Table 2.

Preclinical trials with marine macroalgae-derived anti-diabetic compounds. Adapted with permission from Ref. [118]. Copyright 2018 Elsevier.

Macroalgae	Major Compound	Effects	References
Brown Algae
Pelvetia siliquosa	Fucosterol	Inhibition of blood glucose level and glycogen degradation	[122]
Pelvetia babingtonii	Methanol extract	α-Glucosidase inhibition and suppression of postprandial hyperglycemia	[123]
Ecklonia stolonifera	Polyphenols	α-Glucosidase inhibition; suppression of the increase in plasma glucose	[44]
	Phlorotannins	PTP1B and α-glucosidase inhibition	[131]
	Fucosterol	RLAR, HRAR, PTP1B, α-glucosidase activities, and AGE formation inhibition	[141]
Eisenia bicyclis Ecklonia stolonifera	Dieckol Eckol 7-Phloroeckol Phlorofucofuroeckol-A	α-Glucosidase, and PTP1B	[131]
Ecklonia cava	Dieckol 7-Phloroeckol Phlorofucofuroeckol-A 6,6-Bieckol Fucodiphloroethol-G	Activation of both AMPK and Akt signal pathways; improvement of insulin sensitivity; α-Glucosidase and α-amylase inhibition	[130]
Ecklonia kurome	Phlorotannins	α-Amylase inhibition; amelioration of hyperinsulinemia	[142]
Laminaria japonica	Polysaccharides	Reduced fasting blood glucose; increased the levels of insulin and amylin	[55]
	Butyl-isobutyl-phthalate	α-Glucosidase inhibition	[143]
Sargassum ringgoldianum	Polyphenols	α-Amylase and α-glucosidase inhibition	[144]
Sargassum yezoense	Sargaquinoic acid Sargahydroquinoic acid	Enhances the transcriptional activities of PPARα and PPARγ	[145]
		Amelioration of insulin resistance	[146]
Sargassum wightii	Fucoidan	α-d-glucosidase inhibition	[147]
Sargassum polycystum	Extract	Increasing insulin sensitivity	[117]
Sargassum hemiphyllum	Fucoxanthin	α-Amylase and α-glucosidase inhibition, and insulin release enhancement	[148]
Sargassum thunbergii	Thunberol	PTP1B inhibition	[149]
Sargassum coreanum	Extract	Alteration of the hepatic glucose metabolic enzyme activities and improvement of insulin resistance	[150]
Undaria pinnatifida	Fucoxanthin	HRAR, RLAR, PTP1B inhibition, and AGE formation	[151]
		Improve insulin signaling
Eisenia bicyclis	Phlorotannins	Inhibition of AGEs and α-amylase	[152]
	Fucoxanthin	Inhibition of RLAR, HRAR, PTP1B activities and AGE formation	[151]
	Fucosterol	Inhibition of RLAR, HRAR, PTP1B, α-glucosidase activities, and AGE formation	[141]
Ascophyllum nodosum	PhlorotanninsFucoidan	α-Amylase and α-glucosidase inhibition	[153]
Ishige okamurae	Diphlorethohydroxycarmalol	α-Amylase and α-glucosidase inhibition	[133]
	Extract	Alteraation of the hepatic glucose metabolic enzyme activities, and improvement of insulin resistance	[140]
Ishige foliacea	Octaphlorethol A	Increase in GLUT4-mediated glucose utilization via activation of AMPK in muscle	[154]
Red Algae
Kappaphycus alvarezii, Eucheuma denticulatum	Extract	Inhibitory activity towards α-amylase	[155]
Gracilaria lemaneiformis	Polysaccharide	Inhibitory activity towards α-glucosidase	[156]
Gelidim amansii	Ethanol extract	Significant decrease of plasma glucose	[157,158]
Porphyra yezoensis	Porphyran	Increase of adiponectin levels	[159]
Green Algae
Ulva rigida	Ethanol extract	Regeneration of β-cells and/or potentiate the insulin resistance	[127]
Ulva fasciata	Sulfated polysaccharides	Reduce blood glucose level, and restore hepatic glycogen content	[160]
Ulva lactula	Polysaccharides	α-amylase, maltase, and sucrase inhibition; Delay glucose absorption	[125]