• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.859-864
• /
• 1995

Mono- and oligosaccharides are derivatized with p-aminobenzoic ethyl ester (ABEE), strongly absorbs UV light at 254 nm, in the presence of sodium cyanoborohydride. C18-bonded silica column is used for the separation of sugar-ABEE derivatives in an isocratic mode. RP-HPLC conditions are optimized by using ternary mixture as mobile phase and $45^{\circ}C$ as a column temperature. Sugar-ABEE derivatives are separated well within a short run time (ca. 25 min) by reverse-phase partition chromatographic mode. The ($1{\rightarrow}6$) linkage type of dihexose-ABEE derivatives has shorter retention time than ($1{\rightarrow}4$)-linkage type. After acid hydrolysis of glycoproteins with 2M trifluoroacetic acid, monosaccharide composition and contents are determined. This procedure is very useful for the simultaneous analysis of neutral and amino sugars in a single chromatographic step using RP-HPLC without reacetylation of deacetylated amino sugars, which are produced by acid hydrolysis.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.7
• /
• pp.1037-1043
• /
• 2005

Kinetic study on the cleavage of N-methylphthalamic acid (NMPA) in mixed acidic aqueous-acetonitrile solvent reveals the formation of both phthalic anhydride (PAn) (through O-cyclization) and N-methylphthalimide (NMPT) (through N-cyclization). The formation of NMPT varies from $\sim$20% to $\sim$3% with the increase in the content of acetonitrile from 2 to 70% v/v. Pseudo first-order rate constants for the formation of PAn are more than 4-fold larger than those for the formation of NMPT at 2% v/v $CH_3CN$ in mixed aqueous solvents. Pseudo first-order rate constants for alkaline hydrolysis of NMPT reveal a nonlinear decrease with increase in the content of $CH_3CN$ in mixed aqueous solvents.

• YAKHAK HOEJI
• /
• v.36 no.2
• /
• pp.137-139
• /
• 1992

A new method for xenbucin, which is a antihypercholesteremic agent, is described. Friedel-Crafts reaction of biphenyl with ethyl ${\alpha}-chloro-{\alpha}-(methylthio)acetate(1)$ afforded ethyl 2-methylthio-2-(4-biphenylyl)acetate(2). Ethyl 2-(4-biphenylyl)butyrate(4) was obtained by ethylation of (2) with NaH and $C_2H_5I$, followed by desulfurization of the resultant ethyl 2-methylthio-2-(4-biphenylyl)butyrate(3) with zinc dust in acetic acid. Xenbucin was synthesized by hydrolysis of (4).

• Archives of Pharmacal Research
• /
• v.4 no.2
• /
• pp.117-122
• /
• 1981

The carpophores of a mushroom, Naematoloma fasciculare (Fr.) Karst, were extracted with 0.2 N NaOH and the extract was dialyzed through visking tube. It was found to contain an antitumor activity against sarcoma 180 implanted in mice. The components of this aqueous extract were found to be a polysaccharide and a protein by color reactions including Anthrone and Lowery-Folin tests. The hydrolysis of the polysaccharide with 3% HCL-Me-OH and trimethylsily lation of the hydrolysate yielded five monosaccharides, i. e. glucose, frutose, mannose, galactose and xylose, which were detected and analyzed by GLC. After hydrolysis of the protein with 6N HCl, 15 amino acids, including aspartic acid and glutamic acid, were detected and analyzed by an auto amino acid analyzer.

• Bulletin of the Korean Chemical Society
• /
• v.19 no.9
• /
• pp.993-999
• /
• 1998

Acid catalyzed hydrolysis of 1-phenoxyethyl propionate, Ⅰ, has been studied using the PM3 method in the gas phase. The first step of the reaction is the protonation of basic sites, three different oxygens in Ⅰ, producing three protonated species Ⅱ, Ⅲ and Ⅳ. All possible reaction pathways have been studied from each protonated structure. Changes in the reaction mechanisms have also been discussed from the results obtained by varying a nucleophile from a water monomer to a water dimer to a complex between one water molecule and an intermediate product (propionic acid or phenol) produced in the preceding unimolecular dissociation processes. Minimum energy reaction pathway is 2-W among the possible pathways, in which water dimer acts as an active catalyst and therefore facilitates the formation of a six-membered cyclic transition state. Lower barrier of 2-W is ascribed to an efficient bifunctional catalytic effect of water molecules. PM3-SM3.1 single point calculations have been done at the gas-phase optimized structure (SM3.1/PM3//PM3) to compare theoretical results to those of experimental work.

• The Korean Journal of Pesticide Science
• /
• v.6 no.3
• /
• pp.218-223
• /
• 2002

The rate of hydrolysis of insecticide, O,O-diethyl-O-(1-phenyl-3-trifluoromethylpyrazol-5-yl)phosphorothioate (Flupyrazofos) have been investigated in 25% (v/v) aqueous dioxane (${\mu}=0.1M$) at $45^{\circ}C$. The hydrolysis mechanism of flupyrazofos proceeds through the specific acid ($A_{AC}2$) catalysis below pH 4.0, specific base ($B_{AC}2$) catalysis above pH 11.0 and general acid & base ($B_{AC}2$) catalysis between pH 5.0 and pH 10.0 via trigonal-bipyramidal ($d^2sp^3$) intermediate as evidence by solvent effect ($|m|{\ll}|{\ell}|$), rate equation ($kt=ko+k_H+ [H_3O^+]+k_{OH}[OH^-]$) and product analysis. The half-life ($T\frac{1}{2}$) of hydrolytic degradation in neutral media at $45^{\circ}C$ was ca. 3 months.

• Fisheries and Aquatic Sciences
• /
• v.25 no.6
• /
• pp.335-349
• /
• 2022

To optimize the hydrolysis conditions in the production of antioxidant hydrolysates from tuna cooking juice concentrate (TC) to maximize the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, TC containing 48.91% protein was hydrolyzed with Alcalase 2.4 L, and response surface methodology (RSM) was applied. The optimum hydrolysis conditions included a 2.2% (w/v) Alcalase concentration and 281 min hydrolysis time, resulting in the highest DPPH radical scavenging activity of 66.49% (0.98 µmol Trolox/mg protein). The analysis of variance for RSM showed that hydrolysis time was an important factor that significantly affected the process (p < 0.05). The effects of different drying methods (freeze drying, hot air drying, and vacuum drying) on the DPPH radical scavenging activity and amino acid (AA) profiles of TC hydrolysate (TCH) were evaluated. Vacuum-dried TCH (VD) exhibited an increase in DPPH radical scavenging activity of 81.28% (1.20 µmol Trolox/mg protein). The VD samples were further fractionated by ultrafiltration. The AA profiles and antioxidant activities in terms of the DPPH radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power, and ferrous ion chelating activity were investigated. Glutamic acid, glycine, arginine, and cysteine were the major AAs found in the TCH fractions. The highest DPPH radical scavenging activity was found in the VD-1 fraction (< 5 kDa). The VD-3 fraction (> 10 kDa) exhibited the highest ABTS radical scavenging activity and ferric reducing antioxidant power. The ferrous ion chelating activity was the highest in VD-1 and VD-2 (5 to 10 kDa). In conclusion, this study provided the optimal conditions to obtain high antioxidant activities through TCH production, and these conditions could provide a basis for the future application of TCH as a functional food ingredient.

• Fisheries and Aquatic Sciences
• /
• v.25 no.2
• /
• pp.76-89
• /
• 2022

The Lophius litulon liver was used as raw material for the extraction of fish oil via various extraction methods. The extraction rate by water extraction, potassium hydroxide (KOH) hydrolysis and protease hydrolysis were compared and the results revealed the protease hydrolysis extraction had a higher extraction rate with good protein-lipid separation as observed by optical microscope. Furthermore, subsequent experiments determined neutrase to be the best hydrolytic enzyme in terms of extraction rate and cost. The extraction conditions of neutrase hydrolysis were optimized by single-factor experiment and response surface analysis, and the optimal extraction rate was 58.40 ± 0.25% with the following conditions: enzyme concentration 2,000 IU/g, extraction time 1.0 h, liquid-solid ratio 1.95:1, extraction temperature 40.5℃ and pH 6.5. The fatty acids composition in fish oil from optimized extraction condition was composed of 19.75% saturated fatty acids and 80.25% unsaturated fatty acids. The content of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 8.06% and 1.19%, respectively, with the ratio (6.77:1) surpassed to the recommendation in current researches (5:1). The results in this study suggest protease treatment is an efficient method for high-quality fish oil extraction from Lophius litulon liver with a satisfactory ratio of DHA and EPA.

• Journal of the Korean Wood Science and Technology
• /
• v.38 no.2
• /
• pp.149-158
• /
• 2010

Organosolv pretreatments which utilized sulfuric acid, sodium hydroxide and ammonia as catalysts were conducted to screen the effective catalyst for organosolv pretreatment of Liriodendron tulipifera. The enzymatic hydrolysis was achieved effectively with sulfuric acid (74.2%) and sodium hydroxide (63.7%). They were thus considered as effective catalysts for organosolv pretreatment of L. tulipifera. The organosolv pretreatments with sulfuric acid and sodium hydroxide showed a different behavior on the reaction mechanism. The pretreatment with sulfuric acid increased the biomass roughness and pore numbers. On the other hand, the pretreatment with sodium hydroxide enhanced the surface area due to the size reduction and minor defiberization which were caused by hemicellulose degradation at an initial stage and more defiberization by lignin degradation at a later stage. The organosolv pretreatment with sodium hydroxide was performed at several different conditions to evaluate effectiveness of sodium hydroxide as a catalyst for organosolv pretreatment. According to the results of enzymatic digestibility, the changes of chemical composition and the morphological analysis of pretreated biomass, it was suggested that the pretreatment time impacted primarily on enzymatic hydrolysis. Increase in surface area during the pretreatment was a major cause for improvement in enzymatic digestibility when sodium hydroxide was used as a catalyst.

• Microbiology and Biotechnology Letters
• /
• v.44 no.1
• /
• pp.48-54
• /
• 2016

In this study, biosugar production by the red-algae Eucheuma cottonii was investigated using dilute sulfuric acid-catalyzed hydrolysis and data analysis by response surface methodology. This approach yielded 25.8 g/l total reducing sugar under the conditions of $160.1^{\circ}C$, 1% (v/v) sulfuric acid, and 13.1 min. The sugar concentration showed a linear inverse correlation with the combined severity factor (CSF) of the reaction conditions. CSF was calculated as $log(t{\cdot}e{xp}[(T_H-T_R)/14.75])-pH$, where t is the coupling reaction time, $T_H$ is the target temperature, and $T_R$ is the reference temperature ($100^{\circ}C$). In addition, levulinic acid production showed a linear positive correlation with CSF. E. cottonii may represent a useful feedstock for sugar production in the field of bioenergy.