Biological and therapeutic properties of the seaweed polysaccharides

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Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 1 of 50

REVIEW ARTICLE

Biological and therapeutic properties of the
seaweed polysaccharides
Leonel Pereira1*
Author’s affiliations:
1. MARE (Marine and Environmental Sciences Centre), Department of Life Sciences, Faculty of
Sciences and Technology, University of Coimbra, Coimbra, Portugal

* Corresponding author: Leonel Pereira, E-mail: leonel.pereira@uc.pt

Abstract
Seaweed polysaccharides isolated from the cell walls of various species of algae, possess
immunomodulatory, anti-inflammatory, antiviral, antitumor, antithrombotic, anticoagulant
and antioxidant bioactivities.
Within the group of polysaccharides extracted from algae there are the phycocolloids. Collo-
ids are extracted compounds that form colloidal solutions, an intermediate state between a
solution and a suspension; they can be used commercially as thickeners, gelling agents and
stabilizers for suspensions and emulsions. Hydrocolloids are carbohydrates that when dis-
solved in water form viscous solutions.
Sulfated galactans (e.g. agars, carrageenans, porphyrans) can be obtained from red algae,
(e.g. ulvans) from green algae, alginates and other sulfated polysaccharides (e.g. ascophyl-
lan, laminaran and fucoidan) are obtained from selected brown algae. The historic origin of
the main phycocolloids and other seaweed polysaccharides (e.g. agar, carrageenan, alginic
acid - alginates), their chemistry, uses and bioactivities are described in this review.

Keywords: Macroalgae; Hydrocolloids; Sulfated galactans; Sulfate content; Bioactivities

1. Introduction a) the green algae are included in the phy-
lum Chlorophyta and their pigmentation is
Seaweeds (or macroalgae) are aquatic pho- identical to that of terrestrial plants (chloro-
tosynthetic organisms belonging to the do- phyll a, b and carotenoids);
main Eukarya and to kingdoms Plantae
(green and red algae) and Chromista (brown b) the red algae belong to the phylum Rho-
algae). Although classification systems dophyta and their photosynthetic pigments
have varied greatly over time and according are chlorophyll a, phycobilins (R-phyco-
to the authors, it is generally agreed that: cyanin and R-phycoerythrin) and caroteno-

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 2 of 50

ids, mostly β-carotene, lutein and zeaxan- amount from the algae. All these polysac-
thin; charides are water soluble and could be
 extracted with hot water or alkaline solution
c) the brown algae are included in the phy- [11].
lum Ochrophyta (or Heterokontophyta),
class Phaeophyceae and their pigments en- The historic origin of the main phycocollo-
close chlorophylls a, c and carotenoids, ids (agar, carrageenan, and alginate) and
dominated by fucoxanthin [1-3]. other seaweed polysaccharides (e.g. ulvan,
 porphyran, fucoidan, laminaran, ascophyl-
Macroalgae are known to be enriched in lan), their chemistry, uses and bioactivities
polysaccharides, with concentrations that are described in this review.
can vary in the range of 4% to 76% of dry
weight [4]. Globally, these are mainly struc-
tural cell wall polysaccharides, although 2. Polysaccharides from green algae
considerable amounts of mucopolysaccha- (Chlorophyta)
rides and storage polysaccharides can occur
in specific species [3,5,6]. 2.1. Ulvan

The seaweed hydrocolloids, associated with Ulvan is a sulfated, water-soluble polysac-
the cell wall and intercellular spaces, are charide which have physio-chemical and
mainly produced by red and brown algae. biological features of great potentials in
Several species of red algae (Rhodophyta) food, pharmaceutical, agricultural, and
produce galactans (e.g. carrageenans and chemical applications [12,13].
agars) and of brown algae (Phaeophyceae) Ulvan may represent 8 - 29% of algal dry
produce uronates (alginates) [7-10]. weight and is produced by some species
Sulfated galactans (e.g. agars and carragee- belonging to the Phylum Chlorophyta
nans) can be obtained from red algae, and (green algae), mostly belonging to the Class
alginates and other sulfated polysaccharides Ulvophyceae [14]. It is mainly made up of
(e.g. laminaran and fucoidan) are obtained disaccharide repeating sequences composed
from brown algae. Phycocolloids are used of sulfated rhamnose and glucuronic acid,
in food industries as natural additives and iduronic acid, or xylose [15,16].
have different European codes: E400 (al- The two major repeating disaccharides are
ginic acid), E401 (sodium alginate), E402 aldobiuronic acids designated as: type A,
(potassium alginate), E403 (ammonium ulvanobiuronic acid 3-sulfate (A3s) and
alginate), E404 (calcium alginate), E405 type B, ulvanobiuronic acid 3-sulfate (B3s)
(propylene glycol alginate), E406 (agar), (Figure 1). Partially sulfated xylose residues
E407 (carrageenan) and E407a (semi- at O-2 can also occur in place of uronic
refined carrageenan or ―processed Eucheu- acids. Low proportions of galactose, glu-
ma seaweed‖) [10]. Agar, alginates and cose, mannose and protein were also gener-
carrageenans are the ones with the highest ally described as components of ulvan. Ad-
economic and commercial significance, ditionally, minor repeating units were being
since these polysaccharides exhibit high reported to contain sulfated xylose, replac-
molecular weights, high viscosity and ex- ing the iduronic acid or glucuronic acid
cellent gelling, stabilizing and emulsifying components [12,13,17].
properties. They are extracted in fairly high

Copyright 2018 KEI Journals. All Rights Reserved http://journals.ke-i.org/index.php/IBR

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 3 of 50

 (ulvanobiuronic acid – type A) (ulvanobiuronic acid – type B)

 Figure 1 - Idealized structure of the chemical units of Ulvan.

Ulvan have exhibited strong antioxidant stable supramolecular structures via elec-
[18,19], anticoagulant, antithrombotic [20], trostatic interactions and could also form
antitumor [21], immune-stimulatory [22], stabilized membranes. Ulvan/chitosan poly-
anti-inflammatory [22,23], antiviral [24,25], electrolytes were found to mimics the
antibacterial [26], antiprotozoal [12], anti- extracellular matrix structure providing
hypercholesterolemic [27], and antihyperli- points of attachment for osteoblasts, be-
pidemic [28] activities; used also for hyper- lieved to be enhanced by the nanofibrous
plasia prevention, gastrointestinal, rege- structure of this construct. It is suggested
nerative and nanomedicine applications that this construct could be a suitable scaf-
[29,30]. fold for applications in tissue engineering
 [32,33].
Alves et al. [31] determined the cytotoxicity
of ulvan via MTT test (Methyl Thiazolyl
Tetrazolium - colorimetric assay for assess- 3. Polysaccharides from red algae (Rho-
ing cell metabolic activity), using fibrob- dophyta)
last-like cells were incubated with ulvan, in
vitro. Quantified protein and total DNA 3.1. Carrageenans
stands data were directly correlated with Carrageenan has been used in Europe and
hyaluronic acid use as control (non- Asia for centuries as a thickening and stabi-
cytotoxic); in the studies conducted by lizing agent in food. In Europe, the use of
these researchers [31], ulvan showed en- carrageenan began in Ireland more than 600
couraging results in terms of cytotoxicity. years ago when, in the small village on the
Meanwhile, cytotoxicity is one of the most southern coast of Ireland, called "Carrag-
important factors to determine the use of a hen", the flans were made by cooking "Irish
biomaterial for medical purposes, as in tis- Moss" (Irish Moss - Chondrus crispus) in
sue engineering and wound healing [32]. milk. The name carrageenin, the ancient
Ulvan can be used in biomedical applica- name of carrageenan, was first used in 1862
tions, especially in tissue engineering. Bio- to designate the extract obtained from C.
functionalized ulvan hydrogels with ALP crispus, in reference to the name of the
(Alkaline Phosphatase) enzyme served as small Irish town [36]. The procedure for the
inducers of mineralization in osteoblastic extraction of carrageenans was described
differentiation [32,33] and the cytocompa- for the first time by Schmidt in 1844 [37].
tibility of ulvan as well as it relative mem- The name was later changed to carrageenan
brane are promising features for scaffold to comply with the ―-an‖ suffix for the
development [34,35]. The inter-molecular names of polysaccharides.
charges of ulvan and chitosan (i.e. anionic
and cationic charges respectively) produced

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Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 4 of 50

The Irish moss has been used in industry sausages, patties and low-fat hamburgers
since the 19th Century, in the clarification of [7,9,37,46-48].
beer [39]. The industrial extraction of car-
rageenan had its start in 1930 in New- The most commonly used commercial car-
England, from Chondrus crispus and Mas- rageenans are extracted from Kappaphycus
tocarpus stellatus thalli, for the preparation alvarezii and Eucheuma denticulatum [45].
of chocolate milk. The interruption of agar Primarily wild-harvested genera such as
imports during World War II, led to its re- Chondrus, Furcellaria, Gigartina, Chon-
placement by carrageenan. This situation dracanthus, Sarcothalia, Mazzaella, Iri-
was the starting point of a booming industry daea, Mastocarpus, and Tichocarpus are
[40]. also mainly cultivated as carrageenan raw
 materials, and producing countries include
Fractionation of crude carrageenan extracts Argentina, Canada, Chile, Denmark,
started in the early 1950s [41,42], resulting France, Japan, Mexico, Morocco, Portugal,
in the characterization of the different car- North Korea, South Korea, Spain, Russia,
rageenan types. A Greek prefix was intro- and the US [8,10,47].
duced to identify the different carrageenans.
In the same period, the molecular structure The carrageenan market is the largest of the
of carrageenans was determined [43,44]. seaweed-derived, food hydrocolloids mar-
The structure of 3,6-anhydro-D-galactose in kets and currently holds the fourth largest
kappa (κ) carrageenan, as well as the type share (in $ value) of the wider global hy-
of linkages between galactose and anhydro- drocolloids market, behind gelatin, starch
galactose rings, was determined. and pectin [49]. In 2014, the global hydro-
 colloids market was valued at US$ 5.4 Bil-
Today, the industrial manufacture of carra- lion but projected to reach US$ 7.6 Billion
geenan is no longer limited to extraction by 2020 [50]. Industry estimates for
from C. crispus, and numerous red seaweed 2015/2016 put a value of US$ 600-700 Mil-
species (Gigartinales, Rhodophyta) are lion on the global carrageenan market with
used. For a long period of time, these sea- a projected average growth of ≈ 3% per
weeds have been harvested from naturally year (Compound Annual Growth Rate -
occurring populations. Seaweed farming CAGR). Most recent market research pre-
started almost 200 years ago in Japan. dicted that the global market for carragee-
Scientific information about the seaweed nan would approach US$ 1 Billion by 2024
life cycles allowed artificial seeding in the [49,51].
1950s. Today, lots of seaweed taxa are cul-
tivated, lowering the pressure on naturally Current industry estimates for the global
occurring populations [45]. production capacity of carrageenan range
 from about 70,000-80,000 dry MT per year
The modern industry of carrageenans dates [52] to over 110,000 MT per year [53]. Cy-
from the 1940‘s where it was found to be berColloids‘ (www.cybercolloids.net) esti-
the ideal stabilizer for the suspension of mate for current global usage, as based on
cocoa in chocolate milk. In the last decades, end-sales data, is for 68,000 dry MT or ap-
due to its physical functional properties, proximately 80% of the estimated produc-
such as gelling, thickening, emulsifying and tion capacity (Campbell and Hotchkiss
stabilizing abilities, carrageenans have been 2017). Most of this carrageenan (≈ 90%)
employed in food industry to improve the comes from species and strains of Kappa-
texture of cottage cheese, puddings and phycus and Eucheuma or ―cottonii‖ and
dairy desserts, and in the manufacture of ―spinosum‖ respectively as they were re-
 ferred to historically and still are by the

Copyright 2018 KEI Journals. All Rights Reserved http://journals.ke-i.org/index.php/IBR

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 5 of 50

industry. In 2016, CyberColloids estimated included in these estimates. The remainder
the global production of Kappaphycus for of the carrageenan produced comes from
the carrageenan industry to be in the region cold-water species that are harvested mostly
of 1.5 Million wet MT or 200,000 dry MT in South America, approximately 15,000
[51] with most cultivation occurring in In- dry MT and from the dwindling remnants
donesia and the Philippines. Eucheuma is of a small, traditional N. Atlantic industry
not cultivated on such a large-scale as Kap- which produces only a few hundred dry MT
paphycus, current estimates put production annually from Chondrus crispus [54].
for the carrageenan industry in the range of
0.3 Million wet MT or 40,000 dry MT [51]. Main commercial carrageenans (Figure 2)
It must be noted that a substantial market are usually classified into κ (kappa), ι (iota),
for sea vegetables also exists which is not and λ (lambda) carrageenans [9].

(β) Beta-carrageenan

(κ) Kappa-carrageenan (ι) Iota-carrageenan (λ) Lambda-carrageenan

Figure 2 - Idealized structure of the chemical units of the main types of Carrageenan.

3.2. Biological activities of Carrageenans ―arroz caldo‖ has hypoglycemic effects in
normal subjects. A study done on another
From a human health perspective, it has seaweed extract showed that when incorpo-
been reported that carrageenans have anti- rated into ―puto‖, ―siomai‖ and a meal
oxidant, anticancer, antihyperlipidemic, composed of rice and meatballs with sweet-
anticoagulant, immunomodulatory, antifun- and-sour sauce, agar had a glucose lowering
gal, antiviral properties, gastric discomfort effect in normal people [69]. The study
management, and digestive health support conducted by Panlasigui et al. [57] indicates
[55-65]. Carrageenans are also classically that regular inclusion of carrageenan in the
used as agents for the induction of experi- diet may result in reduced blood cholesterol
mental inflammation and inflammatory pain and lipid levels in human beings.
[66].
Historically, Irish Moss or Carrageen
Previous studies conducted by Panlasigui et (Chondrus crispus and Mastocarpus stella-
al. [67], and by Dumelod et al. [68], showed tus) has many medical applications, some
that carrageenan incorporated into common of which date from the 1830s. It is still used
Philippine foods such as ―fishballs‖ and in Ireland to make traditional medicinal teas

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 6 of 50

and cough medicines to combat colds, and bone fracture [81]. C. ocellatus is an
bronchitis, and chronic coughs. It is said to important economic original alga that can
be particularly useful for dislodging mucus produce carrageenan. Antitumor, antiviral,
and has antiviral properties. Carrageenans anticoagulant, and immunomodulatory ac-
are also used as suspension agents and sta- tivities of carrageenan have been found in
bilizers in other drugs, lotions and medicin- this species, however, many evidences indi-
al creams. Other medical applications are as cated that λ-carrageenan, which contained
an anticoagulant in blood products and for 1,4-linked D-galactose 2,6-disulfate units,
the treatment of bowel problems such as and highly sulfated group, has more bioac-
diarrhea, constipation and dysentery. They tivities than other carrageenan types
are also used to make internal poultices to [59,77,79].
control stomach ulcers [70-72].
Carrageenans extracted from several algae,
Many reports exist of anticoagulant activity i.e., Chondrus crispus, Mastocarpus stella-
and inhibited platelet aggregation of carra- tus, Kappaphycus alvarezii, Eucheuma den-
geenan [73-77]. Among the carrageenan ticulatum, Gigartinaceae and Phyllophora-
types, λ-carrageenan (primarily from C. ceae, enter cough medicines, toothpastes,
crispus) has approximately twice the activi- lotions, sun ray filterers, shaving creams,
ty of unfractionated carrageenan and four shampoos, hair conditioners, and deodo-
times the activity of κ-carrageenan (Kappa- rants. More than 20% of carrageenan pro-
phycus alvarezii – formerly Eucheuma cot- duction is used in pharmacy and cosmetol-
toni, and E. denticulatum – formerly E. spi- ogy. They are said to be invaluable for the
nosum). The most active carrageenan has manufacture of wash-removable creams and
approximately one fifteenth the activity of ointments. Excipients of algal origin are
heparin [73], but the sulfated galactan from used in vanishing creams—the rapid evapo-
Grateloupia indica collected from Indian ration of the emulsion‘s aqueous phase on
waters, exhibited anticoagulant activity as the skin leaves a thin protective medicated
potent as heparin [78]. The principal basis oily microfilm. Dried and pulverized Litho-
of the anticoagulant activity of carrageenan thamnium and Phymatolithon are used to
appeared to be an antithrombotic property make absorbent face and/or beauty masks
[73,74]. λ-carrageenan showed greater an- [82,83].
tithrombotic activity than κ-carrageenan,
probably due to its higher sulfate content, Carrageenans are selective inhibitors of
whereas the activity of the unfractionated several enveloped and nonenveloped virus-
material remained between the two. It was es and act predominantly by inhibiting the
found that toxicity of carrageenans de- binding or internalization of virus into the
pended on the molecular weight and not the host cells [84,85]. Carrageenans are excep-
sulfate content. Similar results were ob- tionally potent inhibitor of Human Papillo-
tained with λ-carrageenan of Coccotylus mavirus (HPV) in vitro by inhibiting the
brodiei (as Phyllophora brodiaei) which initial stage of infection [84]. Notably, they
gave the highest blood anticoagulant activi- are also extremely effective against a range
ty. Carrageenan of Grateloupia turuturu of sexually transmitted HPV types that lead
also showed anticoagulant activity [78-80]. to cervical cancer and genital warts [86,87].
Several in vitro studies suggest that carra-
Chondrus ocellatus is distributed sponta- geenans may also have antiviral properties,
neously in intertidal zone of the southeast inhibiting the replication of herpes and he-
seaside of China [59]. In ancient times the patitis A virus [86,88-90]. More recently,
alga was not only edible, but was also used Schiller and coworkers demonstrated that
as a medicine to cure chronic constipation carrageenan is an extremely potent infec-

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 7 of 50

tion inhibitor of a broad range of genital centrations about 1000 times higher than
Human papillomaviruses (HPVs) and there those required to inhibit Papillomaviruses
are indications that carrageenan-based sex- [84]. However, carrageenans may serve as
ual lubricant gels may offer protection models for designing novel anti-HIV
against HPV transmission [84,91,92]. agents, improving their therapeutic proper-
ties through chemical modifications [97].
The antimicrobial activities of numerous
algae species have been tested and reported, Carlucci and colleagues [98,99] found that
presenting an extended spectrum of action -type carrageenan is active against the
against bacteria and fungi [93]. Carragee- replication of HSV upon its firm interaction
nans have proved to have effects against that leads to inactivation of HSV virion
some bacterial strains such as Salmonella [98]. They also discovered that the -
enteritidis, S. typhimurium, Vibrio mimicus, carrageenan and moderately cyclized / -
Aeromonas hydrophila, Escherichia coli, carrageenan isolated from Gigartina
Listeria monocytogenes and Staphylococcus skottsbergii exert promising antiviral activi-
aureus. The growth of all the bacterial ties towards diverse strains of Herpes simp-
strains except L. monocytogenes was signif- lex virus HSV-1 and HSV-2, during virus
icantly inhibited by them, particularly by attachment stage [90,99]. Surprisingly, sim-
the ι-carrageenan. A growth inhibition ex- ilar results were reported by different group
periment using S. enteritidis showed that of researchers, who analyzed the chemical
the inhibitory effect of the carrageenans structure and antiviral activity of carragee-
was not bactericidal but bacteriostatic. Re- nan (λ, κ, and ι) against HSV-2 infection
moval of the sulfate residues eliminated the [100,101]. The data obtained in the work of
bacteriostatic effect of ι-carrageenan, sug- Soares [64] revealed that the viral infection
gesting that the sulfate residues in carragee- by Lentivirus was reduced upon exposure to
nan play an essential role in this effect [94]. a pre-treatment with extracts from female
In 2014, Sebaaly et al. [95] reported that gametophytes (FG) and tetrasporophytes
carrageenans isolated from the red alga Co- (T) of Chondracnthus teedei var. lusitani-
rallina sp. exhibited antibacterial activity cus. Although the inhibitions were not sta-
against Staphylococcus epidermis. Infrared tistically significant, FG (producers of κ/
spectroscopy (FTIR) showed that the iso- hybrid carrageenan) and T (producers of ξ-
lated carrageenan was of λ-type [95]. carrageenan) of C. teedei var. lusitanicus
extracts was able to reduce 14% of the virus
Researchers from the Population Council infection, and the Tetra extract was able to
[96] (http://www.popcouncil.org/), a non- reduce, approximately, 35% of the virus
profit research organization in the USA, infection [64].
conducted a clinical trial investigating
whether a carrageenan-based sexual lubri- A recent in vitro study conducted by Gras-
cant was effective as a topical microbicide sauer and colleagues [85] reported the inhi-
by blocking Human Immunodeficiency bitory effects of -carrageenan against Hu-
virus (HIV) infection in women. The study man rhinovirus (HRV) proliferation by pre-
was conducted from March 2004–2007 in venting the primary phases of virus replica-
South Africa and enrolled more than 6000 tion. They have suggested that this effect is
volunteers. The results demonstrated that possibly attributed to the suppression of the
the experimental microbicide gel was safe allosteric activity of virus particles during
for use but does not provide protection their entry [85,102]. Additionally, -
against HIV [61,62,96]. These results are carrageenan was proven to be effective
consistent with in vitro assays since carra- against dengue virus replication in mosqui-
geenan was active against HIV only at con- to and mammalian cells; however, the mode

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 8 of 50

of antiviral action of -carrageenan in both So, the studies of Yuan et al. [112] suggest
cell types was interestingly distinctive. In that carrageenan oligosaccharides and their
Vero cell line, the inhibitory activity has derivatives show relevant antioxidant ac-
been exerted at early stage of virus adhe- tivity both in vitro and in a cell system.
sion probably due to some primary recep-
tors, whereas in mosquito cell it affected the According Sokolova et al. [113], antioxi-
cell proliferation and protein synthesis dant actions of λ-, ξ-, κ-, κ/β- and κ/ι-
[103,104]. carrageenans against reactive oxy-
gen/nitrogen species depend on polysaccha-
Carrageenan from red marine algae is ride concentration and such structural cha-
known to be also a potent inflammatory racteristics as presence of hydrophobic 3,6-
agent in rodents, primes mice leucocytes to anhydrogalactose unit, amount and position
produce tumor necrosis factor-α (TNF-α) in of sulfate groups, and an oxidant agent, on
response to bacterial lipopolysaccharide which sample antioxidant action is directed.
[105]. Moreover, some types of carragee- The results of Sokova et al. [113] indicated
nans induce potent macrophage activation that carrageenans possess antioxidant ca-
[106,107], while some carrageenans and pacity in vitro, and this action notably de-
fucoidan appear to inhibit macrophage pends on the structure of the polysaccharide
functions [108,109]. However, sulfated itself than the reducing capacity of the po-
polysaccharides may have potential bio- lysaccharides.
medical applications in stimulating the im-
mune system or in controlling macrophage Affording the works of Sokolova et al.
activity to reduce associated negative ef- [114], a carrageenan food supplement
fects [22]. brings about the decrease in the level of
cholesterol and low-density lipoprotein cho-
Exposure of human (and other mammals) lesterol, and the supplementation with car-
cells to ultraviolet (UV) light induces vari- rageenans produces moderate modulation of
ous deleterious responses. Damage to cells all links of the immunity.
by UVA is thought to involve reactive oxy-
gen species, including singlet oxygen, the Until 1935, pneumonia was the leading
superoxide and hydroxyl radicals, and hy- recorded cause human death in the USA.
drogen peroxide. Some of the major harm- 100 years ago, five of the top ten causes of
ful effects are DNA damage, systemic im- death in men were respiratory diseases.
mune suppression, and accelerated aging Today, asthma is the leading cause of juve-
[110,111]. When thymic lymphocytes were nile school absenteeism and is increasingly
exposed to a dose of 90 mJ/cm2 UVA, their an affliction of adults. Red algae (carragee-
viability was decreased by about 60%. nophytes) containing carrageenan have
However, the viability of lymphocytes was been used for millennia as treatments for
significantly increased compared with the respiratory ailments, especially intractable
control group when carrageenan oligosac- sinus infections and lingering pneumonias.
charides and their derivatives were pre- Asthma was not separated out as such in the
administered to cells before UVA radiation. old literature [115].
This phenomenon showed that carrageenan A recent in vivo study in mice has revealed
oligosaccharides and their derivatives can that the low molecular weight carrageenans
protect the lymphocytes against UVA in- (3, 5, and 10 kDa), as well as acetylated and
jury. As like a H2O2 induced oxidative sulfated derivatives, have substantial inhibi-
stress model, the chemical modification of tory effects against influenza virus. Fur-
carrageenan oligosaccharides also had no thermore, the smallest -carrageenan with
significant effect on their protective effect. appropriate sulfation and acetylation degree

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 9 of 50

was the greatest antiviral candidate against fluenza virus illness this combinational
influenza virus [116]. therapy meets an urgent medical need
[125,126].
Acute viral upper respiratory tract infection,
also known as common cold, is the most Marine algae are prolific sources of sulfated
frequently observed infectious disease in polysaccharides, which may explain the low
human beings. Children get four to eight incidence of certain cancers in countries
upper respiratory infections per year and that traditionally consume marine food.
adults suffer from two to four episodes per Breast cancer is one of the most common
year [117]. In most of cases, common cold types of non-skin cancer in females. In the
is caused by respiratory viruses such as study made by Murad et al. [127], extracted
rhinovirus, coronavirus, parainfluenza, in- sulfated carrageenan, predominantly con-
fluenza, respiratory syncytial virus, adeno- sisting of ι-carrageenan extracted from the
virus, enterovirus and metapneumovirus red alga Palisada perforata (as Laurencia
[118-121]. According to the work of Koe- papillosa), has demonstrated potential cyto-
nighofer et al. [122], the administration of toxic activity against the MDA-MB-231
carrageenan nasal spray in children as well cancer cell line. These findings suggest that
as in adults suffering from virus-confirmed sulfated carrageenan may serve as a poten-
common cold reduced duration of disease, tial therapeutic agent to target breast cancer
increased viral clearance and reduced re- via prompting apoptosis [127].
lapses of symptoms. Carrageenan nasal
spray appeared as an effective treatment of λ-Carrageenan is a seaweed polysaccharide
common cold in children and adults [122- which has been generally used as pro-
124]. inflammatory agent in the basic research,
however, how the immunomodulating ac-
A nasal spray containing ι-carrageenan on- tivity of λ-carrageenan affects tumor micro-
ly, or together with ―Zanamivir‖, provides environment remains unknown. Luo et al.
an easy to apply treatment of upper respira- [128] found that intratumoral injection of λ-
tory tract infections in patients under suspi- carrageenan could inhibit tumor growth in
cion to be influenza A (H1N1) infected B16-F10 and 4T1 bearing mice and enhance
[125,126]. Patients would benefit from the tumor immune response by increasing the
fast and efficient treatment of uncompli- number of tumor-infiltrating M1 macro-
cated influenza in the upper respiratory phages, DCs and more activated CD4+CD8+
tract. Due to the faster influenza virus T lymphocytes in spleen. In addition, λ-
clearance from the upper respiratory tract carrageenan could enhance the secretion of
and the independent antiviral mechanism of IL17A in spleen and significantly increase
carrageenan and ―Zanamivir‖ the likelihood the level of TNF-α in tumor, most of which
to develop escape mutations against ―Za- was secreted by infiltrating macrophages.
namivir‖ will be reduced. Both individual Moreover, λ-carrageenan exhibited an effi-
compounds can reduce severity and/or du- cient adjuvant effect in OVA-based preven-
ration of the influenza illness and a combi- tative and therapeutic vaccine for cancer
nation is expected to work similarly. Addi- treatment, which significantly enhanced the
tionally, due to the broad antiviral effec- production of anti-OVA antibody. The tox-
tiveness of carrageenan, patients will re- icity analysis suggested that λ-carrageenan
ceive in parallel a treatment of concomitant was with a good safety profile. Thus, λ-
viral infections. Therefore, patients will carrageenan might be used both as a potent
benefit from a decreased probability to de- antitumor agent and an efficient adjuvant in
velop complications. In consideration of the cancer immunotherapy [128].
complications known to accompany an in-

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 10 of 50

Carrageenans extracted from Chondracan- 3.3. Agar
thus teedei var. lusitanicus were studied in
order to determine their potential antifungal Agar is the Malay name for red algae, also
activity [64,65]. FTIR-ATR and FT-Raman called agar-agar and Kanten. It is an extract
spectroscopic analysis confirmed the pres- of red algae, sold in granular, powder form,
ence of a hybrid κ/ι-carrageenan belonging as flakes or long strips. This colloid is
to the gametophyte phase and a hybrid ξ/θ- widely used as a gelling agent and rarely
carrageenan in the tetrasporophyte phase eaten on its own. In its pure form, agar is a
[7,9,10,129]. κ/ι and ξ/θ-carrageenan in- tasteless and odorless polysaccharide;
duced the formation of swollen hyphal which normally contains proteins, vitamins
segments in Alternaria infectoria, upon and minerals, as the red algae from which it
exposure to 125 μg mL–1 and 60 μg mL−1, is derived [83,131].
respectively. The observed phenotype was Kanten was discovered by accident. For
similar to those induced by antifungals tar- more than a thousand years, the Japanese
geting the fungal cell wall. When exposed have eaten a dish called ―Tokoroten‖,
to 87.5 μg mL−1 of kappa/iota carrageenan, which is prepared for the abolition of red
Aspergillus fumigatus hyphae became algae Gelidium amansii (called in Japan as
shortened and highly branched, a phenotype ―Tengusa‖), and then letting the mixture
commonly observed in response to antifun- stiffen. At some point toward the end of the
gals. These morphological alterations were 17th Century, leftover ―Tokoroten‖ away
associated with a decrease of the β-glucan outside on a freezing cold day. When it was
content in A. infectoria after exposure to found later, it had become a dry, whitish
150 μg mL−1 of kappa/iota and to 100 μg solid [131,132].
mL−1 of ξ/θ-carrageenan. On the other
hand, the chitin cell wall content of A. fu- Agar is light in color, semi-transparent, and
migatus decreased significantly upon expo- very brittle when dry. When soaked it ab-
sure to 150 μg mL−1 of both extracts, which sorbs water and, in contrast to gelatin (pre-
triggered an increase in the content of β- pared from animal origin), it must have
glucan. Overall, the present work shows allowed to swell up completely before the
that carrageenans extracted from C. teedei water is warmed to a temperature above its
var. lusitanicus cause alterations on the A. melting point of 85 °C. Agar can be used as
fumigatus and A. infectoria cell walls, indi- a gelling agent as it cools [38,131].
cating a marked antifungal activity [64,65].
Agar consists of a mixture of at least two
According the works of Azizi et al. [130], polysaccharides, i.e. agarose and agaropec-
the slow silver (Ag) release, κ- tin [133]. Typically, agarose is the predo-
carrageenan/silver nanoparticles (Ag-NPs) minant fraction of agar (50-90%) [134,135]
presented good antibacterial activities and the responsible for its gelling properties
against Staphylococcus aureus, Methicillin [135]. It consists of high molecular weight
resistant Staphylococcus aureus, Peseudo- polysaccharides composed of repeating
monas aeruginosa and Escherichia coli units of (1→3)-β-D-galactopyranosyl-
with maximum zones of inhibition 11 +/- 2 (1→4)-3,6-anhydro-α-L galactopyranose
mm. Cytotoxicity study showed that the (Figure 3), although some variations can
bio-nanocomposite hydrogels with non- occur, depending on factors such as the
toxic effect of concentration below 1000 species of seaweed, as well as environmen-
μg/mL have great pharmacological poten- tal and seasonal conditions [133]. In turn,
tial and a suitable level of safety for use in agaropectin is a less clearly defined, it is a
the biological systems [130]. more complex polysaccharide of lower mo-
lecular weight than agarose and it has

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 11 of 50

thickening properties [38,133]. Its structure The most important commercial agarophyte
is essentially made up of alternating (1→3)- genera are Gelidium, Pterocladiella, Geli-
β-D-galactopyranose and of (1→4)-3,6- diella, and Gracilaria. Agar has also been
anhydro-α-L-galacto-pyranose residues found in species of Ceramium, Phyllopho-
[133,136]. ra, Ahnfeltia, Campylaephora, Acanthopho-
lis, and Gracilariopsis [137].

Figure 3 – Idealized structure of the chemical units of Agar

3.4. Biological activities of Agar cate that CDSAM was more useful than
standard media in accurately evaluating the
Agar has been used as functional dietary efficacy of antifungal drugs. Agar propor-
fiber for diabetics in the health food market tion method for drug susceptibility tests has
because of its non-nutritive nature. Never- been used since 1957 [142]. More recently,
theless, its α-glucosidase inhibitory ability the test has been replaced by more rapid
should also be considered for retarding the tests [143].
carbohydrate digestion. Some inhibitors
with pseudo-saccharide structure including The possibility to use agar and agarose
acarbose and 1-deoxynojirimycin have been beads for sustained release of water soluble
used very successfully in controlling dis- drugs has been investigated [144]. Agarose
eases such as diabetes, obesity or hyperli- has a significantly lower sulfate content,
pemia [138,139]. better optical clarity and increased gel
strength with respect to agar, but it is consi-
Agar has medicinal or pharmaceutical in- derably more expensive [145]. Agar beads
dustrial applications including use as sus- containing phenobarbitone sodium as a wa-
pending agent for radiological solutions ter soluble and hypnotic drug were prepared
(barium sulfate), as a bulk laxative as it [146]. The encapsulation procedure consists
gives a smooth and non-irritating hydrated in dissolving the drug in a hot (around 70
bulk in the digestive tract, and as a forma- °C) agar aqueous solution and then drop-
tive ingredient for tablets and capsules to ping the solution in a cold bath containing a
carry and release drugs. Pharmaceutical non-solvent for agar (acetone or ethyl ace-
grade agar has a viscous consistency. In tate). Agar beads instantaneously form by
microbiology, agar is the medium of choice gelation. The results of dissolution and re-
for culturing bacteria on solid substrate. lease studies indicated that agar beads could
Agar is also used in some molecular micro- be useful for the preparation of sustained
biology techniques to obtain DNA informa- release dosage forms, although no many
tion [140]. More recently, agar was used in further studies have been developed [147].
a newly-developed medium, i.e., combined
deactivators-supplemented agar medium Antitumor activity was found in an agar-
(CDSAM), to evaluate the viability of der- type polysaccharide from cold water extrac-
matophytes in skin scales [141]. The expe- tion of a Gracilaria species and hydroly-
rimental data from this clinical study indi- sates of agar resulted in agaro-oligo-

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 12 of 50

saccharides with activity against α- inflammatory cytokine and an enzyme as-
glucosidase and antioxidant ability sociated with the production of nitric oxide
[139,148]. It has also been reported that [154].
agar leads to decreases in the concentration
of blood glucose and exerts an anti- Among therapeutics for liver diseases, pro-
aggregation effect on red blood cells [4]. It tective drugs have been attracted more and
has as well employed as an anti-rheumatic more attentions, such as antioxidant preven-
agent for prolonged treatments, and in the tion approaches. The in vitro and in vivo
stabilization of cholesterol solutions [149]. antioxidative activities of agaro-
oligosaccharides with the model related
Several antitumor oligosaccharides (GSO) with liver disease was tested by [155]. Aga-
include sulfated disaccharide and neoagaro- ro-oligosaccharides derived from red sea-
tetraose have been discovered in the Deles- weed polysaccharide have been reported to
seriaceae (Ceramiales, Rhodophyta) [150]. possess antioxidant activity. Overall, the
These oligosaccharides were prepared by results of the study made by Chen and col-
spray dried and proved the physiological leagues [155] indicate that agaro-
activity by reducing the number of revertant oligosaccharides can exert their in vitro and
colonies of Salmonella typhimurim and in vivo hepatoprotective effect through sca-
mildly inhibiting angiogenesis on the venging oxidative damage induced by reac-
chicken chorioallantoic membrane (CAM). tive oxygen species (ROS).
GSO was assumed to have a desmutagenic
activity and no harmful side effects such as Agaro-oligosaccharides and neoagaro-
blood coagulation of fibrinolysis. GSO with oligosaccharides have been reported to pos-
high safety owed various physiological ac- sess lots of biological activities, such as
tivity, which is expected to apply in future antioxidative activities [156], moisturizing
food and medical supplies [151]. effect on skin [157], and anti-inflammation
effects [158], which suggested that these
Agarose can be separated from the agar oligosaccharides merit further investigation
with a yield of 42%, and the agar content as functional foods to control inflammation.
varied seasonally from 26% - 42% in Geli- Neoagaro-oligosaccharides derived from
dium spp. in another experiment [152,153]. agarose have been demonstrated to possess
a variety of biological activities, such as
In recent years, versatile biological activi- antibacterial and antioxidative activities
ties of agaro-oligosaccharides have been [159].
observed, and the structure and bioactivity
relationship research also revealed that the
functionality is directly correlated to the 3.5. Porphyran
degree of polymerization. Agaro-
oligosaccharides were hydrolytically ob- Porphyran is a sulfated polysaccharide iso-
tained from agar using hydrochloric acid, lated from selected (red) algae of the Order
citric acid, and cationic exchange resin (sol- Bangiales, Phylum Rhodophyta, especially
id acid) [139]. Agaro-oligosaccharides have from the genus Porphyra/Pyropia
been reported to display antioxidant effects, [160,161]. The chemical structure of por-
such as inhibiting the production of lipid phyran contains a linear backbone of alter-
peroxide radicals and inhibiting the produc- nating 3-linked β-D-galactose and 4-linked
tion of nitric oxide (NO) [139]. Agaro- α-L-galactose-6-sulfate or 3,6-anhydro-α-L-
oligosaccharides have also been shown to galactose units (Figure 4) [79,162].
suppress the production of a pro-

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 13 of 50

Figure 4 - Idealized structure of the chemical units of Porphyran (after [327]).

3.6. Biological activities of Porphyran be exploited by ―nutraceutical‖ companies
that market them as ―health products‖
Non-starch polysaccharide (NSP) has been [57,68,176,180-187].
consumed for centuries and has been recog-
nized as having nutritional benefits. Many Porphyran is effective against contact
reports have demonstrated that ingestion of hypersensitivity induced by 2, 4, 6 tri-
NSP lowers serum cholesterol and lipo- nitrochlorobenzene. The mechanism is sug-
protein levels [170-172], helps to normalize gested to operate by suppressing the serum
serum glucose and insulin levels [173] and levels of IgE and IFN-ƴ. Porphyran has
promotes normal laxation [174]. Porphyran, excellent inhibitory activities against hyalu-
which is considered an NSP, can be ex- ronidase, responsible for the release of his-
tracted with hot water from Porphy- tamine from mast cells [188].
ra/Pyropia spp. [161,175], edible species
cultivated abundantly in eastern Asia. Por- Some sulfated polysaccharides from red
phyran is distributed in the intercellular algae also showed anti-viral activities to-
matrix of the algal body and its basic struc- wards viruses responsible for human infec-
ture is closely related to that of agar [176]. tious diseases. Porphyran is reported to in-
It has also been reported that porphyran hibit HIV reverse transcriptase in vitro. It
also has health benefits as other NSPs: e.g., has minimal effects on human DNA and
prebiotic activity [177], antitumor activity RNA polymerase activity. Some agaroids,
[178,179], and antihyperlipidemic activity such as high molecular weight, galactan
[180]. The study in rats [180] suggested that sulfate also have antiviral properties against
dietary porphyran prevents hypercholeste- the Herpes simplex virus, human cytomega-
rolemia that is induced by feeding diet con- lo virus (HCMV), dengue virus (DENV),
taining 1.5% cholesterol 0.5% bile salts. respiratory syncytial virus (RSV) and in-
However, little is known about how dietary fluenza virus due to the inhibition of the
porphyran affects growth and lipid metabol- initial viral attachment to host cells [189-
ism in the feeding of a normal diet [176]. 194].

Porphyran produces hypocholesterolemic Upon the intraperitoneal administration of
and hypolipidemic effects due to reduced porphyran to aging mice, the activities of
cholesterol absorption in the gut, with in- superoxide dismutase and glutathione pe-
creased fecal cholesterol content and a hy- roxidase as well as the total antioxidant
poglycemic response. It is also reported to capacity were increased signiﬁcantly and
reduce total cholesterol, free cholesterol and the level of lipid peroxidation was
the levels of triglycerides and phospholipids signiﬁcantly decreased, suggesting that
in the liver. These substances are likely to porphyran has antioxidant activity both in
vitro and in vivo [195].

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 14 of 50

In human gastric cancer cells, porphyran Furthermore, polysaccharides prepared
displays antitumor properties, in particular from Pyropia yezoensis (as Porphyra ye-
the ester sulfates of the polysaccharides zoensis) considerably inhibited human gas-
may be related to the antitumor activities tric and lung cancer cell growth, and degra-
reported. The degree of polyanionic proper- dation products of these polysaccharides
ties may be intimately related to this activi- resulting from an ultrasonic treatment
ty. Porphyran reportedly induced apoptosis significantly increased this antiproliferative
by caspase-3 or caspase-9 activation, while eff ect against only human gastric cancer
decreasing the Insulin-like, growth Factor-I cells [198]. Porphyra/ Pyropia sp. also re-
receptor (IGF-IR) phosphorylation and portedly contains various anticancer com-
down regulated a serine/threonine kinase pounds other than porphyrans [199-201]. In
(Akt) phosphorylation. The caspase-induce a human case-control study, it was reported
apoptosis was activated in a sequential cas- that a high rate of intake of nori (Porphy-
cade of cleavages from their inactive forms. ra/Pyropia sp.) may decrease the risk of
Activation of caspase-3 leads to the clea- breast cancer [202].
vage of many proteins, one of which is poly
(ADP-ribose) polymerase (PARP) [196]. Additionally, porphyrans reportedly im-
The cleavage of the poly (ADP-ribose) po- proved lipid and glucose metabolism
lymerase is the hallmark of apoptosis. The [203,204] and iron deficiency [205]. In the
expression level of antiapoptotic molecules, works of Wang et al. [206] the hypolipi-
such as B-cell lymphoma 2 (Bcl-2), gradu- demic and antioxidant effects of porphyran
ally decreased, whereas the proapoptotic from the red algae Pyropia haitanensis (as
molecule Bcl-2-associated death promoter Porphyra haitanensis) as a dietary supple-
(BAD), opposed the action of Bcl-2, which ment were evaluated in mice. The results
increased in response to levels of exposure suggested that porphyran could be used as
porphyran. Porphyran decreased the expres- functional foods and natural drugs in pre-
sion levels in Gastric cancer cell lines venting the hyperlipidemia and this activity
(AGS) by negatively regulating the insulin- might be attributed to its antioxidant poten-
like, growth Factor-I receptor (IGF-IR) tial [206].
phosphorylation which is a potent mitogen
and growth stimulatory factor for several 4. Polysaccharides from brown algae
kinds of cells (over-expression and en- (Ochrophyta, Phaeophyceae)
hanced activation of which is frequently
observed in Human cancers) [196]. Thus, 4.1. Fucoidan
Insulin-like, growth Factor-I receptor (IGF-
IR) phosphorylation was decreased in por- Fucans are sulfated polysaccharides which
phyran-treated AGS cells, which correlated comprise a fucose backbone. One of the
with Akt activation. Porphyran down regu- best studied fucans from the brown algae is
lates Akt phosphorylation. The PI3- ki- fucoidan, which was first isolated by Kylin
nase/Akt pathway is viewed as a key player [207]. The fucoidan from Fucus vesiculosus
to cell survival in different systems. The has been available commercially for dec-
IGF-I stimulation induced Akt activation ades (Sigma-Aldrich Chemical Company,
decreased in cells treated with porphyran, St. Louis, MO, US). Early work on its
which suggested that inhibition of Akt structure showed that it contained primarily
phosphorylation may be an important me- (1→2) linked 4-O-sulfated fucopyranose
chanism for porphyran-induced apoptosis residues (Figure 5). However, 3- linked
[196,197]. fucose with 4-sulfated groups was subse-
quently reported to be present on some of

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 15 of 50

the fucose residues. Additionally, it was nodosum contained a predominant disacc-
determined to contain branches every 2-3 haride motif with sulfate at the 2-position of
fucose residues. Subsequently, Chevolot the 3-linked fucose and sulfate groups on
and colleagues reported that the fucoidan the 2- and 3-positions of the 4-linked fucose
from Fucus vesiculosus and Ascophyllum [137,208].

 Figure 5 - Idealized structure of the chemical units of Fucoidan

4.2. Biological activities of Fucoidan Several studies reported that the anti-
 coagulant functionalities of fucoidans ex-
Fucoidan can be easily ―cooked‖ out of tracted from Fucus vesiculosus and Eklonia
most edible brown algae by simmering for cava were due to thrombin-inhibition-
20-40 min. in water. When consumed, it mediated via plasma anti-thrombin-III; their
seemed to reduce the intensity of the in- anti-coagulant activity was like that of he-
flammatory response and promote more parin [13,213,214]. Moreover, fucoidans
rapid tissue healing after wound or surgical from Ascophyllum nodosum, Fucus distich-
trauma. This led to recommendations that ous, F. evanescens, F. serratus, Laminaria
brown seaweed broth be administered after digitata, Saccharina latissima and S. lon-
auto-collision, sports injuries, bruising falls, gissima were also described to possess
muscle and joint damage and deep tissue strong anticoagulant activities both in vitro
cuts, including surgery [209]. and in vivo models [213,214].
However, the commercial importance of In general, structural-bioactive studies sug-
fucoidans is presently much lower than that gested that the anticoagulant /anti-thrombin
of seaweed hydrocolloids; these polysac- activities of fucoidans were mainly depen-
charides are now attracting considerable dent on the content and/or positioning of
attention because of the growing market for sulfate groups, as well as the molecular
them as ―bioactive polysaccharides‖ in a weight of the polymers [213]. Likewise,
wide arena of diverse applications [210]. their monomeric composition, types of lin-
More recently, anticoagulant and antith- kages and branching might also exert mod-
rombotic activities are amongst the most erate modulation on the biological proper-
studied biological effects of fucoidans. ties of fucoidans [13,210,215]. In this con-
Commonly, the anti-coagulant activity of text, it is possible that the greater anticoagu-
fucoidans is mediated through the activa- lant/antithrombin activities exhibited by
tion of thrombin inhibitors, although direct longer fucoidans are due to the higher con-
thrombin inhibition and competitive bind- tent of fucose and sulfate groups
ing of fibrinogen to block the actions of [13,209,213,215,216], though this is still
thrombin are also possible [210-212]. under debate [3,217].

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Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 16 of 50

Fucoidans are also reported to inhibit the Antitumor activities of fucoidans include
replication of several enveloped viruses the inhibition of tumor proliferation, the
such as Human immune-deficiency and stimulation of tumor cell apoptosis, block-
human cytomegalovirus, among others ing of tumor cell metastasis and enhance-
[13,213]. The mechanisms for such activity ment of various immune responses [223]. In
are thought to occur via inhibition of cell this context, fucoidans from several ma-
infection by viral sorption, or hampering of croalgal species (e.g. Saccharina japonica,
viral-induced, syncytium formation S. latissima, Laminaria digitata, Fucus ser-
[13,215]. Fucoidans from Saccharina japo- ratus, F. distichus and F. vesiculosus)
nica, Cladosiphon okamuranus, Adenocys- proved to be useful and were regarded as
tis utricularis, Stoechospermum margina- good candidates for future cancer therapy
tum, Cystoseira indica, Dictyota mertensii, [213,215]. Besides those, the commercial
Lobophora variegata, Fucus vesiculosus, fucoidans branded ―Tokida‖ (from cultured
Spatoglossum schroederi and Undaria pin- Cladosiphon okamuranus) and that from
natifida showed impressive, positive results the Korean cultured sporophyte (Miyeok-
in both in vitro and in vivo models of infec- gui) of U. pinnatifida also revealed promis-
tion by poliovirus III, adenovirus III, ing antitumoral activities, as tested in in
ECHO6 virus, coxsackie B3 virus, coxsack- vitro models [215].
ie A16, Newcastle disease virus (NDV),
Herpes simplex virus (HSV-1, HSV-2), Other important, demonstrated biological
HIV and avian reverse transcriptase activities of fucoidans included antioxidant,
[13,212,215]. anti-inflammatory and anti-allergic, al-
though others cannot be forgotten, e.g. he-
Fucoidan isolated from the brown seaweed pato-protection, cardio-protection, stomach
Fucus vesiculosus [218] shows inhibitory protection and anti-obesity [13,213,215].
effect on the replication of DNA viruses: Examples of fucoidans showing promising
Herpes virus (HSV-1, HSV-2) and Human antioxidant activities in in vitro models in-
cytomegalo virus (HCMV) [218-220]. cluded those obtained from Saccharina
These compounds are also active against japonica, Canistrocarpus cervicornis, Fu-
RNA viruses: Vesicular stomatitis virus cus vesiculosus, Dictyota cervicornis, Sar-
(VSV), Sinbis virus (SINV), and HIV-1 gassum filipendula and Dictyopteris delica-
[221]. However, this compound is not ac- tula [13,213,215,224], while the anti-
tive against Coxsackievirus, Poliovirus, and inflammatory activity of several fucoidans
Parainfluenza virus. A water-soluble, non- (Laminaria digitata, Fucus evanescens, F.
carbohydrate component of fucoidan iso- serratus, F. distichus, F. spiralis, Ascophyl-
lated from F. vesiculosus can inhibit HIV lum nodosum, Cladosiphon okamuranus,
Reverse transcriptase (RT) in vitro at μg Padina gymnospora and Saccharina latis-
mL-1 [220]. Pre-incubation of cell-free virus sima) have been described through inhibi-
to 200 μg mL-1 causes 100% reduction in tion of leucocyte recruitment, in an inflam-
the amount of HIV-1 p24 antigen released. mation model in rats [225]. Moreover, inhi-
Tests show that these effects are not due to bition of the expression of inducible nitric
the killing of target cells. In fact, fucoidan oxide synthase (iNOS) has also been dem-
produced no adverse effects on cell prolife- onstrated for fucoidans, such as that from
ration and protein metabolism. The pre- the Sigma-Aldrich Chemical Co. (from F.
incubation of target cells with fucoidan pro- vesiculosus). Furthermore, commercial fu-
tects them from HIV-1 infection [220]. In coidans (from Mekabu and Sigma-Aldrich
addition to its antiviral activity, fucoidan Chemical Co.) together with those isolated
possesses low anticoagulation properties from A. nodosum, F. evanescens, C. oka-
[212,218-220,222]. muranus and from other several members

Pereira L. International Biology Review, vol. 2, issue 2, June 2018 Page 17 of 50

of the Order Laminariales (Phaeophyceae) Laminarans are basically a class of low-
were described to exhibit anti- molecular weight storage β-glucans, which
complementary activities, rendering their are composed of (1,3)- β -D-glucan [232].
potential as anti-allergen [13,121,213,215]. They consist of (1,3)- β -D-glucopyranose
 residues with some 6-O-branching in the
The sulfated and acetylated fucoidan frac- main chain and some β-(1,6)-intra-chain
tion, containing fucose, galactose, mannose, links are also present. For example, lamina-
glucose and uronic acid residues, was iso- ran from Eisenia bicyclis is composed of a
lated from the brown alga Padina boryana linear chain of (1,3) and (1,6) linkage in a
[226]. The anticancer effect of native and ratio of 2:1 (1,3)- β -D-glucans [233]. The
modified fucoidan fractions was studied in molecular weight of laminaran is approx-
vitro on the colorectal carcinoma cells imately 5 kDa and is dependent upon the
DLD-1 and HCT-116. All fucoidans had no degree of polymerization which is in the
cytotoxicity under 400 μg/mL and inhibited range of 20-25 glucose moieties [234,235].
colony formation of cancer cells at concen- The molecular weight of laminaran from
tration of 200 μg/mL [226]. Saccharina longicruris is reported to be in
 the range of 2.89 - 3.32 kDa depending on
4.3. Laminaran the extraction conditions [236], including
 the solvent type used [228]. Not all lamina-
Laminarans are a category of small glucans rans are the same characteristics, different
present in either soluble or insoluble form. species of raw material present different
The first form is characterized by its com- structures of molecules, therefore different
plete solubility in cold water, while the oth- biological properties [228,229].
er is only soluble in hot water [207,298].
This polysaccharide is composed of D- In nature, laminarins exist in either soluble
glucose with β-(1,3) linkages, with β-(1,6) or insoluble forms. The soluble form is cha-
intra-chain branching (Figure 6) [17,227- racterized by complete solubility in cold
229]. Laminaran, also known as ―lamina- water, and the insoluble form can be dis-
rin‖ or ―leucosin‖, was first isolated from solved only in hot-water solutions. The so-
members of the Laminariaceae (Phaeophy- lubility of laminarins is determined by the
ceae) by Schmiedeberg [230]. Laminaran is branching factor: laminarins with the high-
a food reserve of brown algae. It is located est branching are easily dissolved in cold
in vacuoles present in cells. Laminaran is water in comparison with laminarins with
found in the fronds of Laminaria and Sac- less branching. Moreover, the degree of
charina species [231]. polymerization of water-soluble laminarins
 is approximately 20-25 glucose units
 [236,237].

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