Yong-Ki Hong

Pukyong National University, Tsau-liang-hai, Busan, South Korea

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Publications (68)94.44 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Undaria pinnatifida (Harvey) Suringar and Saccharina japonica Areschoug are two common seaweeds, and both are known to have numerous pharmacological properties that include neuroprotective effects. In a previous study, we found that the ethanol extracts of U. pinnatifida (UPE) and S. japonica (SJE) had neurite promoting activities on developing hippocampal neurons. In the present study, we studied and compared the effects of UPE and SJE on neuronal maturation. Both UPE and SJE promoted neurite outgrowth in a dose-dependent manner with optimal concentrations of 5 and 15 μg/mL, respectively. Initial neuronal differentiation was significantly promoted by UPE and SJE. Subsequently, treatment with both increased indices of axonal and dendritic cytoarchitecture, such as, the numbers and lengths of primary processes, although only UPE had a significant effect on branching frequencies. In addition, UPE and SJE showed no evidence of cytotoxicity, rather they protected neurons from naturally occurring death in vitro. These results indicate that UPE and SJE promote axodendritic maturation and neuronal survival and suggest that these algal extracts, especially UPE, have beneficial effects on the nervous system.
    The American journal of Chinese medicine. 11/2014;
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    ABSTRACT: The acute-phase response (APR) is an important systemic reaction that occurs within hours of an inflammatory signal caused by physical bodily injury or microbial infection. To investigate the APR of the olive flounder (Paralichthys olivaceus) following infection with a pathogen, we established an expressed sequence tag (EST)-based cDNA microarray chip composed of 13,061 PCR-amplified cDNAs encoding unique genes selected from an olive flounder EST analysis. Microarray analyses showed that the set of genes involved in the APR was strongly up-regulated in the liver of the olive flounder after infection with Edwardsiella tarda. Among the up-regulated genes, catechol-O-methyltransferase domain-containing protein 1, six-transmembrane prostate protein, haptoglobin precursor, and toll-like receptor 5 soluble form were particularly strongly up-regulated. Interestingly, the toll-like receptor 5 soluble form, which has not yet been detected in mammals, was up-regulated as much as 250-fold upon E. tarda infection. These results suggest that the APR mechanism of fish may be regulated differently from that of mammals. The data described here contribute toward our collective understanding of APR, especially in fish.
    Veterinary Immunology and Immunopathology 09/2014; · 1.88 Impact Factor
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    ABSTRACT: In this study, the recovery of algal oil from Enteromorpha intestinalis based on an acidic-hydrothermal reaction was investigated. Overall, the algal oil yield after the acidic-hydrothermal reaction was increased under the conditions of high reaction temperature, high catalyst concentration, and long reaction time within the tested ranges. Significantly, catalyst concentration, compared with reaction temperature and time, less affected algal oil recovery. The optimal acidic-hydrothermal reaction conditions for production of algal oil from E. intestinalis were as follows-200 °C reaction temperature, 2.92 % catalyst concentration, 54 min reaction time. Under these conditions, an 18.6 % algal oil yield was obtained. By increasing the combined severity factor, the algae oil recovery yield linearly increased.
    Applied Biochemistry and Biotechnology 07/2014; · 1.89 Impact Factor
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    ABSTRACT: This study employed a statistical methodology to investigate the optimization of conversion conditions and evaluate the reciprocal interaction of reaction factors related to the process of red-algae Gracilaria verrucosa conversion to sugars (glucose, galactose), levulinic acid and 5-hydroxymethylfurfural (5-HMF) by acidic hydrolysis. Overall, the conditions optimized for glucose formation included a higher catalyst concentration than did those for galactose, and these conditions for galactose were similar to those for 5-HMF. Levulinic acid production, meanwhile, was optimized at a higher reaction temperature, a higher catalyst concentration, and a longer reaction time than was glucose, galactose or 5-HMF production. By this approach, the optimal yields (and reaction conditions) for glucose, galactose, levulinic acid, and 5-HMF were as follows: glucose 5.29 g/L (8.46 wt%) (reaction temperature 160 °C, catalyst concentration 1.92 %, reaction time 20 min), galactose 18.38 g/L (29.4 wt%) (160 °C, 1.03 %, 20 min), levulinic acid 14.65 g/L (18.64 wt%) (180.9 °C, 2.85 %, 50 min), and 5-HMF 3.74 g/L (5.98 wt%) (160.5 °C, 1 %, 20 min).
    Bioprocess and Biosystems Engineering 07/2014; · 1.87 Impact Factor
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    ABSTRACT: Phlorotannins are polyphenols of marine algae, particularly brown seaweed, having multiple biological activities. A reverse phase-high performance liquid chromatography method was developed for rapid and routine quantification of two major phlorotannins, dieckol and phlorofucofuroeckol-A (PFE-A), from boiling water- and organic solvent-extracts of brown seaweeds Ecklonia cava, E. stolonifera and Eisenia bicyclis. The regression equations for dieckol and PFE-A were as follows: the concentration (mg ml(-1)) = 16.56 x peak height (cm) + 0.44, and the concentration = 20.60 x peak height (cm) + 0.11, with correlation coefficients of 0.996 and 0.999, respectively. Compared to organic solvent extraction, the recovery yield of dieckol from boiling water extracts of E. cava, E. stolonifera and E. bicyclis was 86%, 93%, and 98%, respectively. The recovery yield of PFE-A was 74%, 86% and 62%, respectively. Antioxidant activity was detected in each E. bicyclis water extract (91%), followed by E. stolonifera (90%) and E. cava (74%). Dieckol and PFE-A showed almost 9- and 7-fold stronger antioxidant activity than the standard butylhydroxytoluene, and 6-and 4-fold greater than L-ascorbic acid in molar concentration, respectively.
    Journal of environmental biology / Academy of Environmental Biology, India. 07/2014; 35(4):713-9.
  • Botanical Sciences. 03/2014; 92(1):103-109.
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    ABSTRACT: Neurotrophic factors are essential for the differentiation and maturation of developing neurons as well as providing survival support to the mature neurons. Moreover, therapeutically neurotrophic factors are promising to reconstruct partially damaged neuronal networks in neurodegenerative diseases. In the previous study, we reported that the ethanol extract of an edible marine alga, Gelidium amansii (GAE) had shown promising effects in the development and maturation of both axon and dendrites of hippocampal neurons. Here, we demonstrate that in primary culture of hippocampal neurons (1) GAE promotes a significant increase in the number of filopodia and dendritic spines; (2) promotes synaptogenesis; (3) enhances N-methyl-D-aspartic acid (NMDA) receptor recruitment; and (4) modulates NMDA-receptor-mediated postsynaptic current. Taken together these findings that GAE might be involved in both morphological and functional maturation of neurons suggest the possibility that GAE may constitute a promising candidate for novel compounds for the prevention and treatment of neurodegenerative diseases.
    In Vitro Cellular & Developmental Biology - Animal 01/2014; · 1.29 Impact Factor
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    ABSTRACT: The lacy crust bryozoan Membranipora membranacea frequently colonizes the late harvested blades of aquacultured Saccharina japonica. From proteomic profiles of S. japonica, 145 and 91 protein spots were detected from colonized and healthy tissues, respectively. Among them, 69 and 32 spots were significantly up- and downregulated, respectively, in expression level upon colonization. In M. membranacea colonized tissue, tripartite motif protein 2-like, microcompartments protein, carboxysome peptide shell peptide, trypsin precursor-like, transmembrane protein, two-component response regulator PilR, spermine/spermidine synthase, vanadium-dependent bromoperoxidase, peptide chain release factor 1, interaptin, 50S ribosomal protein L1P, plus agglutinin and leucine-rich repeat protein were upregulated, whereas protoporphyrinogen oxidase, PIH1 domain-containing protein 2, GTPase-activating protein alpha, cytoplasmic threonyl-tRNA synthetase, flavanone 3-hydroxylase, and eukaryotic translation initiation factor 3 proteins were downregulated. Moreover, DEAD/DEAH box helicase, glutamyl-tRNA reductase, and chaperone DnaJ protein were newly expressed in the colonized tissue. Most of the up- and downregulated proteins are known to be related to stress control, defense mechanisms, signal transduction, photosynthesis, protein metabolism, and the cytoskeleton.
    Journal of Applied Phycology 01/2014; 26(1). · 2.33 Impact Factor
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    ABSTRACT: Moringa oleifera Lam. (Moringaceae) by virtue of its high nutritional as well as ethnomedical values has been gaining profound interest both in nutrition and medicinal research. The leaf of this plant is used in ayurvedic medicine to treat paralysis, nervous debility and other nerve disorders. In addition, research evidence also suggests the nootropic as well as neuroprotective roles of M. oleifera leaf in animal models. The aim of the present study was to evaluate the effect of M. oleifera leaf in the primary hippocampal neurons regarding its neurotrophic and neuroprotective properties. The primary culture of embryonic hippocampal neurons was incubated with the ethanol extract of Moringa oleifera leaf (MOE). After an indicated time, cultures were either stained directly with a lipophilic dye, DiO, or fixed and immunolabeled to visualize the neuronal morphology. Morphometric analyses for neurite maturation and synaptogenesis were performed using Image J software. Neuronal viability was evaluated using trypan blue exclusion and lactate dehydrogenase assays. MOE promoted neurite outgrowth in a concentration-dependent manner with an optimal concentration of 30μg/mL. As a very initial effect, MOE significantly promoted the earlier stages of neuronal differentiation. Subsequently, MOE significantly increased the number and length of dendrites, the length of axon, and the number and length of both dendrite and axonal branches, and eventually facilitated synaptogenesis. The β-carotene, one major compound of MOE, promoted neuritogensis, but the increase was not comparable with the effect of MOE. In addition, MOE supported neuronal survival by protecting neurons from naturally occurring cell death in vitro. Our findings indicate that MOE promotes axodendritic maturation as well as provides neuroprotection suggesting a promising pharmacological importance of this nutritionally and ethnomedically important plant for the well-being of nervous system.
    Journal of ethnopharmacology 12/2013; · 2.32 Impact Factor
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    ABSTRACT: Seaweeds, particularly species of red macroalgae, are promising resources for bioethanol production because of their exceptionally high carbohydrate content. Of 20 seaweeds evaluated, Palmaria palmata (Rhodymenia palmata) contained the highest carbohydrate content (469.8 mg g−1 seaweed) with a carrageenan content of 354 mg g−1 seaweed. Such a high carrageenan content makes the high-volume production of bioethanol feasible. Acid hydrolysis of P. palmata in 0.4 M H2SO4 at 125 °C for 25 min released 27 mg of glucose, 218.4 mg of reducing sugars, and 127.6 mg of galactose per gram of seaweed. Ethanol fermentation of these hydrolysis products using an inoculum concentration of 1.5 mg mL−1 at 30 °C and 72 h in a shaking incubator at 130 rpm yielded 17.3 mg of ethanol per gram of seaweed.
    Journal of Applied Phycology 07/2013; · 2.33 Impact Factor
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    ABSTRACT: This study explores the possibility of producing ethanol using the acid hydrolysate of three abundant agar-containing red seaweeds (agarophytes): Gelidium amansii, Gracilaria tenuistipitata, and Gracilariopsis chorda. The main component in the seaweed samples was agar, which ranged from 20 to 51 % (g g−1 dry weight). After optimizing acid hydrolysis, 100 g of seaweed was hydrolyzed at 130 °C for 15 min with 0.2 M H2SO4. Then, 120 mL of a 1:2 mixture of the hydrolysate broth and basal medium was fermented in a 200-mL bottle at 30 °C for 96 h. Of the three seaweeds, G. amansii had the best ethanol yield, producing 0.23 g g−1 of galactose or 45 % of the theoretical yield. This yield increased to 60 % after detoxification of the hydrolysate with activated carbon
    Journal of Applied Phycology 05/2013; · 2.33 Impact Factor
  • Yong-Ki Hong, Ji Young Cho
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    ABSTRACT: Seaweed-associated bacteria play a role in helping to protect host organisms from biofouling by producing anti-fouling compounds. In a first step to develop such anti-fouling compounds, we isolated epibiotic bacteria from seaweed and subsequently screen culture extracts for anti-fouling activities. The active epibiotic bacterium studied was isolated from Undaria pinnatifida and identified as Streptomyces violaceoruber based on 16S rDNA sequence analysis. Two active compounds were isolated from the culture extracts by silica gel chromatography and high-performance liquid chromatography, and their structures were analyzed by nuclear magnetic resonance and high-resolution electron ionization mass spectrometry. The compounds were identified as furanone derivatives: 3-octa-1′,3′-dienyl-4-methylfuran-2(5H)-one and 3-octa-1′-enyl-4-methylfuran-2(5H)-one, respectively. These compounds showed anti-fouling activities against the following fouling organisms: zoospores of Ulva pertusa, the diatom Navicula annexa, and the mussel Mytilus edulis, with an EC50 (minimum concentration for 50 % spore inhibition) range of 0.02–0.1 μg/ml. In the acute toxicity tests on juvenile rockfish Shebastes shlegelli, brine shrimp Artemia salina, and microalga Tetraselmis suecica, the two compounds showed LC50 (concentration lethal to 50 % of the spores) ranges of 13.9–118.9 and 14.8–81.9 μg/ml, respectively.
    Fisheries Science 05/2013; 79(3). · 0.90 Impact Factor
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    ABSTRACT: An alginate-degrading bacterium, identified as Shewanella oneidensis PKA 1008 by 16S ribosomal RNA sequence analysis, was isolated from the green alga Ulva pertusa. Optimal conditions for the alginate-degrading ability of its crude enzyme were then determined. The optimal culture conditions for the growth of S. oneidensis PKA 1008 were pH 9, 2% NaCl, , and 24 hours incubation time. The crude enzyme produced by S. oneidensis PKA 1008 showed the highest alginate-degrading activity at pH 9, and produced 1.001 g of reducing sugar per liter in 3.5% (w/v) sodium alginate for 1 hour.
    Korean Journal of Microbiology and Biotechnology 01/2013; 41(3).
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    ABSTRACT: Sargassum fulvellum (Turner) C. Agardh is an edible brown macroalgae having pharmacological importance. In previous reports, we described the screening of marine algae for their neuritogenic activity in developing hippocampal neurons and found that ethanol extract of S. fulvellum (SFE) possesses promising neurite-outgrowth-promoting activity. In this study, we evaluated whether the initial neurite promoting effect of SFE was followed on the further neuronal maturation and synapse formation. SFE exhibited dose-dependent effect on neurite maturation with an optimum concentration of 5 μg/mL. The initial neuronal differentiation is significantly promoted by SFE. Subsequently, compared with control culture, SFE increased the indices of axonal and dendritic developments such as the number and the length of primary processes, and branching frequencies. In addition to its effect on neurite development, SFE significantly increased the number of puncta for postsynaptic density-95, synaptic vesicle 2, and synapse (about 35%, 67%, and 125%, respectively, of control). Moreover, SFE dose-dependently protects neurons from naturally occurring death in normal culture condition. Taken together, our data demonstrate that SFE can promote neuronal maturation and synaptogenesis and support neuronal survival, suggesting the beneficial effect of this alga in nervous system.
    In Vitro Cellular & Developmental Biology - Animal 08/2012; 48(8):535-44. · 1.29 Impact Factor
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    ABSTRACT: Neurotrophic factors are vital not only to support neuronal development but also to protect mature neurons from atrophy in neurodegenerative diseases. As an effort to explore natural sources that possess neurotrophic activity, we screened common marine algae for their neuritogenic activity in the developing rat hippocampal neurons in culture. Of the 22 seaweed species examined, ethanol extracts of Gelidium amansii (GAE) exhibited potent neuritogenic activity, followed by Undaria pinnatifida and Sargassum fulvellum extracts. The effects of GAE were dose dependent with an optimum concentration of 15 µg/mL. The GAE significantly promoted the initial neuronal differentiation from the stage I into the stage II and increased the indices of axonal and dendritic development such as the length, the numbers of primary processes, and branching frequencies by a minimum of twofold compared with the vehicle control. These results show that marine algae are promising candidates for neurotrophic potentials. Copyright © 2012 John Wiley & Sons, Ltd.
    Phytotherapy Research 03/2012; · 2.40 Impact Factor
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    ABSTRACT: Apidaecin Ib had strong antimicrobial activity against several tested Gram-negative bacteria including Escherichia coli, Enterobacter cloacae, and Shigella flexneri (MECs; 0.3-1.5 µg/mL), but showed no activity against all the tested Gram-positive bacteria including Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus and one yeast, Candida albicans (MECs; >125 µg/mL). Interestingly, this peptide showed potent antibacterial activity only against Edwardsiella species (MECs; 0.6-3.6 µg/mL) among the tested fish pathogenic bacteria through a bacteriostatic process and showed no significant hemolytic activity. Apidaecin Ib took an unordered structure in all environments and also had very weak membrane perturbation activity even at 25 µM. Anti-Edwardsiella activity of apidaecin Ib is stronger than those of other antimicrobial polypeptides or antibiotics, but its activity is salt-sensitive. These results suggest that apidaecin Ib has Edwardsiella species-specific antibacterial activity and could be applied as new preventive or control additives for Edwardsiella species infection in freshwater fish aquaculture.
    Bulletin- Korean Chemical Society 01/2012; 33(1). · 0.84 Impact Factor
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    ABSTRACT: The non-utilized biomass of the aquacultured seaweed Undaria pinnatifida, particularly the rhizoid, is an alternative source of arachidonic acid (AA). Of the five aquacultured kelps that were tested, U. pinnatifida yielded the highest amount of AA, which was isolated from the rhizoids. Its identity (C20:4 n-6) was confirmed from gas chromatography-mass spectrometry spectral data. The optimal conditions for post-harvest storage or pretreatment of the rhizoids in Provasoli's enriched seawater for AA extraction were determined to be pH 7.8, 2% -enriched air, 20 light, and . Under these conditions, the AA content after 1 day of storage was enhanced by up to 127%. In the absence of light under ambient aeration, the AA content after 1 day of storage diminished to 90%. Rhizoids collected late in the season (April and May) contained the highest amounts of AA (approximately 2.5 mg/g tissue).
    Fisheries and aquatic sciences. 01/2012; 15(2).
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    ABSTRACT: An improved strain of the red seaweed Porphyra suborbiculata containing an increased amount of the essential amino acid L-lysine was obtained through mutation and analog enrichment. Mutagenesis using a 10% lethal dose of ultraviolet irradiation and an enrichment culture with the L-lysine analog aminoethyl-L-cysteine (AEC) was repeated to select the most productive strain using monospores of P. suborbiculata. The concentrations of AEC required to produce 50 and 100% inhibition of survival were 60 and 115 mM in the parent strain, and 72 and 135 mM in the selected AEC-resistant strain, respectively. The AEC-resistant strain, L130, produced 1.74-fold more lysine compared to its parent strain. Thus, mutagenesis with analog enrichment shows promise for selecting seaweed strains that can overproduce this essential amino acid.
    Fisheries and aquatic sciences. 01/2012; 15(2).
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    ABSTRACT: Dichloromethane, ethanol, and boiling water extracts of the green seaweed Codium fragile, used as an herbal medicine and known as an invasive species over the world, were examined for anti-inflammatory, antipyretic, and analgesic activities in mice. The dichloromethane and ethanol extracts inhibited inflammatory symptoms of mouse ear edema and erythema by 74% or higher. The extracts also demonstrated inhibition of pyrexia, similar to that of acetyl salicylic acid. Eicosapentaenoic acid was isolated from the seaweed as the main active anti-inflammatory compound. These findings are consistent with various claims that the seaweed can be used as remedies for inflammation-related symptoms.
    Journal of Life Science. 01/2012; 22(6).
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    ABSTRACT: In this study, hydrolysis of marine algal biomass Kappaphhycus alvarezii using two different acid catalysts was examined with the goal of identifying optimal reaction conditions for the formation of sugars and by-products. K. alvarezii were hydrolyzed by autoclave using sulfuric acid or hydrochloric acid as catalyst with different acid concentrations (0.1-1.0 M), substrate concentrations (1.0-13.5%), hydrolysis time (10-90 min) and hydrolysis temperatures (100-130 (°)C). A difference in galactose, glucose, reducing sugar and total sugar content was observed under the different hydrolysis conditions. Different by-product compounds such as 5-hydroxymethylfurfural and levulinic acid were also observed under the different reaction conditions. The optimal conditions for hydrolysis were achieved at a sulfuric acid concentration, temperature and reaction time of 0.2 M, 130 °C and 15 min, respectively. These results may provide useful information for the development of more efficient systems for biofuel production from marine biomass.
    Bioprocess and Biosystems Engineering 09/2011; 35(1-2):123-8. · 1.87 Impact Factor

Publication Stats

342 Citations
94.44 Total Impact Points

Institutions

  • 1997–2014
    • Pukyong National University
      • • Department of Biotechnology
      • • Department of Food Science and Technology
      Tsau-liang-hai, Busan, South Korea
  • 2001–2008
    • Soonchunhyang University
      • Department of Marine Biotechnology
      Asan, South Chungcheong, South Korea
  • 2002
    • Florida Atlantic University
      • Department of Chemistry and Biochemistry
      Boca Raton, Florida, United States
  • 1996
    • Kangwon National University
      Shunsen, Gangwon, South Korea
  • 1995–1996
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
    • Yeungnam University
      Daikyū, Daegu, South Korea