• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.190-194
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• 2005

This study was conducted to investigate the changes in contents of total flavonoid and total polyphenol of three leafy vegetables, spinach(Spinacia oleracea L.), chard(Beta vulgaris L.), whorled mallow(Malva verticillata L.) by various blanching times. Total flavonoid and total polyphenol contents of spinach were 21.01 and 25.58 mg/g, those of chard were 26.02 and 35.14 mg/g, and those of whorled mallow were 16.80 and 19.94 mg/g, respectively. Total flavonoid and total polyphenol contents of chard were the highest among the leafy vegetables. Total flavonoid and total polyphenol contents of leafy vegetables were decreased according to blanching time. Especially, total flavonoid content of chard showed significant loss of $15-30\%$ by blanching time. Total polyphenol content of whorled mallow showed loss of $37-39\%$, but the decrease was not significant.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.353-358
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• 2023

Barley (Hordeum vulgare) belongs to the Poaceae family. This study compared the polyphenol and flavonoid levels of unfermented and fermented barley sprouts using spectrophotometric assays. The findings indicated that fermentation greatly boosted the flavonoid content but caused only a slight increase in the polyphenol content. However, this does not imply that fermentation has no effects whatsoever on the polyphenol content of barley sprouts. This was due to the fact that some flavonoids cannot be detected by the wavelength used to calculate the overall polyphenol concentration. Both samples were subjected to high-performance liquid chromatography analysis and detected the flavonoids lutonarin, saponarin, isoorientin, isovitexin, and tricin-all of which have bioactive properties-most notably known for their antioxidant activity. These results augment the ongoing phytochemical profiling research and can possibly valorize the already thriving barley industry.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1387-1390
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• 2008

This study evaluated the effects of heat treatment on antioxidant activity of Rehmannia radix Libosch (RRL). RRL was heated at various temperatures ($110-150^{\circ}C$) for various times (1-5 hr), and the total polyphenol, flavonoid content, and antioxidant activity were investigated. With increased heating temperature and exposure time, total content of polyphenol, flavonoid, as well as antioxidant activity increased. The highest total polyphenol and flavonoid contents were 21.65 and 3.56 mg/g, respectively, these values were occurred after heating for 3 hr at $150^{\circ}C$ (RRL was 5.09 and 0.83 mg/g, respectively). The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was highest value of 83.46% after heating for 3hr at $150^{\circ}C$. The 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) cation radical scavenging activity was highest value of 20.43mg ascorbic acid (AA) eq/g after heating for 2 hr at $150^{\circ}C$. There were highly significant differences in the total polyphenol, flavonoid content, and antioxidant activity among heating temperatures and times (p<0.001), with heating temperature having the greater effect.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.569-580
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• 2023

The aim of this study was to investigate the antioxidant effects of O. robusta stem extract (ORE) and to determine the total polyphenol and flavonoid contents. Free radical scavenging properties were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)), and ·OH (hydroxyl radical) scavenging assays. Total polyphenol and flavonoid contents were measured using Folin-Ciocalteu reagent and aluminum chloride colorimetric methods, respectively. Active compounds of ORE were determined using high-performance liquid chromatography (HPLC). The results of the study showed that ORE exhibited DPPH, ABTS, and ·OH radical scavenging activities in a dose-dependent manner. Especially, 1,000 ㎍/mL of ORE showed the strongest radical scavenging properties against DPPH, ABTS, and ·OH. ORE contained total polyphenol content of 57.4 mg GAE/g and total flavonoid content of 5.4 mg QE/g, which may contribute to their antioxidant effects. As a result of HPLC, the contents of active compounds in ORE, dihydrokaempferol (0.65 ㎍/mL), and 3-O-methylquercetin (1.10 ㎍/mL) were confirmed. In conclusion, ORE may be useful as a functional material with antioxidant properties.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.307-312
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• 2003

Antioxidative activities of Methanol and Ethanol extract of branch, bark, leaves, fruits, wood of Hovenia dulcis THUNBER var. koreana Nakai were analyzed for total poly phenol, flavonoid, antioxidant capacity and DPPH free radical scavanging activitiy. The most total polyphenol and flavonoid contents measerd extract from bark and fruits. Extract from fruits and bark show hight on antioxidant capacity and DPPH free radical scavanging activitiy. There was a good correlation between total polyphenol or flavonoid contents and antioxidant activity.

• Korean Journal of Plant Resources
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• v.26 no.3
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• pp.347-354
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• 2013

Apple and pear are popular fruits consumed in Korea and are common fruit in daily diet. In order to compare the antioxidant activity of the apple and pear peels, total polyphenol contents, total flavonoid contents, $ABTS^+$ free radical scavenging activity, and DPPH free radical scavenging activity were measured from hot water, ethanol, and methanol extracts of the two fruit peels. The total polyphenol and flavonoid contents were highest in 95% methanol extracts of the apple peelsand 70% ethanol extract of the pear peels, respectively. Total polyphenol contents of the pear peels were higher than that of apple peels, and total flavonoid contents of the apple peels were higher than that of pear peels. The apple and pear peels had the highest $ABTS^{+{\cdot}}$ and DPPH free radical scavenging activity in 95% methanol extracts and 70% ethanol extracts, respectively. $ABTS^{+{\cdot}}$ and DPPH free radical scavenging activity of pear peels was higher than that of apple peels, and the DPPH free radical scavenging activity of apple and pear peels were detected in hot water, 95% methanol, and 70% ethanol extracts, respectively. Ascorbic acid, a synthetic antioxidant used as positive control, had significantly higher scavenging activity than the apple and pear peels. In conclusion, the apple and pear peelshave great potential as natural antioxidants. Therefore, above results should be considered to provide the possibility for the development of high functional antioxidants.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.828-831
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• 2007

We evaluated the effects of heat treatment on various properties of onion extracts (Allium cepa). Onion was heated at various temperatures ($110-150^{\circ}C$) for various times (1-5 hr), and the total polyphenol, flavonoid, and free sugar contents, and antioxidant activity were investigated. With increased heating temperatures and exposure times, the total contents of polyphenols and flavonoids, as well as antioxidant activity increased. The highest total polyphenol content (189.80 mg/100g) occurred after heating for 2 hr at $140^{\circ}C$. The highest total flavonoid content (252.51 mg/100g) occurred after heating for 3 hr at $150^{\circ}C$. The antioxidant activity assessed using the DPPH method was highest, at 2.1 mg/mL ($IC_{50}$ value), after heating for 2 hr at $150^{\circ}C$. Correlations between antioxidant activity and the total polyphenol, total flavonoid, and fructose contents were highly significant (all p<0.01). The optimal heating time and temperature were 2 hr and $130^{\circ}C$.

• Korean Journal of Medicinal Crop Science
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• v.14 no.5
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• pp.307-310
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• 2006

This study purposed to look for its uses by analyzing useful substances in kenaf (Hibiscus cannabin us L.) leaves based on the total polyphenol and flavonoid contents in the leaves, DPPH radical scavenging activity of leaf extract, SOD activity, etc. by different growth stage and variety. According to the results of experiment, the total polyphenol content was highest in Everglade-41 (27.9 mg/g dw.), the total flavonoid content was highest in Tainung-2 (42.3 mg/g dw.), and SOD activity was highest in Dowling (96.1 %). However, DPPH radical scavenging activity was similar among the three varieties.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.268-273
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• 2005

Changes in contents of phytochemical compounds (${\beta}$-carotene, ascorbic acid, chlorophylls, total flavonoid, total polyphenol) and hazardous factors (microbial counts, nitrate) of spinach (Spinacia oleracia L.) were investigated by conventional and microwave blanching methods. ${\beta}$-Carotene and chlorophylls contents of spinach were significantly increased by blanching, with conventional blanching resulting in higher contents than microwave blanching. In contrast, contents of ascorbic acid, total flavonoid, and total polyphenol of blanched spinach decreased, with microwave blanching resulting in higher ascorbic acid, total flavonoid, and total polyphenol contents than conventional blanching. Total plate count and total coliforms of blanched spinach significantly decreased, with conventional blanching showing less than 20-25% of microwave blanching. Nitrate content of blanched spinach also showed decreasing pattern, with decrease due to microwave blanching being lower, although not significantly, than that of conventional blanching.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1320-1326
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• 2018

This study investigated the antioxidant and neuronal cell protective effects of activity of water and 70% ethanol extracts from Stachys sieboldii Miq. according to different drying method(hot air drying and freeze-drying). The total flavonoid and total polyphenol content in water extracts was significantly higher after freeze-drying compared to hot air drying(p<0.05). DPPH and ABTS radical scavenging were increased in a dose-dependent manner. The DPPH and ABTS radical scavenging activity of water extract were significantly higher after free-drying compared to hot air drying(p<0.05). In a cell viability using MTT, the water extract according to hot air drying and freeze-drying of Stachys sieboldii Miq. showed protective effect against H2O2-induced nurotoxicity. The results suggest that the water extracts of Stachys sieboldii Miq. after freeze-drying has antioxidant activities and may be useful for neurodegenerative disorders.