• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.390-396
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• 1994

Age and growth of Ecklonia stolonifera Okamura were investigated by random quadrate sampling method at monthly intervals from February 1993 to January 1994 in Pusan Bay, southeastern coast of Korea. The size of various parts of the collected plants was periodically measured individually. An allometric relationship was established according to the total length, blade length, stipe length, stipe diameter and weight of frond. Each age group was divided according to the range of stipe length by the allometric relation. The population of E. stolonifera consisted of five age groups; 1 year ($41.5\%$), 2 years ($25.9\%$), 3 years ($21.1\%$), 4 years ($7.8\%$) and 5 years ($3.5\%$). During a year, biomass of the population increased drastically from May to September, but gradually decrease from October to January. Zoosporangial sori were observed on blades of three or more years old, from October to December. New populations were formed by zoospores, developed on shoots of three or more years old, and also they were vegetatively formed from stoloniferous haptera on two or more year old mother thalli.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1226-1232
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• 2004

Extracts from seventeen seaweeds were determined for tyrosinase inhibitory activity using mushroom tyrosinase with L-tyrosine as a substrate. Only one of them, Ecklonia stolonifera OKAMURA (Laminariaceae) belonging to brown algae, showed high tyrosinase inhibitory activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction from the methanolic extract of E. stolonifera, led us to the isolation of phloroglucinol derivatives [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 1~5 were found to inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with $IC_{50}$ values of 92.8, 126, 33.2, 177, and 2.16 ${\mu}g$ /mL, respectively. It was compared with those of kojic acid and arbutin, well-known tyrosinase inhibitors, with $IC_{50}$ values of 6.32 and 112 ${\mu}g$ / mL, respectively. The inhibitory kinetics analyzed from Lineweaver-Burk plots, showed compounds 1 and 2 to be competitive inhibitors with $K_i$ of $2.3{\times}10^{-4}\;and\;3.1{times}10^{-4}$ M, and compounds 3~5 to be noncompetitive inhibitors with $K_i$ of $1.9{\times}10^{-5},\;1.4{\times}10^{-3}\;and\;1.5{\times}10^{-5}$ M, respectively. This work showed that phloroglucinol derivatives, natural compounds found in brown algae, could be involved in the control of pigmentation in plants and other organisms through inhibition of tyrosinase activity using L-tyrosine as a substrate.

• Journal of Life Science
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• v.20 no.11
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• pp.1640-1647
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• 2010

Seaweeds have been recognized as a health food, having anti-obesity, anti-constipation and anticoagulation activities, and the use of seaweeds in the food, medicine, and cosmetic industries have recently significantly increased. In this study, methanol extracts were prepared from 35 different seaweeds (17 phaeophyta, 11 rhodophyta and 7 chlorophyta), and thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (aPTT) were determined in order to develop safe and novel anticoagulation agents from natural products. In TT experiments, Ecklonia cava, Ecklonia stolonifera, Eisenia bicyclis (Kjellman) Setchell, Ishige foliacea, I. okamurai, Sargassum confusum and S. yamade showed strong thrombin inhibition activity among the 35 different seaweeds. In PT experiments, the inhibitions of prothrombin were identified in the selected seaweeds from TT experiment, with the exception of S. yamade. In aPTT experiments, the seaweeds with blood coagulation inhibition factors were E. cava, E. stolonifera, E. bicyclis (Kjellman) Setchell, I. foliacea, I. okamurai, S. confusum and Hixikia fusiforme Okamura. Further anticoagulation assay with the selected 8 seaweeds suggested that S. confusum is most effective in antithrombosis, and E. stolonifera, E. bicyclis (Kjellman) Setchell, and I. foliacea have high potential as antithrombosis agents. Based on components-activity correlation analysis, flavonoids are considered as active anticoagulation components of seaweeds These results suggest that edible seaweeds, especially S. confusum, have potential as safe and novel anticoagulants, and S. yamade and H. fusiforme Okamura could be used as a thrombin-specific and coagulation factor-specific inhibitors.