Antidiabetic and Antioxidant Effects of Polyphenols in Brown Alga Ecklonia stolonifera in Genetically Diabetic KK-Ay Mice

Abstract

The dietary intake and control of blood glucose levels are very important in hyperglycemic patients and alpha-glucosidase inhibitors are a cost-effective means to preventing the progression of diabetes. In search of a natural inhibitor from food materials, alpha-glucosidase inhibitory activity and the anti-hyperglycemic effects of a brown alga, Ecklonia stolonifera, were investigated using non-insulin dependent diabetic mice. Methanolic extract of E. stolonifera (MEE), which contains a high content of polyphenols, showed strong inhibition of alpha-glucosidase in vitro. Male KK-A(y) mice, a genetically non-insulin dependent diabetic model, showed hyperglycemia with aging, but the ingestion of MEE suppressed the increase in plasma glucose and lipid peroxidation levels in unfasted KK-A(y) mice dose dependently. In KK-A(y) mice, which were fed the MEE diet for 4 weeks, MEE moderated the elevation of plasma glucose levels after the oral administration of maltose. The polyphenols in MEE were estimated to be phlorotannins by HPLC-PDA and LC/MS analyses. These results demonstrate that E. stolonifera, seaweed typically used as a health food, has strong antidiabetic and antioxidant effects in vivo, thus, it may have beneficial properties in the prevention of diabetes and could be useful in the development of an antidiabetic pharmaceutical and functional food.

Anticancer effects of seaweed compounds fucoxanthin and phloroglucinol, alone and in combination with 5-fluorouracil in colon cells

“…Another important compound found in macroalgae is carotenoids, which are essential components in photosynthesis and exhibit a powerful antioxidant activity (Takaichi, 2011). Polyphenols, also designated by phlorotannins, known as effective antioxidants are found as well in macroalgae, especially in brown algae (Iwai, 2008). Iodine, calcium, phosphorous, magnesium, iron, sodium, potassium and chlorine are the main mineral elements presents and they are accountable for several macroalgae health benefits.…”

Protein Tyrosine Phosphatase 1B and α-Glucosidase Inhibitory Phlorotannins from Edible Brown Algae,Ecklonia stoloniferaandEisenia bicyclis

“…17) Phlorotannins are secondary metabolites polymerizing phloroglucinol (1,3,5-trihydroxybenzene) through an ether, phenyl, or 1,4-dibenzodioxin linkage. These polyphenolic compounds are responsible for a variety of bioactivities, including anti-diabetic complications, 17,18) and antitumorial, 19) hepatoprotective, 20) anti-plasmin inhibiting, 21) algicidal, 22) tyrosinase inhibiting, 23) antiinflammatory, 24,25) nitrite-scavenging, 26) anti-skin aging, 27,28) antioxidative, [29][30][31] anti-cholinesterase, 32,33) antiAlzheimer, 34) anti-hyperlipidemic, 35) anti-diabetic, [36][37][38][39] anti-allergic, 40) and angiotensin converting enzyme-I inhibitory activities. 41) As part of our continuous search for antidiabetic agents from natural sources, we investigated the MeOH extract and solvent-soluble fractions of the two selected brown algae, E. stolonifera and E. bicyclis, together with six isolated phlorotannins against -glucosidase and PTP1B.…”

Hepatoprotection by chemical constituents of the marine brown algaSpatoglossum variabile: A relation to free radical scavenging potential

“…They are also reported to be rich sources of bioactive natural substances with antioxidant and hepatoprotective potential. Some bioactive metabolites from seaweeds, such as sulfated polysaccharides, have antiviral activity, and other metabolites such as Kahalalide F from Bryopsis species are possible drug candidates for the treatment of lung cancer and tumors (Wong et al, 2000;Smit, 2004;Kim et al, 2005;Iwaki, 2008). The hypolipidemic activities of ethanol extracts of Spatoglossum asperum J.Agardh (Dictyoaceae), Solieria robusta (Grev.)…”