The effects of alkali treatment time and extraction time of native agar and alkali treated agar obtained from Gracilaria vermiculophylla were studied. The response characteristics were mainly agar yield and gel strength.Alkali treatment was carried out at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 h. Agar yield and gel strength decreased with the increase in the time of the alkali treatment. The highest yield (15.3%) and highest gel strength (1,064 g cm −2 ) were obtained at 0.5 h, and therefore this time was used for the next experiment. The extraction of both native and alkali treated agars was carried out at 1.5, 2.0, 2.5, and 3.0 h. The best extraction time for alkali treated agar was 1.5 h, and for native agar 2.5 h. The alkali treated agar obtained with the different alkali treatment and extraction times showed higher melting (92.4-99.7°C) and gelling (35.7-39.6°C) temperatures. Native agar was lower in melting (60.2-64.1°C) and gelling (20.4-23.4°C) temperatures. The 3,6-anhydrogalactose content decreased with increasing alkali treatment time, with the opposite effect during the extraction of native and alkali treated agars.

The brown alga Eisenia arborea is the second most abundant brown alga along the western coast of the Baja California Peninsula of Mexico. Samples of E. arborea were collected in Bahía Asunción, BCS, over 10 months. Chemical composition was analyzed from dried alga (%, dw): moisture (10.34%), protein (9.44%), ash (24.77%), lipids (0.60%), fiber (5.22%), and carbohydrates (49%). Gross energy was 9.8 kJ g −1 . Seven minerals were analyzed and the four most abundant were K, Na, Mg, and Ca, ranging from 907 to 7,946 mg.100 g −1 . The concentrations of six vitamin levels were also determined: A, C, E, D 3, B 2 , and B 1 . Seventeen amino acids were analyzed and the most abundant were glutamic acid, aspartic acid, and leucine. Total fatty acids ranged from 21 to 65 mg.100 g −1 (dw). Individual concentrations were also determined for arachidonic acid, alpha linolenic acid, linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid. Saponins, cyanogenic glycosides, and alkaloids were not detected. Our results suggest that E. arborea is a good candidate to be tested as supplement food for animals, including humans. It contains essential amino acids, is low in lipids and fiber, and could be a source of vitamins and minerals.

Biofouling causes major economic losses in the maritime industry. In our site study, the Bay of La Paz (Gulf of California), biofouling on immersed structures is a major problem and is treated mostly with copper-based antifouling paints. Due to the known environmental effect of such treatments, the search for environmentally friendly alternatives in this zone of high biodiversity is a priority to ensure the conservation and protection of species. The aim of this work was to link chemical ecology to marine biotechnology: indeed, the natural defense of macroalgae and sponge was evaluated against biofoulers (biofilm and macrofoulers) from the same geographical zone, and some coatings formulation was done for field assays. Our approach combines in vitro and field bioassays to ensure the selection of the best AF agent prospects. The 1st step consisted of the selection of macroalgae (5 species) and sponges (2 species) with surfaces harboring a low level of colonizers; then extracts were prepared and assayed for toxicity against Artemia, activity towards key marine bacteria involved in biofilm formation in the Bay of La Paz, and the potency to inhibit adhesion of macroorganisms (phenoloxidase assays). The most active and non-toxic extracts were further studied for biofouling activity in the adhesion of the bacteria involved in biofilm formation and through incorporation in marine coatings which were immersed in La Paz Bay during 40 days. In vitro assays demonstrated that extracts of Laurencia gardneri, Sargassum horridum (macroalgae), Haliclona caerulea and Ircinia sp. (sponges) were the most promising. The field test results were of high interest as the best formulation were composed of extracts of H. caerulea and S. horridum and led to a reduction of 32% of biofouling compared with the control.

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The fucosterol has been reported numerous biological activities. In this study, the activity in vitro of the fucosterol from Sargassum horridum as potential human acetylcholinesterase inhibitor was evaluated. The structural identification was obtained by nuclear magnetic resonance (NMR) spectroscopy and based on experimental data, we combined docking and molecular dynamics simulations coupled to the Molecular-Mechanics-Generalized-Born-Surface-Area approach to evaluating the structural and energetic basis for the molecular recognition of fucosterol and neostigmine at the binding site of acetylcholinesterase (AChE). In addition, the Lineweaver-Burk plot showed the nature of a non-competitive inhibition. The maximum velocity (V) and the constant of Michaelis-Menten (K) estimated for fucosterol (0.006 µM) were 0.015 1/V (ΔA/h and 6.399 1/[ACh] mM, respectively. While, for neostigmine (0.14 µM), the V was 0.022 1/V (ΔA/h) and K of 6.726 1/[ACh] mM, these results showed a more effective inhibition by fucosterol respect to neostigmine. Structural analysis revealed that neostigmine reaches the AChE binding site reported elsewhere, whereas fucosterol can act as a no-competitive and competitive acetylcholinesterase inhibitor, in agree with kinetic enzymatic experiments. Binding free energy calculations revealed that fucosterol reaches the acetylcholinesterase binding site with higher affinity than neostigmine, which is according to experimental results. Whereas the per-residue decomposition free energy analysis let us identify crucial residues involved in the molecular recognition of ligands by AChE. Results corroborate the ability of theoretical methods to provide crucial information at the atomic level about energetic and structural differences in the binding interaction and affinity from fucosterol with AChE.

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