• Reproductive and Developmental Biology
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• v.34 no.4
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• pp.305-308
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• 2010

In this study, we conducted an oral glucose tolerance test (OGTT) so as to compare antidiabetic activities of general potatoes, purple-flesh potatoes, and potato pigments in rats at various concentration levels. After allowing the rats to abstain from food for 12 hours, 10%/20% general potato, purple-flesh potato, and potato extract was orally administered to rats at 100 and 500 mg/kg concentrations. The blood glucose level was measured after an hour. Then, immediately, 1.5 g/kg of sucrose was administered through the abdominal cavity and the blood glucose measured after 30, 60, 120, and 180 minutes. 20% purple-flesh potato group and 10% general potato group, both 100 and 500 mg/kg, showed a significant concentration-dependent decrease in blood glucose levels after 30 minutes. The 100 mg/kg potato pigment group also showed a statistically significant decrease after 30 minutes. In conclusion, administration of 10% general potato, 20% purple-flesh potato, and potato pigment can reduce blood glucose level in an OGTT using rats.

• The Korean Journal of Community Living Science
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• v.26 no.2
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• pp.405-414
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• 2015

This study examines the effects of purple Kohlrabi fresh and peel ethanol extracts on the antioxidative activity and antiproliferation of human cancer cells (Hep G2 human liver, HCT-116 human colon, and A549 human lung cancer cells.) The total flavonoid and anthocyanin content of purple Kohlrabi ethanol extracts were much greater in the peel than in the flesh. The DPPH radical scavenging activity and antioxidative index of purple Kohlrabi peel extracts were similar to those of the BHA and the BHT. Antiproliferation effects of purple Kohlrabi peel extracts on human cancer cells (Hep G2, HCT-116, and A549) strengthened in a dose-dependent manner. In particular, the antiproliferation activity of purple Kohlrabi peel extracts exceeded 40% in colon cancer cells. These results indicate that the purple Kohlrabi peel may contain bioactive compounds such as flavonoids as well as anthocyanin and that these compounds may facilitate cancer prevention.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.10
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• pp.1476-1480
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• 2010

Physicochemical properties of flours prepared from sweet potatoes with different flesh color (white, yellow/orange and purple) were investigated. Sweet potatoes were soaked in solutions of antibrowning agents such as sodium metabisulfite and citric acid, and freeze or hot air-dried prior to grinding to produce sweet potato flours. Sweet potato flours with different flesh colors showed differences in chemical composition. Purplefleshed sweet potato flour had higher protein, ash, and dietary fiber contents that white and yellow/orangefleshed sweet potato flours. Average particle size of yellow/orange-fleshed sweet potato flour was higher than those of white/yellow or purple-fleshed sweet potato flour. Both water absorption index (WAI) and oil absorption capacity of flours prepared from sweet potatoes by hot-air drying were higher than those from sweet potatoes by freeze drying.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.141-146
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• 2005

The objective of this study was to determine the characterisics of quality and antioxidant with various sweet potato(SP) varieties. The differences of skin color between general and colored SP was not significant. The flesh color of steamed SP was the lower than flesh of raw SP, and especially steamed purple SP(5.24) was lower than flesh SP(22.0). In physical characteristics, the hardness of raw SP showed the low values and the springness, gumness and hardness among steamed SP varieties was not significant. The total phenol content(TPC) of purple, yellow-fleshed and general SP had 13.1, 6.22 and 3.02 mg/g, respectively. In DPPH, the purple-fleshed SP had the highest free radical scanvering. Also, shingunmi$(88.5\%)$, Saengmi$(80.9\%)$ and Shinchunmi$(78.9\%)$ show the high antioxidant activities. The redness of SP was positively correlated with TPC in raw and steamed. However, the yellowness of flesh SP was negatively correlated with DPPH.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.819-825
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• 1995

Two sweet potato CV.(Ipomoea batatas) were examined, i.e. purple flesh sweet potato(PSP) and light yellow flesh sweet potato(LYSP) which varied in degree of sweetness. On a fresh weight basis, nitrogen free extract in cultivars ranged from $25.73{\sim}26.24%$ and PSP contained more crude fat than LYSP. Total amino acids of PSP and LYSP were 5676.57mg% and 4550.86mg%, respectively. Aspartic acid, serine, alanine and valine were the major components in sweet potatoes. Sulfur-containing amino acids are the first limiting amino acid in PSP. The major fatty acids in PSP and LYSP analyzed by GC were palmitic acid, linoleic acid. The content of the saturated fatty acid was less than that of the unsaturated fatty acid. Carbohydrate contents were $75.43{\sim}79.10%$ and neutral sugars contents were $67.22{\sim}64.85%$(dry wt). Two sweet potato CV. contained the most glucose of all neutral sugars. PSP contained 11.88% for uronic acid, 59.42% for starch. Free sugars of PSP(0.82%) was much less than that of LYSP(2.53%). The contents of thiamin, riboflavin and niacin were similar, and the ascorbic acid contents in PSP and LYSP were 63.4mg% and 48.7mg%(dry wt), respectively. Comparing the mineral content in PSP, K was the greatest element in concentration followed by mg, Ca, Na. The total dietary fiber(TDF) value was 13.43% in PSP, 9.79% in LYSP respectively. The ratio of soluble dietary fiber(SDF) content and insoluble dietary fiber(IDF) content to TDF content for PSP were 57.6%, 42.4%, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.108-109
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• 2005

• Journal of Applied Biological Chemistry
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• v.49 no.3
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• pp.75-81
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• 2006

A full-length cDNA encoding dihydroflavonol 4-reductase (st-dfr) of potato was isolated by rapid amplification of cDNA ends, and their expression was investigated from purple-fleshed potato (Solanum tuberosum L. cv. Jashim). The st-dfr exists as a member of a small gene family and its transcripts was abundant in the order of tuber flesh, stem, leaf, and root. The expressions of st-dfr gene were light inducible and cultivar dependant. Transgenic potato plants harboring antisense st-dfr (AS-DFR) sequences were analyzed. The accumulation of mRNA was nearly completely inhibited as a result of introducing an AS-DFR gene under the control of the 35S CaMV promoter into the red tuber skin Solanum tuberosum L. cv. Desiree. The anthocyanin content of the tuber peels of the transgenic lines was dramatically decreased by up to 70%. The possible production of flavonols in the peels of AS-DFR transgenic potatoes was discussed.

• Journal of Applied Biological Chemistry
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• v.57 no.4
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• pp.353-358
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• 2014

Antioxidant activities of ethanol and water extracts of flesh, leaves, and peels of green and purple Kohlrabi were measured by rancimat method, total phenolic compound (TPC), DPPH radical scavenging effect, chelating effect, and reducing power analysis. The highest TPC was observed in ethanol extract from green peel and water extract from purple leaf with 12.00 and 11.70 mg/g of dry sample, respectively. The ethanol extracts from purple Kohlrabi leaf and peel exhibited strong DPPH radical scavenging effects with reducing power while water extracts from purple Kohlrabi leaf and peel also showed strong DPPH radical scavenging with chelating effects. Antioxidant index of ethanol and water extracts from green and purple Kohlrabi measured by rancimat was lower than butylated hydroxytoluene. These results suggest that extracts from purple Kohlrabi leaf and peel exhibited higher antioxidant activities than those of green Kohlrabi, and can be potentially used as proper natural antioxidants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.1
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• pp.37-46
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• 2011

Polyphenolic content and antimutagenicity of the methanol extracts prepared from 22 cultivars of sweet potato with different flesh colors were investigated using Folin-Ciocalteu's phenol reagent method and Ames test, respectively. There was a remarkable cultivar difference in the polyphenolic content of sweet potato. Su, Hayanmi and Shinhwangmi among 17 cultivars of non-purple sweet potato had higher polyphenolic contents of 21.4, 21.5 and $20.3{\mu}g$ (GAE/g dried sweet potato), respectively, whereas Manami and Yeonhwangmi were very much lower at 4.6 and $4.8{\mu}g$. Mokpo No.62, Borami, Sinjami, Jami and Ayamurasaki had much higher polyphenolic contents of 67.7, 76.9, 44.9, 128.3 and $93.2{\mu}g$, respectively, than non-purple sweet potato. The methanol extract from the sweet potato effectively inhibited the reverse mutation induced by 1-NP, daunomycin, Trp-P-1, Trp-P-2 and 2-AA on S. Typhimurium TA 98, and by 1-NP on S. Typhimurium TA 100. These results suggest that the antimutagencity properties may be influenced by the tested mutagen and strain rather than the polyphenolic content of non-purple and purple sweet potato. However, in the purple sweet potatoes, a high polyphenolic content may influence the antimutagencity properties.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1180-1183
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• 1996

Growth characteristics and changes of pigment content of purple sweet potato (PSP) during growth were investigated. Vine length of PSP was increased to the maximum length of 130 cm after 100 days of growth. Numbers of branches and nodes were increased to the maximum of 21and 550, respectively, after 120 days of growth. Vine weight was also increased to the maximum of 4,384 kg/10a after 120 days of growth, while the weight of marketable root was increased continuously to the end of the growth period of 150 days to reach the production of 1,875 kg/10a. Uniquely considerable amount of anthocyanin pigment has been developed in both skin and flesh of young roots harvested after 40 days of growth. The pigment content was increased slowly until 140 days of growth then decreased. This fact indicates that the best time for harvesting of PSP is 140 days after planting.