. 2020 Sep 30;18(10):501. doi: 10.3390/md18100501

Table 2.

Phenolic compounds found in brown seaweeds.

Seaweed Extraction Chemical Analysis	Compounds Antioxidant Activity (When Provided)	Ref.
A. nodosum, F. spiralis MeOH, AC, Hexane UPLC, MS, NMR	Phlorotannins (4–6, 9–12 PGU)	[107]
A. nodosum, Fucus spiralis, F. vesiculosus, Pelvetia canaliculata, Saccharina longicruris MeOH, W UPLC, HRMS	Phlorotannins (3–50 PGU)	[108]
Carpophyllum flexuosum, Carpophyllum plumosum, Ecklonia radiata W, MAE HPLC-DAD-ESI-MS, NMR	Bifuhalol, bifuhalol dimer, bifuhalol trimer, hydroxytrifuhalol, trifuhalol, tetrafuhalol DPPH = 2.7–37.4 mg GAE/g; FRAP = 4.4–62.1 mg GAE/g	[109]
Cystoseira barbata TFA, W LC-QTOF-MS	Phloroglucinol, rutin, phlorofucofuroeckol, 3-O-rutinosyl-kaempferol, catechin-catechin-O-gallate, gallocatechin, gallocatechin-O-glucuronide, 1-hydroxy-2-(β-d-glucopyranosyloxy)-9,10 anthraquinone, 2-O-(6,9,12-octadecatrienoyl)-3-O-(nonadecanoyl)glyceryl β-galactopyranoside, chlorogenic acid butyl ester, phloroglucinol, quercetin EC_{50, DPPH} = 11.7 µg/mL; EC_{50, OH} = 11.4 µg/mL; EC_{50, RP} = 51 g/mL; EC_{50, CA} = 40 g/mL	[110]
C. barbata AC, MeOH, W UHPLC-DAD-QTOF-MS	Fucophlorethol and eckol derivatives (3–7 PGU) EC_{50, DPPH} = 14 µg/mL; EC_{50, ABTS} = 0.5 µM Trolox; EC_{50, RP} = 16–35 µg/mL	[111]
Cystoseira nodicaulis, Cystoseira tamariscifolia, Cystoseira usneoides, F. spiralis AC, Hexane, W HPLC-DAD-ESI-MSⁿ	Fucophloroethol, fucodiphloroethol, fucotriphloroethol, 7-phloroeckol, phlorofucofuroeckol, bieckol, dieckol EC_{50, SRSA} = 0.93–4.02 mg/mL; EC_{50, LPIA} = 2.32–>9.1 mg/mL	[96]
Cystoseira nodicaulis, F. serratus, F. vesiculosus, Himanthalia elongata EtOH, W UPLC-ESI-MS	Phlorotannin (3–16 PGU) EC_{50, DPPH} = 4–28 μg/mL; FRAP = 101–307 μg TE/mg	[21]
Durvillaea antarctica, Lessonia spicata EtOH, EE, EtOAc, W HPLC-MS-MRM	Phlorotannin (3–8 PGU), flavonoids EC_{50, DPPH} = 0.97–1.24 mg/mL; FRAP = 2.95–6.20 mM TE/kg; ORAC = 4.75–25.9 μM TE/g	[112]
Eisenia bicyclis EtOH HPLC-PDA	Eckol, phlorofucofuroeckol-A, dieckol, 6,6′-bieckol, 8,8′-bieckol	[113]
Ecklonia cava EtOH UPLC-PDA	Phloroglucinol, eckol, eckstolonol, triphlorethol-A, dieckol	[114]
E. cava EtOH, US HPLC-DAD-ESI/MS, NMR	Dieckol, phlorofucofuroeckol-A, 2,7-phloroglucinol-6,6-bieckol, pyrogallol-phloroglucinol-6,6-bieckol	[115]
E. cava EtOH, W RP-HPLC	Dieckol ABTS = 1.3 g VCE/g; DPPH = 0.4 g VCE/g	[116]
Ecklonia stolonifera EtOH, W HPLC-PDA, NMR	2-phloroeckol, dioxinodehydroeckol, eckol, phlorofucofuroeckol B, 6,6’-bieckol, dieckol, 974-B, phlorofucofuroeckol A	[117]
F. vesiculosus MeOH, W Q-ToF-MS, UPLC-TQD-MS/MS-MRM	Phlorotannins (3–18 PGU) EC_{50, DPPH} = 18.2 μg/mL	[118]
F. vesiculosus AC, EtOAc, EtOH, MeOH, W HPLC-DAD-ESI/MSⁿ	Fucodiphlorethol A, trifucodiphlorethol isomers, phlorotannins (3–10 PGU) EC_{50, DPPH} = 2.79–4.23 μg/mL; Fe²⁺-CA = 25.1–47.6%; RP = 17.8–910.7 mg ASEs/g	[119]
F. vesiculosus AC, W UPLC-DAD-ESI/MSⁿ	Fucols, fucophlorethols, fuhalols, phlorotannin derivatives (3–22 PGU), fucofurodiphlorethol, fucofurotriphlorethol, fucofuropentaphlorethol	[120]
Halidrys siliquosa AC, W MALDI-TOF-MS, NMR	Diphlorethol, triphlorethol, trifuhalol, tetrafuhalol EC_{50, DPPH} = 0.02–1.00 mg/mL; EC_{50, RP} = 0.06–0.62 mg/mL; EC_{50, NBT} = 0.66–2.44 mg/mL; ORAC = 5.39 μmol TE/mg; BCB = 0.21–1.50 g/mL	[121]
H. elongata MeOH, W HPLC-DAD, HPLC-ESI-MS/MS	Phloroglucinol, gallic acid, chlorogenic acid, caffeic acid, ferulic acid, hydroxybenzaldehyde, kaempferol, myricetin, quercetin EC_{50, DPPH} = 14.5 μg/mL	[20]
Hydroclathrus clathratus, Padina minor, Padina sp., Sargassum oligosystum, Sargassum aff. bataanens, Sargassum sp. MeOH, W GC-MS-EI-SIM	2,4,6-tribromophenol; 2,4,6-tribromoanisol; 2′-hydroxy-2,3′,4,5′- tetrabromodiphenyl ether; 2’-methoxy-2,3′,4,5′-tetrabromodiphenyl ether; 6-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether; 6-methoxy-2,2′,4,4′- tetrabromodiphenyl ether; 2′,6-dihydroxy-2,3′,4,5′-tetrabomodiphenyl ether; 2′,6-dimethoxy-2,3′,4,5′-tetrabromodiphenyl ether; 2,2′-dihydroxy- 3,3′,5,5′-tetrabromodiphenyl; 2,2′-dimethoxy-3,3′,5,5′-tetrabromodiphenyl	[122]
L. digitata MeOH, W RP-UPLC-UV-MSⁿ, MALDI-TOF-MS, NMR	Di–fuhalols (6–7 PGU), fucols (3–7 PGU), fucophlorethols (3–16 PGU), fuhalols (4–5 PGU), phlorethols (3–18 PGU)	[123]
Leathesia nana CH₂Cl₂, EtOH, W HRESIMS, NMR	2,2′,3,3′-tetrabromo-4,4′,5,5′-tetrahydroxydiphenylmethane; 3-bromo-4- (2,3-dibromo-4,5-dihydroxybenzyl)-5-methoxymethylpyrocatechol; 2,3,3′-tribromo-4,4′,5,5′-tetrahydroxyl-1′-ethyloxymethyldiphenyl methane; 2,3-dibromo-4,5-dihydroxybenzaldehyde; 2,3-dibromo-4,5- dihydroxybenzyl alcohol; 2,3-dibromo-4,5-dihydroxybenzyl methyl ether; 2,3-dibromo- 4,5-dihydroxybenzyl ethyl ether; 3,5-dibromo-4-hydroxybenzaldehyde; 3,5-dibromo-4-hydroxybenzoic acid; 3-bromo-4,5-dihydroxybenzoic acid methyl ester, 3-bromo-5-hydroxy-4-methoxybenzoic acid, 3-bromo-4-hydroxybenzoic acid EC_{50, DPPH} = 14.5 µg/mL	[124]
Lessonia trabeculate MeOH, W, MWE HPLC-DAD-ESI-MS/MS	Phlorotannins derivatives (2–3 PGU), gallocatechin derivative, p-coumaric acid derivative	[103]
Padina tetrastromatica PE, MeOH, CHCl₃, MEK, Soxhlet HPLC-UV, UPLC-MS/MS	Fucophlorethol (2–18 PGU) EC_{50, DPPH} = 17 µg/mL	[125]
Sargassum fusiforme EtOH, W UPLC-DAD-ESI-MS/MS	Eckol, dieckol, dioxinodehydroeckol, fuhalols (2–12 PGU), phlorethols/fucols/fucophlorethols (2–11 PGU), eckols (2–8 PGU) EC_{50, DPPH} = 15–150 µg/mL; FRAP = 1.29 mg TE/mg	[126]
Sargassum muticum EtOH, W, PHLE LC × LC-DAD-ESI-MS/MS	Decafuhalol, dihydroxytetrafuhalol, dihydroxypentafuhalol, dihydroxyhexafuhalol, dihydroxyheptafuhalol, dihydroxyoctafuhalol, dihydroxynonafuhalol, heptaphlorethol, hexafuhalol, hexaphlorethol, hydroxytetrafuhalol, hydroxypentafuhalol, hydroxyhexafuhalol, nonafuhalol, octafuhalol, pentafuhalol, pentaphlorethol, tetrafuhalol, trifuhalol, trihydroxyhexafuhalol, trihydroxyheptafuhalol, trihydroxyoctafuhalol ABTS = 0.65–2.29 mmol TE/g	[127]
Silvetia compressa EtOH, US HPLC-DAD, HPLC-TOF-MS	Dihydroxytetrafuhalol, dieckol, eckol derivative, eckstolonol, 7-phloroeckol (3 PGU), dihydroxypentafuhalol, phlorofucofuroeckol A, pentafuhalol, trifuhalol	[128]

ABTS: 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid); AC: acetone; ASE: ascorbic acid equivalents; BCBM: β-carotene bleaching; CA: chelating ability; DPPH: 2,2-diphenyl-1-picrylhydrazyl; EE: ethyl ether; EI-SIM: electron ionization selected ion monitoring mode; EtOAc: ethyl acetate; EtOH: ethanol; FRAP: ferric reducing antioxidant power; LC × LC: two-dimensional liquid chromatography; LPIA: Lipid peroxidation inhibition assay; MALDI-TOF: matrix-assisted laser desorption/ionization time-of-flight; MEK: methyl ethyl ketone; MeOH: methanol; MRM: multiple reaction monitoring; MWE: microwave-assisted extraction; NBT: superoxide anion scavenging test; ORAC: oxygen radical absorbance capacity; PDA: photodiode array; PGU: phloroglucinol units; PHLE: pressurized hot liquid extraction; RP: reducing power; RP-UPLC: reversed phase UPLC; SRSA: superoxide radical scavenging assay [96]; TE: trolox equivalents; TEAC: trolox equivalent antioxidant capacity; TFA: trifluoroacetic acid; TQD-MS: tandem quadrupole mass spectrometer; US: ultrasound; W: water.