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

Abstract

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.

Immunomodulatory and Antitumoral Activity of Gold Nanoparticles Synthesized by Red Algae Aqueous Extracts

“…Lastly, in the bands at 1200 and 1050 cm −1 , a reduction in intensity was observed. The results obtained for both seaweed are in accordance with other works that have proposed that the carbonyl group from proteins is able to bind metals, and, as a result, they could most possibly cap AuNPs and, thus, prevent agglomeration [ 20 , 21 , 62 ]. The modifications observed in the region of 1200–1000 cm −1 could indicate that sulfonic groups from polysaccharides are involved in metal binding.…”

Valorisation of the Invasive Macroalgae Undaria pinnatifida (Harvey) Suringar for the Green Synthesis of Gold and Silver Nanoparticles with Antimicrobial and Antioxidant Potential

“…There are some previous reports on the reducing power of this species; however, results are expressed as optical density [38] or as IC 0.5 [39], so a comparison is not possible. When comparing this result with the ones obtain for other brown seaweed aqueous extracts obtained and analysed by the same methods, it was observed that UP presents a lower reducing capacity than C. baccata [40], S. polyschides [41], S. muticum [42], D. antarctica [43], and D. menziesii [44]; nevertheless, this reducing capacity is sufficient to synthesize gold and silver nanoparticles. Other works also confirmed the observation that UP possesses the lowest reducing power among other brown seaweeds [45,46].…”

Structural characterization, antioxidant and anti-uropathogenic potential of biogenic silver nanoparticles using brown seaweed Turbinaria ornata

“…Also, AgNPs are intended to transport electrons to the reactive media in order to neutralize the unstable DPPH free radicals ( Chandraker et al, 2022a ). Prior to the present study were the seaweed Ecklonia cava ( Venkatesan et al, 2016 ), Desmarestia antarctica , and Iridaea cordata ( González-Ballesteros et al, 2021 ) mediated AgNPs studied for their antioxidant activity and provided similar results.…”