• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.266-271
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• 2014

The effects of antioxidants on the properties of Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) blends were studied for the functions of the screw speed and loaded duration of high shear rate processing in order to investigate the degradation for PC/ABS blends. Tris-(2,4-di-tert-butyl-phenyl phosphate) (A1) and Bis(2,4-dicumylphenyl) pentaerythritol diphosphite (A3) as phosphite antioxidants and Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (A2) as a phenolic antioxidant are used. The thermal properties were detected by TGA and severely decreased, after the processing. The stress-induced and thermal degradation for PC/ABS blends with the antioxidant A3 was retarded better than the others. By using UTM, the mechanical properties also showed individually decreased according to the antioxidants, after the processing, especially, the elongations showed considerable decline behaviors, while the tensile strengths of PC/ABS blends changed very little. For example, in the operating conditions of 1000rpm of screw speed and 20 seconds of loaded period, the elongations decreased from 148% before the processing, to 91.6% with the A1, to 63% with the A2 and to 131% with the A3 after the processing, respectively. In order to get the morphological properties, the size distributions of the dispersed phases for PC/ABS were investigated by SEM analysis and tended to decrease, as the screw speed and loaded period of the processing increased. Therefore, we confirmed that the antioxidant A3 was the best of all of three to inhibit the stress-induced degradation of PC/ABS blends during the high shear rate processing.

• Korean Journal of Food Science and Technology
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• v.51 no.6
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• pp.524-530
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• 2019

Kelp (Saccharina japonica) contains various bioactive compounds, including vitamins, minerals (especially iodine and potassium), alginic acid, fucoxanthin, and various antioxidants. Kelp is mainly used as a dried product. The purpose of this study was to investigate the stabilities of antioxidant capacities and fucoxanthin of kelp by different conventional drying conditions including hot air drying at 70℃ and natural drying methods. Fucoxanthin, total phenolic contents, and total antioxidant capacity by ABTS, DPPH, and FRAP assays were significantly decreased after 5 to 10 h of hot air drying at 70℃. The assay values were also significantly decreased by 50% after 2 days of drying due to ultraviolet exposure. The findings demonstrate that heat and ultraviolet exposure during drying of kelp could affect the degradation of bioactive compounds, especially fucoxanthin and polyphenols. Optimal conditions should be considered during kelp drying and storage.

• Journal of Microbiology and Biotechnology
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• v.30 no.3
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• pp.359-367
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• 2020

Neurodegenerative disorders in the elderly are characterized by gradual loss of memory and cognitive function. Oxidative stress caused by reactive oxygen species is associated with progressive neuronal cell damage and death in Alzheimer's disease, one of the most common neurodegenerative disorders. An edible brown seaweed, Ecklonia cava, contains a variety of biologically active compounds such as phlorotannins. In this study, we comparatively evaluated the total phenolic content, antioxidant capacity, and neuroprotective effects of the phlorotannin-rich extract from E. cava (PEEC). The total phenolic content of PEEC and dieckol was 810.8 mg gallic acid equivalents (GAE)/g and 996.6 mg GAE/g, respectively. Antioxidant capacity of PEEC was 1,233.8 mg vitamin C equivalents (VCE)/g and 392.1 mg VCE/g determined using ABTS and DPPH assays, respectively, while those of dieckol were 2,238.4 mg VCE/g and 817.7 mg VCE/g. High-performance liquid chromatography results revealed 48.08 ± 0.67 mg dieckol/g of PEEC. PEEC had neuroprotective effects in pheochromocytoma (PC-12) and human neuroblastoma (SH-SY5Y) cells against H₂O₂- and AAPH-induced oxidative damage, partly due to reduced intracellular oxidative stress. PEEC treatment inhibited acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner. Taken together, these findings suggest that PEEC is a good source of antioxidants and neuroprotective materials.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.252-260
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• 2014

Contents of carotenoids, phenolic compounds, volatile organic compounds, and alkaloids in leaves, internodes, fruits, and roots of tomatoes in different developmental stages were measured. Lycopene, ${\beta}$-carotene, and lutein were detected in all the tested parts except roots and green fruits. Lycopene content in red fruits was $49.04{\mu}g{\cdot}g^{-1}$ FW, while that in the other parts was below $40{\mu}g{\cdot}g^{-1}$ FW. ${\beta}$-Carotene and lutein contents in 24th leaves were 5.81 and $6.40{\mu}g{\cdot}g^{-1}$ FW, respectively, and were greater than those in the other parts. Caffeic, chlorogenic, and vanillic acids were detected in all the tested parts except roots. The content of chlorogenic acid in the 18th leaves was $40.11{\mu}g{\cdot}g^{-1}$ FW, while that in the other parts was lower than $31.00{\mu}g{\cdot}g^{-1}$ FW. The contents of caffeic and vanillic acids in the 24th leaves were 9.18 and $1.64{\mu}g{\cdot}g^{-1}$ FW, respectively, and were greater than those in the other parts. Moreover, younger leaves contained the more diverse volatile organic compounds including monoterpenes and sesquiterpenes. Contents of dehydro-tomatine and ${\alpha}$-tomatine were greatest in leaves, followed by internodes, roots and fruits. Younger leaves and internodes contained more dehydro-tomatine and ${\alpha}$-tomatine than older leaves and internodes. The contents of dehydro-tomatine and ${\alpha}$-tomatine in the 24th leaves were 0.89 and $1.42mg{\cdot}g^{-1}$ FW, respectively, and were greatest among all the tested parts. Our results indicated that, except lycopene, tomato leaves included greater secondary metabolites contents than red fruits. The results suggest that inedible parts of tomato plants can be used as raw material for antioxidants, anti-inflammatory agents, fungistats, and pesticides.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.333-338
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• 2012

Lichens are a symbiosis between fungi, algae and cyanobacteria. Our group recently studied the antioxidant properties of some bacterial species isolated from Arctic lichens and we confirmed that they possess high antioxidant activities. In this paper, we investigated the antioxidant capacity of 5 microorganisms newly isolated from 4 Arctic lichen species, Cladonia sp., Sterocaulon sp., Umbilicaria sp. and Cetraria sp., using various solvent extractions. We carried out 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity test and ferric reducing antioxidant power (FRAP) assay. Also total phenolic and flavonoid content assays were performed. Among the bacterial culture extracts of the tested lichen-microorganisms, ethyl acetate extracts of Burkholderia sordidicola S5-B(T) had not only a high antioxidant activity (72.9%) when compared with the ascorbic acid used as the control (51.3%) in the DPPH assay, but also a high amount of phenolic content as well as flavonoid content. As a result, these lichen-microorganisms may be potentially useful sources of natural antioxidants.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2763-2769
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• 2015

Background: Cancer is an unnatural type of tissue growth in which the cells exhibit unrestrained division, leading to a progressive increase in the number of dividing cells. It is now the second largest cause of death in the world. The present study concerned antioxidant, anticancer and anticholinesterase activities and protocatechuic, catechin, caffeic acid, syringic acid, p-coumaric acid and o-coumaric concentrations in methanol extracts of flowers, fruits and seeds of Hypericum amblysepalum. Materials and Methods: Antioxidant properties including free radical scavenging activity and reducing power, and amounts of total phenolic compounds were evaluated using different tests. Protocatechuic, catechin, caffeic acid, syringic acid, p-coumaric acid and o-coumaric concentrations in extracts were determined by HPLC. Cytotoxic effects were determined using the MTT test with human cervix cancer (HeLa) and rat kidney epithelium cell (NRK-52E) lines. Acetyl and butyrylcholinesterase inhibitory activities were measured by by Ellman method. Results: Total phenolic content of H. amblysepalum seeds was found to be higher than in fruit and flower extracts. DPPH free radical scavenging activity of the obtained extracts gave satisfactory results versus butylated hydroxyanisole and butylated hydroxytoluene as controls. Reducing power activity was linearly proportional to the studied concentration range: $10-500{\mu}g/mL\;LC_{50}$ values for H. amblysepalum seeds were 11.7 and 2.86 respectively for HeLa and NRK-52E cell lines. Butyryl-cholinesterase inhibitory activity was $76.9{\pm}0.41$ for seed extract and higher than with other extracts. Conclusions: The present results suggested that H. amblysepalum could be a potential candidate anti-cancer drug for the treatment of human cervical cancer, and good source of natural antioxidants.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.34-34
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• 2017

Various extracts of roots, stems, and leaves of Phalaenopsis Sogo Yukidian 'V3' were evaluated for total phenolics, total flavonoids, and antioxidant capacity. The conjugate form of stem samples contained the highest total phenolics ($5.092{\pm}0.739mg$ gallic acid equivalent per g dry weight） and the highest total flavonoids ($2.218{\pm}0.021mg$ rutin equivalent per g dry weight) was found in the hexane extract of leaves. The ethyl acetate extract of roots showed the maximum antioxidant activity as compared to other extracts. Of which, the $IC_{50}$ value of this sample were 0.070 mg/mL and 0.450 mg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and reducing power, respectively, while the lipid peroxidation inhibition (LPI) value was as 94.2% by ${\beta}$-carotene bleaching method. Five phenolic compounds including caffeic acid, syringic acid, vanillin, ellagic acid, and cinnamic acid were quantified by high-performance liquid chromatography (HPLC). It is suggested that roots of the hybrid Phalaenopsis Sogo Yukidian 'V3' can be explodited as an effective source of antioxidants.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1216-1220
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• 2003

The antioxidative activities of methanol extracts of chestnut flower (Castanea Crenata Flos.) were determinated in vitro using an experimental model system. Solid yield of chestnut flower extracts was 6.26% and total phenolic acid accounted for about 20% of the crude extract. The DPPH radical scavenging activity of methanol extracts prepared from chestnut flower was 17.22%. Although the DPPH radical scavenging activity of chestnut flower extracts was lower than that of other antioxidants, chestnut flower extracts showed continuous activity by time course. The SOD-like activities of methanol extracts prepared from chestnut flower were 65.10%, 95.70% in BHT, 93.29% in quercetin, and 30.30% in ascorbic acid. Chestnut flower extracts showed 51.45% inhibitory effect on peroxidation of egg yolk lecithin.

• Journal of Ginseng Research
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• v.36 no.1
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• pp.93-101
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• 2012

This study evaluated the anti-cholinesterases (ChEs) and antioxidant activities of white ginseng (WG) and black ginseng (BG) roots of Panax ginseng (PG), P. quinquefolium (PQ), and P. notoginseng (PN). Ginsenosides $Rg_1$, Re, Rf, $Rb_1$, Rc, $Rb_2$, and Rd were found in white PG, whereas Rf was not found in white PQ and Rf, Rc, and $Rb_2$ were not detected in white PN. The major ginsenoside content in steamed BG including $RK_3$, $Rh_4$, and 20(S)/(R)-$Rg_3$ was equivalent to approximately 70% of the total ginsenoside content. The WG and BG inhibited acetylcholinesteras (AChE) and butyrylcholinesterase (BChE) in a dose dependent manner. The efficacy of BG roots of PG, PQ, and PN on AChE and BChE inhibition was greater than that of the respective WG roots. The total phenolic contents and 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) scavenging activity were increased by heat treatment. Among the three WG and BG, white PG and steamed black PQ have significantly higher contents of phenolic compounds. The best results for the DPPH scavenging activity were obtained with the WG and BG from PG. These results demonstrate that the steamed BG roots of the three studied ginseng species have both high ChEs inhibition capacity and antioxidant activity.

• Preventive Nutrition and Food Science
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• v.10 no.4
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• pp.316-325
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• 2005

The antioxidant potential of a $75\%$ methanolic extract of highbush blueberry (Vaccinium corymbosum L.) and its different fractions was investigated using different reactive oxygen species (ROS), nitric oxide (NO.), metal chelating and lipid peroxidation assays. Methylene chloride and $75\%$ methanol fractions showed equally high activities $(IC_{50} 0.010 mg/mL)$ for hydroxyl radical (HO) scavenging. Higher hydrogen peroxide $(H_2O_2)$ scavenging values were reported for the ethyl acetate and methylene chloride fractions and their $IC_{50}$ values were 0.20 and 0.15 mg/mL, respectively. Nitric oxide (NO.) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activities were higher in ethyl acetate and methylene chloride fractions. Chloroform and water fractions showed higher activities in superoxide $(O_2.)$ scavenging. All fractions showed strong metal chelating capacities compared with the commercial antioxidants tested. The $0.1\%$ ethyl acetate fraction showed notable capacity to suppress lipid peroxidation in both fish oil and linoleic acid. Phenolic content was measured in all the fractions and methanolic extract. Among the fractions, ethyl acetate fraction showed the highest phenolic content.