Evaluation of the Antioxidant Capacities of Antarctic Macroalgae and Their Use for Nanoparticles Production

Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work.

Fatty acid trophic transfer of Antarctic algae to a sympatric amphipod consumer

The shallow benthos along the western Antarctic Peninsula supports brown macroalgal forests with dense amphipod assemblages, commonly including Gondogeneia antarctica (Amsler et al. 2014). Gondogeneia antarctica and most other amphipods are chemically deterred from consuming the macroalgae (Amsler et al. 2014). They primarily consume diatoms, other microalgae, filamentous macroalgae and a few undefended macroalgal species, including Palmaria decipiens (Aumack et al. 2017). Although unpalatable when alive, G. antarctica and other amphipods will consume the chemically defended brown algae Himantothallus grandifolius and Desmarestia anceps within a few weeks of death (Amsler et al. 2014).

Photovoltaic cells based on the use of natural pigments: Phycoerythrin from red-antarctic algae as sensitizers for DSSC

DSSC assembled with purified R-phycoerythrin show acceptable efficiency conversion values, especially when extracted from Palmaria decipiens. They showed up to 0.12 % conversion efficiency values. Adsorption of the protein onto the electrode surface plays a relevant role in DSSC performance impacting on the performance. The use of dyes easily obtained in a place as Antarctica is an alternative to explore to solve the energy issue.

The biology of an Antarctic rhodophyte, Palmaria decipiens: recent advances

Palmaria decipiens (Reinsch) R.W. Ricker (1987) represents one of the dominant rhodophyte species in Antarctic coastal ecosystems. Due to its high abundance in the intertidal and upper subtidal it plays a key role in ecosystem structure and function, providing habitat, food and shelter for a multitude of associated organisms. The physiology, reproductive strategy and life cycle of P. decipiens is considered as being well adapted to the Antarctic environment, which is characterized by permanent low water temperatures and a strong seasonality in light climate. With its obvious ecological significance and adaptive strategies P. decipiens was frequently studied as a typical representative of an endemic Antarctic macroalga. Here we provide an overview of the recent literature, summarizing the knowledge gained about the alga during the last 25 years. This review focuses on the species life cycle and physiological responses, such as temperature requirements, photosynthetic characteristics, pigment content and protective mechanisms with regard to enhanced ultraviolet radiation (UV-B radiation, 280–315 nm and UV-A radiation, 315–400 nm). The ecology of P. decipiens is reviewed focussing on grazing activity and abundance patterns. Since most studies on P. decipiens have been conducted at King George Island off the western Antarctic Peninsula this overview serves as a summary of baseline data from an ecosystem particularly prone to environmental change.