Suk Woo Kang

Fucoxanthin as a major carotenoid in Isochrysis aff. galbana: Characterization of extraction for commercial application

Fucoxanthin, a main marine carotenoid, in five species of fucoxanthin-containing microalgae, was quantified by high-performance liquid chromatography. Among the studied species, Isochrysis aff. galbana contained the highest amount of fucoxanthin (18.23 mg/g dried sample). This microalga showed good fucoxanthin extraction efficiency under the tested solvents (methanol, ethanol, acetone, and ethyl acetate), with the exception of n-hexane. In addition, most fucoxanthin (∼95%) could be extracted by a single extraction in ethanol within 5 min, and only 15% degradation of fucoxanthin was detected during ethanol extraction for 24 h. The two-phase solvent system of n-hexaneethanol-water with a volume ratio of 10:9:1 was determined to be the best system for the separation of fucoxanthin and lipids from extracts of I. aff. galbana. Under these conditions, fucoxanthin was fractionated in the hydroalcohol phase apart from the hexane phase containing lipids. These results imply that I. aff. galbana can be a commercial source for the spontaneous production of valuable fucoxanthins and lipids.

Effect of Pressurized Liquids on Extraction of Antioxidants from Chlorella vulgaris

Chlorella vulgaris is a green microalga that contains various antioxidants, such as carotenoids and chlorophylls. In this study, antioxidants from C. vulgaris were extracted using pressurized liquid extraction (PLE), which has been recently used for bioactive compound extraction. The antioxidant capacity of individual compounds in chlorella was determined by online HPLC ABTS(*+) analysis. According to the antioxidant analysis of total extracts, the extraction yield, radical scavenging activity, and phenolic compounds using PLE were relatively high compared to those obtained using maceration or ultrasound-assisted extraction. On the basis of online HPLC ABTS(*+) analysis, the 15 major antioxidants from chlorella extracts were identified as hydrophilic compounds, lutein and its isomers, chlorophylls, and chlorophyll derivatives. Using PLE at high temperature (85-160 degrees C) significantly increased antioxidant extraction from chlorella, improving the formation of hydrophilic compounds and yielding more antioxidative chlorophyll derivatives. Online HPLC ABTS(*+) analysis was a useful tool for the separation of main antioxidants from PLE extracts and allowed the simultaneous measurement of their antioxidant capacity, which clearly showed that PLE is an excellent method for extracting antioxidants from C. vulgaris.

Rapid identification of furanocoumarins in Angelica dahurica using the Online LC-MMR-MS and their nitric oxide inhibitory activity in RAW 264.7 cells

INTRODUCTION Angelica dahurica (Fisch. Ex hoffm.) Benth. Et Hook. is a perennial herb that grows throughout Korea whose dried roots have been used to treat various diseases in Korean traditional medicine. The root extract contains diverse constituents, and it is necessary to determine the active compounds. OBJECTIVE To investigate the nitric oxide (NO) inhibitory activity in a root extract of A. dahurica and identify the most active compounds using LC-NMR-MS. METHODOLOGY In search of the anti-inflammatory constituents of A. dahurica extract, the HPLC-based activity profiling approach was used to investigate the extracts NO inhibitory activity. To directly identify the compounds, a hyphenated LC-NMR-MS technique was applied. Reversed-phase isocratic chromatography was performed using the acetonitrile-water solvent system on a C(30) column. The identification of the compounds was based on information from ESI/MS and 1H-NMR. RESULTS NO inhibitory activities for five main fractions of the extract were evaluated, which were identified by LC-NMR-MS as containing furanocoumarins: byakangelicol, oxypeucedanin, imperatorin, phellopterin and isoimperatorin. CONCLUSION The results obtained showed that the anti-inflammatory activities of A. dahurica could be linked to imperatorin and phellopterin.

Determination of major phlorotannins in Eisenia bicyclis using hydrophilic interaction chromatography: Seasonal variation and extraction characteristics

In this study, a hydrophilic interaction chromatography (HILIC) condition was developed for the simultaneous determination of five major phlorotannins from an extract of Eisenia bicyclis (Kjellman) Setchell with good linearity (r(2)>0.999). Based on this method, the seasonal variations and extraction characteristics, in terms of total extraction yield and the content of the phlorotannins, were investigated under various extraction conditions. In results, the yields and phlorotannins were increased two-to-four times in summer (June-October) and then, were decreased to normal levels in winter (November-March). In the extraction of E. bicyclis, ethanol percentage in water, extraction time and washing time significantly affected the yield of the extract and the phlorotannins, whereas the temperature and the sample/solvent ratio impacted the extraction to a lesser degree. These results will be useful information in the application of this macroalga in the commercial areas related to nutraceuticals, pharmaceuticals, and cosmeceuticals.

Absolute configuration-dependent epoxide formation from isoflavan-4-ol stereoisomers by biphenyl dioxygenase of Pseudomonas pseudoalcaligenes strain KF707

Biphenyl dioxygenase from Pseudomonas pseudoalcaligenes strain KF707 expressed in Escherichia coli was found to exhibit monooxygenase activity toward four stereoisomers of isoflavan-4-ol. LC–MS and LC–NMR analyses of the metabolites revealed that the corresponding epoxides formed between C2′ and C3′ on the B-ring of each isoflavan-4-ol substrate were the sole products. The relative reactivity of the stereoisomers was found to be in the order: (3S,4S)-cis-isoflavan-4-ol > (3R,4S)-trans-isoflavan-4-ol > (3S,4R)-trans-isoflavan-4-ol > (3R,4R)-cis-isoflavan-4-ol and this likely depended upon the absolute configuration of the 4-OH group on the isoflavanols, as explained by an enzyme–substrate docking study. The epoxides produced from isoflavan-4-ols by P. pseudoalcaligenes strain KF707 were further abiotically transformed into pterocarpan, the molecular structure of which is commonly found as part of plant-protective phytoalexins, such as maackiain from Cicer arietinum and medicarpin from Medicago sativa.

Aceriphyllum rossii Extract and Its Active Compounds, Quercetin and Kaempferol Inhibit IgE-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis

Aceriphyllum rossii contains an abundant source of natural flavonoids with potential antioxidant, anticancer and anti-inflammatory properties. However, the effect of A. rossii extract (ARE) on immunoglobulin E(IgE)-mediated allergic responses remains unknown. In the present study, the effects of ARE and its active compounds, quercetin and kaempferol, on IgE-mediated rat basophilic leukemia mast cell activation and passive cutaneous anaphylaxis (PCA) were investigated. ARE, quercetin, and kaempferol inhibited secretion of β-hexosaminidase and histamine, and reduced the production and mRNA expression of interleukin-4 and tumor necrosis factor-α. ARE also decreased the production of prostaglandin E2 and leukotriene B4 and expression of cyclooxygenase 2 and 5-lipoxygenase. Furthermore, ARE, quercetin, and kaempferol inhibited IgE-mediated phosphorylation of Syk, phospholipase Cγ, protein kinase C (PKC)μ, and the mitogen-activated protein kinases, extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. ARE, quercetin, and kaempferol markedly suppressed mast cell-dependent PCA in IgE-sensitized mice. These results indicate that ARE and its active constituents, quercetin and kaempferol, may be a useful therapy for immediate-type hypersensitivity.

Content of antioxidative caffeoylquinic acid derivatives in field-grown Ligularia fischeri (Ledeb.) Turcz and responses to sunlight.

Ligularia fischeri (Ledeb.) Turcz, a commercial leafy vegetable, contains caffeoylquinic acid derivatives (CQAs) as major phenolic constituents. The HPLC chromatograms of leaf extracts collected from different areas in Korea showed a significant variation in CQA amount, and two tri-O-caffeoylquinic acids (triCQAs) were purified and structurally identified by NMR and MS from this plant. Radical scavenging activities among CQAs were found to be increased in proportion to the number of caffeoyl groups. Since this plant prefers damp and shady growth conditions, the effects of sunlight were investigated by growing plantlets in sunlight and shade for four weeks. Greater leaf thickness and higher phenolic contents were found for leaves grown in sunlight than in shade. Four major CQAs-5-mono-O-caffeoylquinic acid (5-monoCQA), and 3,4-, 3,5-, and 4,5-di-O-caffeoylquinic acid (diCQA)-were induced by solar irradiation, whereas the content of these compounds decreased steadily in shade leaves. The leaves of L. fischeri clearly showed adaptation responses to sunlight, and these characteristics can be exploited for cultivation of this plant for potential use as a nutraceutical and functional food.

Edible Seaweed, Eisenia bicyclis , Protects Retinal Ganglion Cells Death Caused by Oxidative Stress

The purpose of the present study was to determine whether edible seaweed, Eisenia bicyclis, is effective in blunting the negative influence of N-methyl-d-aspartate (NMDA) on rat retinas and of oxidative stress-induced transformed retinal ganglion cell (RGC-5 cell line) death. The ethanol extract of E. bicyclis (EEEB) significantly attenuated the negative insult of l-buthionine-(S,R)-sulfoximine plus glutamate on RGC-5 cells. Treatment of the RGC-5 cells with EEEB reduced the reactive oxygen species and recovered the reduced glutathione level caused by various radical species such as H2O2, OH·, or O2·−. Moreover, EEEB inhibited lipid peroxidation on rat brain homogenates caused by sodium nitroprusside. Applying NMDA to the retina affected the thickness of the inner plexiform layer (IPL) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) produced a positive effect on ganglion cells. Importantly, EEEB protected the thinning of IPL and increased TUNEL positive cells in the ganglion cell layer (GCL). Five phlorotannin derivatives were isolated using chromatographic methods and liquid chromatography-mass spectroscopy analysis which has been known as an antioxidant. In conclusion, EEEB has a neuroprotective effect in vitro and in vivo. Furthermore, the major constituents of this extract, phlorotannins, could possibly be active compounds due to their antioxidative potency.

Fast identification of flavonoids in the roots of Sophora flavescens by on-flow LC-NMR

, has been used for various diseases including atherosclerosis and arrhythmias. For the direct identification of the compounds present in Sophorae radix, the hyphenated LC-NMR technique has been applied. WET solvent suppression and scout scan techniques were used to suppress solvent peaks in on-flow LC-NMR experiment. Six prenylflavonoids were identified successfully as kushenol U (1), kurarinone (2), sophoraflavanone G (3), leachianone A (4), kuraridin (5) and kushenol A (6). Key words:

Preparative Isolation of Antioxidant Flavonoids from Small Black Soybeans by Centrifugal Partition Chromatography and Sequential Solid-Phase Extraction

Unlike other members of the leguminous family that are generally used as food, Rhynchosia volubilis, a small soybean with a black seed coat, is used as a folk medicine in Korea. Using an on-line high performance liquid chromatography-2,2ʹ-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation screening system, one peak in the ethyl acetate fraction exhibited outstanding antioxidant capacity. To purify and determine the antioxidant compounds associated with this peak, we developed a centrifugal partition chromatography (CPC) method. The ethyl acetate fraction (500 mg) was subjected to CPC using a two-phase solvent system of n-hexane–ethyl acetate–ethanol–water (0.1:8:2:7, v/v) with a dual-mode CPC (descending-ascending order) in a bid to separate glycitin (3.1 mg), daidzin (14.4 mg), 6ʹʹ-O-acetyl genistin (6.9 mg), 6ʹʹ-O-acetyl daidzin (5.3 mg), and a mixture of epicatechin and genistin. The mixture was further separated through solid-phase extraction to yield epicatechin (6.8 mg) and genistin (23.5 mg), respectively. Structural identification of the R. volubilis flavonoids was performed by NMR and ESI-MS.