• Weed & Turfgrass Science
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• v.4 no.4
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• pp.308-314
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• 2015

This study was conducted to establish a fluorescence assay system for high efficient mass screening of the herbicides causing rapid membrane peroxidation, based on the fact that peroxide in cellular leakage could be fluorometrically determined through the fuorescent compounds formed after reacting with homovanillic acid (HVA) and peroxidase (HRP). The assay procesure established in this study was as follows. Only single disc (4 mm diameter) excised from cucumber cotyledon is placed on the well containing test solution ($200{\mu}L$) with 96-well microplate. The plate is shaking-incubated for 8 h under light condition. Then after removing the cucumber disc, HVA and HRP are supplied in the medium buffer and incubated for 5 min at room temperature. Fluorescence values are determined at Ex 320 nm/Ex 425 nm. The higher fluorescence values are obtained in the treatment of chemical having higher herbicidal activity. Using this assay with 96-well microplates, a large number of herbicides inducing rapid membrane peroxidation seemed to be screened more efficiently than spectrophotometric microtiter assay reported previously.

• Journal of Life Science
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• v.25 no.7
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• pp.733-739
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• 2015

Microalgae are a renewable natural resource that requires only sunlight, carbon dioxide, phosphorus, and nitrogen for rapid growth. They produce a broad variety of basic chemical substances―such as vitamins, fatty acids and carotenoids―that have high added value potential for the pharmaceutical and food industries. The aim of this study was to develop axenic culture and to establish a cell growth assay for microalgae. A further experiment was carried out to determine the yield of astaxanthin derived from microalgae. The axenic culture was developed using a mixture of antibiotics [ampicillin (100 ${\mu}g/ml$), streptomycin (10 ${\mu}g/ml$), chloramphenicol (10 ${\mu}g/ml$), penicillin (10 ${\mu}g/ml$), neomycin (50 ${\mu}g/ml$), gentamycin (50 ${\mu}g/ml$), kanamycin (10 ${\mu}g/ml$), and nystatin (1.5 ${\mu}g/ml$)] and then used to extract a variety of useful components from the microalgae. The optimal concentration for the antibiotic mixture was 1-3 percent. A spectrophotometric cell growth assay was also established. Astaxanthin was extracted from Haematococus lacustris with a yield of $1.9{\times}10^{-3}{\mu}g/l$ per 1 ml of culture medium. In conclusion, the axenic culture method developed here allows extraction of high-quality astaxanthin and other useful components from microalgae.

• Environmental Engineering Research
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• v.18 no.4
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• pp.253-257
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• 2013

Exposure assessment for three major active ingredients used for humidifier disinfectants, polyhexamethylene guanidine (PHMG), oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride (PGH), and 5-chloro-2-methylisothiazol-3(2H)-one/2-methylisothiazol-3(2H)-one (CMIT/MIT) mixture, was conducted in a bedroom using an air sampler for a refined risk assessment. The experimental site was selected to reflect consumer exposure conditions. Aerosols formed by a humidifier were sampled during 8 hr at 7.5 L/min. Absorbed PHMG and PGH by the sampler were quantified using a spectrophotometric method, and high performance liquid chromatography-ultraviolet detection was used for CMIT/MIT. Three exposure scenarios were assumed for adding humidifier disinfectants to the humidifier water at 1, 2, and 10 times the volume recommended by the product suppliers, and the humidifier was on at its maximum rate of producing aerosols in order to consider reasonable worst-cases. The sampled mass of PHMG and PGH ranged 200 to $2,800{\mu}g$ and 140 to $1,900{\mu}g$, respectively, under different exposure conditions, whereas the absorbed mass of CMIT/MIT was barely detected at the detection limit of 0.11/0.29 mg/L, only at 10 times the recommended level. The resulting risk quotients for PHMG and PGH ranged 1,400 to 20,000 and 1,000 to 13,000, indicating that health risks could be significant. For CMIT/MIT mixture, risk quotients were much smaller than estimated by assuming that they are conservative in the indoor environment, probably due to oxidative reactions. The refined exposure assessment presented here may provide a useful tool for assessing risks posed by active ingredients in spray-type biocidal products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.2
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• pp.117-122
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• 1985

The effects of various factors on the color stability of plum nectar were studied. The data showed that pH and temperature were the most important factors affecting the rate of color loss. The concentration of ascorbic acid affected the rate of color loss in plum nectar. Although the color loss could be influenced by the presence of sugars and their degradation products such as 5-hydroxymethyl-2-furfural(HMF), HMF did not accumulate in sufficient amounts during the storage in the plum nectar to affect appreciably the degradation rate. The pigment was very unstable in the fermented juice and its. spectrophotometric spectrum was changed differently from that of natural plum color material. Materials present in plum nectar itself apparently have an appreciable effect on the rate of color loss.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.5
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• pp.642-648
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• 2011

The purpose of this study was to determine the capsaicinoid and antioxidant compounds and to evaluate the biological activity of 40 different pepper (Capsicum annuum L.) breeding lines. Capsaicinoid and ascorbic acid content were measured with HPLC. Total polyphenolic and flavonoid contents and antioxidant activity were measured with spectrophotometric methods. The antiproliferative qualities of the samples against human breast tumor cells (MCF7) were assessed with a MTT assay. The nitric oxide content in the culture media was measured to evaluate the anti-inflammatory qualities of the samples using Raw264.7 macrophages. The capsaicinoid, ascorbic acid, polyphenolic and flavonoid content of the 40 pepper breeding lines were 0.1~204.2 mg/100 g (dry weight basis, DWB), 279.1~1695.5 mg/g (DWB), 2.6~10.2 mg/g (DWB), and 1.4~5.7 mg/g (DWB), respectively. The highest antioxidant, antiproliferative, and anti-inflammatory qualities were found in breeding line numbers 2500, 3201, and 3232, respectively. This study provides basic information useful to plant breeders and biotechnologists who are planning to breed pepper genotypes with high phytochemical content.

• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.624-637
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• 2020

High-quality and high-phytonutrient watermelon fruits have strong market opportunities besides their health related benefits. Hence, investigating quality and nutritional related traits of watermelon genetic resources could provide important baseline data in breeding for increased lycopene content thereby increasing the marketability of watermelon. To this end, we have examined some fruit morphological traits and lycopene content of 105 genetic resources. Seeds, originally obtained from 22+ countries, were obtained from the National Agrobiodiversity Center, Jeonju, South Korea, grown in an experimental field and harvested at a fully mature stage. The size of pistil scar (SPS), the width of stripes (WS), weight of fruit (WF), length of fruit (LF), width of fruit (WIF), the thickness of pericarp (TP), soluble solids content (SSC), fruit shape in longitudinal section, ground color of skin, the intensity of the green color of skin, fruit shape at the apical part, grooving distribution, conspicuousness of stripes, and main color of the flesh were recorded on the field and inside laboratory and the lycopene was measured using spectrophotometric and HPLC methods. Watermelon fruits have shown a diverse morphological characters. Red and pink fleshed fruits dominated in the entire collections. Fruits with higher thickness of rind were found to exhibit less soluble solid content (SSC). Korean origin fruits were characterized by intermediate SSC while the United States of America (USA), Russia (RUS), Tajikistan (TJK), Turkmenistan (TKM), Taiwan (TWN), and Uruguay (URY) originated fruits had the highest SSC. The lycopene content varied between 41.37 and 182.82 ㎍/g, 2.81 and 163.72 ㎍/g, and 3.54 and 255.47 ㎍/g using HPLC, UV-Vis spectrophotometer, and microplate reader spectrophotometer, respectively. Red- and pink-fleshed fruits had the highest levels of lycopene content compared to the yellow- and orange-fleshed. Lycopene content had a significant positive correlation with SSC, however, no correlations were detected between lycopene and other quantitative fruit morphological characters. Our study demonstrated high diversity exists in fruit morphological traits and lycopene content of the germplasm collections which provide beneficial baseline data for a future breeding program and utilization of watermelon germplasm collections in gene banks for the maintenance and improvement of the current levels of production, marketability, and health-related benefit of watermelon fruits.

• Journal of the Korean Chemical Society
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• v.29 no.6
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• pp.629-636
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• 1985

The rates of solvolysis of trans-$[Co(AA)_2Cl_2]^+$ in which AA indicates ethylenediamine(en), N-ethylethylenediamine (N-eten), N-methylethylenediamino (N-meen) and trimethylenediamine(tn) respectively have been investigated using conductometric and spectrophotometric methods at various pressure up to 2,000 bar in acetone-water mixture. The activation volumes (${\Delta}V^{\neq}) obtained from the pressure effect on rate constants were -0.2∼0.9 $cm^3mole^{-1}$ for en, -0.2∼0.6 $cm^3mole^{-1}$ for N-eten, -0.8∼6.0 $cm^3mole^{-1}$ for N-meen and 0.7∼7.0$cm^3mole^{-1}$ for tn. The rates of solvolysis of these complexes were analyzed by comparing with the results obtained from excess free energy ($G^E$) and free energy cycle. It was found that $S_N1$ character was increased with decreasing the pressure and increasing the content of acetone in the mixture solvent. In addition to that, the effect of charge separation on the mechanism of solvolysis was discussed.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.75-84
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• 1981

Ultraviolet spectrophotometric investigations have been carried out on the systems of mesitylene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_3(CH_3)_3{\cdot}X_2$ or $C_6H_3(CH_3)_3{\cdot}IX$ (X denotes halogen atoms). The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. Thermodynamic parameters, ${\Delta}H$, ${\Delta}G$ and ${\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the mesitylene complexes at each temperature decrease in the order, ICl > IBr > $I_2$ > $Br_2$. This order may be a measure of their relative acidities toward mesitylene, which is explaned in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order Benzene < Toluene < Xylene < Mesitylene Thus, analysis of these findings is discussed.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.161-168
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• 1965

The effect of solvents on the stabilities of the $C_6H_6{\cdot}I_2$ complex and the $C_6H_6{\cdot}ICl$ complex has been investigated through ultraviolet spectrophotometric measurements. The equilibrium constants obtained at room temperature for the formation of $C_6H_6{\cdot}I_2$ complex are 0.090, 0.216 and 0.328$ lmole^{-1}$ in chloroform, cyclohexane and n-hexane, respectively. The corresponding equilibrium constants at room temperature for $C_6H_6{\cdot}ICl$ complex are 0.125, 0.676 and 0.689 $lmole^{-1}.$ These results indicate that the stabilities of the two complexes increase with decreasing dielectric constants of the solvents used, the increase in stability being more rapid in the $C_6H_6{\cdot}ICl$ complex than in the $C_6H_6{\cdot}I_2$ complex. This may support the conclusion that the dative ionic structures, $C_6H_6^+{\cdots}I_2^-$ and/or ($C_6H_6I)^+{\cdots}Cl^-,$ play important roles on the reasonance stabilization of both the $C_6H_6{\cdot}I_2$ complex and the $C_6H_6{\cdot}ICl$ complex, the roles being more important in the latter complex than in the former complex.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.3
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• pp.467-473
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• 2010

The objectives of this study were to determine various bio-active components from some brown rice and milled rice of some cultivars, as well as to assess their contribution to the radical scavenging linked-antioxidant activity. DPPH or ABTS radical scavenging activities, and reducing power have been used to investigate the relative antioxidant activities of 70% ethanol extracts. The contents of total polyphenol, total flavonoid, $\gamma$-oryzanol, and vitamin E in the extracts were also measured by spectrophotometric methods or HPLC. The antioxidant components and antioxidant activities of 70% ethanol extracts from brown rice were higher than those from milled rice. In addition, our results showed that the high level of antioxidant compounds was found in brown rice of Hongjinju, and the antioxidant activities of the 70% ethanol extracts from pigmented brown rices, such as Hongjinju and Heugkwang, were comparably higher than the others.