Research Assistant, The American University in Cairo
extraction of metabolites from marine sources
Recently, there has been a growing interest in sulfated polysaccharides extracted from various natural sources due to their versatile biological activities that find great use in biomedical and industrial applications. In the present study, sulfated polysaccharides were extracted from green algae, Ulva lactuca and red algae, Jania rubens collected from Alexandria city coast, Egypt. Conventional and ultrasonic-assisted extraction methods were investigated under different operating parameters and the optimum conditions for extraction were obtained based on the yield. Algal extracts with optimum SPs yields were then tested for their phenolic and sugar contents, as well as their 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) antioxidant activities. Optimum yields of both green and red algae were obtained via extraction under ultrasonic conditions for 4h. Higher yields were produced from the green algae as compared to the red ones. However, red algal extracts showed relatively higher antioxidant activities, possibly due to their higher mannose content.
Abstract: Cold-water corals, such as Lophelia pertusa, are key habitat-forming organisms found throughout the world's oceans to 3000 m deep. The complex three-dimensional framework made by these vulnerable marine ecosystems support high biodiversity and commercially important species. Given their importance, a key question is how both the living and the dead framework will fare under projected climate change. Here, we demonstrate that over 12 months L. pertusa can physiologically acclimate to increased CO2, showing sustained net calcification. However, their new skeletal structure changes and exhibits decreased crystallographic and molecular-scale bonding organization. Although physiological acclimatization was evident, we also demonstrate that there is a negative correlation between increasing CO2 levels and breaking strength of exposed framework (approx. 20-30% weaker after 12 months), meaning the exposed bases of reefs will be less effective 'load-bearers', and will become more susceptible to bioerosion and mechanical damage by 2100.
Pub.: 21 Aug '15, Pinned: 15 Jun '17