• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.14-14
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• 2010

Vitamin C (ascorbic acid) is an essential component for collagen biosynthesis and also for the proper functioning of the cardiovascular system in humans. Unlike most of the animals, humans lack the ability to synthesize ascorbic acid on their own due to a mutation in the gene encoding the last enzyme of ascorbate biosynthesis. As a result, vitamin C must be obtained from dietary sources like plants. In this study, we have developed two different kinds of transgenic potato plants (Solanumtuberosum L. cv. Taedong Valley) overexpressing strawberry GalUR and mouse GLoase gene under the control of CaMV 35S promoter with increased ascorbic acid levels. Integration of the these genes in the plant genome was confirmed by PCR and Southern blotting. Ascorbic acid(AsA) levels in transgenic tubers were determined by high-performance liquid chromatography(HPLC). The over-expression of these genes resulted in 2-4 folds increase in AsA intransgenic potato and the levels of AsA were positively correlated with increased geneactivity. The transgenic lines with enhanced vitamin C content showed enhanced tolerance to abiotic stresses induced by methyl viologen(MV), NaCl or mannitol as compared to untransformed control plants. The leaf disc senescence assay showed better tolerance in transgenic lines by retaining higher chlorophyll as compared to the untransformed control plants. Present study demonstrated that the over-expression of these gene enhanced the level of AsA in potato tubers and these transgenics performed better under different abiotic stresses as compared to untransformed control. We have also investigated the mechanism of the abiotic stress tolerance upon enhancing the level of the ascorbate in transgenic potato. The transgenic potato plants overexpressing GalUR gene with enhanced accumulation of ascorbate were investigated to analyze the antioxidants activity of enzymes involved in the ascorbate-glutathione cycle and their tolerance mechanism against different abiotic stresses under invitro conditions. Transformed potato tubers subjected to various abiotic stresses induced by methyl viologen, sodium chloride and zinc chloride showed significant increase in the activities of superoxide dismutase(SOD, EC 1.15.1.1), catalase, enzymes of ascorbate-glutathione cycle enzymes such as ascorbate peroxidase(APX, EC 1.11.1.11), dehydroascorbate reductase(DHAR, EC 1.8.5.1), and glutathione reductase(GR, EC 1.8.1.7) as well as the levels of ascorbate, GSH and proline when compared to the untransformed tubers. The increased enzyme activities correlated with their mRNA transcript accumulation in the stressed transgenic tubers. Pronounced differences in redox status were also observed in stressed transgenic potato tubers that showed more tolerance to abiotic stresses when compared to untransformed tubers. From the present study, it is evident that improved to lerance against abiotic stresses in transgenic tubers is due to the increased activity of enzymes involved in the antioxidant system together with enhanced ascorbate accumulated in transformed tubers when compared to untransformed tubers. At moment we also investigating the role of enhanced reduced glutathione level for the maintenance of the methylglyoxal level as it is evident that methylglyoxal is a potent cytotoxic compound produced under the abiotic stress and the maintenance of the methylglyoxal level is important to survive the plant under stress conditions.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.192-199
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• 2000

Lactic acid bacteria (LAB) fermented food was prepared from milk or egg white powder (EWP) and added with five kinds of freeze drying protectant (FDP). Effects of FDP on growth and acid production of LAB were investigated. Effects of FDP on organoleptic properties of LAB fermented food were also studied. (1) Some of FDPs showed protective effect against damage to Lactobacillus acidophilus in LAB fermented food during freeze drying, while FDP did not show any protective effect against damage to L. acidophilus during freezing. This protective effect differed with substrate and concentration of FDP (2) Optimum concentration of Tween 80 and ascorbate added to milk sample was 0.2 % (W/V) and 1 %(W/V), respectively. Optimum concentration of raffinose and ascorbate added to EWP sample was 3 %(W/V) and 1 %(W/V), respectively (3) Among FDPs added to L. casei fermented food, raffinose and ascorbate added to EWP sample showed FDP effect. Among FDPs added to L. delbrueckii fermented food, raffinose added to EWP sample showed FDP effect. (4) Samples added with MSG showed MSG taste. Milk sample added with ascorbate showed slightly more acid taste than reference sample, while taste of EWP sample added with ascobate did not differ with reference sample. Tween 80 added to milk sample or EWP sample improved texture of LAB fermented food.

• Journal of Plant Biotechnology
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• v.41 no.2
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• pp.73-80
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• 2014

Pretreatment of chinese cabbage leaves with $100{\mu}M$ sodium nitroprusside (SNP), a nitric oxide (NO) donor, effectively improved their tolerance to subsequent $2{\mu}M$ paraquat (PQ)-induced oxidative damage. The fresh weight, and chlorophyll and protein contents in primary leaves treated with PQ alone were noticeably reduced over 24 h light incubation. However, these leaf injury symptoms were significantly alleviated with $100{\mu}M$ SNP pretreatment for 3 h prior to PQ exposure. In additions, the increase of the contents of malondialdehyde (MDA) and $H_2O_2$ due to PQ exposure were significantly inhibited by SNP pretreatment. Together with the protective effects of SNP against PQ toxicity in leaves, the changes of ascorbate-glutathione cycle enzymes activities were examined. In the PQ alone treatment, the activities of APX, DHAR, and GR after 6 h incubation were rapidly reduced and showed 19%, 50% and 39% respectively, compared with those of the control. However, the decreases in these enzyme activities were significantly inhibited by SNP pretreatment. As a result, their activities were higher than those of PQ alone treatment by 5 times, 2 times, and 1.5 times, respectively, at 6 h incubation. Thereafter, these enzymes decrease their activities gradually showing high levels than those of PQ alone. Based on the above results, it can be assumed that the activation of ascorbate-glutathione cycle by SNP pretreatment in chinese cabbage leaves exposed to PQ can prevent $H_2O_2$ accumulation, thereby leading to protection against PQ-induced oxidative stress. Also, these results indicate that NO acts as an protectant against PQ stress in the leaves of chinese cabbage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.132-137
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• 1993

These studies were carried out to investigate the effects of ascorbate and $\alpha$-tocopherol administration on the biochemical parameters of liver function and hydroperoxidation in liver of chronically ethanol-treated rats. Forty healthy Sprague-Dawley (SD) rats weighing about 120g were used for this experiment and divided into the following 5 groups: control group (CON), ethanol control group (ECON), ascorbate treated group (EASC), $\alpha$-tocopherol treated group (ETOC) and ascorbate.$\alpha$-tocopherol mixture treated group(EASC + ETOC). Ethanol was administered orally by 5ml per kg, body weight per day for 8weeks. Antioxidants treated groups were administered orally by 5mg per kg body weight per day in saline solution for 3 weeks. Lipid hydroperoxides were analyzed by using chemiluminescense-high performance liquid chromatography (CL-HPLC) method phosphatidylcholine hydroperoxide value (PCOOH) in liver tissues. Ethanol treatment significantly (p<0.05) resulted in an increase in GPT and GOT activities and liver hydroperoxide values comparing with the untreated control, while administration of $\alpha$-tocopherol and ascorbate+$\alpha$-tocopherol to the chronically ethanol-treated rats significantly (p<0.001) decreased GPT and GOT activities and liver hydroperoxide value. These results indicate that dietary $\alpha$-tocopherol and $\alpha$-tocopherol combined with ascorbate administration may inhibit the formation of liver lipid hydroperoxidation in vivo and were very effective in recovering the liver function in chronically ethanol-treated rats.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.1
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• pp.41-47
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• 2015

The objective of this study was to evaluate quality properties including acid value (AV) and peroxide value (POV) of brown rice packaged with antioxidant allyl mercaptan sachet or oxygen scavenging sachet. To prepare the antioxidant allyl mercaptan sachet, allyl mercaptan was encapsulated by rice flour and put in small roll paper pouch. The oxygen scavenging sachet consists of diatomite, sodium L-ascorbate and activated carbon. The results of this study showed that antioxidant allyl mercaptan sachet had no antioxidant effect on deterioration of brown rice, but oxygen scavenging sachet effectively inhibited rancidity of brown rice. Therefore, the developed oxygen scavenging sachet can be effectively utilized in food packaging system for quality stability.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.32-39
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• 2013

The relationship between relative water contents of lettuce leaves and biochemical activities in lettuce was examined in this study to explore an adaptation response of lettuce to water stress from soils. Soil water contents and relative water contents of leaves were positively related to show $R^2$=0.8728. Hydrogen peroxide contents of leaves rapidly increased with reduction of soil water content, whereas soluble protein contents and dry matters rapidly decreased. And chlorophyll a and b contents of leaves decreased with increase in carotenoid content. Furthermore, the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR) increased dramatically, and mRNA transcript levels of APX, MDHAR and DHAR also increased. Relationship of relative water content of lettuce leaves to hydrogen peroxide, to ascorbate peroxidase activity, to dehydroascorbate reductase activity, and to monodehydroascorbate reductase activity was shown to be positively correlated. It is highly plausible from this study that these enzyme activities could be developed as an indicator of water states in soils.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.324-331
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• 1988

Ascorbate oxidizing enzyme from the crude extract of Pleurotus ostreatus was purified by ammonium sulfate precipitation, preparative polyacrylamide gel electrophoresis, DEAE Sepharose CL-6B ion exchange chromatography and Sephadex G-150 gel filtration chromatography. The molecular weight of the enzyme estimated by Sephadex G-150 gel filtration chromatography was 140,000 and that of its subunit by SDS-polyacrylamide gel electrophoresis 66,000. The optimum pH for the maximum activity of the enzyme was 5.2 and the isoelectric point of the enzyme was 6.0 Km values for L-ascorbic acid and D-isoascorbic acid were both 2.2.$\mu$M, which indicates that the enzyme has the asme affinity towards both substrates.

• Korean Journal of Poultry Science
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• v.17 no.2
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• pp.123-126
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• 1990

Antioxidant activity of ginseng was studied in a chicken model system containing sodium nitrite, sorbic acid and ascorbate with or without ginseng. Results obtained are as follows. 1. The antioxidant effect of ginseng increased with increasing concentration but the increment decreased with increasing concentration. 2. In the sample containing sodium nitrite, sorbic acid and ascorbate, the addition of ginseng enhanced the antioxidant effect. Treatment with ginseng, nitrite, sorbic acid and asrorbate( G-NaSoAs) showed the highest antioxidant activity whereas that with nitrite and sorbic acid(NaSo) did the lowest.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.397-408
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• 1993

Gas exchange rates and concentrations of ascorbate and glutathlone were measured in needles of eastern white pine(Pinus strohltr) trees differing in foliar sensitivity to ambient oxidant pollution during a ten month period beginning in mid-June, 1988. Current-year needle dry mass and length was 60 to 75% and 45 to 60% less, respectively, in sens~tive trees than in a tolerant tree. Net photosynthesis ($P_n$) and needle conductance ($g_n$) were greatest in the tolerant individual through late September when the rates begin to decline In trees. Needle transpiration rates showed a trend similar to $P_n$ and $g_n$. Ascorbate and total glutathione concentrations in current-year needles increased through the summer and fall, reached a maximum in mid-winter, and then decreased in the spring. Consistently throughout the year, ascorbate concentration was highest in the tolerant tree until the initial springtime decline began in April. The difference In needle ascorbate between the tolerant and sensitive individuals was greater in the summer months (25 to 30%) than in the winter months (8 to 19%). Glutathione content was similar, as was the ratio or oxidized /reduced glutathione, in both tolerant and sensitive trees.

• Journal of Life Science
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• v.12 no.6
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• pp.786-795
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• 2002

Three-day-old sunfower(Helianthus annuus L.) seedlings were do-rooted and incubated in the nutrient solutions that contained either deficient or sufficient boron supply, and exposure to various pH and temperatures. In the absence of boron, no adventitious roots were formed in the majority of the seedlings. Boron caused the development of numerous adventitious roots in the lower part of the hypocotyl. The low pH damage was ameliorated by the simultaneous application of calcium, implying the involvement of calcium-requiring process in overcoming proton toxicity. Borate showed a strong ameliorative effect with $Ca^{2+}$. These results suggest that the primary target of proton toxicity may be linked to a disturbance of the stability in the pectic polysaccharide network, where calcium plays a key role in plant roots. Maximum temperature for the growth of adventitious roots was $25^{\circ}C$. Although cessation of growth is the most apparent symptom of boron deficiency, exogenous ascorbate improved adventitious root growth in plants in the absence of boron. From the results it is suggested that the inhibition of adventitious root resulting from boron deficiency, low pH and temperature damage may be a consequence of disrupted ascorbate metabolism.