• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1309-1314
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• 2006

This study analyzed the contents of vitamin C, polyphenol compounds, and evaluated the inhibitory activities against xanthine oxidase and tyrosinase of Lepista nuda extract prepared by the reflux and microwave-assisted methods. The vitamin C content of the fresh L. nude was $9.92{\pm}0.02$ mg/100 g. The content of phenolic compounds in the fresh L. nuda was $1.87{\pm}0.02\;mg/g$. The ethanol extracts prepared by reflux method and microwave-assisted method showed the highest phenol contents of $12.06{\pm}0.12\;mg/g\;and\;11.84{\pm}0.17\;mg/g$, respectively. The inhibitory rates on xanthine oxidase and tyrosinase of ethanol extracts prepared by the microwave assisted method showed the highest value of 99.78% and 30.30% at the concentration of $3,000{\mu}g/mL$. The inhibitory activities on xanthine oxidase and tyrosinase were increased depending on the extract concentration.

• Food Science and Industry
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• v.43 no.3
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• pp.48-54
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• 2010

• The Korean Journal of Food And Nutrition
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• v.33 no.4
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• pp.419-427
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• 2020

The purpose of this study was to investigate the qualitative changes of the citron by identifying the type of solution and addition of the solution to prevent the browning reaction of the citron in a way that inhibits the browning of the citron. The browning inhibitor solution was investigated using the individual and mixture, and the results of the degree of browning and chromaticity showed that vitamin C+NaCl+cyclodextrin (CD) had the lowest browning of 0.52. In chromaticity, the ΔE values indicate that the higher the value, the greater the change in color, and the lowest value of the vitamin C+NaCl+CD mixture was 47.0, indicating that there was minimal browning compared to other treatment. The active change of the polyphenol oxidase (PPO) in the citron increased enzyme activity as the browning progressed, and the vitamin C+NaCl+CD solution was the lowest at 68.40 μ/g among the anti-browning solution. Based on these research results, it seems that the CD mixing solution can be used as a citron browning inhibitor.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.27-28
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• 1973

The activities of peroxidase and polyphenoloxidase were investigated in the rice leaves(the upper halves) diseased with Akagare or Helminthosporium oryzae. The activity of polyphenoloxidase was slightly lower than that of peroxidase in the healthy leaves but it increased 56% in the diseased leaves while peroxidase decreased 35%. It was expected that polyphenoloxidase is dominant in the oxidation of polyphenols, and hydrogen peroxide may accumulate to harmful level due to the decrease of peroxidase activity resulting in non-enzymatic oxidation of polyphenols in the diseased leaves.

• Preventive Nutrition and Food Science
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• v.6 no.2
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• pp.107-111
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• 2001

Physical and chemical characteristics of four white-and one yellow-fleshed peach cultivars were compared at optimum maturity stage. In addition, differences of phenolic composition, polyphenol oxidase (PPO) activities and PPO isozyme patterns in two peach types were also investigated. There are no significant differences in firmness and color values between two peach types, except for "Yumyung", a white-fleshed peach with the highest firmness, and "Hwangdo", a yellow-fleshed peach with the highest yellowness (b)* value. In general, the soluble solid/titratable acidity ratios, ascorbic acid and total phenolic contents were significantly higher for white-fleshed peaches than those for yellow-fleshed peach (p<0.05). Three major phenolic compounds, catechin, neochlorogenic acid and chlorogenic acid, were found in both the white-and yellow-fleshed peaches. Among them, catechin was the predominant phenolic compound in the white-fleshed peaches, followed by neochlorogenic acid, and chlorogenic acid. Meanwhile, neochlorogenic acid was present in the highest level of the yellow-fleshed peach, but levels of two other phenolic compounds were lower. PPO activities of the white-fleshed peaches were generally higher than that of the yellow-fleshed peach, with the one major band and two minor bands, and there were no big differences in PPO isozyme patterns between two different peach cultivars.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.67-73
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• 2014

Mulberry fruits were semi-dried using hot air ($60-100^{\circ}C$) or cool air ($20-40^{\circ}C$), and the effects of the drying temperature and processing time on the quality of the final dried mulberry fruits were investigated. Response surface methodology was employed to establish a statistical model and predict the conditions resulting in minimal loss of the total phenolic content (TPC) and ascorbic acid. Thus, using overlapped contour plots, the optimal conditions for producing semi-dried mulberry fruits, which reduced the moisture residue to 45% and minimized the nutrient losses of TPC and ascorbic acid, were determined for the hot-air process ($60.7^{\circ}C$ for 5.4 h) and cool-air process ($34.8^{\circ}C$ for 23.3 h). Plus, a higher drying temperature was found to lead to a faster loss of moisture and ascorbic acid, while the TPC was significantly decreased in the cool-air dried mulberry fruits due to the higher activity of polyphenol oxidase between 30 and $40^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.11
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• pp.1471-1477
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• 2009

This study was conducted to examine the antioxidant activities of the extracts from aerial parts and roots of Syneilesis palmata. The ethanol extract of aerial parts showed the highest content of flavonoid compounds (31.72 mg/g), and the ethanol extract of roots has the highest content of total polyphenol compounds (68.11 mg/g). The water extract of S. palmata roots showed the highest xanthine oxidase inhibition of 99.29% and the ethanol extract of aerial parts showed 98.48% at 1.0 mg/mL. The ethanol extract of roots showed the highest value of nitrite scavenging ability of 70.89% at pH 1.2, SOD-like activity of 13.06% and electron donating ability of 98.58% at 1.0 mg/mL concentration. The effect of tyrosinase inhibition was found at only the ethanol extracts of roots (9.33%). We found that root extracts contain abundance polyphenol compounds and their antioxidant activities were greater than those of the extracts of aerial part.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.12
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• pp.1912-1917
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• 2015

Pancreatic lipase is a potential therapeutic target for the treatment of diet-induced obesity in humans. As part of our continuing search for novel bioactive compounds, the convenient enzymatic transformation of caffeic acid into neolignans as well as related oxidized-products enhanced pancreatic lipase inhibitory activity. Enzymatic transformation of caffeic acid (1) using polyphenol oxidase originating from Korean pear yielded four oxidized metabolites, which were identified by different spectroscopic techniques ($^1H$,$^{13}C$ NMR, DEP/T, $^1H-^1H$ COSY, HMBC, HMQC, and NOESY). The anti-obesity efficacy of caffeic acid reactant was tested by in vitro porcine pancreatic lipase assay. All tested samples showed dose-dependent pancreatic lipase inhibitory activities. Four oxidative products including phellinsin A (2), caffeicinic acid (3), isocaffeicinic acid (4), and 7,8-erythro-caffeicin (5) were isolated and identified. The major metabolites (2~5) were evaluated for their pancreatic lipase inhibitory activity, and oxidized-products (2~3) improved potency against pancreatic lipase when compared to original caffeic acid. This result suggested that the neolignans isolated from oxidative transformation of caffeic acid might be beneficial in the treatment of obesity and relevant diseases, and the convenient enzymatic transformation by polyphenol oxidase may be a valuable method for structural modification and enhancement of activity.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.3
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• pp.185-191
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• 1973

Effects of nitrogen sources on chlorophyll, activity of some oxidases in soybean leaves were investigated in relation to phosphorus sensitivity. Ammonium and urea culture accelerated leaf senescence more in phosphorus sensitive cultivars. The leaf senescence patterns affected by nitrogen sources were clearly indicated by intact leaf absorbance. Absorption maximum (670nm in methanol extraction or 685nm in intact leaf), was not changed by nitrogen source in the same method. According to leaf senesence pattern general physiological sensitivity pattern was discussed. IAA-oxidase activity was higher in the phosphorus tolerant cultivars and nitrate treatment than in the sensitive cultivars and ammonium treatment. Glycolate oxidase activity was higher in the sensitive cultivars and nitrate treatment. Polyphenol oxidase activity was higher in the tolerant cultivars and urea treatment. It is concluded that the excess ammonium, to which excess phosphorus is highly similar in physiological effect, disturbs the photosynthetic system by inhibition of ATP generation (photo-and oxidative phosphorylation).

• Applied Biological Chemistry
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• v.47 no.1
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• pp.92-95
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• 2004

Biological activities and anticarcinogenicity of Korean Pear peel were investigated, Electron donating activity and superoxide dismutase (SOD)-like activity of fraction II, III were up to 80% and 50-60% at 50 ppm, respectively, Inhibitory effects on xanthine oxidase were about 80% at 50 ppm, breast adenocarcinoma was about 60% at 2,000 ppm, higher III than II Inhibitory effect on prostate adenocarcinoma was about 23% at 500 ppm. In conclusion, Korean pear peel was expected to use as a functional material.