Table 1.

Antidiabetic activity of isolated phlorotannins *.

Compound	Source	Activity	Reference
6,6′-Bieckol	Ecklonia cava Ecklonia bicyclis	α-Glucosidase inhibition AR inhibition Protection against GIOS ↓Glucose-induced β-cells damage	[29,30,31]
8,8′-Bieckol	Ecklonia bicyclis	AR inhibition	[30]
DDBT	Sargassum patens	α-Glucosidase inhibition α-Amylase inhibition	[32]
Dieckol	Ecklonia cava Ecklonia stolonifera Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition ↓ Postprandial hyperglycaemia ↓ Serum insulin ↓ G6P AR inhibition PTP1B inhibition ↑ GLUT4 expression Inhibition of AGEs formation Protection against GIOS ↓Glucose-induced β-cells damage ↑ Glucose uptake Akt up-regulation ↓ C-peptide ↑ Adiponectin	[29,30,33,34,35,36,37,38,39]
Dioxinodehydroeckol	Ecklonia stolonifera Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition AR inhibition	[34,37,40]
Diphlorethohydroxycarmalol	Ishige okamurae	α-Glucosidase inhibition α-Amylase inhibition ↓ Postprandial hyperglycaemia Protection against GIOS ↓Glucose-induced β-cells damage	[41,42]
Eckol	Eisenia bicyclis Ecklonia stolonifera Ecklonia cava	α-Amylase inhibition AR inhibition PTP1B inhibition Inhibition of AGEs formation	[33,34,37]
Fucodiphloroethol-G	Ecklonia cava	α-Glucosidase inhibition	[29]
Fucofuroeckol-A	Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition	[40]
Hydroxybenzodioxin	Eisenia bicyclis	α-Amylase inhibition Inhibition of AGEs formation	[33]
Octaphlorethol-A	Ishige foliacea	α-Glucosidase inhibition ↓ Serum insulin ↓ G6P expression ↓PEPCK expression ↑Glut4 translocation/expression ↓Glucose-induced β-cells damage ↑ AMPK activation ↑ Glucose uptake	[43,44,45,46]
2-Phloroeckol	Ecklonia stolonifera	AR inhibition	[37]
7-Phloroeckol	Ecklonia cava Ecklonia stolonifera Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition AR inhibition PTP1B inhibition Inhibition of AGEs formation	[29,33,34,37]
Phlorofucofuroeckol-A	Ecklonia cava Ecklonia stolonifera Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition ↓ Postprandial hyperglycaemia AR inhibition PTP1B inhibition Inhibition of AGEs formation	[29,30,34,37,47]
Phloroglucinol	Ecklonia stolonifera Eisenia bicyclis	α-Glucosidase inhibition α-Amylase inhibition AR inhibition Inhibition of AGEs formation	[34,37,48,49]

* AGEs: advanced glycation end-products; Akt: protein kinase B; AMPK: AMP-activated protein kinase; AR: aldose reductase; DDBT: 2-(4-(3,5-dihydroxyphenoxy)-3,5-dihydroxyphenoxy) benzene-1,3,5-triol; G6P: glucose-6-phosphatase; GIOS: glucose-induced oxidative stress; GLUT4: glucose transporter 4; PEPCK: phosphoenolpyruvatecarboxykinase; PTP1B: protein tyrosine phosphatase 1B.