In . J. Mol. Sci. 2020, 21, 41; doi:10.3390/ijms21010041 www.mdpi.com/jou nal/ijms
Re iew
An i-Obesi y E ec s o Mic oalgae
Saioa Gómez-Zo i a 1,2,†, Jeni e T epiana 1,†, Mai ane González-A ceo 1, Leixu i Agui e 1,2,
Iñaki Mil on-Laskiba 1,2, Ma cela González 3, I zia Esebe i 1,2,*,
Al edo Fe nández-Quin ela 1,2,* and Ma ía P. Po illo 1,2
1 Nu i ion and Obesi y G oup, Depa men o Nu i ion and Food Science, Uni e si y o he Basque
Coun y (UPV/EHU) and Lucio Lasca ay Resea ch Ins i u e, 01006 Vi o ia, Spain;
[email protected] (S.G.-Z.); jeni e . [email protected] (J.T.); mai [email protected] (M.G.-A.);
leixu i.agui [email protected] (L.A.); inaki.mil [email protected] (I.M.-L.); ma iapuy.po [email protected] (M.P.P.)
2 CIBEROBN Physiopa hology o Obesi y and Nu i ion, Ins i u e o Heal h Ca los III, 01006 Vi o ia, Spain
3 Nu i ion and Food Science Depa men , Facul y o Biochemis y and Biological Sciences, Na ional
Uni e si y o Li o al and Na ional Scien i ic and Technical Resea ch Council (CONICET),
San a Fe 3000, A gen ina; maidagon@ bcb.unl.edu.a (M.G.)
* Co espondence: i zia .eseb[email p o ec ed]s (I.E.); al edo. e nan[email p o ec ed] (A.F.-Q.);
Tel.: +34-945014363 (I.E.); Tel.: +34-945013066 (A.F.-Q.)
† These au ho s con ibu ed equally o his wo k.
Recei ed: 14 Oc obe 2019; Accep ed: 17 Decembe 2019; Published: 19 Decembe 2019
Abs ac : In ecen yea s, mic oalgae ha e a ac ed g ea in e es o hei po en ial applica ions in
nu aceu ical and pha maceu ical indus y as an in e es ing sou ce o bioac i e medicinal p oduc s
and ood ing edien s wi h an i-oxidan , an i-in lamma o y, an i-cance , and an i-mic obial
p ope ies. One po en ial applica ion o bioac i e mic oalgae compounds is obesi y ea men . This
e iew ga he s oge he in i o and in i o s udies which add ess he an i-obesi y e ec s o
mic oalgae ex ac s. The scien i ic li e a u e supplies e idence suppo ing an an i-obesi y e ec o
se e al mic oalgae: Euglena g acilis, Phaeodac ylum ico nu um, Spi ulina maxima, Spi ulina pla ensis,
o Ni zschia lae is. Rega ding he mechanisms o ac ion, mic oalgae can inhibi p e-adipocy e
di e en ia ion and educe de no o lipogenesis and iglyce ide (TG) assembly, hus limi ing TG
accumula ion. Inc eased lipolysis and a y acid oxida ion can also be obse ed. Finally, mic oalgae
can induce inc eased ene gy expendi u e ia he mogenesis ac i a ion in b own adipose issue, and
b owning in whi e adipose issue. Along wi h he educ ion in body a accumula ion, o he
hallma ks o indi iduals wi h obesi y, such as enhanced plasma lipid le els, insulin esis ance,
diabe es, o sys emic low-g ade in lamma ion a e also imp o ed by mic oalgae ea men . No only
he an i-obesi y e ec o mic oalgae bu also he imp o emen o se e al como bidi ies, p e iously
obse ed in p eclinical s udies, has been con i med in clinical ials.
Keywo ds: mic oalgae; obesi y; iglyce ide; adipose issue; adipocy e; mice
1. In oduc ion
Mic oalgae a e p oka yo ic o euka yo ic mic oscopic single-cell o ganisms, ound in esh wa e
and ma ine sys ems. They p oduce app oxima ely hal o he a mosphe ic oxygen and use he
g eenhouse gas ca bon dioxide o g ow pho o-au o ophically. Toge he wi h bac e ia, mic oalgae
p o ide ene gy o all he ophic le els abo e hem. Al hough mic oalgae show a g ea biodi e si y,
he ones mos s udied a e Chlo ella, Spi ulina, Haema ococus, Dunaniella y Scenedesmus.
Mic oalgae p oduce a g ea a ie y o compounds, such as pho osyn he ic pigmen s
(ca o enoids and chlo ophylls), s e ols, polyunsa u a ed a y acids, i amins, mine als, ibe ,
polysaccaha ides, enzymes, pep ides, and oxins. I is impo an o emphasize ha he chemical
In . J. Mol. Sci. 2020, 21, 41 2 o 21
composi ion o mic oalgae depends on he species and he cul i a ion condi ions, such as
empe a u e, illumina ion, pH, CO2 supply, sal , and nu ien s [1,2]. They ha e a ac ed g ea in e es
in ecen yea s due o hei po en ial applica ions in nu aceu ical and pha maceu ical indus ies, and
a e a majo sou ce o bioac i e medicinal p oduc s and ood ing edien s wi h an i-oxidan , an i-
in lamma o y, an i-cance , and an i-mic obial p ope ies [2,3].
One o he po en ial applica ion ields o he mic oalgae bioac i e compounds is obesi y, which
has become a se ious heal h p oblem due o i s high p e alence, and because i is a majo isk ac o
o a wide ange o ch onic diseases, including diabe es, ca dio ascula diseases, and cance [4–6].
Nowadays, app o ed new-gene a ion an i-obesi y medica ions o e a sa e and ole able adjunc o
li es yle in e en ions o he majo i y o indi iduals wi h obesi y. Ne e heless, depending on
pa ien ole abili y o side e ec s, poo adhe ence o discon inua ion can be ea men limi a ions. In
ac , his si ua ion educes ea men bene i s [7].
In his con ex , he p esen e iew ga he s in i o and in i o s udies add essed o analyze he
an i-obesi y e ec s o mic oalgae ex ac s, bu no hose whe e isola ed mic oalgae compounds ha e
been used.
2. In Vi o S udies
To da e, se e al in i o s udies ha e been conduc ed o analyze he e ec s o mic oalgae ex ac s
on adipogenesis and me abolic p ocesses in ol ed in iglyce ide (TG) accumula ion (Table 1; Figu e
1).
In . J. Mol. Sci. 2020, 21, 41 3 o 21
Table 1. E ec s o mic oalgae in p e-adipocy es and ma u e adipocy es.
Re e ence
Numbe s
Cell Line Mic oalgae and Doses Expe imen al Design E ec s Mechanisms
[8] Human adipose-de i ed
s em cells
Euglena g acilis Z
ex ac (5%,10%, o
20%)
Cells we e ea ed du ing
di e en ia ion
(7 days) and adipocy e
ma u a ion
(7 addi ional days)
A 10% and 20%:
↓ lipid con en 44% and 74% espec i ely
A 20%:
↓ Adipogenesis
A 20%:
↓ C/EBPα and PPARγ
gene and p o ein
exp essions
↓ C eb, S ebp1c, C/ebpβ
and C/ebpδ gene
exp ession
↓ Fabp4 and Lpl gene
exp ession
[9]
3T3-L1 p e-adipocy es
Spi ulina maxima ex ac
(50 and 100 µg/mL)
Cells we e ea ed on day
0, 2, 4, and 6 o
di e en ia ion (cell
ha es ing on day 8)
A 100 µg/mL:
↓ Adipogenesis (dose dependen )
A 100 µg/mL:
↓ FAS and C/EBPα
p o ein exp ession
A 50 and 100 µg/mL:
↓ PPARγ and aP2 p o ein
exp ession
↓ SREBP1c, ACC,
LPAATβ, lipin1, and
DGAT-1 p o ein
exp ession
C3H10T1/2
mesenchymal s em cells
Spi ulina maxima ex ac
(100 µg/mL)
Cells we e ea ed on day
0, 2, 4, and 6 o
di e en ia ion (cell
ha es ing on day 8)
↓ Adipogenesis
↓ C/EBPα, PPARγ, and
aP2 p o ein exp ession
↓ SREBP1c, FAS, ACC,
LPAATβ, lipin1 and
DGAT-1 p o ein
exp ession
[10] 3T3-L1 p e-adipocy es
Phaeodac ylum
ico nu um ex ac (250
and 400 µg/mL)
Cells we e ea ed du ing
di e en ia ion
(6 days)
A 250 µg/mL
↓ Lipid accumula ion
A 400 µg/mL
↓ Adipogenesis
A 400 µg/mL
↓ PPARγ and ↑ UCP1
p o ein exp ession
[11] 3T3-L1 p e-adipocy es
Phaeodac ylum
ico nu um ex ac
(100 mg/L)
Cells we e ea ed on day
7 o di e en ia ion o 24
h (cell ha es ing on day
8)
No di e ences in lipid con en o
cy o oxici y
↑ Cd36 and Cp 1 gene
exp ession
In . J. Mol. Sci. 2020, 21, 41 4 o 21
Special no e: Do ed lines inco po a ed o sepa a ion be ween di e en s udies. ACC: Ace yl-CoA ca boxylase, AP2: a y acid binding p o ein, C/EBP: CCAAT-
enhance -binding p o ein, CD36: clus e o di e en ia ion 36, CPT1: ca ni ine palmi oyl ans e ase 1, CREB: cAMP egula o y elemen -binding p o ein; DGAT-1:
diacylglyce ol O-acyl ans e ase, FABP4: a y acid-binding p o ein 4, FAS: a y acid syn hase, LPAATβ: lysophospha idic acid acyl ans e ase β, LPL: lipop o ein
lipase, PPARγ: pe oxisome p oli e a o ac i a ed ecep o γ, SREBP1c: s e ol egula o y elemen -binding p o ein 1c, UCP: uncoupling p o ein. ↑ signi ican inc ease,
↓: signi ican dec ease.
In . J. Mol. Sci. 2020, 21, 41 5 o 21
Figu e 1. An i-obesi y mechanisms o ac ion desc ibed in in i o s udies (* ex i o). ACC: ace yl-CoA
ca boxylase, AP2: a y acid binding p o ein, C/EBP: CCAAT-enhance -binding p o ein, CPT1:
ca ni ine palmi oyl ans e ase 1, CREB: cAMP egula o y elemen -binding p o ein; DGAT-1:
diacylglyce ol O-acyl ans e ase, FABP4: a y acid-binding p o ein 4, FAS: a y acid syn hase,
LPAATβ: lysophospha idic acid acyl ans e ase β, PGC-1α: pe oxisome p oli e a o -ac i a ed
ecep o gamma co-ac i a o 1α, PRDM16: PR domain-con aining 16, PPARγ: pe oxisome
p oli e a o ac i a ed ecep o γ, SREBP1c: s e ol egula o y elemen -binding p o ein 1c. ↑ signi ican
inc ease, ↓: signi ican dec ease.
Sugimo o e al. [8] used an aqueous ex ac o Euglena g acilis Z (Euglena), unicellula
pho osyn hesizing g een algae. Euglena con ains i amins, mine als, unsa u a ed a y acids, and
accumula es c ys alline β-1,3-glucan, a polysaccha ide also known as pa amylon, which is
conside ed a unc ional die a y ibe . The au ho s ob ained human adipose-de i ed s em cells
(hASCs) om a non-diabe ic emale dono wi h a body mass index (BMI) o 26 kg/m2, and
di e en ia ed hese cells in o adipocy es o 7 days (0–7 days). Cells we e cul u ed o an addi ional
7-day ma u ing pe iod (8–14 days). Cy o oxici y was no obse ed in cells ea ed wi h any o he
checked Euglena ex ac dilu ions used (1.25%, 2.5%, 5%, 10%, 20%, o 40%). When he lipid con en
o cells incuba ed wi h he ex ac a doses o 5%, 10%, o 20% was analyzed, he au ho s obse ed
ha Euglena ex ac educed cellula TG con en 17%, 44%, and 74%, in line wi h he inc eased
concen a ion o he ex ac in he medium.
In o de o explo e he mechanism unde lying his e ec , he au ho s s udied he adipogenic
pa hway. Adipogenesis is a igh ly egula ed cellula di e en ia ion p ocess, which allows adipose
issue expansion. In his p ocess, mesenchymal s em cells become p e-adipocy es and p e-adipocy es
di e en ia e in o ma u e adipocy es, he cells ha a e able o accumula e iglyce ides in o lipid
d ople s [12]. Fo his pu pose, hey measu ed gene and p o ein exp essions o pe oxisome
p oli e a o -ac i a ed ecep o γ (PPARγ) and CCAAT-enhance -binding p o ein α (C/EBPα), he
mas e egula o s o adipocy e-di e en ia ion. While he gene exp ession o Ppa γ and C/ebpα we e
inc eased du ing adipocy e-di e en ia ion in he con ol cells, hese we e ep essed by 23% when
20% o Euglena ex ac was added o he medium. P o ein amoun s o PPARγ and C/EBPα we e also
signi ican ly educed, which is consis en wi h his esul . The au ho s also obse ed an inhibi ion
induced by he Euglena ex ac in gene exp ession o adipogenic ma ke s exp essed downs eam in
he adipocy e di e en ia ion p ocess, and egula ed by PPARγ and C/EBPα, such as a y acid
binding p o ein (Ap2) (also known as a y acid bonding p o ein 4, Fabp4) and lipop o ein lipase (Lpl).
These esul s show ha Euglena ex ac inhibi s adipocy e-di e en ia ion h ough supp ession o
mas e egula o s in ol ed in ha me abolic pa hway.
Fu he mo e, since Ppa γ exp ession is enhanced a he ea ly phase o adipocy e-di e en ia ion
by wo membe s o he C/EBP p o ein amily, C/EBPβ and C/EBPδ, as well as by s e ol egula o y
elemen -binding ansc ip ion ac o 1c (SREBP1c) and cAMP egula o y elemen -binding p o ein
(CREB), hei gene exp ession was also de e mined in hASCs. Fo his pu pose, cells we e cul u ed
wi h o wi hou Euglena ex ac (20%) du ing he i s h ee days in he di e en ia ion p ocess. All
hese genes we e down egula ed when Euglena ex ac was p esen in he medium, showing ha i s
inhibi o y e ec on adipocy e-di e en ia ion was caused by ep essing he ea ly s age o adipocy e-
In . J. Mol. Sci. 2020, 21, 41 6 o 21
di e en ia ion. These obse a ions we e con i med when adipogenesis was e alua ed by
de e mining Oil Red O om cells ea ed wi h 20% o ex ac du ing adipocy e-di e en ia ion (days
0–7) and om hose cells ea ed du ing adipocy e ma u a ion (days 8–14). Cons an supplemen a ion
(day 0–14) wi h Euglena ex ac inhibi ed lipid accumula ion by app oxima ely 50% as compa ed o
he con ol cells. When supplemen a ion wi h he alga ex ac ook place only du ing he adipocy e
di e en ia ion pe iod (days 0–7) lipid accumula ion was inhibi ed by 60%, bu app oxima ely 96% o
he accumula ed lipids emained in he cells ea ed wi h he ex ac on days 7–14. The e o e, he
au ho s concluded ha Euglena ex ac supp esses adipocy e-di e en ia ion a he ea ly s age, hus
con ibu ing o i s an i-obesi y e ec .
Ano he mic oalga s udied by se e al au ho s is Spi ulina maxima. I con ains pigmen p o eins
such as chlo ophyll a and C-phycocyanin, which ha e been epo ed as possessing an i-oxidan , an i-
in lamma o y (bo h pigmen s), and an i-diabe ic ac ions (C-phycocyanin). Seo e al. [9] pe o med an
in i o s udy o explo e whe he an e hanolic ex ac o his mic oalga also showed an i-obesi y and
adipocy e b owning p ope ies. Fo his pu pose, 3T3-L1 p e-adipocy es and C3H10T1/2 cells, a
cellula line unc ionally simila o mesenchymal s em cells, we e ea ed du ing he di e en ia ion
pe iod (0–8 days) wi h 50 o 100 µg/mL o he mic oalga ex ac . P e iously no cy o oxici y had been
con i med a hese concen a ions. In 3T3-L1 p e-adipocy es, he addi ion o he ex ac o he
di e en ia ion medium dec eased TG accumula ion in a dose dependen manne . This e ec was due
o lowe p o ein exp ession o he adipogenic egula o s C/EBPα, PPARγ, and aP2, meaning ha
adipogenesis was inhibi ed. The same esul s we e obse ed when he au ho s ea ed C3H10T1/2
cells wi h he ex ac a a concen a ion o 100 µg/mL.
In addi ion, he au ho s explo ed lipogenesis, he me abolic p ocess h ough which a y acids
a e es e i ied wi h glyce ol o hei s o age as iglyce ides, and ha allows adipocy es o inc ease
hei size. Mo e speci ically, he au ho s measu ed enzymes in ol ed in de no o lipogenesis, he
biosyn he ic pa hway by which ace yl-CoA is con e ed o a y acids be o e hey a e es e i ied wi h
glyce ol o syn hesize iglyce ides. Fo ha pu pose, au ho s measu ed p o eins such as acyl-CoA
ca boxylase (ACC) and a y acid syn hase (FAS), as well as ma ke s in ol ed in iglyce ide
assembly, such as lysophospha idic acid acyl ans e ase β (LPAATβ), lipin-1 and diacylglyce ol
acyl ans e ase-1 (DGAT1). In his ega d, hey obse ed ha ea ing 3T3-L1 p e-adipocy es du ing
di e en ia ion wi h he e hanolic ex ac led o educ ions in he p o ein exp essions o SREBP1, ACC,
and FAS, as well as o LPAATβ, lipin-1, and DGAT1. As a as C3H10T1/2 cells a e conce ned,
incuba ing cells wi h he ex ac ob ained om Spi ulina maxima du ing di e en ia ion educed
p o ein exp essions o he h ee la e lipogenic ma ke s (LPAATβ, lipin-1, and DGAT1). The au ho s
concluded ha his ex ac signi ican ly supp essed lipogenesis ei he in 3T3-L1 adipocy es o
C3H10T1/2 cells. Finally, he au ho s epo ed b owning e ec s ex i o, in cells ob ained om he
s omal ascula ac ion o mice ed a high- a die (HFD) supplemen ed wi h an e hanolic ex ac o
he alga (150 o 450 mg/kg/day). Cells we e di e en ia ed in o whi e adipocy es, and highe p o ein
exp ession o PR domain con aining 16 (PRDM16) and uncoupling p o ein 1 (UCP1) was de ec ed in
he adipose p ima y cells. The exp ession o pe oxisome p oli e a o -ac i a ed ecep o gamma
coac i a o 1-alpha (PGC1α) was up egula ed only by he highe dose.
Using Phaeodac ylum ico nu um, a dia om mic oalga ich in eicosapen anoic acid (EPA) and he
ca o enoid ucoxan hin, Koo e al. [10] aimed o e alua e he an i-obesi y e ec o a comme cially
a ailable ex ac , con aining 3.5–6% ucoxan hin (w/w), on lipid accumula ion in 3T3-L1 adipocy es.
The cells we e cul u ed du ing he di e en ia ion pe iod o six days wi h he Phaeodac ylum
ico nu um ex ac (100, 125, 200, 250, and 400 µg/mL), ucoxan hin (ac i e p inciple; 10, 20, and 40
µg/mL) o cu cumin as con ol (20 µg/mL). The mic oalga ex ac educed adipogenesis in 3T3-L1
p eadipocy es a a concen a ion o 250 µg/mL, and consequen ly educed cellula lipid accumula ion
was obse ed. When looking a he mechanisms unde lying his e ec , he au ho s epo ed ha
al hough no changes we e obse ed in he p o ein exp ession o he adipogenic ac o C/EBPα,
Phaeodac ylum ico nu um ex ac dec eased PPARγ p o ein exp ession and inc eased ha o UCP1,
mainly a he highes dose (400 µg/mL). The e o e, he au ho s concluded ha Phaeodac ylum
In . J. Mol. Sci. 2020, 21, 41 7 o 21
ico nu um ex ac exhibi s an i-obesi y e ec s by con olling lipid me abolism h ough PPARγ and
UCP1.
Finally, Gille e al. [11] incuba ed 3T3-L1 cells on day 7 o di e en ia ion wi h an e hanolic ex ac
o he same mic oalga, a a dose o 100 mg/L o 24 h. Mo eo e , hey also es ed i s bioac i e
compound ucoxan hin a a concen a ion o 5 µM. Acco ding o he au ho s, each 100 mg/L o he
mic oalga con ained 3.6 µM o ucoxan hin. Rega ding he mic oalga e ec , he au ho s did no
app ecia e signi ican e ec s on lipid con en o cell oxici y, al hough clus e o di e en ia ion 36
(Cd36) and ca ni ine palmi oyl ans e ase 1a (Cp 1a) mRNA le els we e signi ican ly inc eased.
Fu he mo e, Cp 1a gene exp ession was simila ly induced by ucoxan hin incuba ion. Consequen ly,
i can be p oposed ha he e ec o he mic oalga ex ac on Cp 1a exp ession we e due, a leas in
pa , o i s ucoxan hin con en .
3. Animal S udies
S udies using animal models and di e en expe imen al app oaches o analyze he po en ial
an i-obesi y e ec o mic oalgae ha e e ealed bene icial e ec s on body weigh managemen and
ene gy me abolism (Table 2; Figu e 2).
In . J. Mol. Sci. 2020, 21, 41 8 o 21
Table 2. E ec s o mic oalgae in animal s udies.
Re e ence
Numbe s
Animal
Model
Mic oalgae and Doses Expe imen al Design E ec s Mechanisms
[9]
Male ICR
mice (4 weeks
old)
Spi ulina maxima ex ac
(SM70EE; 150 and 450
mg/kg BW/day)
6 weeks
HFD: high- a die
(60% o ene gy om
a )
SM150: HFD + SM70EE
150 mg/kg BW/day
SM450: HFD + SM70EE
450 mg/kg BW/day
SM450 g oup:
↑ Se um HDL-c
SM150 and SM450 g oups:
↓ Final body weigh
↓ Body weigh gain
↓ Subcu aneous and abdominal
WAT
↓ Se um TG, TC, LDL-c and
glucose le els
↓ Adipogenesis in WAT
SM450 g oup:
↑ pAMPK, PRDM16 and
PGC1α p o ein exp ession in
WAT
↑ UCP1 p o ein exp ession in
BAT
SM150 and SM450 g oups:
↓ C/EBPα, PPARγ, and aP2
p o ein exp ession in WAT
↑ UCP1 p o ein exp ession in
WAT
↑ PRDM16 p o ein exp ession
in BAT
[13]
Male
Sp ague-
Dawley a s
(5 weeks old)
Spi ulina maxima
(62.5, 125, and 250 mg/kg
BW/day)
4 weeks
LFD: low- a die (10%
o ene gy om a )
HFD: high- a die
(60% o ene gy om
a )
SM 62.5: HFD + 62.5
mg/kg BW/day
SM 125: HFD + 125
mg/kg BW/day
SM 250: HFD + 250
mg/kg BW/day o
SM 62.5, 125, and 250 SM g oups:
↓ Epididymal adipocy e size
↑ B own adipose issue index
↑ Se um adiponec in
↓ Se um TNF-α
↓ HOMA-IR
↑ Se um HDL-c/TC
↓ Se um ALT
SM 125 and SM 250 g oups:
↓ Body weigh gain
↑ B own adipose issue
↓ Se um lep in
↓ Se um insulin
↓ Se um TC
SM 250 g oup:
↓ Epididymal adipose issue index
↓ Se um glucose
SM 125 and SM 250 g oups:
↓ FAS p o ein exp ession
(epididymal AT)
↓ Fasn gene exp ession
(epididymal AT)
↑ AdipoR gene exp ession
(epididymal AT)
↑ pAMPK p o ein exp ession
(epididymal AT and skele al
muscle)
↑ AdipoR1, Cp 1 and Ucp2
gene exp ession (skele al
muscle)
↓ S eb 1 and N κβ gene
exp ession (epididymal AT)
SM 250 g oup:
↑ A gl and Cp 1 gene
exp ession (epididymal AT)
The dose is no speci ied:
In . J. Mol. Sci. 2020, 21, 41 9 o 21
↑
pACC, AdipoR1, NAMPT,
and SIRT1 p o ein exp ession
(epididymal AT)
↓ SREBP1 and FAS p o ein
exp ession (epididymal AT)
↑ AdipoR1, NAMPT and
SIRT1 p o ein exp ession
(skele al muscle)
[11]
Male
C75BL/6J
mice
(6–8 weeks
old)
Phaeodac ylum ico nu um
(PE) ex ac
(100 and 300 mg/kg
BW/day)
26 days
HFD: high- a die 45%
o ene gy om a )
PE100: HFD + PE 100
mg/kg BW/day
PE300: HFD + PE 300
mg/kg BW/day
PE300 g oup:
↓ Final body weigh
↓ To al body a mass
↓ Epididymal and inguinal issue
↓ Adiposi y index
↑ Ene gy expendi u e
PE100 and PE300 g oup:
↑ % o small adipocy es in
inguinal WAT
PE100 g oup:
↑Cd36 and Ppa gc1a gene
exp ession in BAT
PE300 g oup:
↓Lipe, Plin1, and Lpl gene
exp ession in epididymal
WAT
↑Ucp1 and Cp gene
exp ession in inguinal WAT
↑BAT ac i a ion
PE100 and PE300 g oup:
↓Lipe and Fasn gene
exp ession in BAT
↑UCP1 p o ein exp ession in
BAT
[10]
Female
C57BL/6J
mice
(8 weeks old)
Phaeodac ylum ico nu um
(PE) ex ac
(0.81, 1.62, and 3.25 mg/kg
BW/day)
6 weeks
HFD: High- a die
PE-L: HFD + PE
0.81 mg/kg BW/day
PE-M: HFD + PE 1.62
mg/kg BW/day
PE-H: HFD + PE 3.25
mg/kg BW/day
PE-H g oup:
↓ Plasma LDL-c
PE-M g oup:
↓ Plasma TG
PE-M and PE-H g oups:
↓ Subcu aneous a olume
PE-L, PE-M and PE-H g oups:
↓ Body weigh gain
↓ inguinal a depo s
↓ To al and abdominal a
olume
PE-H g oup:
↓ C/EBPα p o ein exp ession
in WAT
PE-M and PE-H g oups:
↑ UCP1 p o ein exp ession in
WAT
PE-L, PE-M, and PE-H
g oups:
PPARγ p o ein exp ession in
WAT
In . J. Mol. Sci. 2020, 21, 41 16 o 21
Table 3. E ec s o mic oalgae in clinical s udies.
Re e ence
Numbe s
Pa icipan s
Mic oalgae and
Doses
Expe imen al Design E ec s
[17]
52 seden a y young men (26 ±
5 yea s) wi h BMI ≥ 25 kg/m2
27 subjec s wi h o e weigh
and 25 subjec s wi h obesi y
A h ospi a
(Spi ulina) maxima
4.5 g/day
Two in e en ion g oups:
Sm: S. maxima supplemen a ion
C: Con ol (Placebo)
Du a ion: 6 weeks + 2 weeks o wash-ou + 6
weeks (c osso e o he supplemen a ion
in e en ions)
In a-g oup (p e ea men
s. pos ) compa isons (Sm):
↓TC and TG: only in subjec s
wi h dyslipidemia.
LDL-c: no changes
↑ HDL-c: only in in subjec s
wi h dyslipidemia.
In e -g oup compa isons
(Sm s. C):
↓TC: only in in subjec s wi h
obesi y.
TG: no changes
↓ LDL-c: in in subjec s wi h
o e weigh , obesi y o
dyslipidemia.
HDL-c: no changes
↓ BMI: in subjec s wi h
obesi y o dyslipidemia.
[18]
50 pa ien s (25 women and 25
men, 25–60 yea s old)
wi h obesi y (BMI ≥ 30 kg/m2)
and well-con olled
hype ension
A h ospi a
pla ensis
Fou -daily dosage
o 500 mg each
Two in e en ion g oups:
Placebo
Spi ulina
Du a ion: 12 weeks
E ec s s. placebo:
↓ BMI and wais
ci cum e ence
↓ Se um TC, LDL-c, glucose,
and insulin
↑ To al an ioxidan s a e
[19]
56 indi iduals wi h obesi y
(20–50 yea s old) wi h BMI ≥ 30
kg/m2
A h ospi a
pla ensis
Twice-daily
dosage o 500 mg
each
Two in e en ion g oups:
In e en ion g oup: supplemen a ion o S.
pla ensis in a dosage o 500 mg wice a day
o e 12 weeks
Con ol g oup: wo pills o placebo daily o e
12 weeks.
↓ BMI (↓ BW)
↓ TC
TG: no changes
LDL-c: no changes
HDL-c: no changes
VEGF: no changes
↓ Appe i e
In . J. Mol. Sci. 2020, 21, 41 17 o 21
[20]
52 subjec s wi h o e weigh o
obesi y wi h BMI be ween 25
and 40 kg/m2
Spi ulina pla ensis
Fou -daily dosage
o 500 mg/day
Two in e en ion g oups
In e en ion SP g oup: supplemen a ion o SP
ex ac ( ou able s pe day) o 12 weeks wi h
a es ic ed calo ie die
Placebo g oup:
placebo ex ac ( ou able s pe day) o
12 weeks wi h a es ic ed calo ie die
↓ Body weigh
↓ Wais ci cum e ence
↑ Body a educ ion
↓ Plasma TG, LDL-c
↓ LDL-c/HDL-c a io
Special no e: Do ed lines inco po a ed o sepa a ion be ween di e en s udies. BMI: body mass index; BW: body weigh ; C: con ol (Placebo); HDL-c: high densi y
lipop o ein -choles e ol; LDL-c: low densi y lipop o ein-choles e ol; Sm: Spi ulina wi hou exe cise; TC: o al choles e ol; TG: iglyce ides; VEGF: ascula
endo helial g ow h ac o . ↑ signi ican inc ease, ↓: signi ican dec ease.
In . J. Mol. Sci. 2020, 21, 41 18 o 21
The esul s showed a signi ican dec ease in TC and TG along wi h a signi ican inc ease in HDL-
choles e ol in he Sm g oup a e ea men , when compa ed wi h he basal le els. These changes
we e obse ed only among dyslipidemic subjec s. Howe e , LDL-choles e ol showed no change. In
addi ion, he au ho s compa ed he a ia ion o each pa ame e be ween bo h expe imen al g oups
and obse ed ha plasma TC le el dec eased signi ican ly in obese subjec s in he Sm ea men , and
LDL-choles e ol was lowe in o e weigh , obese, and dyslipidemic subjec s en olled in he Sm
ea men , when compa ed o hose in he placebo g oup. By con as , TG and HDL-choles e ol le els
we e no modi ied. As a as BMI is conce ned, a signi ican educ ion was only obse ed in obese
and dyslipidemic subjec s a e ea men . These esul s sugges ha Spi ulina maxima
supplemen a ion esul s in a pa ial imp o emen o blood lipid p o ile and BMI in men wi h excess
body weigh and dyslipidemia.
Using he same mic oalga, Szulinska e al. [18] ca ied ou a andomized, double-blind, placebo-
con olled ial add essed on 25–60 yea old indi iduals wi h obesi y (BMI ≥ 30 kg/m2), wi h well-
con olled hype ension and wi hou o he como bidi ies. Pa icipan s we e di ided in o wo
expe imen al g oups: placebo g oup ( ou capsules pe day o mic oc ys alline cellulose o e 3
mon hs) and spi ulina g oup ( ou capsules pe day o Hawaiian Spi ulina o e 3 mon hs). Each
spi ulina capsule con ained 0.5 g o Spi ulina maxima. A he end o he expe imen al pe iod, spi ulina
g oup showed lowe BMI, wais ci cum e ence, se um TC, LDL-choles e ol, glucose and insulin and
o al an ioxidan s a e han he placebo g oup. No di e ences in se um HDL-choles e ol and TG we e
obse ed be ween g oups.
In ano he andomized doubled-blind, placebo-con olled ial conduc ed by Zeinalian e al.
[19], he e ec o Spi ulina pla ensis supplemen a ion on BMI, se um lipids, appe i e, and se um
ascula endo helial g ow h ac o (VEGF) was s udied. Indi iduals wi h obesi y we e di ided in o
wo g oups, he placebo g oup and he g oup ha ecei ed Spi ulina pla ensis wice daily (500 mg
each dose). A e 12 weeks o in e en ion, a dec ease in body weigh , and hus in BMI, was obse ed,
along wi h a educ ion appe i e in he g oup ea ed wi h Spi ulina pla ensis. Wi h ega d o se um
lipids, he only change was a signi ican educ ion in TC, while LDL-choles e ol and TG emained
unchanged a e he in e en ion. Despi e a signi ican inc ease in HDL-choles e ol in bo h ea ed
and placebo g oups a he end o he expe imen al pe iod, he e was no change in he mean
di e ences be ween he wo g oups. VEGF is an impo an angiogenic ac o implica ed in no mal
and pa hological essel o ma ion ha can be an impo an bioma ke o obesi y and obesi y- ela ed
cance p og ession. In his s udy, VEGF emained unchanged a e ea men wi h Spi ulina pla ensis.
The au ho s concluded ha a dose o 1 g/day o Spi ulina pla ensis o 12 weeks had bene icial e ec s
modula ing body weigh and appe i e, while i only modi ied he se um lipid p o ile pa ially.
Spi ulina pla ensis was also used in a andomized, double-blinded, placebo-con olled clinical
ial epo ed by Youse i e al. [20]. Obese o o e weigh subjec s (BMI: 25–40 kg/m2) we e dis ibu ed
in o wo g oups, a placebo and a Spi ulina pla ensis- ea ed g oup, who ollowed a es ic ed calo ie
die o 12 weeks. The mic oalga was adminis e ed in ou able s o 500 mg/capsule daily. A he end
o he in e en ion, body weigh and wais ci cum e ence we e educed in he mic oalga-
supplemen ed g oup compa ed o he con ol g oup. Mo eo e , in his g oup body a educ ion was
highe han ha obse ed in he placebo g oup. Rega ding plasma pa ame e s, TG, LDL-choles e ol,
and he LDL/HDL a io we e educed a he end o he ea men pe iod compa ed wi h he baseline
in he mic oalga- ea ed g oup. Based on hese esul s, he au ho s sugges ed ha Spi ulina pla ensis
could be a use ul as a complemen a y he apy o educe weigh and TG le els.
5. Concluding Rema ks
Da a epo ed in he li e a u e, and ga he ed in he p esen e iew, show ha he e is scien i ic
e idence suppo ing he an i-obesi y e ec o se e al mic oalgae: Euglena g acilis, Phaeodac ylum
ico nu um, Spi ulina maxima, Spi ulina pla ensis, and Ni zschia lae is. Wi h he excep ion o one s udy,
he published wo ks ca ied ou in animal models ha e add essed he e ec s o mic oalgae in animals
submi ed o an obesogenic eeding pa e n. Consequen ly, he esul s ha e shown he abili y o
mic oalgae o o al o pa ially p e en obesi y de elopmen associa ed o his die a y pa e n.
In . J. Mol. Sci. 2020, 21, 41 19 o 21
P eclinical s udies ha e e ealed some o he mechanisms o ac ion unde lying his e ec .
Depending on he species and concen a ion, mic oalgae can inhibi p e-adipocy e di e en ia ion,
hus educing he numbe o ma u e adipocy es eady o accumula e TG. Mo eo e , hey educe de
no o lipogenesis and TG assembly, hus limi ing he amoun o TG o be s o ed. An inc ease in
lipolysis and a y acid oxida ion can also be obse ed. Finally, mic oalgae can induce an inc ease in
ene gy expendi u e ia he mogenesis ac i a ion in b own adipose issue, as well as by inducing
b owning in whi e adipose issue. I could be hough ha a po en ial oxic e ec o some cons i uen
common in mic oalgae could be esponsible, a leas in pa , o he educed lipid e en ion and
weigh educ ion. Howe e , his possibili y can be disca ded because in i o s udies ha e shown no
cy o oxici y o mic oalgae ex ac s in a wide ange o doses. In pa allel wi h he educ ion in body a
accumula ion, o he ea u es which a e ypical o indi iduals wi h obesi y, such as enhanced plasma
lipid le els, insulin esis ance o diabe es, and low-g ade in lamma ion, a e also imp o ed by
mic oalgae ea men .
The an i-obesi y e ec o mic oalgae, as well as he imp o emen o se e al como bidi ies
obse ed in p eclinical s udies, has been con i med in clinical ials. In his case, due o he
expe imen al design cha ac e is ics, he ole o mic oalgae in obesi y ea men , a he han in obesi y
p e en ion, has been e idenced.
Conce ning he limi a ions o he epo ed s udies, i should be poin ed ou ha mo e esea ch
is needed o de e mine which bioac i e compounds, p esen in mic oalgae, a e esponsible o hei
an i-obesi y e ec s, as well as o look o po en ial syne gies among hem. In addi ion, al hough
se e al mechanisms ha e been p oposed o explain he an i-obesi y e ec s o mic oalgae, u he
s udies a e needed in o de o gain mo e insigh conce ning his issue. Fo ins ance, in se e al s udies
inc eased exp ession o genes ela ed o he mogenesis has been ound, sugges ing he ac i a ion o
his p ocess, bu addi ional s udies a e needed o con i m ha in ac he mogenesis, and
consequen ly ene gy expendi u e, a e inc eased.
Au ho con ibu ions: Concep ualiza ion, S.G.-Z. and J.T.; W i ing—O iginal D a P epa a ion, S.G.-Z., J.T.,
M.G.-A., L.A., I.M.-L., M.G., I.E. and A.F.-Q.; W i ing—Re iew and Edi ing, M.P.P., S.G.-Z., I.E. and A.F.-Q.;
P ojec Adminis a ion, M.P.P.; Funding Acquisi ion, M.P.P. and A.F.-Q. All au ho s ha e ead and ag eed o
he published e sion o he manusc ip .
Funding: This s udy was suppo ed by g an s om he Go e nmen o he Basque Coun y (ELKARTEK) unde
g an KK-2019/00031, Ins i u o de Salud Ca los III (CIBERobn) unde G an CB12/03/30007, and Uni e si y o
he Basque Coun y unde G an GIU18-173.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
Abb e ia ions
ACC
acyl-CoA ca boxylase
AdipoR1
adiponec in ecep o
ALT
alanine amino ans e ase
Ap2
a y acid binding p o ein
ATGL
adipose iglyce ide lipase
AUC
a ea unde he cu e
BAT
b own adipose issue
BMI
body mass index
CLS
c own-like s uc u es
C/EBPα
CCAAT-enhance -binding p o ein α
CD36
clus e o di e en ia ion 36
CPT1a
ca ni ine palmi oyl ans e ase 1a
CREB
cAMP egula o y elemen -binding p o ein
DGAT1
diacylglyce ol acyl ans e ase-1
EPA
eicosapen anoic acid
FABP4
a y acid binding p o ein 4
FAS
a y acid syn hase
In . J. Mol. Sci. 2020, 21, 41 20 o 21
G6PDH
glucose-6-phospha e dehyd ogenase
hASCs
human adipose-de i ed s em cells
HDL
high-densi y lipop o ein
HFD
high- a die
HOMA-IR
Homeos a ic Model Assessmen o Insulin Resis ance
HSL
ho mone sensi i e lipase
LDL
low-densi y lipop o ein
LPAATβ
lysophospha idic acid acyl ans e ase β
LPL
lipop o ein lipase
MAC-2
mac ophage ma ke galec in-3
ME
malic enzyme
MEST
mesode m-speci ic ansc ip homolog p o ein
NAMPT
nico inamide phospho ibosyl ans e ase
ND
no mal die
NFκΒ
nuclea ac o κΒ
pAMPK
5’ AMP-ac i a ed p o ein kinase
Plin1
pe ilipin 1
PGC1α
pe oxisome p oli e a o -ac i a ed ecep o gamma coac i a o 1-alpha
PPAR γ
pe oxisome p oli e a o -ac i a ed ecep o γ
PRDM16
PR domain con aining 16
SIRT1
si uin 1
SREBP1c
s e ol egula o y elemen -binding ansc ip ion ac o 1c
TC
o al choles e ol
TG
iglyce ide
UCP1
uncoupling p o ein 1
VEGF
ascula endo helial g ow h ac o
WAT
whi e adipose issue
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