• Journal of Life Science
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• v.21 no.11
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• pp.1631-1635
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• 2011

The capability of synthesizing polyphenol glycosides was examined using recombinant amylosucrase from the hyperthermophilic bacterium Deinococcus geothermalis. Based on the action mode of amylosucrase, sucrose and twenty-one polyphenols were used as a donor and acceptors respectively. The transglycosylation reaction by amylosucrase produced one or two major polyphenol glycosides depending on the type of polyphenols used. The synthesized polyphenol glycosides were detected by thin-layer chromatography. The structures of the newly synthesized polyphenol glycosides were predicted based on the transglycosylation mechanism of the enzyme. According to the acceptability of the polyphenols, the structural characteristics of polyphenol as an efficient acceptor were evaluated. The results indicate that amylosucrase is an efficient catalyst for the enzymatic synthesis of polyphenol glycosides, which have high potentials in food, cosmetics, and pharmaceutical industries.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.3
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• pp.198-204
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• 1988

This study was aimed at obtaining elementary data on enzymatic browning of potato and potato products and examining the inhibitory method of browning. Therefore, we extracted polyphenol oxidase from potatoes(Solanum tubersum L.), and investigates its general properties and inhibiting effects of its activity with the different concentrations of sulfites($Na_2S_2O_4,\;Na_2SO_3{\cdot}7H_2O,\;NaHSO_3$). The optimum pH and temperature of polyphenol oxidase were observed to be 6.5 and $37^{\circ}C$ respectively. The polyphenol oxidase at PH5 was very stable, and the activity of polyphenol oxidase between pH $5.0{\sim}9.0$ was estimated to be relatively high, showing $72{\sim}75%$ of its activity at pH5. The polyphenol oxidase was very stable when heated at $40^{\circ}C$ for one hour, and almost 50% of enzyme activity was decreased when heated at $70^{\circ}C$ for twelve minutes. At 0.1mM concentrating of sulfites the relative activity of polyphenol oxidase was 98% in all the three cases of sulfites. Thus sulfites at 0.1mM concentration was found to have little inhibiting effect on polyphenol oxidase activity. At 1mM concentration of sulfites $NaHSO_3$ showed the lowest 36% relative activity among the three. At 5mM concentration of sulfites, the relative activity of $Na_2SO_3{\cdot}7H_2O$ was the lowest 14%.

• Korean Journal of Oriental Medicine
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• v.16 no.3
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• pp.175-178
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• 2010

The aim of this study is to compare antioxidant activity and total polyphenol contents between before and after fermentation of Ssanghwa-tang according to solvent partition. Ssanghwa-tang was fermented with Lactobacilus fermentum. Ssanghwa-tang and the fermented Ssanghwa-tang were fractioned by solvent partition with ethyl acetate, butanol and water. The Ssanghwa-tangs and their solvent fractions were evaluated for total polyphenol contents and DPPH radical scavenging activity. The antioxidant activity as well as the total polyphenol contents were highest in each ethyl acetate fraction and significantly (p<0.05) increased after fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.844-847
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• 2001

Factors affecting thermostability of polyphenol oxidase (PPO) from potato were studied for the purpose of providing useful information for food processing operations. The enzyme was most stable at pH 7.0 and it was inhibited to 70% after heat treatment at 8$0^{\circ}C$ for 1 min. The z-value for the thermal inactivation of the PPO was 12.17$\pm$0.58$^{\circ}C$. The thermostability of the enzyme was reduced by addition of sodium chloride. And the activity was inhibited by addition of reducing reagents such as 2-mercaptoethanol and dithiothreitol.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.170-172
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• 1992

Four types of polyphenol oxidase were isolated from the crude extract of a Ligularia fischeri by gel filtration on Sephadex G-150. Optimum pH and temperature for the activity of partially purified enzyme were 7.5 and $25^{\circ}C$, respectively. It was stable at temperature $40^{\circ}C$ when examined at pH 7.5 for 5 min, and lost 90% of its activity at $70^{\circ}C$ in 30 min at pH 7.5. The enzyme has good activity on catechol and chlorogenic acid but was inactive on dopamine.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.421-425
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• 2007

The inhibitory effect of onion extract on polyphenol oxidase (PPO) and browning of peach juice was investigated. Various reducing agents such as L-ascorbic acid, L-cysteine, dithiothreitol, glutathione, and sodium pyrosulfite strongly inhibited polyphenol oxidase extracted from peach. The enzyme was also inhibited by addition of water extract of onion. Regardless of substrates used, the addition of heated onion extract exhibited stronger inhibitory effect on peach polyphenol oxidase activity than that of the fresh one. The inhibitory effect of onion extract was dependent on heating temperature and time. The onion extract inhibited the peach polyphenol oxidase non-competitively. The heating of onion extract in the presence of glucose, glycine stimulated the inhibitory effect of the onion extract, which suggests non-enzymatic browning products produced during heating might be responsible for the stronger inhibitory action of the heated onion extract. The retardation of peach juice browning by onion extract seems to be caused by inhibition of peach PPO.

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.184-188
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• 2011

The melatonin, total polyphenol contents, and DPPH radical scavenging activity were determined in alfalfa, chicory, rape, red kale and sunflower after germination for four days at $24{\pm}0.1^{\circ}C$. Compared with seeds, melatonin content was increased in all sprouts, at the highest level in red kale (2,502.9 pg/g, 5.6 times higher than seed) followed by rape (2,430.1 pg/g), chicory (2,037.7 pg/g), alfalfa (1,160.8 pg/g) and sunflower (768.2 pg/g) sprout, however, the addition of tryptophan (0.5 mM), the precursor of melatonin synthesis, did not show any desirable effect. Both polyphenol content and DPPH radical scavenging activity were substantially increased in chicory (8.7 mg/g, 66%), rape (10.7 mg/g, 51%) and red kale (11.0 mg/g, 53%) sprouts, but not in alfalfa and sunflower sprouts. Melatonin content per gram polyphenol (ng/g) was also increased in all sprouts through germination. Germination was effective in increasing melatonin in all seeds tested, while its effect on polyphenol content and DPPH radical scavenging activity was species dependent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.3
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• pp.241-245
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• 1991

A polyphenol oxidase from the crude extract of Aster scaber was partially purified by (NH4)2 SO4 precipitation and subsequent Sephadex G-150 chromatography. The final preparation showed five peaks of enzyme activity. Optimum pH and temperature for the activity of polyphenol oxidase were 7.0 and $30^{\circ}C$, respectively. Enzyme activity was stable at $40^{\circ}C$ for 5min in pH 7.0 reaction mixture but ceased completely at $60^{\circ}C$ for 30min and $70^{\circ}C$ for 5min at pH 7.0. The olyphenol oxidase has good activity acid but was inactive on DL-depa. The apparent Km for catechol was about 17.6mM.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.946-951
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• 2016

In this study, Ilex serrata Thunb was extracted with 70% methanol and concentrated under reduced pressure to measure its total polyphenol contents; furthermore, we examined the effect of electron donating ability of the various extracts. The extract was fractionated using different solvents such as methylene chloride, ethyl acetate, and methanol to investigate total polyphenol contents and electron donating abilities. The total polyphenol contents were $1,058.59{\pm}85.85{\mu}g\;GAE/mL$ in 70% methanol, $297.29{\pm}29.43{\mu}g\;GAE/mL$ in methylene chloride, $313.28{\pm}9.22{\mu}g\;GAE/mL$ in ethyl acetate, and $837.82{\pm}31.16{\mu}g\;GAE/mL$ in methanol. The total polyphenol contents showed significant differences (p<0.05) between the solvents. The electron donating abilities were $72.93{\pm}0.29%$ for 70% methanol extract, $14.02{\pm}2.01%$ for methylene chloride, $24.05{\pm}1.75%$ for ethyl acetate, and $84.08{\pm}1.95%$ for methanol. The electron donating abilities were significantly different (p<0.05) between the solvents. The two portions of Ilex serrata Thunb extracts obtained from methanol showed significantly relevant results in the total polyphenol contents and electron donating ability, which was higher than the original extract.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.116-119
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• 2000

This study was conducted to investigate antiallergy of the polyphenol fractions isolated from persimmon leaves (Diospyros kaki folum). The result of the passive cutaneous anaphylaxis (PCA) reaction of expriment on anti-allergy, the allergy remarkably decreased in polyphenol fraction I, II and III groups in comparison with the control group. After antigen challenge, histamine content of blood of the polyphenol groups was lowered to near the normal group.