Abstract
The green macroalgae, Enteromorpha compressa (Linnaeus) Nees, Ulva lactuca, and E. linza, were seasonally collected from Abu Qir bay at Alexandria (Mediterranean Sea) This work aimed to investigate the seasonal environmental conditions, controlling the green algal growth, predominance, or disappearance and determining antioxidant activity. The freshly collected selected alga (E. compressa) was subjected to pigment analysis (chlorophyll and carotenoids) essential oil and antioxidant enzyme determination (ascorbate oxidase and catalase). The air-dried ground alga was extracted with ethanol (crude extract) then sequentially fractionated by organic solvents of increasing polarity (petroleum ether, chloroform, ethyl acetate, and water). Antioxidant activity of all extracts was assayed using different methods (total antioxidant, DPPH [2, 2 diphenyl-1-picrylhydrazyl], ABTS [2, 2 azino-bis ethylbenzthiazoline-6-sulfonic acid], and reducing power, and β-carotene linoleic acid bleaching methods). The results indicated that the antioxidant activity was concentration and time dependent. Ethyl acetate fraction demonstrated higher antioxidant activity against DPPH method (82.80%) compared to the synthetic standard butylated hydroxyl toluene (BHT, 88.5%). However, the crude ethanolic extract, pet ether, chloroform fractions recorded lower to moderate antioxidant activities (49.0, 66.0, and 78.0%, resp.). Using chromatographic and spectroscopic analyses, an active compound was separated and identified from the promising ethyl acetate fraction.
Highlights
For many generations, marine algae have been extensively used in coastal regions in the Far East as food for humans and animals and as organic fertilizers
Species of Ulva and Enteromorpha attached to rocky substrata in the intertidal zone located in the Mediterranean Sea at Abu Qir bay exemplify those marine algae exposed to severe environmental stress [4]
Adhered sand was removed from the algae by washing with seawater and the material was transported to the laboratory of Phycology at Cairo University
Summary
Marine algae have been extensively used in coastal regions in the Far East as food for humans and animals and as organic fertilizers. The high protein, lipid, and vitamin content of marine algae have encouraged their cultivation and use as a food source in many parts of the world [1]. These algae contain various secondary products such as flavonoids, terpenoids, and alkaloids, some with potent antioxidant, antimicrobial, antineoplastic, and antiviral action [2]. Periodic exposure to high solar flux, elevated temperature, and dehydration during low tidal periods generates acute physiological stress such as increased levels of reactive oxygen species (ROS) which are modulated by the increased production of various compounds with antioxidant activity [3]. Species of Ulva and Enteromorpha attached to rocky substrata in the intertidal zone located in the Mediterranean Sea at Abu Qir bay exemplify those marine algae exposed to severe environmental stress [4].
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