Abstract
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.
Highlights
In all aerobic organisms, oxygen is a crucial element in their metabolic pathways
Disturbance of the equilibria of prooxidant/antioxidant reactions in cells can lead to redox imbalance and oxidative stress, which causes an excessive generation of reactive oxygen species (ROS) and free radicals, in turn resulting in severe cellular damage (Figure 1) [3,5,6,7,8,9]
The most common electron transfer (ET)-based assays include the determination of the total phenolics content (TPC) using the Folin–Ciocalteu reagent [42], the trolox equivalence antioxidant capacity (TEAC)/2,2-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) diammonium salt (ABTS+) radical scavenging [43], the ferric reducing antioxidant power (FRAP) [44,45], and 1,1-diphenyl-2-picrylhydrazyl (DPPH) [46,47] assays
Summary
Oxygen is a crucial element in their metabolic pathways. A high redox potential milieu stimulates the production of free radicals, defined as chemical species with unpaired valence electrons [1]. Disturbance of the equilibria of prooxidant/antioxidant reactions in cells can lead to redox imbalance and oxidative stress, which causes an excessive generation of ROS and free radicals, in turn resulting in severe cellular damage (Figure 1) [3,5,6,7,8,9]. The most common ET-based assays include the determination of the total phenolics content (TPC) using the Folin–Ciocalteu reagent [42], the trolox equivalence antioxidant capacity (TEAC)/2,2-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) diammonium salt (ABTS+) radical scavenging [43], the ferric reducing antioxidant power (FRAP) [44,45], and 1,1-diphenyl-2-picrylhydrazyl (DPPH) [46,47] assays. Thiobarbituric acid reactive substances (TBARS) [67] total phenolics content (TPC) using Folin-Ciocalteu reagent [42] trolox equivalence antioxidant capacity (TEAC) using ABTS [43]
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