Ki-Wan Lee

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.

Antioxidant Effect of Enzymatic Hydrolyzate from a Kelp, Ecklonia cava

The potential antioxidative activity of water-soluble enzymatic hydrolyzates from a kelp, Ecklonia cava was evaluated by free radical scavenging and lipid peroxidation assays. To prepare water-soluble hydrolyzates from E. cava the seaweed was enzymatically hydrolyzed by five carbohydrases (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme and Alcalase). Among all the hydrolyzates, Celluclast hydrolyzate effectively scavenged free radicals released from DPPH (1,1-diphenyl-2- pricrylhydrazyl) and recorded around 73% scavenging activity at the concentration of 4 mg . This hydrolyzate was thermally stable and DPPH radical scavenging activity remained 80% or higher at heating temperatures of 40 and 60 up to 12 h and around 80% at 100 up to 8 h. AMG and Ultraflo hydrolyzate inhibited the lipid peroxidation of fish oil as that of -tocopherol. These results suggested that an enzymatic extraction will be an effective way for the production of a potential antioxidant from seaweeds.

Enzymatic Hydrolysis for Effective Extraction of Antioxidative Compounds from Hizikia fusiformis

Hizikia fusiformis hydroysates by five carbohydrases (Viscozyme, Celluclast, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme and Alcalase) were investigated for their extraction efficacy (yield and total total polyphenolic content) and antioxidative activity (DPPH radical and hydrogen peroxide scavenging activity). Termamyl and Ultraflo of the carbohydrases and Flavourzyme and Alcalase of proteases were selected by their high eficacy of extraction and antioxidative activity. Selected enzymes were used to investigate the optimum enzymatic reaction time and dosage (enzyme/substrate ratio) suitable for hydorolysis. Optimum reaction time for the enzymatic hydrolysis was 3 days and optimum dosage of hydrolysis was observed as 5%. Simultaneously, Ultraflo of the two carbohydrases and Alcalse of the two proteases were selected as the most effective enzymes. Combination of Ultraflo and Alcalase under optimum hydrolysis conditions could intensify the extraction efficacy of antioxidative materials form H. fusiformis. The hydrolysate obtained by combining the enzymes was separated into four different molecular weight fractions (30 kD) and recorded the polyphenolic content distribution and respective antioxidative ability. The fraction 1kD indicated comparatively higher antioxidative activities related to their polyphenolic content.

Antioxidant Activities of Chlorophyta and Phaeophyta from Jeju Island

Antioxidative activities of Chlorophyta and Phaeophyta in Jeju Island were measured by superoxide anion (), hydroxyl radical (), hydrogen peroxide () and DPPH free radical scavenging assays. Methanolic and aqueous extracts of the seaweeds were prepared at both temperatures, higher (70) and room temperature (20), and screened for the construction of an extract bank from seaweeds in Jeju Island. A variety of extracts showed positive effect against reactive oxygen species (ROS). Especially, Sargassum thunbergii methanolic extract at 70 (70ME, 97.41%), S. fulvellum methanolic extract at 20 (20ME, 84.66%), Codium fragile aqueous extract at 70 (70AE, 96.61%) and S. thunbergii 20ME (97.44%) exhibited the highest scavenging activities against , , and DPPH free radicals, respectively. Total phenolic contents also examined but did not show a positive correlation with ROS scavenging abilities (except for a few extracts). These results indicate that further investigation is needed to identify and purify the responsible antioxidative components.

Antioxidant Activities of Red Algae from Jeju Island

The aim of the present study was to evaluate the antioxidant activity of red algae in Jeju Island. The algal extracts were obtained with MeOH and fresh water at 20 and 70°C, and screened for antioxidant activities using hydroxyl radical (HO·), superoxide anion (O2–), hydrogen peroxide (H2O2) and DPPH free radical scavenging assays. Among them, Gracilaria verrucosa methanolic extract at 20°C (20ME, 96.85%), G. textorii aqueous extract at 20°C (20AE, 88.01%), Grateloupia filicina 20AE (85.35%), and Polysiphonia japonica 20ME (94.92%) exhibited the highest scavenging activities against HO·, O2–, H2O2, and DPPH free radicals, respectively. Moreover, P. japonica (20ME and 70ME) is correlated between DPPH free radical scavenging activity and polyphenolic contents. These results indicate that some red algae in Jeju Island could be potential candidates for development of antioxidants.

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.

Screening of Extracts from Red Algae in Jeju for Potentials MarineAngiotensin - I Converting Enzyme (ACE) Inhibitory Activity

Hypertension is a worldwide problem of epidemic proportions, affecting 15-20% of adults. It is the most common serious chronic health problem because it carries a high risk factor for arteriosclerosis, stroke, myocardial infarction and end-stage renal disease. Angiotensin I Converting Enzyme (ACE) belongs to the class of zinc metal proteases and is located in the vascular endothelial lining of the lungs (Miyoshi et al. 1991). This enzyme plays a key role in the control of blood pressure, by virtue of the rennin-angiotensin system (Ondetti et al . 1982; Rencland and Lithell 1994; Fujita and Yokoyama 2000). ACE acts as an exo-peptidase that cleaves a dipeptide of C-terminus of angiotensin I peptide to produce the potent vasoconstrictor angiotensin II (Curtiss et al. 1978; Maruyama et al. 1989; Dzau 2001) and inactivates bradykinin (Ukeda et al. 1991). A number of ACE inhibitors have been extensively used in the treat of essential hypertension and heart failure in human; these include alacepril, benazepril, captopril, cilazapril, enalapril, fosinopril, lisinopril, moexipril, perindopril, quinapril, ramipril, tandolapril, and zofenopril (Kato and Suzuki 1971; Ondetti 1977; Sawayama et al. 1990). However, these commercial drugs are believed to cause certain side effects, such as cough, taste disturbances and skin rashes (Atkinson and Robertson 1979). Therefore, searching ACE inhibitors from natural resources have become more important. Recently, many researchers have studied inhibitory activities on anti-ACE and antihypertensive effects after oral or intravenous administration in animal experiments and in clinical trials (Shin et al. 2001; Sato et al. 2002; Seppo et al. 2003). Also, much attention for the natural products and functional natural biomaterials has been paid to marine algae. In fact, for several centuries mankind has been exploiting the properties of certain foods to mitigate or prevent diseases. A number of investigators have studied the various bioactivities of algae and have found that seaweeds have not only nutritional effects but also beneficial properties to cure various diseases and keep good health (Joshipura et al. 2001). Marine algae have been consumed in Asian countries since ancient times, while in Western countries they have been utilized as sources of phycocolloids, Algae Volume 21(3): 343-348, 2006

Potential of Benthic Diatoms Achnanthes longipes, Amphora coffeaeformisand Navicula sp. (Bacillariophyceae) as Antioxidant Sources

Reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radicals and superoxide anions, which are produced because of exogenous factors (tobacco smoke, ionizing radiation and certain pollutants) and endogenous factors (normal aerobic respiration) have been implicated in cellular processes such as mutagenesis, carcinogenesis and premature aging. ROS have the ability to react with a large variety of easily oxidisable cellular components, such as proteins, lipids and lipoproteins (Fridovich 1995). Oxidation is one of the major reasons of food deterioration, resulting to the destruction of fat-soluble vitamins and development of off colors and toxicants (Yang et al. 2000; Ukeda et al. 2002). Besides, in the food industry lipid peroxidation is an important deteriorative reaction during processing and storage. Commercial antioxidant supplements such as butylated hydroxyl anisole (BHA), butylated hydroxy tolouene (BHT), α-tocopherol and propyl gallate (PG) have been used in order to reduce oxidative damages in human body (Sherwin 1990; Gulcin et al. 2002). However, it is suspected that those antioxidants are responsible for some side effects such as liver damage and carcinogenesis. Antioxidants are involved with the oxidation mechanism by scavenging free radicals, chelating catalytic metals and by acting as oxygen scavengers (Shahidi and Wanasundara 1992; Buyukokuroglu et al. 2001). As a natural antioxidant source, plants have an ability to absorb the sun’s radiation for generating high levels of oxygen as secondary metabolites of photosynthesis. Oxygen is easily activated by ultra violet (UV) radiation and heat from the sunlight to produce toxic ROS. Therefore, plants produce various antioxidative comAlgae Volume 24(1): 47-55, 2009

Radical Scavenging Potential of Hydrophilic Phlorotannins of Hizikia fusiformis

Hizikia fusiformis is well known edible brown seaweed both in Korea and Japan. It has been intensively studied due to its pronounced health benefits. In this study, the radical scavenging (antioxidative) activities of its hydrophilic phlorotannin constituents were studied. An aqueous extract/original extract (OE) of H. fusiformis was initially prepared with heat, enzymes and pH control treatments. Then the original extract was further fractionated (with methylene chloride and methanol) and crude hydrophilic phlorotannin extract (CHPE) was prepared. The radical scavenging activities of both OE and CHPE were determined by using electron spin resonance (ESR) spectrophotometric assays such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and alkyl radical assays. The CHPE reported significantly (p ) than that of the OE (0.21 mg ). Both OE and CHPE have reported good radical scavenging activities and those activities were dose-dependent. The CHPE have demonstrated significantly higher radical scavenging activities than that of the OE. In comparison, the DPPH radical (6 10 M) scavenging activities of all the CHPE concentrations (0.25, 0.5 and 1 mg ) tested were significantly higher (37.3, 78.2 and 91.6%, respectively) than that of the OE counterparts (11.4, 34.6 and 61.7%, respectively). Alkyl radical scavenging percentages of CHPE at 0.0625, 0.125, 0.25 and 0.5 mg were significantly higher (34.3, 69.2, 80.4 and 88.7%, respectively) than that of the OE (16.6, 41.4, 62.3 and 77.4%, respectively). The percentages of hydroxyl radical scavenging activities of CHPE at the concentrations of 0.25, 0.5 and 1 mg were 32.5, 59.4 and 84.2 % respectively. Moreover, the hydroxyl radical scavenging activity of OE was quite lower than that of the CHPE. Therefore, these results suggest that the hydrophilic phlorotannins of H. fusiformis are potential radical scavengers thus, a great source of antioxidative nutraceuticles.