• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.786-790
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• 2004

2-Aminoethanethiol (aet) has been used to make self-assembled monolayer (SAMs) on gold electrodes, which are subsequently modified with 3,4-dihydroxy phenylalanine (dpa). Such modified electrodes having various types of Au/aet-dpa were employed in the electrocatalytic oxidation of NADH. The purpose of this study to characterize the responses of such modified electrodes in terms of the immobilization procedure, pH of the solution and applied potential. The reaction of the surface immobilized dpa with NADH was studied using the rotating disk electrode technique and a value of $2.2{\times}10^4M^{-1}s^{-1}$ was obtained for the second-order rate constant in 0.1 M Tris/$NO_3^-$buffer (pH=8.0). The hydration behavior of the films was characterized by quartz crystal microbalance. When used as a NADH sensor, the Au/aet-dpa electrode exhibited good sensitivity and an excellent correlation (r ${\geq}$ 0.99) for NADH concentration which extended to $3.8{\times}10^{-3}$ M.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.3
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• pp.327-334
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• 2018

Studies on seaweed-based materials have been progressing steadily day by day. In this experiment, we checked the anti-oxidant, whitening, and moisturizing activities of fermented extract from a mixture of Undariapinnatifida, Saccharina japonica, and Gloiopeltis furcate. Also, Lactobacillus sakei strains of kimchi were used as the lactic acid bacteria. The physiological status of the combined seaweed extracts was also investigated. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging results showed that the inhibitory effects of the combined seaweed extracts were higher than the positive control. Furthermore, 3,4-dihydroxy-L-phenylalanine (L-DOPA) and Mushroom tyrosinase tests were conducted during the whitening efficacy experiment. Hence, it was confirmed that the whitening activity of fermented extracts was greater than the extracts without fermentation. HPLC analysis of fucose (an active ingredient of seaweed) was also performed and a standard method for solvent conditions was newly established. This study suggests that the composite of algae extract has potentials to be used as anti-oxidant and whitening agents in cosmetics.

• Journal of Veterinary Science
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• v.21 no.2
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• pp.23.1-23.10
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• 2020

The identification of biomarkers that distinguish diseased from healthy individuals is of great interest in human and veterinary fields. In this research area, a metabolomic approach and its related statistical analyses can be useful for biomarker determination and allow non-invasive discrimination of healthy volunteers from breast cancer patients. In this study, we focused on the most common canine neoplasm, mammary gland tumor, and herein, we describe a simple method using ultra-high-performance liquid chromatography to determine the levels of tyrosine and its metabolites (epinephrine, 3,4-dihydroxy-L-phenylalanine, 3,4-dihydroxyphenylacetic acid, and vanillylmandelic acid), tryptophan and its metabolites (5-hydroxyindolacetic acid, indoxyl sulfate, serotonin, and kynurenic acid) in canine mammary cancer urine samples. Our results indicated significantly increased concentrations of three tryptophan metabolites, 5-hydroxyindolacetic acid (p < 0.001), serotonin, indoxyl sulfate (p < 0.01), and kynurenic acid (p < 0.05), and 2 tyrosine metabolites, 3,4-dihydroxy-L-phenylalanine (p < 0.001), and epinephrine (p < 0.05) in urine samples from the mammary gland tumor group compared to concentrations in urine samples from the healthy group. The results indicate that select urinary tyrosine and tryptophan metabolites may be useful as non-invasive diagnostic markers as well as in developing a therapeutic strategy for canine mammary gland tumors.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.286-292
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• 2007

Free amino acids and volatile compounds of fresh garlic and its liqueur were investigated to search elution profile of those components as basic data for development of garlic liqueur. The garlic was soaked in 20% alcohol solution and then sampled every week for 5 weeks. The major free amino acids were L-aspartic acid, L-glutamic acid, L-arginine, L-alanine, L-proline, L-asparagine and L-serine. Neutral amino acids such as L-threonine, L-proline, L-valine and L-leucine, and aromatic amino acids such as tyrosine and phenylalanine were eluted over 80% of those content in fresh garlic after 3 weeks of soaking, but acidic, basic and sulfur containing amino acids were below 80% even after 5 weeks. Sulfide compounds such as diallyl trisulfide, diallyl disulfide, methyl allyl disulfide, 2-vinyl-4H-1,3-dithi in, 3-vinyl-3,4-dihydro-1,2-dithiin, 3,5-diethyl-1,24-trithiolane, isobutyl isothiocyanate and diallyl sulfide were identified as major volatile compounds of fresh garlic by using GC/MS. Among volatile compounds of fresh garlic, allyl alcohol, diallyl disulfide, 3,5-diethyl-1,2,4-trithiolane, diallyl trisulfide and 3,4-dimethoxy furan were eluted to liqueur, but those compounds except 3,5-diethyl-1,2,4-trithiolane were lowered in liqueur during soaking. Furfural, 5-methylfurfural, 5-hydroxymethylfurfural, dimethyl pyrazine, furfuryl alcohol, 3-hydroxy-2-bytanone and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyr-an-4-one were generated newly and their content increased in liqueur during soaking.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1787-1791
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• 2007

Several hydroxylated cinnamic acid derivatives were prepared from the corresponding acids and amino acid residues, and their hypocholesterolemic activities were evaluated in high cholesterol-fed mice. The presence of the double bond in hydroxylated cinnamide derivatives decreases cholesterol-lowering activities and the number of free phenolic hydroxy groups affect greatly the activities. 3,4-Dihydroxy hydrocinnamides obtained from amino acid derivatives containing a hydrophobic side chain such as alanine, valine, phenylalanine, and isoleucine exhibited potent cholesterol-lowering activities.

• Natural Product Sciences
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• v.3 no.2
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• pp.111-121
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• 1997

Tyrosinase catalyzes the rate-limiting steps in melanin biosynthesis which is involved in skin-coloring and local hyperpigmentation of human beings, and unfavorable darkening of food products, Inhibitory effects on 3,4-dihydroxy-phenylalanine (dopa) oxidase activity of tyrosinase by 594 kinds of herbal extracts prepared from herbal medicines and wild plants in Korea were estimated. Two herbal extracts prepared from radicis cortex of Morus alba and rhizoma of Curcuma longa were selected as those exhibiting potent inhibitory effects on the enzyme activity. These herbal extracts were subjected to sequential fractionations with methylene chloride, ethyl acetate, n-butanol, and polar residue. The inhibitory effects on dopa oxidase activity of tyrosinase were shown in ethyl acetate fraction of Morus alba, and in methylene chloride fraction of Curcuma langa. The ethyl acetate fraction of Marus alba exhibited 50% of inhibition on dopa oxidase activity of tyrosinase at the concentration of 12 ${\mu}g/ml$, and methylene chloride fraction of Curcuma langa at 51 ${\mu}g/ml$.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.454-460
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• 2000

It is difficult to accurately evaluate the effect of lipophilic compounds in aqueous reaction system of enzymes because they are immiscible with water. To screen lipophilic inhibitors of tyrosinase which catalyzes the synthesis of melanin in vivo, an optically clear organic system composed of organic solvent, surfactant, and water, often called reverse micelles(RM), was introduced. Optimal RM to let tyrosinase act normally was composed of isooctane as an organic solvent and dioctyl sulfosuccinate(AOT) of 100 mM as a surfactant. When a molar ratio of water to surfactant was 15, tyrosinase(105.3 units) in RM showed a similar reactivity toward 3,4-dihydroxyphenylalanine(0.18 mM) as in the aqueous assay system. In the presence of cinnamic acid, the product formation of tyrosinase reaction was proportional to the reaction time. This indicates that the inhibitory effect of lipophilic compounds could be analyzed in RM.