EVALUATION OF ANTIOXIDANT CAPACITY OF METHANOL EXTRACT AND ITS SOLVENT FRACTIONS OBTAINED FROM FOUR MOROCCAN MACRO ALGAE SPECIES
European Scientific Journal May 2014 edition vol.10
EVALUATION OF ANTIOXIDANT CAPACITY OF METHANOL EXTRACT AND ITS SOLVENT FRACTIONS OBTAINED FROM FOUR MOROCCAN MACRO ALGAE SPECIES
Doctor Halima Chernane 0
0 Cadi Ayyad University/ Morocco Mounir Mansori, Doctoral Candidate Salma Latique, Doctoral Candidate Prof. Mimoun El Kaoua Cadi Ayyad University /Department of Biology, Laboratory of Biotechnology, Valorization and Protection of Agro-Resources , Morocco
In vitro antioxidant activities of methanolic extract and its solvent fraction (petroleum ether (PE), ethyl acetate (EA), dichloromethane (DCM), butanol (BuOH) and aqueous) were obtained from four Moroccan macroalgae species: Ulva rigida, Enteromorpha intestinalis, Fucus spiralis and Bifurcaria bifurcata using DPPH scavenging activity, metal chelating activity and total phenol content. Brown algae, Bifucaria bifurcata and Fucus spiralis contained higher amounts of polyphenols than green algae, Enteromorpha intestinalis and Ulva rigida . DCM fraction of Fucus spiralis and EA fraction of Bifucaria bifurcate showed higher phenolic content (29,79 and 24,44 mg gallic acid equivalent/g DW extract respectively) when compared to other solvent fraction and total methanol extract. DPPH radical scavenging activity of algae species extract tested showed lower activity than that of a standard compounds: ascorbic acid (EC 50 = 0,11 mg /ml) and α tocopherol (EC 50 = 0,215 mg /ml). Aqueous fraction of Enteromorpha intestinalis exhibited the most effective scavenging ability on DPPH radical (68,70%) than other fraction at the concentration of 3 mg/ml followed by aqueous and EA fraction of Fucus spiralis (49,50% and 50% respectively). The antioxidant activity of seaweed extracts increased in concentration-in a dependent manner. In accordance with DPPH results, potent chelation abilities were again detected in methanolic extract and its solvent fraction. All solvent and aqueous fraction of Ulva rigida and Fucus spiralis exhibited equivalent chelating effects as compared to EDTA-Na2 standard compound (IC50 was lower than 0,05mg/ml). The other fractions of Bifucaria bifurcata
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and Enteromorpha intestinalis showed less potent chelating effect as
compared to other seaweeds (IC50 was high than 0,4mg/ml). However, there
was no direct relationship between antioxidant activity and the phenolic
content, suggesting that polyphenol play a minor role in the metal chelating
ability and other compounds such as polysaccharides, protein, organic acid
which can contribute to the overall antioxidant activities.
Introduction
Seaweed of marine macro algae are a potential renewable resource in
marine environment. About 6000 species of seaweed have been identified
and have been grouped into different class which includes: green
(Chlorophyceae), brown (Pheophyceae) and red (Rhodophyceae) based on
their pigmentation (Dawczynski et al., 2007). Algae, as photosynthetic
organisms, are exposed to a combination of light and high oxygen
concentration at the origin of the formation of free radicals and other
oxidative reagents. But, the awareness of the lack of structural damage in
their organs has led the scientific community to consider that their protection
against oxidation comes from their natural content, or production under
stress in antioxidant substances. Seaweed provides an excellent bioactive
compounds with potential antioxidant activity such as polyphenol,
carotenoids, alkaloids, terpens, and tocopherol (Ragan Glombitza, 1986; Heo
et al., 2009; Hu et al., 2008). Polyphenols derived from seaweed may be
more potent that analogous polyphenols derived from terrestrial plant
sources due to the presence of up to eight interconnected phenol rings
(Hemat, 2007). Phlorotanins, a group of phenolic compounds which are
restricted to polymers of phloroglucinol have been identified from several
brown algae (Koivikko et al., 2007). These compounds have been reported to
possess strong antioxidant activity. In addition, polysaccharides have also
been demonstrated to possess excellent antioxidant potential (Yan et al.,
1999; Zhao et al., 2008). Carotenoids, the natural pigments react rapidly also
with free radical and retard or decrease the extent of oxidative deterioration
(Akoh and Min, 1997). Reactive oxygen species such as hydroxyl, super
oxide and peroxyl radicals which are formed in human tissues cells result in
extensive oxidative damage that leads to age related degenerative conditions,
cancer and a wide range of other human diseases (Reaven and Witzum,
1996, Aruoma 1999). Thus, the consumption of antioxidants and addition of
antioxidant in food materials protect the body as well as foods against these
events. Seaweed constitutes a commercially important renewable resource
and can be used as fertilizers, food additives and animal feed. Any studies
evaluating the antioxidant proprieties of seaweed enhance their utility value.
The coastlines of Morocco are an abundant resource of seaweeds
with bro (...truncated)