Electrochemistry-guided isolation of antioxidant metabolites from Sargassum elegans

Revealing the Potential of Fucus vesiculosus Linnaeus for Cosmetic Purposes: Chemical Profile and Biological Activities of Commercial and Wild Samples

The natural products industry is gaining increasing interest, not only due to modern lifestyles becoming more aware of environmental and sustainability issues but also because of the loss of efficacy and undesirable side effects of synthetic ingredients. This pioneering study provides a comprehensive comparison between extracts obtained from wild and commercial samples of Fucus vesiculosus Linnaeus, highlighting their multifaceted benefits in cosmetic applications. The antiaging potential of acetone (70 and 90%) and ethanol 60% extracts from wild and commercial samples of F. vesiculosus, focusing on their application in cosmetics, was explored. The extracts were chemically characterized, their carotenoid profiles being established by HPLC, and the total phenolic content and phlorotannins by spectrophotometry. The extracts were evaluated for their antioxidant potential against the physiologic free radicals superoxide anion radical (O2•-) and nitric oxide (•NO), for their ability to inhibit the enzymes hyaluronidase and tyrosinase, and for their anti-inflammatory potential in the macrophage cell model RAW 264.7. The acetone 70% extract of wild F. vesiculosus was the richest in fucoxanthin, which accounted for more than 67% of the total pigments identified, followed by the acetone 90% extract of the same sample, where both fucoxanthin and pheophytin-a represented 40% of the total pigments. The same behavior was observed for phenolic compounds, with the ethanol 60% presenting the lowest values. A chemical correlation could be established between the chemical composition and the biological activities, with acetone extracts from the wild F. vesiculosus, richer in fucoxanthin and phlorotannins, standing out as natural ingredients with anti-aging potential. Acetone 90% can be highlighted as the most effective extraction solvent, their extracts presenting the highest radicals scavenging capacity, ability to inhibit tyrosinase to a greater extent than the commercial ingredient kojic acid, and potential to slow down the inflammatory process.

Metabolites with Antioxidant Activity from Marine Macroalgae

Reactive oxygen species (ROS) attack biological molecules, such as lipids, proteins, enzymes, DNA, and RNA, causing cellular and tissue damage. Hence, the disturbance of cellular antioxidant homeostasis can lead to oxidative stress and the onset of a plethora of diseases. Macroalgae, growing in stressful conditions under intense exposure to UV radiation, have developed protective mechanisms and have been recognized as an important source of secondary metabolites and macromolecules with antioxidant activity. In parallel, the fact that many algae can be cultivated in coastal areas ensures the provision of sufficient quantities of fine chemicals and biopolymers for commercial utilization, rendering them a viable source of antioxidants. This review focuses on the progress made concerning the discovery of antioxidant compounds derived from marine macroalgae, covering the literature up to December 2020. The present report presents the antioxidant potential and biogenetic origin of 301 macroalgal metabolites, categorized according to their chemical classes, highlighting the mechanisms of antioxidative action when known.

Secondary Metabolites and Biological Activity of Invasive Macroalgae of Southern Europe

In this review a brief description of the invasive phenomena associated with algae and its consequences on the ecosystem are presented. Three examples of invasive algae of Southern Europe, belonging to Rodophyta, Chlorophyta, and Phaeophyta, were selected, and a brief description of each genus is presented. A full description of their secondary metabolites and biological activity is given and a summary of the biological activity of extracts is also included. In Asparagopsis we encounter mainly halogenated compounds. From Caulerpa, several terpenoids and alkaloids were isolated, while in Sargassum, meroterpenoids prevail.

Marine natural products

This review covers the literature published in 2012 for marine natural products, with 1035 citations (673 for the period January to December 2012) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1241 for 2012), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

In vitro antioxidant properties of crude extracts and compounds from brown algae

Research on the bioactives from seaweeds has increased in recent years. Antioxidant activity is one of the most studied, due to the interest of these compounds both as preservatives and protectors against oxidation in food and cosmetics and also due to their health implications, mainly in relation to their potential as functional ingredients. Brown algae present higher antioxidant potential in comparison with red and green families and contain compounds not found in terrestrial sources. In vitro antioxidant chemical methods, used as a first approach to evaluate potential agents to protect from lipid oxidation in foods, confirmed that the brown algae crude extracts, fractions and pure components are comparatively similar or superior to synthetic antioxidants. Particular emphasis on the fucoidan and phlorotannin polymeric fractions is given, considering variations associated with the species, collection area, season, and extraction and purification technologies.

Rapid screening and guided extraction of antioxidants from microalgae using voltammetric methods

Currently, microalgae draw much attention as a promising source of natural antioxidants to replace synthetic antioxidants for food applications. In this paper, the use of voltammetric techniques as a fast alternative for chemical assays to determine the antioxidant power of microalgal biomass is discussed. It was found that antioxidant activities determined by square wave voltammetry correlate well with the results from other established antioxidant assays, such as Trolox equivalent antioxidant capacity (R(2) = 0.737), ferric reducing antioxidant potential (R(2) = 0.729), and AAPH-induced oxidation of linoleic acid (R(2) = 0.566). Besides yielding quantitative data on the antioxidant activity, square wave voltammetry provides additional information on the antioxidant profile of microalgal biomass as the peak potentials of antioxidant components are determined. Consequently, square wave voltammetry can be used as a tool for optimizing the extraction processes to recover antioxidant components from microalgae.