Ecklonia cava is a brown algae found abundantly along the coastal areas of Korea and Japan where it is used traditionally for food and medicine. It has a variety of compounds including peptides, polysaccharides, carotenoids, fucoidans and phlorotannins which have been shown to possess antioxidant, antidiabetic (through their acarbose-like activity, stimulation of adipocyte glucose uptake and protection of β-pancreatic cells against high-glucose oxidative stress), anti-allergic, anti-retro-viral, matrix-metalloprotein inhibitory, activities, as well as others (1-5).
Phlorotannins and their metabolic by-products such as eckol, are only found in the marine algae.
A recent study indicated limited small intestinal absorption followed by gut microbial metabolism of the phlorotannins in the large intestine (6). High colonic metabolism seems to occur, following fermentation of phlorotannins in the large intestine, and this may in turn impact bacterial diversity (7).
The potential anti-oxidant activities of three phlorotannins (phloroglucinol, eckol and dieckol) purified from Ecklonia cava were measured against DPPH, alkyl, hydroxyl and superoxide radicals. While all three phlorotannins showed potential inhibitory effects on H202-mediated DNA damage and free radicals, the eckol samples scavenged up to 93%, which was higher than the other phlorotannins (4).
As well as anti-oxidant studies, it has been shown that ethanolic extracts of E. cava inhibit LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production and inhibit inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in BV2 microglia (8).
Results of several studies suggest brown algal phenolic extracts exert anti-inflammatory effects by down-regulating pro-inflammatory genes.
A phlorotannin extract was shown to dose-dependently decrease the LPS-induced expression of TNF-α and IL-6 in U937 macrophages and prevent ROS production in epithelial cells (p<0.05) (9).
The treatment of TNF-α-challenged Caco-2 cells with brown algae extract suppressed the expression of several pro-inflammatory genes encoding cytokines (IL8, TNFA, IL1B, IL18 and CSF1), chemokines (CXCL10, CCL5), components of the NF-κB pathway (NFKB2 and IKBKB) and other mediators (PTGS2 and MIF) by more than two-fold compared to the negative control (10).
1. Li Y., Quian Z. J., Ryu B., et al. (2009). Chemical components and its antioxidant properties in vitro: an edible marine brown alga, Ecklonia cava. Bioorgan Med Chem 17: 1963–1973
2. Shim S. Y., To L.Q., Lee S. H., et al. (2009). Ecklonia cava extract suppresses the high-affinity IgE receptor, FcRIe expression. Food Chem Toxicol 47:555–560.
3. Heo S. J., Jeon Y. J. (2009). Protective effect of fucoxanthin isolated from Sargassum siliquastrum on UV-B induced cell damage. J Photoch Photobio Biol 95:101–107.
4. Ahn G. N., Kim K. N., Cha S. H., et al. (2007). Antioxidant activities of phlorotannins purified from Ecklonia cava on free radical scavenging using ESR and H2O2-mediated DNA damage. Eur Food Res Technol 226:71–79
5. Kang K. A., Lee K. H., Chae S., et al. (2005). Eckol isolated from Ecklonia cava attenuates oxidative stress induced cell damage in lung fibroblast cells. FEBS Lett 579: 6295–630.
6. Corona G., Ji Y., Anegboonlap P. (2016). Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers. British Journal of Nutrition 115, 1240–1253
7. Brown E., Allsopp, P., Magee, P., et al. (2014). Seaweed and human health. Nutr Rev 72, 205-216
8. Jung W. K., Ahn Y. W., Lee S. H., et al. (2009) Ecklonia cava ethanolic extracts inhibit lipopolysaccharide-induced cyclooxygenase- 2 and inducible nitric oxide synthase expression in BV2 microglia via the MMP kinase and NF-kB pathways. Food Chem Toxicol 47:410–417.
9. Dutot, M., Fagon, R., Hemon, M., et al. (2012). Antioxidant, anti-inflammatory, and anti-senescence activities of a phlorotannin-rich natural extract from Brown Seaweed Ascophyllum nodosum. App. Biochem. and Biotech 167(8)2234-2240
10. Bahar B., O’Doherty J.V., Smyth T.J., Sweeney T. A (2016). Comparison of the effects of an Ascophyllum nodosum ethanol extract and its molecular weight fractions on the inflammatory immune gene expression in vitro and ex vivo. Innov. Food Sci. Emerg. Technol. 37:276–285.