Marine Algal Bioactivities 117
To evaluate antioxidant activity in natural extracts, there are several methods differing in their
reaction mechanism, oxidant, and target species as well as reaction conditions (Karadag et al. 2009).
Several in vitro methods generally used to evaluate the antioxidant potential of natural products comprise
assays related with lipid peroxidation, in which peroxidation levels are assessed using ferric thiocyanate,
the conjugated diene assay, β-carotene bleaching test, thiobarbituric acid reactive substances (TBARS),
aldehyde/carboxylic acid assay, and formic acid measurements (Miguel 2010). Other procedures
determine the free radical scavenging activity: 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, Trolox®
equivalent antioxidant capacity (TEAC) or 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)
(ABTS
•+
), ferric reducing/antioxidant power (FRAP) assay, reducing power (RP), chelating activity,
hydroxyl (OH
•
) radical scavenging and superoxide anion (O 2 ) scavenging activity (Miguel 2010).
With the purpose of identifying novel sources of natural and non-toxic antioxidants from marine
organisms, various species of marine algae have already revealed their antioxidant capacity, and many
compounds have been identified as responsible for these bioactivities (Nahas et al. 2007; El Gamal 2010;
Kumar et al. 2011). Table 1 lists several compounds identified in marine algae with antioxidant capacity.
Nine groups of compounds with proven antioxidant potential were identified, which are present in 24
species of marine algae belonging to 11 families (Heo and Jeon 2009; Li et al. 2009; Ananthi et al.
2010; Chakraborty and Paulraj 2010; Costa et al. 2010; El Gamal 2010; Cho et al. 2011; Ko et al. 2012;
Souza et al. 2012). Bioactive polysaccharides are the most represented group, including the crude and
sulphated polysaccharides, which are present in eight species belonging to four different families, namely
Sargassaceae, Caulerpaceae, Codiaceae, and Gracilariaceae. Sulphated polysaccharides from Gracilaria
caudata showed the best total antioxidant capacity with an IC 50 of 53.9 mg/g of acid ascorbic equivalents
(Costa et al. 2010). In addition, eight terpenoids displaying antioxidant ability (IC 50 ranging between
0.07 [isoepitaondiol] and 0.21 mg algae extract/g DPPH [stypodiol] in DPPH assay) were found in six
species of Sargassaceae, Dictyotaceae, Ishigeaceae, and Ulvaceae (Nahas et al. 2007; El Gamal 2010).
Quinones, as sargaquinone (IC 50 of 0.20 mg algae extract/g DPPH) and stypoldione (IC 50 of 0.18 mg
algae extract/g DPPH), have also demonstrated to possess this bioactivity, being present in three species,
namely Cystoseira crinita, Sargassum micracanthum, and Taonia atomaria (Nahas et al. 2007; El Gamal
2010).
Anti-inflammatory activity
Inflammation is the first response of the immune system, an essential step to fight infection and heal
wounds. Persistent activation of the immune system may, however, cause chronic inflammation giving
rise to chronic diseases, such as arthritis, hepatitis, diabetes, several heart ailments, irritable bowel
syndrome, Alzheimer’s and Parkinson’s diseases, allergies, asthma, and cancer (D’Orazio et al. 2012).
There are several types of cells involved in the inflammatory process as, for example, monocytes
that differentiate into macrophages (Chatter et al. 2011). These are key cells in inflammatory disorders
involving the increased production of cytokines (interleukin-1 beta [IL-1β], interleukin-6 [IL-6],
tumour necrosis factor-alpha [TNF-α]), and other inflammatory mediators (ROS, nitric oxide [NO],
prostaglandin E 2 [PGE 2 ], inducible nitric oxide synthase [iNOS] and ciclooxygenase-2 [COX-2]) (Heo
et al. 2010). Diverse signalling molecules, such as nuclear factor-kappa B (NF-кB) and arachidonic
acid (AA), participate and regulate inflammation through the production of pro- and anti-inflammatory
mediators (Chatter et al. 2011). NF-кB is an important molecular player due to its fast activation
and its capacity to activate the transcription of target genes involved in inflammation, such as those
encoding pro-inflammatory cytokines, adhesion molecules, chemokines, and inducible enzymes
(COX-2 and iNOS; Folmer et al. 2008; Kim et al. 2010). Conversely, AA is released by phospholipase
A 2 (PLA 2 ), being converted into inflammatory mediators by COX, which catalyses the conversion from
AA to prostaglandins (PGs), and by 5-lipooxygenase (5-LOX), which plays a role in the biosynthesis of
leukotrienes (Lts) from AA (Funk 2001).
Hence, modulation of the production of the inflammatory mediators is a central goal in the treatment
of inflammatory medical conditions (Heo et al. 2010). Several natural anti-inflammatory products exert
their function by targeting and modulating the NF-кB signalling pathway (Chatter et al. 2011).
To evaluate antioxidant activity in natural extracts, there are several methods differing in their
reaction mechanism, oxidant, and target species as well as reaction conditions (Karadag et al. 2009).
Several in vitro methods generally used to evaluate the antioxidant potential of natural products comprise
assays related with lipid peroxidation, in which peroxidation levels are assessed using ferric thiocyanate,
the conjugated diene assay, β-carotene bleaching test, thiobarbituric acid reactive substances (TBARS),
aldehyde/carboxylic acid assay, and formic acid measurements (Miguel 2010). Other procedures
determine the free radical scavenging activity: 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, Trolox®
equivalent antioxidant capacity (TEAC) or 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)
(ABTS
•+
), ferric reducing/antioxidant power (FRAP) assay, reducing power (RP), chelating activity,
hydroxyl (OH
•
) radical scavenging and superoxide anion (O 2 ) scavenging activity (Miguel 2010).
With the purpose of identifying novel sources of natural and non-toxic antioxidants from marine
organisms, various species of marine algae have already revealed their antioxidant capacity, and many
compounds have been identified as responsible for these bioactivities (Nahas et al. 2007; El Gamal 2010;
Kumar et al. 2011). Table 1 lists several compounds identified in marine algae with antioxidant capacity.
Nine groups of compounds with proven antioxidant potential were identified, which are present in 24
species of marine algae belonging to 11 families (Heo and Jeon 2009; Li et al. 2009; Ananthi et al.
2010; Chakraborty and Paulraj 2010; Costa et al. 2010; El Gamal 2010; Cho et al. 2011; Ko et al. 2012;
Souza et al. 2012). Bioactive polysaccharides are the most represented group, including the crude and
sulphated polysaccharides, which are present in eight species belonging to four different families, namely
Sargassaceae, Caulerpaceae, Codiaceae, and Gracilariaceae. Sulphated polysaccharides from Gracilaria
caudata showed the best total antioxidant capacity with an IC 50 of 53.9 mg/g of acid ascorbic equivalents
(Costa et al. 2010). In addition, eight terpenoids displaying antioxidant ability (IC 50 ranging between
0.07 [isoepitaondiol] and 0.21 mg algae extract/g DPPH [stypodiol] in DPPH assay) were found in six
species of Sargassaceae, Dictyotaceae, Ishigeaceae, and Ulvaceae (Nahas et al. 2007; El Gamal 2010).
Quinones, as sargaquinone (IC 50 of 0.20 mg algae extract/g DPPH) and stypoldione (IC 50 of 0.18 mg
algae extract/g DPPH), have also demonstrated to possess this bioactivity, being present in three species,
namely Cystoseira crinita, Sargassum micracanthum, and Taonia atomaria (Nahas et al. 2007; El Gamal
2010).
Anti-inflammatory activity
Inflammation is the first response of the immune system, an essential step to fight infection and heal
wounds. Persistent activation of the immune system may, however, cause chronic inflammation giving
rise to chronic diseases, such as arthritis, hepatitis, diabetes, several heart ailments, irritable bowel
syndrome, Alzheimer’s and Parkinson’s diseases, allergies, asthma, and cancer (D’Orazio et al. 2012).
There are several types of cells involved in the inflammatory process as, for example, monocytes
that differentiate into macrophages (Chatter et al. 2011). These are key cells in inflammatory disorders
involving the increased production of cytokines (interleukin-1 beta [IL-1β], interleukin-6 [IL-6],
tumour necrosis factor-alpha [TNF-α]), and other inflammatory mediators (ROS, nitric oxide [NO],
prostaglandin E 2 [PGE 2 ], inducible nitric oxide synthase [iNOS] and ciclooxygenase-2 [COX-2]) (Heo
et al. 2010). Diverse signalling molecules, such as nuclear factor-kappa B (NF-кB) and arachidonic
acid (AA), participate and regulate inflammation through the production of pro- and anti-inflammatory
mediators (Chatter et al. 2011). NF-кB is an important molecular player due to its fast activation
and its capacity to activate the transcription of target genes involved in inflammation, such as those
encoding pro-inflammatory cytokines, adhesion molecules, chemokines, and inducible enzymes
(COX-2 and iNOS; Folmer et al. 2008; Kim et al. 2010). Conversely, AA is released by phospholipase
A 2 (PLA 2 ), being converted into inflammatory mediators by COX, which catalyses the conversion from
AA to prostaglandins (PGs), and by 5-lipooxygenase (5-LOX), which plays a role in the biosynthesis of
leukotrienes (Lts) from AA (Funk 2001).
Hence, modulation of the production of the inflammatory mediators is a central goal in the treatment
of inflammatory medical conditions (Heo et al. 2010). Several natural anti-inflammatory products exert
their function by targeting and modulating the NF-кB signalling pathway (Chatter et al. 2011).