• Archives of Pharmacal Research
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• v.20 no.1
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• pp.34-38
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• 1997

Recombinant human epidermal growth factor (rhEGF), a polypeptide of 53 amino acid residues, is subject to degradation by numerous enzymes, especially proteases, when it is applied on the skin for the treatment of open wound. Amastatin, aprotinin, bestatin, EDTA, EGTA, gabexate, gentamicin, leupeptin, and TPCK were investigated for the possible protease inhibitors, which may use to protect rhEGF from degradation by the enzymes in the skin. Skin homogenates containing protease inhibitors and rhEGF were incubated at $37^{\circ}C$ for 30 minutes. After the reaction was stopped with trifluoroacetic acid, the amount of rhEGF remaining in the sample was determined with an HPLC method. The percentages of rhEGF degraded, at the skin/PBS ratio of 0.25, in the mouse, rat, and human skin homogenate were 85%, 70%, and 46%, respectively. The degree of degradation of rhEGF in the cytosolic fraction was higher than that in the membrane fraction and these enzyme reactions were completed in 30 minutes. Bestatin, EGTA, and TPCK showed significant inhibitory effects on the degradation of rhEGF in the two fractions (p<0.05), while the other protease inhibitors had no significant inhibitory effects or, even resulted in deleterious effects. Therefore, the formulation containing one or several inhibitors among these effective inhibitors would be a promising topical preparation of rhEGF for the treatment of open wound.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4109-4116
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• 2012

An efficient solid-phase methodology has been developed for the synthesis of 2-amino and 2-amidobenzo[d]-oxazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo-[d]oxazole resins 4 by cyclization reaction of 2-hydroxy-phenylthiourea resin 3. The resin-bound 2-hydroxyphenylthiourea 3 is produced by the addition of 2-aminophenol to the isothiocyanate-terminated resin 2 and serve as a key intermediate for the linker resin. This core skeleton 2-aminobenzo[d]oxazole resin 4 undergoes functionalization reaction with various electrophiles, such as alkylhalides and acid chlorides to generate 2-amino and 2-amidobenzo[d]oxazole resins 5 and 6 respectively. Finally, 2-amino and 2-amidobenzo[d]oxazole derivatives 7 and 8 are then generated in good yields and purities by cleavage of the respective resins 5 and 6 under trifluoroacetic acid (TFA) in dichloromethane ($CH_2Cl_2$).

• Journal of Information Display
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• v.6 no.4
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• pp.1-5
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• 2005

Perylene-based pyrrolopyrone derivative (PPD) was synthesized via condensation reaction with perylenetetracarboxylic dianhydride and 1,2-phenylenediarnine as n-type channel material. The structure of PPD was characterized by spectroscopic methods such FT-IR and $^1H$-NMR. PPD exhibited high thermal stability ($T_{d5wt%}: 560^{\circ}C$) and was found to be soluble only in protonic solvents with high acidity such as methane sulfonic acid and trifluoroacetic acid. The PPD solution showed maximum absorption and emission at 601 and 628 nm, respectively. Thin film transistors were fabricated by vacuum deposition and solution casting method. The electron mobilities of the devices were achieved as high as $0.17{\times}10^{-6}cm^2/Vs$ for vacuum deposited device and $0.4{\times}10^{-6}cm^2/Vs$ for spin coated device, respectively.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.713-717
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• 2012

Approximately forty proteins in egg white have been widely studied for their functional properties. To develop a procedure of separation for pure and non-altered proteins from egg white, purification study was conducted to isolate lysozyme, ovotransferrin, and ovalbumin. Ion exchange cartridge can selectively separate proteins from egg white, and reversed-phase HPLC (RP-HPLC) could identify separated proteins. Proteins in egg white were purified by HI trap ion exchange cartridge SP and Q with buffers pH 8.0 and 5.2. C18 column (Phenomenex, USA) was used for RP-HPLC analysis and isocratic mobile phase was used with acetonitrile (ACN)/distilled water (DW)/trifluoroacetic acid (TFA) in the ratio of 50/50/0.1. Comparing the retention times of standards in RP-HPLC experiments showed that ovotransferrin, ovalbumin, and lysozyme in egg white were eluted successively in the RP-HPLC column after the pretreatment in SP and Q ion exchange cartridges.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.333-340
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• 2019

This study attempted to eatablish a high performance liquid chromatography (HPLC) analysis method for the determination of avicularin, quercitrin as a part of the quality control for the development of functional cosmetic materials from Astilbe chinensis extract. HPLC was performed on a Capcell Pak C₁₈ MGII column with a gradient elution of 0.05% (v/v) trifluoroacetic acid (TFA) and acetonitrile at a flow rate of 1.0 mL/min at 30 ℃. The analyte was detected at 254 nm. The HPLC method was performed in accordance with the international conference on harmonization (ICH) guideline (version 4, 2005) of analytical procedures with respect to specificity, precision, accuracy, and linearity. The limits of detection and quantitation of avicularin and quercitrin were 0.094 and 0.285 mg/mL, 0.031 and 0.095 mg/mL respectively. Calibration curves showed good linearity r² > 0.99990 for avicularin and r² > 0.99994 for quercitrin. Precision of analysis was satisfied with less than 0.59% for avicularin and 0.63% for quercitrin. Recoveries of quantified compounds ranged from 100.97 to 101.77% for avicularin and 100.18 to 100.32% for quercitrin. These result indicated that the established HPLC method is very useful for the determination of marker compounds in A. chinensis extracts.

• Analytical Science and Technology
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• v.17 no.3
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• pp.263-270
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• 2004

A method is described for the analysis of short-chain alkylphenol ethoxylates (APEOs), 4-octylphenol-di-ethoxylate (OP2EO) and 4-nonylphenol-di-ethoxylate (NP2EO), in drinking water or wastewater using reversed phase high-performance liquid chromatography with electrospray ionization mass spectrometry. The solvent system was water and methanol containing $10{\mu}M$ trifluoroacetic acid as an ionization solvent. We acidified 1 L of water samples to less than pH 2 with concentrated $H_2SO_4$ and loaded onto Sep-Pak $C_{18}$, and eluted with acetone. The calibration of OP2EO and NP2EO was performed for the concentration range from 20 to 500 ng/L and the correlation coefficients were 0.999 and 0.990, respectively. The limits of detection were 20 ng/L (OP2EO) and 50 ng/L (NP2EO) at a signal-to-noise ratio of 3. Accuracy and precision of this analytical method were 85.8 ~ 122.1% and 8.2 ~ 18.8%, respectively. The proposed method allowed a sensitive and rapid detection of OP2EO and NP2EO and it could be applied for monitoring of APEOs from environmental samples.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.65-72
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• 2010

We used fluorescence detector to analyse total aflatoxins (G1, G2, B1, B2) with TFA (Trifluoroacetic acid) derivation method and PHRED (Photochemical reactor enhanced detection) method. PHRED method was superior in reproduction and convenience, but TFA derivation method was superior in selectivity and sensitivity. The recovery rate of aflatoxin B1, B2, G1 were more than 80%, and G2 was more than 70%. The detection limit of B1, B2, G1 and G2 were respectively 0.05, 0.05, 0.2 and $0.1\;{\mu}g/kg$. Confirmed method was used to analyse total aflatoxins in total 316 items as 9 kinds 137 dried fruits and 10 kinds 179 spices. By the result, Aflatoxins were detected in 27 dried fruits (19.7%) and in 87 spices (48.6%).

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.829-834
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• 2011

Lysozyme in egg white functions as bacteriolysis agent and ovalbumin plays a role as antigen in immune system. Egg white analysis methods usually include electrophoresis, gel permeation chromatography and reversed-phase HPLC(RP-HPLC). Among them, RP-HPLC was selected for rapid analysis and C18 column(Agilent, USA) was used as HPLC column. Optimum conditions were searched by changing mobile phase and temperature. Capacity factor and resolution were calculated and compared for various elution conditions. In the isocratic elution, mobile phase volume ratio was changed from 30/70/0.1 to 60/40/0.1(Acetonitrile(ACN)/Distilled water(DW)/Trifluoroacetic acid(TFA)). ACN composition was increased by 10% and temperature was set as $20^{\circ}C$. In the gradient elution, ACN/DW ratio was changed from 10/90 to 60/40 during 20 minute and temperature was varied as 20, 30 and $40^{\circ}C$. In the isocratic elution, three peaks were separated at 50/50/0.1. Lysozyme and ovalbumin were confirmed as first and third peak in three peaks respectively. In the gradient elution, four peaks were separated at $30^{\circ}C$. Lysozyme and ovalbumin were confirmed as first peak and third peak in four peaks respectively.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.420-424
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• 2019

An HPLC analysis method was developed and standardized for the detection of dieckol as a functional food ingredient in Ecklonia cava extracts. HPLC was performed using a Capcell Pak C18 column ($250{\times}4.6mm$, $5{\mu}m$) with a gradient elution of water and acetonitrile, both containing 0.1% (v/v) trifluoroacetic acid, at a flow rate of 1.0 mL/min at $25^{\circ}C$. The eluate was detected at 230 nm. For validation, the specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ) of dieckol were measured. The calibration curve for the detection of dieckol had high linearity ($R^2=0.9994$), with LOD and LOQ values of 0.38 and $1.16{\mu}g/mL$, respectively. Recovery of the quantified compound ranged from 99.61 to 100.71%. The relative standard deviation values of the intra-day and inter-day precisions were less than 1.7 and 1.25%, respectively. These results indicate that the reported HPLC method is simple, reliable, and reproducible for the detection of dieckol in Ecklonia cava extracts.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.1
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• pp.87-93
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• 2019

This study attempted to eatablish a High Performance Liquid Chromatography (HPLC) analysis method for the determination of (-)-epicatechin gallate as a part of the quality control for the development of functional cosmetic materials from Penthorum chinense Pursh. HPLC was performed on a Unison $US-C_{18}$ column ($4.6{\times}250mm$, $5{\mu}m$) with a gradient elution of 0.05% (v/v) trifluoroacetic acid (TFA) and methyl alcohol at a flow rate of 1.0 mL/min at $30^{\circ}C$. The analyte was detected at 280 nm. The HPLC method was performed in accordance with the International Conference on Harmonization (ICH) guideline (version 4, 2005) of analytical procedures with respect to specificity, precision, accuracy, and linearity. The limits of detection and quantitation were 0.11 and 0.33 mg/mL, respectively. Calibration curves showed good linearity ($r^2$ > 0.9999), and the precision of analysis was satisfied (less than 0.6%). Recoveries of quantified compounds ranged from 99.51 to 101.92%. This result indicates that the established HPLC method is very useful for the determination of marker compound in P. chinense Pursh extracts.