Daekyung Kim

Antioxidant and anti-inflammatory activities of porphyran isolated from discolored nori (Porphyra yezoensis).

We found that discolored waste nori with no commercial value, contains much higher level of porphyran than normal nori that is a sheeted food stuff prepared from P. yezoensis used in sushi. Chemical analyses revealed that mean molecular mass of the porphyran prepared from discolored nori (dc-porphyran) was much lower than that of the porphyran from normal nori (n-porphyran). Dc-porphyran showed slightly greater scavenging activity toward superoxide anion and hydroxyl radical than n-porphyran. Dc-porphyran inhibited nitric oxide (NO) production in LPS-stimulated RAW264.7 cells through preventing the expression of inducible NO synthase, whereas no such activity was observed in n-porphyran. Since acid-hydrolyzed n-porphyran showed the inhibitory activity on NO production from LPS-stimulated RAW264.7 cells, the molecular size of porphyran was suggested to be a critical factor for the activity. Dc-porphyran was separated into 4 fractions (F1-F4) on DEAE-chromatography, and F1 showed the highest inhibitory effect on NO production from LPS-stimulated RAW264.7 cells. Our results indicate that discolored waste nori is useful as a source of porphyran with even better bioactivities than porphyran from normal nori.

Alginate oligomer induces nitric oxide (NO) production in RAW264.7 cells: elucidation of the underlying intracellular signaling mechanism

Alginate is an acidic linear polysaccharide with immune-modulating activities. In this study, we found that enzymatically digested alginate oligomer (AO) with various degrees of polymerization (DP; 2–5) induced a higher level of nitric oxide (NO) production in RAW264.7 cells than undigested alginate polymer (AP). Reverse transcription-polymerase chain reaction and western blot analyses revealed that the expression level of inducible NO synthase in AO-treated RAW264.7 cells was higher than that in AP-treated cells. AO induced nuclear translocation of nuclear factor (NF)-κB p65 subunit in RAW264.7 cells to a greater extent than AP. Although AO and AP induced similar extents of phosphorylation in three mitogen-activated protein (MAP) kinases, c-Jun N-terminal kinase inhibitor exhibited the most potent inhibitory effect on NO induction in AO- and AP-treated RAW264.7 cells, among three MAP kinase inhibitors that were tested. Graphical abstract Alginate is composed of two forms of uronic acids, α-L-guluronate (G) and β-D-mannuronate (M), which in turn form three types of polymer blocks: G-block, M-block, and random block.

Comparative studies on the fish-killing activities of Chattonella marina isolated in 1985 and Chattonella antiqua isolated in 2010, and their possible toxic factors.

Chattonella antiqua isolated in 2010 showed extremely more potent fish-killing activities against red sea bream, Japanese horse mackerel, and blue damselfish than those of Chattonella marina isolated in 1985. Chemiluminescence and electron spin resonance (ESR) analyses suggested greater reactive oxygen species (ROS)-producing activity of C. antiqua than that of C. marina. Sodium benzoate, a hydroxyl radical scavenger, significantly suppressed the fish-killing activity of C. antiqua on blue damselfish. The chlorophyll level in the gill tissue of blue damselfish exposed to flagellate cells increased along with the exposure time, and the cell count of gill-associated C. antiqua estimated with chlorophyll level was higher than that of C. marina. These results suggest that the ROS-producing activity and affinity of Chattonella cells to the gill surface may be important factors influencing the fish-killing activity of Chattonella species. Graphical abstract ROS-mediated gill tissue damage by C. antiqua may lead to fish death

Simultaneous Effect of Salinity and Temperature on the Neutral Lipid and Starch Accumulation by Oceanic Microalgae Nannochloropsis granulata and Chlorella vulgaris

− Because microalgae represent high growth rate than terrestrial plants, and it can accumulate significant lipid and carbohydrate content, and other bioactive compounds such as carotenoid and polyphenol in their body, it has been considered as one of the promising resources in bio-energy, and other industries. Although many studies has been performed about the microalgae-derived biochemical accumulation under various abiotic conditions such as different temperatures, salinities and light intensities, the studies about simultaneous effect of those parameters has rarely been performed. Therefore, this study focused on evaluation of simultaneous effect of different salinity (10, 30, 50 psu) and temperatures (20, 25, 30 °C) on the changes of biomass, lipid, starch and photosynthetic pigment accumulation. As results, the highest growth rate was achieved at 30 °C and 30 psu in the both algal cultures, and the photosynthetic pigment, chlorophyll a and total carotenoid content, were increased in a temperature-dependent manner. The accumulation of lipid and starch contents exhibited different aspects under different combinaCorresponding author: dkim@kbsi.re.kr, ikyeo99@jejunu.ac.kr 염분과 온도의 동시 영향에 따른 해양 미세조류 Nannochloropsis granulata와 Chlorella vulgaris의 중성지질 및 녹말 축적에 관한 연구 237 tions of temperature and salinity. From the results, it is suggested that the changes of microalgal lipid and starch accumulation under different salinities may be affected by the different temperatures.

Production of Nitric Oxide by Marine Unicellular Red Tide Phytoplankton, Chattonella marina

In this chapter, we show several lines of evidence for the production of nitric oxide (NO) by unicellular red tide phytoplankton Chattonella marina under the normal growth conditions. Chemiluminescence (CL) assay suggested that C. marina produced NO in a cell-number-dependent manner, and the level of NO decreased by the addition of carboxy-PTIO, a specific NO scavenger. NO generation by C. marina was also confirmed by a spectrophotometric assay based on the measurement of the diazo-reaction positive substances (NOx) and by fluorometric assay using highly specific fluorescent indicator of NO. Furthermore, the NO level in C. marina was significantly decreased by l-NAME, a specific NO synthase (NOS) inhibitor. The addition of l-arginine increased the NO level, whereas NaNO2 had no effect. These results suggest that a NOS-like enzyme is mainly responsible for NO generation in C. marina.