Soo-Hyun Kim

ANTIOXIDANT POTENTIAL OF ECKLONIA CAVA ON REACTIVE OXYGEN SPECIES SCAVENGING, METAL CHELATING, REDUCING POWER AND LIPID PEROXIDATION INHIBITION

The antioxidative potential of different fractions (respective organic and aqueous fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Ecklonia cava(a brown seaweed) was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, ferrous ion chelating, reducing power and lipid peroxidation inhibition (conjugated diene hydroperoxide and thiobarbituric acid-reactive substances production) assays. The 70% methanol extract showed significant (p< 0.05) activities in all antioxidant assays and contained a high level of total phenolic content. It was observed that the level of hydrophilic phenolic content was higher than that of hydrophobics. Among those organic solvent fractions, ethyl acetate fraction exhibited significant activities due to the highest level of total phenolic content and their IC50 values were 0.013mg/mL, 0.009mg/mL and 0.33mg/mL in DPPH, hydrogen peroxide and nitric oxide radical inhibition, respectively. These activities were superior to those of a commercial synthetic and natural antioxidants tested. The aqueous chloroform and ethyl acetate fractions also exhibited significant (p< 0.05) activities in reactive oxygen species (ROS) scavenging and metal chelating, attributed to the high amount of hydrophilic phenolics. Moreover, E. cava extracts showed strong reducing power and a notable capacity to suppress lipid peroxidation.

Antioxidant Activity of Hizikia fusiformis on Reactive Oxygen Species Scavenging and Lipid Peroxidation Inhibition

Water and organic extracts (diethyl ether, chloroform, ethyl acetate, acetone, ethanol and methanol) obtained from Hizikia fusiformis were screened on reactive oxygen species (ROS) scavenging assays (1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide and hydroxyl radical) and lipid peroxidation (inhibition of linoleic acid oxidation) inhibitory assays. Water, methanol and ethanol extracts showed significant ROS radical scavenging activities. Water extracts showed high scavenging activities on hydrogen peroxide (around 76%) and DPPH radicals (around 75%) while it presented a moderate scavenging activity on hydroxyl radicals (around 54%). Comparatively higher ROS scavenging activities were recorded in hydroxyl radical and DPPH scavenging assays. DPPH radical scavenging activities were well correlated with the polyphenolic content. ROS scavenging and lipid peroxidation inhibition activities indicated that H. fusiformis might be a valuable natural antioxidative source containing both water and fatsoluble antioxidative components.

The depletion of sodium nitrite by lactic acid bacteria isolated from kimchi.

Nitrites, whether added or naturally occurring in foods, are potential carcinogens, and controlling their concentrations is important for maintaining a safe food supply. In this study we investigated the depletion of sodium nitrite (150 microg/mL) during the fermentation in Lactobacilli MRS broth at 5, 10, 15, 20, 25, 30, and 36 degrees C by lactic acid bacteria (LAB-A, -B, -C, and -D) isolated from kimchi and Leuconostoc mesenteroides strain KCTC3100. The four species of lactic acid bacteria isolated from kimchi were identified as L. mesenteroides, and all produced depletion of less than 20% of sodium nitrite after 10 days of incubation at 5 degrees C. There was less than 40% depletion after 9 days at 10 degrees C, 86.4-92.8% after 7 days at 15 degrees C, 81.4-87.8% after 4 days and more than 90.0% after 5 days at 20 degrees C, 76.3-85.7% after 3 days and more than 90.0% after 5 days at 25 degrees C, and more than 90.0% after 2 days at 30 and 36 degrees C. The depletion by LAB isolates was similar or higher than that by L. mesenteroides strain KCTC3100, and in particular, the LAB-D strain showed the highest depletion effect of all the strains tested, up to 15 degrees C. From these results, the strains isolated from kimchi were very effective for the depletion of sodium nitrite at high temperature, and all sodium nitrite was depleted at the initial period of incubation (1-2 days) at 30 and 36 degrees C. But as the temperature was lowered, the depletion effect of sodium nitrite was decreased in all the strains tested from kimchi. This illustrates that the depletion of nitrite by each strain is subject to the influence of temperatures.

Lipid Peroxidation Inhibitory Effects of Hizikia Fusiformis Methanolic Extract on Fish Oil and Linoleic Acid

The lipid peroxidation inhibitory effects of Hizikia fusiformis methanolic extract (HME) on fish oil and linoleic acid were studied by means of peroxide value (PV), thiobarbituric acid-reactive substances (TBARS), conjugated diene hydroperoxides (CDH) and weight gaining assays. Heat and UV light stability were determined by DPPH assay. HME significantly (p<0.05) reduced the lipid peroxidation in a dosedependent manner. Increasing the level of HME from 0.01 to 0.1% caused a higher antioxidative effect than the one produced by butylated hydroxytoluene (BHT) (BHT reported the best effect compared to -tocopherol and butylated hydroxyanisole). HME reduced the formation of primary oxidation products as showed by the lower CDH values compared to its control counterpart. HME reduced also the addition of oxygen to form lipid peroxyl radicals that indicated a low weight gaining in HME-treated oils. Moreover, it could reduce the formation of lipid peroxide. Furthermore, it diminished the total lipid peroxidation resulting in low TBARS values. The heat and UV light study showed that H. fusiformis contained heat- and UV-light resistant antioxidants. These results indicated that the H. fusiformis antioxidants could be useful in preventing oxidative damages of food oils.

Protective effect of enzymatic hydrolysates from highbush blueberry (Vaccinium corymbosum L.) against hydrogen peroxide-induced oxidative damage in Chinese hamster lung fibroblast cell line

Blueberry was enzymatically hydrolyzed using selected commercial food grade carbohydrases (AMG, Celluclast, Termamyl, Ultraflo and Viscozyme) and proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase and Protamex) to obtain water soluble compounds, and their protective effect was investigated against H2O2-induced damage in Chinese hamster lung fibroblast cell line (V79-4) via various published methods. Both AMG and Alcalase hydrolysates showed higher total phenolic content as well as higher cell viability and ROS scavenging activities, and hence, selected for further antioxidant assays. Both AMG and Alcalase hydrolysates also showed higher protective effects against lipid peroxidation, DNA damage and apoptotic body formation in a dose-dependent fashion. Thus, the results indicated that water soluble compounds obtained by enzymatic hydrolysis of blueberry possess good antioxidant activity against H2O2-induced cell damage in vitro.