• Journal of Life Science
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• v.21 no.4
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• pp.610-612
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• 2011

We developed a spectrophotometric assay for the quantitative determination of chlorogenic acid based on the formation of green pigment at $50^{\circ}C$ under glycine and alkaline conditions in 96-well plates. The formation of green pigment was linear with a series of chlorogenic acid concentration (0-$300\;{\mu}M$). Using this method, the content of chlorogenic acid (12.42 mg/g dry weight) in the leaves of blueberry was quantified. This method is high-throughput, cost-effective, rapid, and easy to perform.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.90-95
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• 2001

Kinetic Analysis of Cathepsin B Inhibitor Using a Spectrophotometric Assay. Han, Kil-Hwan and SangDal Kim*. Department of Applied MicrobioJ0f5Yt Yeungnam UniversitYt Kyongsan 77 2-749, Korea - The KHS 10, C4Hl10~6 formula produced from Streptomyces luteogriseus KT-] 0 effectively inhibited a lysosomal cysteine proteinase, cathepsin B. It inhibited the enzyme activity of cathepsin B competitively when the N a-CBZ-Llysine p-nitrophenyl ester HC] (CLN) was used as a substrate. The inhibition const:mt (Ki) of KHS 1 0 for cathepsin B detennined by spectrophotometeric assay was 430 nM. The effective inhibition of cathepsin B was observed at $25^{\circ}C$ :md pH 6.0. The cathepsin B inhibitor, KHSlO needed a preincubation of cathepsin B with the inhibitor for over 5 min. The KHS 10 preserved over 80% inhibition activity even after heat-treatment at $100^{\circ}C$ for ] hr.

• Archives of Pharmacal Research
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• v.14 no.4
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• pp.285-289
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• 1991

A convenient spectrophotometric method was examined for the determination of amantadine sulfate (AMTS) which has no UV-VIS chromopohores. AMTS was ion-paired quantitatively with methyl orange (MO) at $70^{\circ}C$ for 30 min. The ion-paired complex was extracted with dichloromethane and the absorbance was measured at 421.5 nm. A linear relationship was observed in the range of $2.5{\times}10^{-7}\;M$ to $3.75{\times}10^{-6}\;M$ and the correlation coefficient was 0.999 (n=3). This assay method was applied to the quantification of AMTS in commercial tablet form with good recovery and high precision.

• Applied Biological Chemistry
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• v.25 no.3
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• pp.182-188
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• 1982

A fluorometric method is described which permits the assay of trypsin inhibitor contained in a sample in an extremely small amount, utilizing a novel reagent generally called fluorescamine. The fluorometric assay with an enzyme kinetic approach has been found to be at least 100 times more sensitive than the well-known Kunitz's spectrophotometric method, considerably taster and less complicated, when it was demonstrated with the anti tryptic activities of very dilute extracts from soybean, red-bean and mung bean. Details of experimental procedure as well as theoretical considerations will be discussed.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.358-363
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• 2005

We have studied the interaction of 3-nitrotyrosine with peroxynitrite using three different methods; chemiluminescence, spectrophotometry and HPLC. Peroxynitrite-induced luminol or lucigenin chemiluminescence were significantly decreased by 3-nitrotyrosine, in concentration­dependent manners. The intensity of the peroxynitrite spectrum was also markedly reduced in the presence of 3-nitrotyrosine in the spectrophometric assay. However, there was no attenuation of the 3-nitrotyrosine signal in the HPLC assay after mixing with peroxynitrite. The interaction of 3-nitrotyrosine and hypochlorous acid (HOCI) was also studied via the chemilumines-cence assay, where the HOCI-induced responses were markedly inhibited by 3-nitrotyrosine. These results suggest that caution should be taken when studying the levels or interactions of 3-nitrotyrosine.

• Journal of Plant Biology
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• v.12 no.2
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• pp.15-22
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• 1969

By spectrophotometric assay method, the following enzymes could be detected in Dunaliella tertiolecta and Chlorella pyrenoidosa cell-free extracts: Hexokinase; Glucose-6-phosphate, 6-Phosphogluconate and Triosephosphate dehydrogenase; Transketolase; Phosphogluco and Ribosephosphate isomerase; Phosphoglucomutase; Phosphofructokinase; Fructosediphosphate aldorase and Ribulosephosphate 3-epimerase. Such enzymes are in accordance with the proposed pathway of glucose catabolism by D. tertiolecta as well as C. pyrenoidosa. Also, it could be estimated, under the presence of NADP, that pentose phosphate pathway were more active than glycolytic pathway in D. tertiolecta cell-free systems.

• Natural Product Sciences
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• v.13 no.2
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• pp.135-139
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• 2007

Four anthocyanins were isolated from the acidic alcoholic extract of Syzygium cumini fruits growing in Egypt: Pelargonidin-3-O-glucoside, pelargonidin-3,5-O-diglucoside, cyanidin-3-O-malonyl glucoside, and delphenidin-3-O-glucoside. They were identified by the chromatographic, TLC and PC, and spectral analyses, UV, $^1$H-NMR and FAB/MS. The fruits were found to contain 0.03 gm % anthocyanins calculated on fresh weight basis calculated by spectrophotometric assay. Cytotoxic activity of total alcoholic extract of the fruits was performed against several types of tumor cell lines using the SRB assay. The tested extract exhibited significant cytotoxic activity for MCF7 (breast carcinoma cell line) (IC$_{50}$= 5.9 ${\mu}$g/mL), while the IC$_{50}$ was > 10 ${\mu}$g/mL for both Hela (Cervix carcinoma cell line), HEPG2 (liver carcinoma cell line), H460 (Lung carcinoma cell line) and U251 (Brain carcinoma cell line).

• Analytical Science and Technology
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• v.6 no.4
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• pp.405-409
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• 1993

Spectrophotometric assay for memantine HCl was developed by using sodium 1-(4-methoxypheyl) cinnamonitrile-2-sulfonate (MPCN) as an UV labelling reagent. The optimum derivatizing condition was obtained by incubation for 30 min at pH 5.0 in the presence of 20-fold molar excess of the labelling reagent. The absorbance of reaction product was measured at 324.5 nm and detection limit was $0.43{\mu}g/ml$. A linear range was $5.0{\times}10^{-6}{\sim}6.5{\times}10^{-5}M$ of memantine HCl. The linear regression analysis of absorbance at various drug concentration was r=0.9998 (n=6). When applied to memantine HCl ampule and tablet, it gave the mean contents of $100.08{\pm}0.72%$ and $99.75{\pm}0.77%$, respectively.

• Food Science of Animal Resources
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• v.38 no.4
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• pp.806-815
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• 2018

This study was performed to isolate some strains of Bifidobacterium breve from fecal materials of neonates and to screen them for the biotransformation activity of converting linoleic acid into conjugated linoleic acid (CLA). Fecal samples were collected from twenty healthy neonates between 14 and 100 days old, and four hundred colonies were randomly selected from a Bifidobacterium selective transoligosaccharide medium. A duplex polymerase chain reaction technique was developed for the rapid and accurate molecular characterization of the B. breve strains that have been reported to show the species-specific characteristic of CLA production. They are identified by 16S ribosomal DNA, fructose-6-phosphate phosphoketolase encoding genes (xfp), and rapid pulsed field gel electrophoresis. Thirty-six isolates were identified as B. breve, and just two of the 12 neonates were harboring B. breve strains. Each isolate showed different CLA-producing ability in the spectrophotometric assay. All of the positive strains from the primary spectrophotometric assay were confirmed for their CLA-producing activities using gas-chromatographic analysis, and their conversion rates were different, depending on the strain isolated in this study. Some strains of B. breve were successfully isolated and characterized based on the CLA-producing activity, and further studies are necessary to characterize the enzyme and the gene responsible for the enzyme activity.

• Journal of Periodontal and Implant Science
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• v.29 no.1
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• pp.31-40
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• 1999

Many factors may affect periodontal changes during the physiologic conditions of woman(e.g. puberty, menstrual cycle, pregnancy, menopause). Recently many research has focused on the immunological changes of host, but the exact mechanism is not clear. Collagen is a major constituent of periodontium, and collagenase specifically digests the collagen and plays a role in destruction of periodontal tissue. So, I suppose that it participates with the cytokines in the inflammation of gingiva and vascular response during the changes of female sex hormones. Because there are some evidences of the existence of the receptors of estrogen and progesterone in the gingiva, it may be a target tissue of female sex hormones. In this experiment, gingival fibroblast and periodontal ligament cell were cultured in the presence of various concentrations of estrogen or progesterone corresponding to the menstrual cycle and pregnancy. Collagenase activity of the supernatant of culture media was determined by Spectrophotometric collagenase assay. The enzyme activity was calculated by the % decrease of the coated collagen. 1. The estrogen at both concentrations had no effect on the activity of collagenase of the gingival fibroblast. 2. The progesterone had some effect on the collagenase activity of the gingival fibroblast at low and high concentration of menstrual cycle, and elevated the enzyme activity at all range of pregnancy concentrations. 3. In periodontal ligament cells, estrogen elevated the enzyme activity at the early pregnancy concentration and progesterone elevated at the concentration just before menstruation. In this experiment, pregesterone elevated the collagenase activity of gingival fibroblast and periodontal ligament cells. But the mechanism of the up-regulation of the enzyme activity was not confirmed. The more experiments of direct effect of progesterone on gingival at the molecular level(e.g. northern blot analysis) can reveal the exact mechanism.