Ameliorative Effect of Laminarials Brown Algae Distributed in Korea on Diabetic Zebrafish Models for Type 1 and 2

Phlorotannins, belonging to a special class of natural polyphenols, are isolated from several Laminariales brown algae. Phlorotannins have been reported to show various biological activities, such as anti-inflammatory, hepatoprotective, anti-diabetic, antioxidative and anticancer activities [1]. Ten Laminariales brown algae were collected in Korea. We evaluated the anti-diabetic activity of the extracts from the algae in zebrafish models for type 1 and 2 diabetes. Type 1 diabetes zebrafish model was induced by alloxan, which cause pancreatic β-cell necrosis [2]. Type 2 diabetes zebrafish model was induced by insulin. Exposure to excess insulin can induce insulin resistance typical of type 2 diabetes [3]. Following alloxan or insulin treatment, pancreatic islet size and fluorescence intensity were measured. Most of the extracts showed potent anti-diabetic activities for type 1 and 2. Among ten Laminariales algae, Saccharina japonica and Agarum clathratum subsp. yakishiriense revealed the strongest ameliorative effect on pancreatic islet damage in zebrafish for type 1 and 2 diabetic models, respectively. The extracts were investigated inhibitory activities on α-glucosidase, PTP1B and DPP-4. PTP1B and α-glucosidase were significantly inhibited by Eisenia bicyclis, A. clathratum subsp. yakishiriense, Ecklonia kurome, E. stolonifera and E. cava.

This work was supported by a grant from Marine Biotechnology Program (PJT200620, Genome Analysis of Marine Organisms and Development of Functional Applications) funded by Ministry of Oceans and Fisheries.

[1] Kwak JH et al. Chem Commun 2014; 50: 13045 – 13048

[2] Desgraz R et al. Trends Endocrin Met 2011; 22: 34 – 43

[3] Yang X et al. J Endocrinol 2014; 221: 469 – 480