued and widely consumed as a direct human food by Oriental communities [1]. These organisms contain a range of components that have potential health benefits. They are good sources of dietary fiber, polyunsaturated fatty acids, minerals, vitamins and a wide range of phenolic compounds [2,3]. Phlorotannins are unique phenolic compounds that belong to a large class of marine secondary metabolites exclusively produced by brown algae. They are often considered to act as a chemical defense against herbivores and possess primary functions, such as contributing to cell wall structure and reproduction [6]. These potent antioxidant compounds are oligomers or polymers of phloroglucinol (1,3,5-trihydroxybenzene), connected by aryl–aryl bonds (fucols), ether bonds (phlorethols, hydroxyphlorethols, fuhalols), or both (fucophlorethols), or with a dibenzodioxin linkage (eckols and carmalols) [7]
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