• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.3
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• pp.262-268
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• 2007

This study was conducted to investigate various physiochemical activities of carrageenan hydrolysates obtained with organic acid treatments. The hydrolysates treated with citrate and malate at $100^{\circ}C,\;110^{\circ}C\;and\;120^{\circ}C$ had antimicrobial activities against Bacillus cereus and Bacillus subtilis. Especially, the hydrolysates with malate at $120^{\circ}C$ for 180 min treatment had the strongest antimicrobial activity to Bacillus subtilis. Regardless of the hydrolysis conditions, inhibition ratios of tyrosinase activity by citrate and malate under $100{\sim}120^{\circ}C$ were over 97%. Especially, the inhibition ratios for tyrosinase activity of the hydrolysates obtained with citrate at $100^{\circ}C$ for 180 min and at $120^{\circ}C$ for 90 min were 99.4% and 98.2%, respectively. Also, the inhibition ratios for tyrosinase activity of the hydrolysates obtained with malate under the same conditions were about 99.5% and 99.3%, respectively. The APTT as anticoagulant activity of carrageenan hydrolysates with 0.3% malate and citrate at $80^{\circ}C$ for 180 min were $2,451{\pm}18(sec)\;and\;1,617{\pm}15(sec)$, respectively.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.181-190
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• 1995

Malate dehydrogenase in the mosquito ovary after a blood meal, Aedes aegypti, was purified and characterized. MDH purification steps involved DEAE-Sepharose, S-Sepharose and Cibacron blue affinity chromatography. The purified MDH was 70,000 daltons in molecular weight and was a homodimer consisting of tow identical subunits. Optimal activity of purified MDH was obtained pH 9.0-9.2 in malate-oxaloacetate reaction and pH 9.8-10.2, in oxaloactate-malate reaction. With obtained pH 9.0-92 in malate-oxaloacetate reaction and pH 9.8-10.2, in oxaloactate-malate reaction. With malate as substrate, purified mitochondrial MDH (1.28$\times$${10}^{-4}$ M) had lower Km value than cytoplasmic MDH (8.92x${10}^{-3}$ M). MDH activity was inhibited by citrate, $\alpha$-ketoglutarate, and ATP. Inhibition of MDH activity by ATP and citrate was less in malate-oxaloacetate reaction and in oxaloacetate-malate reaction. MDH activity was completely inhibited by ATP in oxaloacetate-malate reaction and not inhibited by citrate in malate-oxaloacetate reaction. Temporal activity change of MDH is similar to that of isocitrate dehydrogenase in the ovary after blood feeding; their activities in the ovary began to rise at 18 hours after a blood meal, and reached at the maximal level at 48 hours.

• The Microorganisms and Industry
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• v.20 no.3
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• pp.70-73
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• 1994

Effects of 13 organic compounds including glucose, fructose, xylose, glutamate, succinate, malate, glycine, lactate, acetate, pyruvate, citrate, formate and cis-aconitate on the oxidation of thiosulfate and the availability of these compounds as the substrate for the respiration by Thiobacillus ocncretivorus, which is known to be an obligated autotroph, were studied. Malate nad glycine at 0.5 per cent concentration nearly doubled the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation. Moreover, some 30 to 40 per cent decrease was recorded by fructose, sulfate-salts medium, some 30 to 40 per cent decrease was recorded by fructose, citrate, xylose, malate, flucose, glutamate and succinate. No respiration could occur when formate and pyruvate were supplied as the substrate for respiration. But it was obvious that flucose, fructose, xylose, glutamate, malate, citrate and succinate could be used as the substrate for respiration to some extent, regarding the fact that some increase in respiration rates could be recorded compared to the result from the salts medium, where neither thiosulfate nor orgnic compounds were added. Thus, it was postulated that this organism could possibly be converted into mixotroph or hetrotroph if appropriate conditions could be prepared.

• Archives of Pharmacal Research
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• v.24 no.1
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• pp.51-54
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• 2001

Three varieties of methyl citrate and 1 -methyl malate were isolated from the fruits of Opuntia ficus-indica var. saboten Makino through in vitro bioassay-guided isolation for the inhibition on monoamine oxidase(MAO). The $IC_50$ values for MAO-B of 1-monomethyl citrate, 1,3-dimethy citrate, trimethyl citrate and 1-methyl malate were 0.19, 0.23, 0.61 and 0.25 mM, respectively. However, on MAO-A, their inhibitions showed only marginal activity.

• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.319-327
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• 2000

This study was conducted to prolong the edible period of Kimchi by adding chitosan (0.25, 0.5%) and sodium salts of various organic acids(0.01~0.04M citrate, malate, lactate) . The edible period was estimated by measuring changes in pH. titratable acidity(TA), PH/TA ratio, ascorbic acid content and pectin fraction during Kimchi fermentation at 2$0^{\circ}C$. The results were compared by estimating the maturity of Kimchi fermentation. Kimchi with the chitosan showed higher pH and titratable acidity throughout the fermentation period than that without chitosan. The pH decreased during the fermentation in the order of control, 0.25% chitosan, 0.5% chitosan, 0.5% chitosan+Na-citrate, 0.5% chitosan+Na-malate and 0.5% chitosan+Na-lactate. But the titratable acidity increased in the order of control, 0.5% chitosan+Na-malate, 0.25% chitosan. 0.5% chitosan+Na-citrate, 0.5% chitosan and 0.5% chitosan+Na-lactate. The PH/TA ratio decreased in the order of control, 0.25% chitosan, 0.5% chitosan+Na-malate, 0.5% chitosan, 0.5% chitosan+Na-citrate and 0.5% chitosan+Na-lactate. Ascorbic acid content in Kimchi was the highest at the 3rd day and then decreased during fermentation. Ascorbic acid content in Kimchi containing 0.5% chitosan and organic acid salts was higher than others. Alcohol insoluble solids( AIS ) in Kimchi decreased during fermentation in the order of control, 0.25% chitosan, 0.5% chitosan, 0.5% chitosan+Na-palate. 7.5% chitosan+Na-lactate and 0.5% chitosan+Na-citrate. During fermentation, hot water soluble pectin (HWSP) of control increased, whereas HCI soluble pectin (HCISP) decreased. By addition of chitosan, however, the results became reverse. Chitosan addition appeared to be effective in improving preservation quality of Kimchi during fermention. The edible period become extended by using chitosan plus organic acids instead of using chitosan only. Overall. addition of 0.5% chitosan+Na-lactate seemed most effective in prolonging the edible periods during Kimchi fermentation.

• Korean Journal of Microbiology
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• v.10 no.4
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• pp.167-174
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• 1972

Effects of 13 organic compounds including glucose, fructose, xylose, glutamate, succinate, malate, glycine, lactate, acetate, pyruvate, citrate, formate and cis-aconitate on the oxidation of thiosulfate and the availability of these compounds as the substrate for the respiration by Thiobacillus ocncretivorus, which is known to be an obligated autotroph, were studied. Malate nad glycine at 0.5 per cent concentration nearly doubled the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation compared to the control. No other organic substances enhanced the thiosulfate oxidation. Moreover, some 30 to 40 per cent decrease was recorded by fructose, sulfate-salts medium, some 30 to 40 per cent decrease was recorded by fructose, citrate, xylose, malate, flucose, glutamate and succinate. No respiration could occur when formate and pyruvate were supplied as the substrate for respiration. But it was obvious that flucose, fructose, xylose, glutamate, malate, citrate and succinate could be used as the substrate for respiration to some extent, regarding the fact that some increase in respiration rates could be recorded compared to the result from the salts medium, where neither thiosulfate nor orgnic compounds were added. Thus, it was postulated that this organism could possibly be converted into mixotroph or hetrotroph if appropriate conditions could be prepared.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.7
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• pp.832-839
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• 2007

This study was conducted to investigate the bioavailability of starfish calcium with substances enhancing calcium absorption. Three week-old young female rats (Sprague-Barley) were divided into 5 groups according to calcium sources and testing agents; calcium carbonate (C), starfish calcium (S), starfish calcium + casein phosphopeptide (S-CPP), starfish calcium+citrate-malate (S-CM), starfish calcium+isoflavone (S-ISO), and were fed experimental diets containing AIN-93G based Ca (0.35% w/w) diet with CPP, CM and ISO for 6 weeks. Blood, femur, urine and feces samples were collected. There was no significant difference among groups in terms of growth and food intake. Serum Ca concentrations were normal in all 5 groups. Serum P concentrations and ALP activities were not significantly different among groups. Ca absorption and retention were significantly increased both in S-CPP and S-CM groups compared to C group (p<0.05). p absorption was significantly higher in S-CPP group than in other groups. While the amount of soluble Ca of intestinal contents did not differ among groups, the amount of insoluble Ca was significantly lower in S-CPP, S-CM and S-ISO groups than in C and S groups. However, the weight, Ca and P concentrations of femur were not significantly different among groups. These results suggest that the addition of CPP and citrate-malate were more effective for enhancing the bioavailability, intestinal absorption and solubility of starfish calcium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.12
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• pp.1548-1553
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• 2008

This study was concerning various physiological activities of agar hydrolysates. All agar hydrolysates showed strong antimicrobial activity against Bacillus subtilis and Bacillus cereus. Also, the agar hydrolysates prepared at the temperature of $110^{\circ}C$ or $120^{\circ}C$ showed antimicrobial activity against St. aureus and E. coli. Among the agar hydrolysates, several hydrolysates treated with citrate or malate at $110^{\circ}C$ or $120^{\circ}C$ conditions showed tyrosinase activity inhibition, and their inhibition rates of tyrosinase activity were about 80%. Some tested samples treated with 0.5% organic acid at $100^{\circ}C$ or $110^{\circ}C$ inhibited the growth of cancer cell. Two agar hydrolysates prepared with 0.5% citrate and lactate at $110^{\circ}C$ for $180^{\circ}C$ min had relatively high cancer cell growth inhibition among the tested samples. The agar hydrolysates treated with citrate and lactate at $110^{\circ}C$ for 180 min obtained the main peaks of six and seven from Sephadex G-15 column chromatography. Among the main peaks, the cancer cell growth inhibition of C-3 and L-3 fractions were higher than that of other fractions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.42-46
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• 2003

This research was carried out for searching the treatment conditions of organic acid and heating to prepare oligomers from the carrageenan. The applied treatments were autoclaving, micraowaving, and ultrasonicating with acetate, citrate, lactate, malate, and succinate. Among several physical depolymerization methods, auo-claving treatment was the most effective for hydrolyzing the carrageenan to low molecular compounds such as oligosaccharides. Citrate or malate was the most effective catalyst in hydrolyzing carrageenan to some oligo-saccharides among 5~7 different organic acids. An acceptable autoclaving condition for hydrolyzing carrageenan to oligosaccharides was to treat for 120 min at 110~12$0^{\circ}C$. The maximum depolymerization ratio produced by autoclaving was about 23.0%. The depolymerized carrageenan prepared by autoclaving at 12$0^{\circ}C$ had oligo-saccharides of 5~7 species.

• Journal of Life Science
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• v.20 no.7
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• pp.1041-1046
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• 2010

Phytoextraction is a technique which uses plants to clean up metal-contaminated soils. Recently, various chelating agents were introduced into this technique to increase the bioavailability of metals in soils. Even though the technique is an economic and environment-friendly method, this cannot be applied in highly metal-contaminated areas because plants will not normally grow in such conditions. Therefore, this research focuses on identifying chelating agents which are biodegradable and applicable to highly metal-contaminated areas. Alunimum (Al) as a target metal and cysteine (Cys), histidine (His), citrate, malate, oxalate, succinate, and ethylenediamine (EDA) as biodegradable chelating agents were selected. Ethylenediamine tetraacetic acid (EDTA) was used as a comparative standard. Plants were grown on agar media containing various chelating agents with Al to analyze the effect on plant growth. His slightly diminished the inhibitory effect of Al on root growth of plants, whereas, Cys, citrate, malate, oxalate, and succinate did not show significant effects. Both EDTA and EDA strongly diminished the inhibitory effect of Al on root growth. The effect of EDA is correlated with decreased Al uptake into the plants. In conclusion, as a biodegradable chelating agent, EDA is a good candidate for highly Al-contaminated areas.