• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.744-750
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• 2015

Purple sweet potatoes were dehydrated with maltodextrin with different dextrose equivalent (DE) values of 4-7, 13-17, 16.5-19.5, and 17-20. Maltodextrin was used as a molecular press dehydrating agent. The molecular dehydration rate of the purple sweet potatoes increased over time. As the DE of maltodextrin increased, the moisture content after 12 h of dehydration decreased from 65.7% to 40.8, 36.1, 34.9, and 28.6% for DE values of 4-7, 13-17, 16.5-17.5, and 17-20, respectively. Additionally, total phenolic content, anthocyanin, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities decreased as the DE value of maltodextrin increased. While maltodextrins with DE values of 16.5-19.5 and 17-20 effectively dehydrated the purple sweet potatoes, total phenolic, anthocyanin, and DPPH radical scavenging activities were lowered during dehydration. The DPPH radical scavenging activities correlated to both the total phenolic content ($r^2=0.96$) and anthocyanin contents ($r^2=0.95$) of the purple sweet potatoes. These results indicate that the purple sweet potatoes were effectively dehydrated with maltodextrin whose DE values ranged 16.5-20, although there were losses in the total phenolic and anthocyanin contents.

• The Korea Journal of Herbology
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• v.26 no.4
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• pp.95-99
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• 2011

Objective : In this study, we demonstrate the protective effect on oxidative DNA damage of leaf extracts from Abeliophylli distichi Folium via its antioxidant activity for the establishment of new value for the herbal medicine. Methods : Abeliophylli distichi Folium leaves were extracted with hot-water and ethylacetate (EtOAC). The 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical and hydroxyl scavenging assay and $Fe^{2+}$ chelating assay were performed for antioxidative effect and ${\varphi}$X-174 RF I DNA cleavage assay and intracellular DNA damage assay were used for inhibitory effect of intracellular DNA damage. Results : In DPPH, Hydroxyl radical scavenging activity and $Fe^{2+}$ chelating activity of EtOAC extracts were 94.72%, 62.88%, 41.13%, and hot-water extracts were 88.86%, 56.7%, 37.4% at 200 ${\mu}g/m{\ell}$, respectively. Also, those extracts showed protective effect of DNA damage against the oxidative stress. Conclusion : These results indicated that the leaf extracts of Abeliophylli distichi Folium can be used as a natural antioxidants, which effectively inhibits the oxidative DNA damage.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3567-3572
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• 2010

Black pine barks from the southern region of Korea were extracted using pressurized hot water and the water soluble extracts were then separated in a stepwise fashion using a variety of solvents, column chromatography (CC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The antioxidant activities of each fraction and the active compounds were determined based on the radical scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), reductive potential of ferric ion, and total phenol contents. A DPPH test showed that the half maximal effective concentration ($EC_{50}$ value : $6.59{\pm}0.31\;{\mu}g/mL$) of the ethyl acetate fraction (ca. 0.67%) was almost the same as that of the control compounds and inversely proportional to the value of the total phenol contents. The cell viability of the water extracts was confirmed by methyl thiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) with enzyme linked immune sorbent assay (ELISA). Catechin, epicatechin, quercetin and ferulic acid were isolated from the ethyl acetate fraction as active compounds and identified by nuclear magnetic resonance. The antioxidant activity as value of DPPH of each of the separated compounds was lower than the ethyl acetate fraction, and ferulic acid was the lowest among these compounds.

• Journal of Life Science
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• v.29 no.2
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• pp.231-238
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• 2019

This study evaluated the antioxidant activity of the extract and fractions of Alnus firma. Alnus firma had the highest total phenolic content ($452.80{\pm}7.01{\mu}g$ gallic acid equivalents/mg) in a methanol (MeOH) fraction and the highest total flavonoid content ($112.29{\pm}11.14{\mu}g$ rutin equivalents/mg) and antioxidant capacity ($936.23{\pm}0.07{\mu}g$ ${\alpha}$-tocopherol equivalents/mg) in an ethylacetate (EA) fraction. The antioxidant activities of various solvent extract fractions of Alnus firma were evaluated using various antioxidant assays, including ${\beta}$-carotene-linoleate assay, reducing power assay, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, metal chelating activity assay, superoxide anion radical scavenging assay, and lipid peroxidation inhibition assay using the ferric thiocyanate method. These activities were compared with those of ascorbic acid, butylated hydroxyanisole (BHA), gallic acid (GA), butylated hydroxytoluene (BHT), and ${\alpha}$-tocopherol. First, at a $250{\mu}g/ml$ concentration, the EA and MeOH fractions of A. firma showed 92.43% and 89.20% DPPH radical scavenging activity, respectively. Second, $50{\mu}g/ml$ of the EA fraction exhibited 72.49% superoxide anion radical scavenging activity, a little greater than the same dose of GA (60.88%). Finally, 0.5 and 1 mg/ml of the EA fraction showed 73.45% and 73.29% inhibition of peroxidation in the ${\beta}$-carotene-linoleic acid system, respectively. The decreasing order of reducing power was EA fraction > n-butanol (BuOH) fraction > dichloromethane (DCM) fraction > n-hexane (HX) fraction. The results obtained in the present study indicated that Alnus firma can be used as an easily accessible potential source of natural antioxidants.

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.237-240
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• 2008

The antioxidant activities of aroma extracts from commercially available red wines in Korea were evaluated. The aroma extracts of the red wines were extracted by simultaneous steam distillation. Antioxidant activity was measured by DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) radical cation scavenging activity. DPPH radical scavenging activity of the aroma extracts in the red wines increased with increases in the amount of wine used for aroma extraction. Antioxidant activities of domestic wine 1, imported wine 7, and imported wine 12 were 97.16, 96.72 and 94.52%/20 mL wine by DPPH assay and 7.09, 8.07 and 7.28 mg ascorbic acid equivalents per mL wine by ABTS assay, respectively. This study demonstrates potent antioxidant activities of the aroma extracts of commercially available red wines in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.5
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• pp.328-334
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• 2000

Sixty local soybean cultivars were evaluated on the antioxidative activity by superoxide dismutase (SOD), 1, 1-diphenyl-2-picrylhydrazyl (DPPH), thiobarbituric acid(TBA), and chemiluminescence using the FI-CL system. Soybean were collected throughout the country, and were grown over two years (1997 and 1998) for measuring antioxidative activity in soybean seeds. There were differences in antioxidative activity depen-ding on the method of measurement and variation of the crop year. Soybeans from Kwangyang-shi-1 (76.78%) in 1997 and Kangjin-gun-3(79.14%) in 1998 showed the highest SOD activity, whereas those from Hwasoon-gun (80.43%) in 1997 and Kangjin-gun-2 (49.82 %) in 1998 exhibited the highest DPPH activity. Soybeans from Chongup-gun-2 (75.77%) in 1997 and from Yochon-shi-5 (69.17%) in 1998 exhibited the highest TBA activity, and those from Jinahn-gun (48.99%) in 1997 and Kohung-gun (49.73%) in 1998 exhibited the highest activity using the chemiluminescence method. These results suggest that it may be possible to develop soybean varieties with higher antioxidative activity.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.470-476
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• 2015

In this study, three dicaffeoylquinic acids (DCQAs) isolated from Gnaphalium affine D. DON. extracts were structurally identified and evaluated for their antioxidant activities, cellular protective effects, and tyrosinase inhibitory activities. The ethyl acetate fraction of G. affine was chromatographed, which yielded 3 DCQA derivatives of 1-3 : 3,5-dicaffoylquinic acid (3,5-DCQA, 1), 4,5-dicaffeoylquinic acid (4,5-DCQA, 2), 1,5-dicaffoylquinic acid (1,5-DCQA, 3). The structure of each compounds was determined using $^1H$ NMR and MS analyses. Compounds of 1-3 showed strong free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities ($FSC_{50}=3.70$, 5.80, and $5.50{\mu}M$, respectively) compared to those of a commonly used lipophilic antioxidant, (+)-${\alpha}$-tocopherol ($21.90{\mu}M$). Cellular protective effects of 1-3 compounds on the $^1O_2$ sensitized photohemolysis of human erythrocytes were similar to (+)-${\alpha}$-tocopherol. 1-3 compounds also exhibited higher tyrosinase inhibitory effects ($IC_{50}=0.15$, 0.16, and 0.13 mM) compared to arbutin (0.33 mM), known as a skin-whitening agent. These results indicate that three DCQA derivatives may be applied as an antioxidant and a skin whitening agent in food or cosmetic industries.

• Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.335-349
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• 2022

To optimize the hydrolysis conditions in the production of antioxidant hydrolysates from tuna cooking juice concentrate (TC) to maximize the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, TC containing 48.91% protein was hydrolyzed with Alcalase 2.4 L, and response surface methodology (RSM) was applied. The optimum hydrolysis conditions included a 2.2% (w/v) Alcalase concentration and 281 min hydrolysis time, resulting in the highest DPPH radical scavenging activity of 66.49% (0.98 µmol Trolox/mg protein). The analysis of variance for RSM showed that hydrolysis time was an important factor that significantly affected the process (p < 0.05). The effects of different drying methods (freeze drying, hot air drying, and vacuum drying) on the DPPH radical scavenging activity and amino acid (AA) profiles of TC hydrolysate (TCH) were evaluated. Vacuum-dried TCH (VD) exhibited an increase in DPPH radical scavenging activity of 81.28% (1.20 µmol Trolox/mg protein). The VD samples were further fractionated by ultrafiltration. The AA profiles and antioxidant activities in terms of the DPPH radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power, and ferrous ion chelating activity were investigated. Glutamic acid, glycine, arginine, and cysteine were the major AAs found in the TCH fractions. The highest DPPH radical scavenging activity was found in the VD-1 fraction (< 5 kDa). The VD-3 fraction (> 10 kDa) exhibited the highest ABTS radical scavenging activity and ferric reducing antioxidant power. The ferrous ion chelating activity was the highest in VD-1 and VD-2 (5 to 10 kDa). In conclusion, this study provided the optimal conditions to obtain high antioxidant activities through TCH production, and these conditions could provide a basis for the future application of TCH as a functional food ingredient.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.31-31
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• 2022

Plant-derived antioxidants are used as a healthy diet and are known to inhibit various human diseases. In this study, we investigated free radical scavenging and antioxidant activity of extracts from three plants (Ammannia multiflora, Ammannia coccinea and Salix gracilistyla) with the most DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity from 196 plant extracts inhabiting along Nakdong River in Republic of Korea. The three extracts also have strong total antioxidant activity. Moreover, the extracts inhibited hydrogen peroxide (H₂O₂)-induced reactive oxygen species production and depolarized mitochondrial membrane potential in RAW264.7 macrophages. In zebrafish larvae, 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescent intensity, induced by H₂O₂, was markedly reduced by the extracts of A. multiflora, A. coccinea and S. gracilistyla. Meanwhile, the extracts were upregulated Nrf2 and HO-1 expression, and an HO-1 inhibitor reversed the extract-induced oxidative responses both in vivo and in vitro. The data suggest that the extracts of A. multiflora, A. coccinea, and S. gracilistyla exert potential free radical scavenging and antioxidant capacities both in vivo and in vitro by activating the Nrf2/HO-1 signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.637-638
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• 2006

Bioassay-guided fractionation of an organic extract of the culture broth from an unidentified marine-derived fungus led to the isolation of a new metabolite, N-[2-(4-hydroxyphenyl) acetyl]formamide (1), along with four known polyketides, 4-hydroxyphenyl acetamide (2), 4-hydroxyphenyl acetic acid (3), 3,4-dihydroxyphenyl acetic acid (4), and N-[2-(4-hydroxyphenyl)ethenyl]formamide (5). The structures of 1-5 were elucidated by spectral data analyses. Among them, compounds 1, 4, and 5 exhibited significant radical scavenging activity against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) with $IC_{50}$ values of 8.4, 11.9, and $0.2{\mu}M$, respectively.