Hyunjong Yu
@snu.ac.kr
Department of Agricultural Biotechnology/Research Professor
Seoul National University
Scopus Publications
Scopus Publications
Hyunjong Yu, Huisu Kim, and Pahn-Shick Chang
Elsevier BV
Jun-Young Park, Hyunjong Yu, Dimitris Charalampopoulos, Kyung-Min Park, and Pahn-Shick Chang
Elsevier BV
Haena Park, Sunghak Choi, Bong Su Kang, Hyunjong Yu, Jaeil Kim, Ho-Sup Jung, Hoon Eui Jeong, and Pahn-Shick Chang
American Chemical Society (ACS)
Inwoo Park, Hyunjong Yu, and Pahn-Shick Chang
Elsevier BV
Jihoon Kim, Hyunjong Yu, Eunhye Yang, Yoonseok Choi, and Pahn-Shick Chang
Elsevier BV
Hyunjong Yu, Sungjun Kim, and Pahn-Shick Chang
Elsevier BV
Juno Lee, Nam-Hyun Kim, Yoonseok Choi, Eunhye Yang, Hyunjong Yu, Chang Woo Kwon, and Pahn-Shick Chang
Elsevier BV
Yoonjee Chang, Jaewoo Bai, Hyunjong Yu, Xu Yang, Pahn-Shick Chang, and Nitin Nitin
Elsevier BV
Abstract We investigated the synergistic antimicrobial activity of erythorbyl laurate (EL) and mild heating co-treatment on the Gram-positive Listeria innocua and Gram-negative Escherichia coli O157:H7 bacteria. EL (2 mM) and mild heating (55 °C for 3 min) resulted in 3.1 and 0.5 log colony forming units (CFU)/mL reductions in the number of L. innocua, respectively, compared to a 6.4 log CFU/mL reduction induced by the combined treatment of EL and mild heating in saline. EL (10 mM) and mild heating (55 °C for 3 min) resulted in 1.3 and 0.7 log CFU/mL reductions in the number of E. coli O157:H7, respectively, compared to a 6.2 log CFU/mL reduction with the combined treatment in saline. EL, a membrane-active compound, showed a strong synergistic effect with mild heating, possibly due to enhanced disruption of the bacterial cell membrane. The synergistic antibacterial effect was evaluated using inoculated English peas (Pisum sativum) and this combined treatment (2 mM EL and mild heating against L. innocua and 10 mM EL and mild heating against E. coli O157:H7) resulted in more than 7 log reductions in the numbers of L. innocua and E. coli O157:H7, inoculated on the surface of fresh peas. The treatments did not show significant difference in the color or texture of treated peas compared to the non-treated controls. This is the first report illustrating synergistic activity of EL and mild heating for both the gram positive (L. innocua) and the gram negative (E. coli O157:H7) bacteria on food. Overall, this research will illustrate the development of more effective and rapid antibacterial surface disinfection method for application in the processing of minimally processed foods.
Jun-Young Park, Min-Ji Choi, Hyunjong Yu, Yoonseok Choi, Kyung-Min Park, and Pahn-Shick Chang
Elsevier BV
Hyukjin Shin, Chang Woo Kwon, Moon-Won Lee, Hyunjong Yu, and Pahn-Shick Chang
Elsevier BV
Jun Heo, Chang Woo Kwon, Juno Lee, Haena Park, Hyunjong Yu, and Pahn-Shick Chang
Elsevier BV
Hyunjong Yu, Yerim Byun, and Pahn-Shick Chang
Elsevier BV
Mixed lauric acid esters (MLE) with antibacterial and antioxidative activities were produced through lipase-catalyzed two-step esterification in solvent-free system without purification. In the first reaction, erythorbyl laurate was synthesized for 72 h. Successive reaction for 6 h at molar ratio of 1.0 (lauric acid to glycerol) produced MLE containing erythorbyl laurate and glyceryl laurate with small amounts of residual substrates, by converting 99.52% of lauric acid. MLE addition (0.5-2.0%, w/w) to Tween 20-stabilized emulsions decreased droplet size, polydispersity index, and zeta-potential, possibly enhancing the emulsion stability. In the emulsions, MLE at 0.5 and 2.0% (w/w) caused 4.4-4.6 and 5.9-6.1 log reductions of Gram-positive (Staphylococcus aureus, Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), respectively, within 12 h. Lipid hydroperoxide concentrations decreased to 50.8-98.3% in the presence of 0.5-2.0% (w/w) MLE. These findings support a novel approach without needing purification to produce multi-functional food additives for emulsion foods.
Eunhye Yang, Hyunjong Yu, SungHak Choi, Kyung-Min Park, Ho-Sup Jung, and Pahn-Shick Chang
Springer Science and Business Media LLC
AbstractWe designed a novel lyophilization method using controlled rate slow freezing (CSF) with lyoprotective agent (LPA) to achieve intact lipid nanovesicles after lyophilization. During the freezing step, LPA prevented water supercooling, and the freezing rate was controlled by CSF. Regulating the freezing rate by various liquid media was a crucial determinant of membrane disruption, and isopropanol (freezing rate of 0.933 °C/min) was the optimal medium for the CSF system. Lyophilized lipid nanovesicle using both CSF and LPA retained 92.9% of the core material and had uniform size distributions (Z-average diameter = 133.4 nm, polydispersity index = 0.144), similar to intact vesicles (120.7 nm and 0.159, respectively), after rehydration. Only lyophilized lipid nanovesicle using both CSF and LPA showed no changes in membrane fluidity and polarity. This lyophilization method can be applied to improve storage stability of lipid nanocarriers encapsulating drugs while retaining their original activity.
Hyunjong Yu, Hyejoo Jeon, Jaeho Myeong, Chang Woo Kwon, and Pahn-Shick Chang
Elsevier BV
Abstract Coffee phenolics are unstable in gastrointestinal tract, but they can be protected during digestion by interaction with milk proteins. The objectives of this study are to evaluate effects of creamers containing milk proteins on the bioaccessibility of chlorogenic acids (CGAs) and antioxidant activity of instant coffee during in vitro digestion. The bioaccessibility of CGAs in instant coffee beverage (IC), instant coffee beverages with creamer A (CRA), with creamer B (CRB), and with skim milk (SM) was 26.4%, 40.5%, 51.7%, and 83.6%, respectively. These results indicated that creamers and skim milk increased the bioaccessibility of CGAs in a manner correlated with protein concentration. After digestion, IC showed the highest decrease (25.6%) in ferric reducing antioxidant power (FRAP), compared to that before digestion; lower decreases were observed in CRA (12.7%), CRB (16.2%), and SM (13.8%). These findings suggest that consumption of instant coffee with creamers helps to retain the biological activity of coffee phenolics during digestion.
Jun-Young Park, Jaeho Myeong, Yoonseok Choi, Hyunjong Yu, Chang Woo Kwon, Kyung-Min Park, and Pahn-Shick Chang
Elsevier BV
Erythorbyl myristate (EM), a potential multi-functional food emulsifier, was newly synthesized by immobilized lipase-catalyzed esterification between antioxidative erythorbic acid and antibacterial myristic acid. The yield and productivity of EM were 56.13 ± 2.51 mg EM/g myristic acid and 1.76 ± 0.08 mM/h, respectively. The molecular structure of EM was identified as (R)-2-((R)-3,4-dihydroxy-5-oxo-2,5-dihydrofuran-2-yl)-2-hydroxyethyl tetradecanoate using HPLC-ESI/MS and 2D [1H-1H] NMR COSY. The hydrophilic-lipophilic balance of EM was 11.5, suggesting that EM could be proper to stabilize oil-in-water emulsions. Moreover, isothermal titration calorimetry demonstrated the micellar thermodynamic behavior of EM and determined its critical micelle concentration (0.36 mM). In terms of antioxidative property, EM exhibited the radical scavenging activity against DPPH (EC50: 35.47 ± 0.13 μM) and ABTS (EC50: 36.45 ± 1.98 μM) radicals. Finally, EM showed bacteriostatic and bactericidal activities against Gram-positive foodborne pathogens (minimum inhibitory concentration: 0.06-0.60 mM; minimum bactericidal concentration: 0.07-0.93 mM).
Yoonjee Chang, Jaewoo Bai, Hyunjong Yu, Pahn-Shick Chang, and Nitin Nitin
Frontiers Media SA
This study evaluated the synergistic antimicrobial activity of erythorbyl laurate (EL) and UV type-A (UVA). To investigate the mode of synergism, changes in gene expression and bacterial inactivation activity were examined. Individual treatments with EL (10 mM) or UVA caused a 1.9- or 0.5-log CFU/ml reduction respectively, whereas EL/UVA co-treatment resulted in a 5.5-log CFU/ml reduction in Escherichia coli viable cell numbers. Similarly, treatment with either EL (2 mM) or UVA for 30 min resulted in a 2.8- or 0.1-log CFU/ml reduction in Listeria innocua, respectively, whereas combined treatment with both EL and UVA resulted in a 5.4-log CFU/ml reduction. Measurements of gene expression levels showed that EL and UVA treatment synergistically altered the gene expression of genes related to bacterial membrane synthesis/stress response. However, addition of 10–50-fold excess concentration of exogenous antioxidant compared to EL reduced the synergistic effect of EL and UVA by approximately 1 log. In summary, the results illustrate that synergistic combination of EL and UVA enhanced membrane damage independent of the oxidative stress damage induced by UVA and thus illustrate a novel photo-activated synergistic antimicrobial approach for the inactivation of both the Gram-positive and Gram-negative bacteria. Overall, this study illustrates mechanistic evaluation of a novel photochemical approach for food and environmental applications.
Su Jeong Ha, Min Jeong Kim, Joon Park, Hyun-Wook Choi, Hyunjong Yu, Pahn-Shick Chang, and Sung Keun Jung
Elsevier BV
Abstract Erythorbyl laurate (EL) can be produced via lipase-catalyzed esterification between erythorbic acid and lauric acid. In this study, we evaluate the anti-inflammatory effect of EL in the early stage of atherosclerosis. EL suppressed tumor necrosis factor (TNF)-α-induced monocyte adhesion to vascular endothelial cells and expression of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs). Additionally, EL suppressed TNF-α-induced p65/IκB kinase (IKK)/IκB phosphorylation in HUVECs. Western blot analysis of cytosolic and nuclear cell fractions and immunofluorescence showed that EL suppressed TNF-α-induced translocation of p65 from the cytoplasm to the nucleus. EL also inhibited phosphorylation of extracellular-signal-regulated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinases (JNK) 1/2 in HUVECs. EL suppressed TNF-α-induced phosphorylation of Akt, IRAK1, and TAK1 in HUVECs. Quantitative RT-PCR analysis showed that EL significantly suppressed TNF-α-induced interleukin (IL)1B, IL6, TNFA, and CCL2 mRNA expression in HUVECs. Additionally, oral administration of EL suppressed TNF-α-induced IL6 and TNFA expression in the mouse aorta. EL could represent a promising functional nutrient that can be ingested for the prevention of vascular inflammation via decreased monocyte infiltration to the vascular endothelium and suppression of inflammatory nuclear factor (NF)-κB and mitogen-activated protein kinases (MAPKs) signaling pathways.
Hyunjong Yu, Kyung-Min Park, and Pahn-Shick Chang
Elsevier BV
Lipase-catalyzed acylation of a hydrophilic tripeptide-KHA (TP-KHA; amino acid sequence Lys-His-Ala) with a lipophilic lauric acid was performed to produce a multi-functional compound, lauroyl tripeptide-KHA (TPL-KHA), with surface, antibacterial, and antioxidant activities. The significant acylation reaction parameters were optimized as follows: organic solvent of 2-methyl-2-butanol, reaction temperature at 55 °C, substrate molar ratio (lauric acid:TP-KHA) of 4.0, and reaction time for 72 h. Structural analyses by LC-ESI-MS and 1H NMR identified that Nε-lauroyl tripeptide-KHA was chemo-selectively synthesized by the acylation reaction under the optimum conditions. TPL-KHA showed the surface activity at the air-water interface with critical micelle concentration (CMC) of 2.71 mM and γCMC of 30.44 mN/m. TPL-KHA exhibited bacteriostatic and bactericidal effects on Gram-positive and Gram-negative foodborne pathogens (minimum inhibitory concentrations: 2.83-4.00 mM, minimum bactericidal concentrations: 3.17-5.83 mM). Moreover, it was demonstrated that TPL-KHA had the ability to scavenge ABTS+ radicals and inhibit the lipid oxidation.
Minje Jo, Kyung-Min Park, Jun-Young Park, Hyunjong Yu, Seung Jun Choi, and Pahn-Shick Chang
Elsevier BV
Abstract In the present study, mono-dispersed 100 nm-sized liposomes (DPPC:cholesterol = 8:2 (mol)) were produced by a novel microfluidic assembly method with optimized flow rate ratio (non-aqueous phase:aqueous phase = 60.0:6.0 (mL/h)). These liposomes were incorporated with ionic surfactants, such as anionic palmitic acid (PAL) or cationic hexadecylamine (HDA), to enhance their colloidal stability, which was confirmed through TEM and ζ-potential analysis. Moreover, to enhance their intestinal stability, the surfaces of liposomes were modified with biodegradable polymers by electrostatic attraction. Specifically, cationic chitosan was coated onto anionic PAL-incorporated liposomes, whereas anionic pectin was used for cationic HDA-incorporated liposomes. Finally, branched-chain amino acids (BCAAs) were encapsulated into the PAL-incorporated liposomes with surface modifications, showing 31.2 % of encapsulation efficiency. This study could contribute a novel approach for microfluidic assembly of the liposomes, providing deeper insight into surface modifications and enhancement of the colloidal stability.
Jin-Woo Kim, Hyunjong Yu, Kyung-Min Park, and Pahn-Shick Chang
Hindawi Limited
In this study, antimicrobial spectrum of erythorbyl laurate (EL) against bacteria and fungi, leading to food-borne and infectious skin diseases, was evaluated for its practical applications in food and cosmetics. Furthermore, the influences of environmental factors including pH, oxidative stress, and dispersion medium on antimicrobial activity of EL were investigated. The three Gram-positive bacteria and the three molds were susceptible to 3.0 mM EL, while the yeast was susceptible to 6.0 mM EL. It was demonstrated EL retained antibacterial activity against Staphylococcus aureus after being oxidized while the antibacterial activity against the three Gram-positive bacteria including S. aureus, Bacillus cereus, and Listeria monocytogenes was significantly enhanced as decrease of pH from 7.0 to 5.0. Moreover, EL exhibited bactericidal effects against both Gram-positive and Gram-negative bacteria in an oil-in-water emulsion. Treatment of 5.0 mM EL for 4 h reduced 5.29 ± 0.24, 6.01 ± 0.18, 5.95 ± 0.13, and 6.24 ± 0.30 log CFU/mL against S. aureus, L. monocytogenes, Pseudomonas aeruginosa, and Escherichia coli, respectively. In a multipassage resistance selection study, it was observed minimum inhibitory concentrations of EL against S. aureus were not increased over 20 passages, indicating EL might not develop drug resistance of bacteria. This study suggests EL has a potential to be applied as the multifunctional additive in food and cosmetics.
Min-Sik Jeon, Kyung-Min Park, Hyunjong Yu, Jun-Young Park, and Pahn-Shick Chang
Elsevier BV
The effect of intense pulsed light (IPL) irradiation on Chromobacterium viscosum lipase was investigated with a primary focus on catalytic activity and molecular structure. During IPL irradiation, lipase activity decreased significantly with increasing pulse fluence (Fp) and exposure time (te). IPL-induced deactivation kinetics were further elucidated based on a two-step series-type deactivation model (constant deactivation rate k1 >k2). Fp was found to be the dominant variable affecting the degree of lipase deactivation, and residual activity was not associated with increasing te below a certain Fp energy density (2.66 mJ/cm2), implying a critical threshold for IPL-induced deactivation of lipase. From the results of fluorescence spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), we determined that IPL-induced deactivation was caused by fragmentation, leading to lipase tertiary structural changes. Furthermore, the results of FindPept analysis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) indicated that the internal sensitive bonds of lipase were cleaved preferentially by IPL, such that IPL irradiation induced site-sensitive fragmentation and peptide bond cleavage.
Jun‐Young Park, Kyung‐Min Park, Yoonjung Yoo, Hyunjong Yu, Chang Joo Lee, Ho‐Sup Jung, Keesung Kim, and Pahn‐Shick Chang
Wiley
A total of 39 agricultural products were screened for natural sources of lipases with distinctive positional specificity. Based on this, Cordyceps militaris lipase (CML) was selected and subsequently purified by sequential chromatography involving anion‐exchange, hydrophobic‐interaction, and gel‐permeation columns. As a result of the overall purification procedure, a remarkable increase in the specific activity of the CML (4.733 U/mg protein) was achieved, with a yield of 2.47% (purification fold of 94.54). The purified CML has a monomeric structure with a molecular mass of approximately 62 kDa. It was further identified as a putative extracellular lipase from C. militaris by the partial sequence analysis using ESI‐Q‐TOF MS. In a kinetic study of the CML‐catalyzed hydrolysis, the values of Vmax, Km, and kcat were determined to be 4.86 μmol·min−1·mg−1, 0.07 mM, and 0.29 min−1, respectively. In particular, the relatively low Km value indicated that CML has a high affinity for its substrate. With regard to positional specificity, CML selectively cleaved triolein at the sn‐1 or 3 positions of glycerol backbone, releasing 1,2(2,3)‐diolein as the major products. Therefore, CML can be considered a distinctive biocatalyst with sn‐1(3) regioselectivity. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2744, 2019.
Jun-Young Park, Su-Kyung Jo, Kyung-Min Park, Hyunjong Yu, Jaewoo Bai, Sangryeol Ryu, and Pahn-Shick Chang
Elsevier BV
Abstract Erythorbyl laurate (EL) is a novel multi-functional emulsifier with antibacterial activity against Gram-positive bacteria. The objective of this study was to find genetic evidences of the antibacterial mechanism of EL against food-borne pathogenic Staphylococcus aureus Newman by transcriptomic analysis. Total RNA samples were extracted from non-treated and 0.1 mM (sublethal concentration) EL-treated S. aureus Newman, and then transcriptional profiling was performed by RNA sequencing (RNA-Seq). In EL-treated S. aureus Newman, 242 and 225 genes out of the 2687 genes, were up-regulated and down-regulated greater than 2-fold change, respectively. The majority of up-regulated genes in EL-treated S. aureus Newman were cell wall stress stimulon including genes related to VraSR two-component regulatory system (vraS, vraR, and vraT), cell envelopment (mur, sgt, fmt, and etc.) and L-lysine biosynthesis (lys, dap, and etc.), and there were significant differences in the regulation of peptidoglycan biosynthesis between EL-treated and control samples (p
Hyunjong Yu, Moon-Won Lee, Hyukjin Shin, Kyung-Min Park, and Pahn-Shick Chang
Elsevier BV
Erythorbyl laurate is a potential food additive as a multi-functional emulsifier having antioxidant and antimicrobial activities. In this study, a gas-solid-liquid multiphase system (GSL-MPS) was established to enhance the production yield of erythorbyl laurate in a lipase-catalyzed solvent-free synthesis. The significant reaction variables were optimized as follows: substrate molar ratio of 2:1 (lauric acid:erythorbic acid) and enzyme concentration of 120 mg/mL (840 PLU/mL). Under these conditions, the maximum production yield in GSL-MPS was 13.974 mg/mL, which is 8.60- and 4.26-fold higher than the yields obtained in an organic solvent monophase system (OS-MPS) and a solid-liquid biphase system (SL-BPS), respectively. Moreover, the operational stability of the immobilized lipase was significantly improved in GSL-MPS compared with OS-MPS. These results indicate that GSL-MPS can be an enzymatic reaction system facilitating efficient production of ester compounds as a means of increasing production yields and the reusability of the immobilized lipase.
Kyung-Min Park, Seon Joo Lee, Hyunjong Yu, Jun-Young Park, Ho-Sup Jung, Keesung Kim, Chang Joo Lee, and Pahn-Shick Chang
Springer Science and Business Media LLC
It has been proposed that the hydrophilic and/or lipophilic characteristics of fatty acid derivatives affect their antibacterial activities according to their ability to incorporate into the bacterial cell membrane. To verify this hypothesis, six kinds of lauric acid derivatives esterified with different non-fatty acid moieties were selected to confirm whether antibacterial activity from their precursor (i.e., lauric acid) is retained or lost. Three compounds, monolaurin, sucrose laurate, and erythorbyl laurate, exerted bacteriostatic and bactericidal effects against Gram-positive bacteria, while the others showed no inhibitory activity. Interestingly, the calculated log P (octanol–water partition coefficient) values of monolaurin, sucrose laurate, and erythorbyl laurate were − 4.122, − 0.686, and 3.670, respectively, relatively lower than those of the other compounds without antibacterial activity. Moreover, the hydrophilic-lipophilic balance values of the three compounds with antibacterial activity were higher than those of the other compounds, corresponding to the log P result.