Jae-Suk Choi

Antifouling activity of seaweed extracts on the green alga Enteromorpha prolifera and the mussel Mytilus edulis

Twenty-seven species of common seaweeds from the coast of Korea havebeen screened for antifouling activity. The seaweed extracts were tested inlaboratory assays against the marine fouling green alga Enteromorphaprolifera and the blue mussel Mytilus edulis. Tissue growth, sporesettlement, zygote formation and germlings of the E. prolifera wereinhibited by methanol extracts of the seaweed Ishige sinicola (= I. foliacea) and Sargassum horneri. Spore settlement was stronglyinhibited by using extract concentrations as low as 30 μg mL-1with I. sinicola and 120 μg mL-1 with S. horneri. The repulsive activity of the foot of the mussel was completely inhibited bymethanol extracts of I. sinicola and Scytosiphon lomentaria atconcentrations of 40 μg per 10 μL drop supplied to eachmussel. These extracts also showed strong antifouling activities onlarval settlement with, respectively, no or only 6% of the spat settlingwhen a test concentration of 0.8 mg mL-1 was used. This work isthe first stage towards the development of novel antifouling agents frommarine macroalgae.

Multiple allelopathic activity of the crustose coralline alga Lithophyllum yessoense against settlement and germination of seaweed spores

A study was made to investigate possible formation by the crustose coralline algaLithophyllum yessoenseof multiple allelopathic-related substances against the settlement and germination of spores of various seaweeds. Seven different solvents (n-hexane, diethyl ether, acetone, ethyl acetate, acetonitrile, methanol, distilled water) and seawater were used to obtain crude extracts and secretory exudates from the coralline alga. The extracts and the algal conditioned seawater were tested for inhibitory activity against the settlement and germination of spores from 17 species representing 15 genera. Spore settlement of 14 species was inhibited over 90% by one or more extracts of the six organic solvents and conditioned seawater. The germination of spores from 13 species was inhibited by one or more extracts of all seven solvents and conditioned seawater. The species where spore settlement was not significantly affected showed strong inhibition of germination, andvice versa.

A procedure for axenic isolation of the marine microalga Isochrysis galbana from heavily contaminated mass cultures

Isochrysis galbana, one of the most widely usedmarine microalgae in the rearing of finfish and shellfish larvae, is masscultured frequently in outdoor tanks. Under prolonged and repeated culture,severe contamination occurs. Axenic isolation of I.galbanafrom such cultures was best achieved by using a ternary procedure involvingpercoll-gradient centrifugation, treatment with antibiotics, and growth on agarmedium. Protozoa and other algae were removed most effectively by isolation ofI. galbana at the 30–40% density layer on apercoll-gradient. Removal of bacteria was accomplished using a mixture of 5antibiotics (250 μg mL−1 ampicillin, 50μg mL−1 gentamycin, 100 μgmL−1 kanamycin, 500 μgmL−1 neomycin, 50 μgmL−1 streptomycin). Axenic colonies were isolated fromasolid medium prepared from 1% purified agar. The ternary procedure isconsideredapplicable to the isolation of other axenic single-celled microalgae fromheavily contaminated cultures.

Moringa oleifera with promising neuronal survival and neurite outgrowth promoting potentials.

ETHNOPHARMACOLOGICAL RELEVANCE 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 Moringa oleifera leaf in animal models. The aim of the present study was to evaluate the effect of Moringa oleifera leaf in the primary hippocampal neurons regarding its neurotrophic and neuroprotective properties. MATERIALS AND METHODS 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. RESULTS MOE promoted neurite outgrowth in a concentration-dependent manner with an optimal concentration of 30 μg/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. CONCLUSIONS 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.

Procedures for the axenic isolation of conchocelis and monospores from the red seaweed Porphyra yezoensis

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-μm mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 μgml−1 GeO2, 10 μgml−1 ampicillin, 40 μgml−1 kanamycin and 200 μgml−1 streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 μg ml−1 nystatin, 2 mgml−1 ampicillin, 400 μgml−1 kanamycin, 50 μgml−1 neomycin and 800 μgml−1 streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel.

Isolation of antifouling active pyroglutamic acid, triethyl citrate and di-n-octylphthalate from the brown seaweed Ishige okamurae

Three antifouling active compounds of L-pyroglutamic acid (PGA), triethyl citrate (TEC) and di-n-octylphthalate (DNOP) were isolated from the brown seaweed Ishige okamurae. Approximately 2.8 mg PGA, 1.7 mg TEC, and 2.0 mg DNOP were isolated from 600 g of I. okamurae powder. The concentrations of PGA, TEC, and DNOP required to cause foot repulsion in 50% of mussels (RD50) were 9, 26, and 0.08 mM, respectively. The PGA, TEC, and DNOP concentrations required to inhibit 50% attachment of algal spores (ID50) were 24, 50 and 0.1 mM, respectively. These compounds showed stable antifouling activities against mussel and algal spore attachment.

Antimicrobial activities of stearidonic and gamma-linolenic acids from the green seaweed Enteromorpha linza against several oral pathogenic bacteria

BackgroundWe found that the edible green seaweed Enteromorpha linza displayed potent antimicrobial activity against Prevotella intermedia and Porphyromonas gingivalis. To elucidate the active component of E. linza, isolation procedures were performed.ResultsThe main active compound was isolated by polarity fractionation, Sephadex LH-20 gel chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). The active compounds were eluted at isocratic 95% acetonitrile by RP-HPLC and identified as unsaturated fatty acids, stearidonic acid (SA, C18:4 n-3) and gamma-linolenic acid (GLA, C18:3 n-6) by gas chromatography–mass spectrometry, 1H nuclear magnetic resonance (NMR) spectroscopy, and 13C NMR spectroscopy. The yields of SA and GLA from dried seaweed tissue were 6.33 × 10-3% and 6.47 × 10-3%, respectively. The minimal inhibitory concentration values of SA and GLA were 39.06 μg/mL against P. intermedia and 9.76 μg/mL against P. gingivalis, respectively. SA and GLA were also active against several other oral pathogens, including Aggregatibacter actinomycetemcomitans, Candida albicans, Fusobacterium nucleatum subsp. vincenti, and Streptococcus mutans, at micromolar concentrations.ConclusionsThese data suggest that the E. linza extracts SA and GLA are useful antimicrobial agents for the prevention and/or treatment of periodontitis.

Mineral Contents and Physiological Activities of Dried Sea Tangle (Laminaria japonica) Collected from Gijang and Wando in Korea.

This research was performed to determine the proximate compositions, mineral contents, alginic acid, antioxidative activities and amino acids of sea tangles collected from Gijang and Wando area. Crude protein and ash contents were higher in Gijang sea tangle, whereas carbohydrate and moisture were higher in Wando in general. Mineral contents of Gijang sea tangle were higher than Wando. Especially, Na and K was the most abundant in both Gijang and Wando sea tangles. Alginic acid content was almost similar in both sea tangles. The major free amino acids were glutamic acid, aspartic acid, alanine, proline and hydroxyproline in both Gijang and Wando sea tangles. Antioxidative activity of methanol extract of sea tangle was measured by using DPPH radical scavenging and SOD-like activity. DPPH radical scavenging and SOD-like activity were about 17% (40 ㎍/㎖) and 7% (5 ㎍/㎖) higher, respectively, in Wando sea tangle. When stimulate the macrophages RAW264.7 cells with lipopolysaccharide (LPS), inhibition of NO synthesis of the methanol extract was 11% higher in Wando sea tangle comparing with Gijang samples.

Investigation of Diseases of Thai koi, Anabas testudineus (BLOCH) from Farming Conditions in Winter

Investigation on health conditions of Thai koi (Anabas testudineus) were carried out through clinical and histopathological observations from different farms of Mymensingh district for seven months during August 2006 to February 2007. Fish sampling and water quality parameters (temperature, dissolved oxygen and pH) were monitored on a monthly basis. Clinical examination of fishes was also carried out for any kind of abnormalities at monthly intervals. Samples of skin, muscle, gill, liver and kidney were observed by histological technique. Among the water quality parameters the values of water temperature, dissolved oxygen were found to be at unfavorable level for fish during the colder months in the farms. Clinically it was observed that fishes were more affected from December to January and almost normal in appearance during August to September and February. Different clinical symptoms like scale loss, dermal lesion, ulcer and loss of caudal fin were noticed in December and January. In histopathological study, structures of fish organs were normal from August to September. In the months of October and November, minor pathologies were found to be started. Marked pathological changes like necrosis, pyknosis, inflammation, hemorrhage, hypertrophy, hyperplasia, missing of primary and secondary gill lamellae were observed in the months of December and January. Whereas, in the month of February the pathological condition of fish gradually reduced. Again when considered individual fish farm, fishes of Reliance Aqua Farm were more affected than Sotota Matshya Hatchery. The study showed that severity of clinical and pathological changes were increased in December and January. During the period EUS and protozoan diseases were noticed in A. testudineus of the investigated farms.

Effects of Polycan on calcium bioavailability in two different rat models of osteoporosis

This study evaluated the effects of Polycan, a β-glucan produced by Aureobasidium pullulans SM-2001, on calcium (Ca) bioavailability in an ovariectomy (OVX) model and a thyroparathyroidectomy (TPTX) model of osteoporosis in the SD rat. Polycan (62.5, 125, and 250 mg/kg body weight) was administered daily with an oral gavage for 4 weeks in both the OVX group (beginning 10 weeks following OVX surgery) and the TPTX group (beginning 4 days following TPTX surgery) while a commercial food product containing 1% milk-borne Ca was available ad libitum. After 4 weeks of Polycan administration, all animals were sacrificed and changes in bone mineral density (BMD) in the femur, tibia, and lumbar vertebrae (L6) were analyzed using dual-energy X-ray absorptiometry. Ca intake was calculated based on the amount of food intake during the 24 h period prior to sacrifice and the Ca balance, absorption, and retention ratios were calculated based on Ca intake, urinary and faecal Ca content, and Ca balance. Polycan treatment resulted in a marked increase in the BMD of the femur, tibia, and L6 relative to the OVX and TPTX controls with concomitant increases in Ca bioavailability and decreases in secreted Ca. These findings indicate that Polycan may enhance the absorption and bioavailability of Ca and improve Ca balance.