Jung Im Lee

Protective effect of isorhamnetin 3-О-β-d-glucopyranoside from Salicornia herbacea against oxidation-induced cell damage

Isorhamnetin 3-O-beta-D-glucopyranoside (1) was isolated from Salicornia herbacea. The inhibitory effects of compound 1 on oxidative stress were evaluated in free-cellular and cellular systems. An increased concentration of compound 1 not only exhibited dose-dependent scavenging activities on the generation of 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and carbon-centered radicals, but also significantly decreased levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner. Further, antioxidative mechanisms by compound 1 were examined by measuring the intracellular glutathione (GSH) level and expression levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione reductase and heme oxygenase-1 (HO-1). Compound 1 significantly elevated GSH level as well as expression levels of antioxidant enzymes which were closely related with amount of cellular ROS. In addition, it significantly inhibited oxidative damage of purified genomic DNA and suppressed activity of myeloperoxidase (MPO), a generator of potent oxidant (hypochlorous acid), in tumor necrosis factor-alpha (TNF-alpha) stimulated human myeloid cells. Therefore, these results suggested that compound 1 has a therapeutic effectiveness in prevention of ROS-induced cellular damage and is a candidate worthy of being developed as a potential natural antioxidant related to oxidative stress.

Evaluation of novel antioxidant triterpenoid saponins from the halophyte Salicornia herbacea.

As a part of an ongoing search for novel antioxidants from the salt marsh plants, bioactivity-isolation and structure determination of constituents from Salicornia herbacea were performed. One new triterpenoid saponin (4), along with three known saponins (1-3), has been isolated from n-BuOH fraction of S. herbacea. On the basis of the spectroscopic methods, the structure of the new saponin 4 was elucidated as 3β-hydroxy-23-oxo-30-noroleana-12, 20(29)-diene-28-oic acid 3-O-β-D-glucuronopyranosyl-28-O-β-d-glucopyranoside. Scavenging effects of saponins 1-4 were examined on 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical and peroxynitrite. Particularly, saponin 3 exerted significant antioxidant activity on both authentic peroxynitrite and peroxynitrite generated from morpholinosydnonimine (SIN-1).

Antioxidant efficacy of extracts from a variety of seaweeds in a cellular system

As a part of an ongoing search for antioxidants frodm marine sources, antioxidant activities of 24 kinds of seaweeds (4 green algae, 8 brown algae, and 12 red algae) were investigated. The seaweeds were extracted by acetone/ dichloromethane and methanol, respectively. The antioxidant properties of both extracts were evaluated using four different activity tests, including degree of occurrence of intracellular reactive oxygen species (ROS), NO, lipid peroxidation, and GSH (glutathione) in mouse macrophage Raw 264.7 cells. The levels of intracellular reactive oxygen species (ROS) and GSH were measured using 2’,7’-dichlorofluorescin diacetate (DCF-DA) and monobromobimane as fluorescence probe, respectively. Moreover, the generation of NO and lipid peroxidation products were determined by each method based on the Griess reaction and TBARS assay. Solvent extracts from seaweeds such asScytosiphon lomentaria, Prionitis cornea, Laruencia okamurae,Callophyllis japonica, Sargassum horneri, Dictyopteris divaricat a,Lomentaria catenata, Corallina confuse, Ishige okamurae, andAhnfeltiopsis flabelliformi exhibited high antioxidant activities in cellular oxidizing systems.

Polyphenol-Rich Fraction of Brown Alga Ecklonia cava Collected from Gijang, Korea, Reduces Obesity and Glucose Levels in High-Fat Diet-Induced Obese Mice

Ecklonia cava (E. cava) is a brown alga that has beneficial effects in models of type 1 and type 2 diabetes. However, the effects of E. cava extracts on diet-induced obesity and type 2 diabetes have not been specifically examined. We investigated the effects of E. cava on body weight, fat content, and hyperglycemia in high-fat diet- (HFD) induced obese mice and sought the mechanisms involved. C57BL/6 male mice were fed a HFD (60% fat) diet or normal chow. After 3 weeks, the HFD diet group was given extracts (200 mg/kg) of E. cava harvested from Jeju (CA) or Gijang (G-CA), Korea or PBS by oral intubation for 8 weeks. Body weights were measured weekly. Blood glucose and glucose tolerance were measured at 7 weeks, and fat pad content and mRNA expression of adipogenic genes and inflammatory cytokines were measured after 8 weeks of treatment. G-CA was effective in reducing body weight gain, body fat, and hyperglycemia and improving glucose tolerance as compared with PBS-HFD mice. The mRNA expression of adipogenic genes was increased, and mRNA expression of inflammatory cytokines and macrophage marker gene was decreased in G-CA-treated obese mice. We suggest that G-CA reduces obesity and glucose levels by anti-inflammatory actions and improvement of lipid metabolism.

In Vitro Evaluation on the Antiobesity Effect of Lignans from the Flower Buds of Magnolia denudata

In the present study, an attempt has been made to isolate antiobesity components from crude extracts of the flower buds of Magnolia denudata by CH(2)Cl(2) and MeOH solvents. The crude extracts were partitioned into n-hexane, 85% aqueous MeOH, n-butanol, and water fractions. Their antiobesity effects were evaluated by measuring the effect on adipogenic differentiation using 3T3-L1 cells. Among the fractions, n-hexane and 85% aqueous MeOH fractions effectively reduced the lipid accumulation and the regulation of the adipogenic transcription factor. Both n-hexane and 85% aqueous MeOH fractions were further separated by diverse chromatographic methods to give four lignans (A-D). In comparative analysis, the presence of the lignans during adipogenic differentiation reduced the absorbance values of eluted Oil Red O solution in the order of potency C > D > B > A. Moreover, C and D effectively downregulated SREBP1, PPARγ, and C/EBPα.

Evaluation of Inhibitory Effect of Phlorotannins from Ecklonia cava on Triglyceride Accumulation in Adipocyte

In the present study, a methanolic extract of Ecklonia cava and its solvent-partitioned fractions were evaluated for their antiadipogenic effect in 3T3-L1 adipocytes. One of them, the n-BuOH fraction, effectively reduced lipid accumulation and glucose consumption. In addition, the presence of the n-BuOH fraction in adipocytes suppressed the regulations of adipogenic transcription factors, PPARγ and SREBP1c, and adipogenic specific genes, FABP4, FABP1, FAS, LPL, HSL, and ACS1. Further purification of n-BuOH fractions led to the isolation of six phlorotannins (1-6). The six phlorotannins effectively suppressed triglyceride accumulation. Comparative analysis showed that lipid accumulation in adipocytes was dramatically attenuated in the presence of eckstolonol (4).

Antioxidant Activity of Oxygen Evolving Enhancer Protein 1 Purified from Capsosiphon fulvescens.

This study was conducted to determine the antioxidant activity of a protein purified from Capsosiphon fulvescens. The purification steps included sodium acetate (pH 6) extraction and diethylaminoethyl-cellulose, reversed phase Shodex C4P-50 column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that the molecular weight of the purified protein was 33 kDa. The N-terminus and partial peptide amino acid sequence of this protein was identical to the sequence of oxygen evolving enhancer (OEE) 1 protein. The antioxidant activity of the OEE 1 was determined in vitro using a scavenging test with 4 types of reactive oxygen species (ROS), including the 2,2-diphenyl-1-picrylhydrazyl radical, hydroxyl radical, superoxide anion, and hydrogen peroxide (H2 O2 ). OEE 1 had higher H2 O2 scavenging activity, which proved to be the result of enzymatic antioxidants rather than nonenzymatic antioxidants. In addition, OEE 1 showed less H2 O2 -mediated ROS formation in HepG2 cells. In conclusion, this study demonstrates that OEE 1 purified from C. fulvescens is an excellent antioxidant.

Antioxidant activity of dihydrofurocoumarins from Corydalis heterocarpa

The aim of this paper is to report the results of investigations into the antioxidant effect of dihydrofurocoumarins (1–6), isolated from the salt marsh plant Corydalis heterocarpa. The scavenging activities of the isolated compounds against DPPH radicals, hydroxyl radicals, and superoxide radicals were evaluated by electron spin resonance. The protective activities of these compounds against hydroxyl radical-mediated genomic DNA damage and peroxynitrite-mediated dihydrorhodamine oxidation were also investigated. The experimental results show that most compounds had antioxidant activity but their capabilities differed a little for the different indicators. Among them, compound 6 exerted the strongest antioxidant activity at a concentration of 100 μM/mL for all tested bioassay systems, compared with other compounds.

Peroxynitrite-scavenging Activity of the Halophyte Limonium tetragonum

Crude extracts of Limonium tetragonum and their solvent-partitioned fractions were evaluated for their potential to scavenge authentic ONOO � , and ONOOderived from 3-morpholinosydnonimine (SIN-1). Four flavonol glycosides (1-4) were isolated by activity-guided separation. Their chemical structures were elucidated by extensive 2 D NMR experiments and by comparison with published spectral data. These compounds were also estimated for their peroxynitrite scavenging effects. The scavenging ratios of compounds 1-4 on authentic ONOOwere 56, 37, 56, and 54%, respectively, at a concentration of 1 µM. On the other hand, the inbihition ratios of compounds 1-4 against ONOOgeneration from SIN-1 were 59, 39, 44, and 54% at the same concentration, respectively.

Isolation and Antioxidant Activity of Methyl Aconitates from Arctic Red Alga Polysiphonia stricta

In our continuing study on the antioxidant activity of Polysiphonia stricta, its crude extract was fractionated into n-hexane, 85% aqueous methanol (85% aq.MeOH), n-butanol (n-BuOH), and water fractions according to solvent polarity. The solvent fractions were evaluated for their potential to inhibit lipid peroxidation and reactive oxygen species (ROS) production in HT 1080 cells. The n-BuOH fraction most strongly inhibited both lipid peroxidation and ROS production in HT 1080 cells. The n-BuOH fraction was further separated by repeated silica gel column chromatography and RP-HPLC to give methyl aconitates (2 and 3). The chemical structure of isolated compounds was determinated by NMR spectral analysis.