• The Korea Journal of Herbology
• /
• v.34 no.4
• /
• pp.19-25
• /
• 2019

Objectives : Thymol (2-isopropyl-5-methylphenol), a natural monoterpenoid phenol, is one of the major odorant constituents found in natural essential oils of various herbal plants, such as Thymus quinquecostatus and Thymus vulgaris. Multiple biological activities of thymol, including antioxidative, antimicrobial, and anti-inflammatory effects, have been reported in numerous in vitro studies, and recently it was suggested that thymol may could inhibit oxidization of L-dihydroxyphenylalanine (L-DOPA) to dopaquinone required in melanogenesis pathway, as an antioxidant. Methods : MTT assay was performed to test the cytotoxic effect of thymol in B16F10 cells. Inhibitory effect of thymol to tyrosinase activities were examined using both mushroom tyrosinase and intracellular tyrosinase. Expression level of tyrosinase in B16F10 cells were investigated by western blot analysis. Results : The cell viability was decreased by thymol treatment in dose-dependant manner, leading significant cytotoxicity in 500 and $1000{\mu}M$ thymol-treated groups. In the alpha-melanocyte stimulating hormone (${\alpha}$-MSH)-induced melanogenesis, administration of thymol significantly decreased extracellular (secreted) melanin content in dose-dependent manner. Cellular tyrosinase activity assay and western blot analysis of intracellular tyrosinase showed that thymol has a strong anti-melanogenic effect by inhibition of tyrosinase activity and by decreasing expression of tyrosinase that contribute to melanin synthesis in the B1610 cells. Conclusions : As the first functional study that prove anti-melanogenic effect of thymol and its underlying mechanism in the living cells, our study suggests the applicability of fragrance as the functional materials of cosmetics or health supplement, not as just an additive.

• Journal of Biomedical Engineering Research
• /
• v.42 no.6
• /
• pp.251-258
• /
• 2021

Hyaluronic acid (HA) microspheres (MSs) crosslinked with polyethylene glycol diglycidyl ether (PEGDE) are prepared using a simple fluidic device (SFD) to investigate the optimized parameters. A solution mixture of PEGDE in 2-methyl-1-propanol was prepared as a continuous phase in SFD. HA solutions of 1 wt% concentration were introduced into SFD as a discontinuous phase. The HA solution prepared by stirring for more than 48 h exhibited spherical MSs at the needle tip inside the ring cap. As the flow rate of the continuous phase increased from 0.7 to 1.9 mL/min, the diameter of the MS decreased from 173±36 ㎛ to 129±13 ㎛. Although the PEGDE concentration in the range of 0.2 to 1.8 vol% did not affect the diameter of the MS, the microstructure of MS, consisting of inner hollow void and wall, was changed. The inner void and wall size decreased and increased from 79.5 ㎛ to 57.2 ㎛ and from 10.3 ㎛ to 21.4 ㎛, respectively, with increasing PEGDE concentration from 0.2 vol% to 1.8 vol%. FT-IR peaks located around 2867 cm^-1 and 1088 cm^-1 indicated that the HA MS prepared at different PEGDE concentrations were chemically crosslinked. The HA MSs containing different PEGDE concentrations exhibited quantitative cell viability of more than 98%. L-929 cells adhered well to the HA MSs and proliferated continuously with increasing culture time to 48 h regardless of PEGDE concentration, implying that the HA MSs are clinically safe and effective.

• Clean Technology
• /
• v.28 no.2
• /
• pp.147-154
• /
• 2022

Titanate nanotubes (TNTs) were synthesized via alkaline hydrothermal treatment using commercial TiO₂ nanoparticles (P25). The TNTs were prepared at various TiO₂/NaOH ratios, hydrothermal temperatures, and hydrothermal times. The synthesized catalysts were characterized by X-ray diffraction, field-emission scanning electron microscopy, N₂ adsorption-desorption isotherms, field-emission transmission electron microscopy, and ultraviolet-visible spectroscopy. TNTs were generated upon a decrease in the TiO₂/NaOH ratio due to the dissolution of TiO₂ in the alkaline solution and the generation of new Ti-O-Ti bonds to form titanate nanoplates and nanotubes. The hydrothermal treatment temperature and time were important factors for promoting the nucleation and growth of TNTs. The TNT catalyst with the largest surface area (389.32 m² g^-1) was obtained with a TiO₂/NaOH ratio of 0.25, a hydrothermal treatment temperature of 130 ℃, and a hydrothermal treatment time of 36 h. Additionally, we investigated the photocatalytic activity of methyl violet 2B (MV) over the TNT catalysts under UV irradiation and found that the degradation efficiencies of the TNTs were higher than that of P25. Among the TNT catalysts, the TNT catalyst that was hydrothermally synthesized for 36 h (TNT 36 h) exhibited a 96.9% degradation efficiency and a degradation rate constant that was 4.8 times higher than P25 due to its large surface area, which allowed for more contact between the MV molecules and TNT surfaces and facilitated rapid electron transfer. Finally, these results were correlated with the specific surface area.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.7 no.2
• /
• pp.79-84
• /
• 2021

Radiopharmaceuticals are important for tumor diagnosis and therapy. To deliver a radiotracer at the desired target excluding non-targeted tissues is difficult The development of a targeted tracer that has a good clearance profile while maintaining high biostability and biocompatibility is key to optimizing its biodistribution and transport across biological barriers. Improving the hydrophilicity of radiotracers by PEGylation can reduce serum binding, allowing the tracer to circulate without retention and reducing its affinity for non-targeted tissues. In this study, we synthesized a new benzamido tracer (SnBz-PEG₃₆) with the introduction of a low molecular weight polyethylene glycol unit (PEG₃₆, ~2,100 Da). The tumor targeting efficiency and biodistribution of [¹³¹I]-Bz-PEG₃₆ or radiotracer-loaded liposomes were evaluated after their administration to normal mice or mouse tumor models including CT26 (xenograft) and 4T1 (xenograft and orthotopic). Most of the radiotracer was cleared out rapidly (1-24 h post-administration) through the kidney and there was little tumor uptake.

• Analytical Science and Technology
• /
• v.36 no.1
• /
• pp.22-31
• /
• 2023

As the use of e-liquid cigarettes is rapidly increasing worldwide, it multiplies the potential risk undisclosed to the health of non- and smokers. To reduce the hazard, each country has its own set of regulations for controlling e-liquids. In Korea, the narrow definition of tobacco makes it difficult and have been steadily occurring tax evasion exploiting the difference in natural and artificial nicotine. Therefore, it is very important to distinguish source of nicotine for their regulation. To find biochemical discriminant markers, this study established analysis methods based on high-performance liquid chromatography coupled with diode array detector (HPLC-DAD) and high-performance liquid chromatography coupled with triple Quadrupole mass spectrometry (HPLC-MS/MS) for nicotine enantiomers and tobacco alkaloids targeted using the difference in pathways of nicotine biosynthesis and chemical synthesis. The method was validated by experimenting linearity (R² > 0.999), recovery (80.99-108.41 %), accuracy (94.11-109.73 %) and precision (0.04-8.27 %). Then, the results for discrimination of the nicotine obtained from analysis of 65 commercial e-liquid products available in Korean market was evaluated. The method successfully applied to the e-liquids and one sample labelled 'synthetic nicotine' for tax exemption was found to contain a natural nicotine product. This method can be used to determine whether an e-liquid product uses natural or artificial nicotine and monitor non-taxable e-liquid products. The method is more scientific than the existing one, which relies only on field evidence.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.3
• /
• pp.316-326
• /
• 2023

Development of carbon-neutral fuel production technologies to solve climate change issues is progressing worldwide. Among them, methane can be produced through the synthesis of hydrogen produced by renewable energy and carbon dioxide captured through a CO₂ methanation reaction, and the fuel produced in this way is called synthetic methane or e-methane. The CO₂ methanation reaction can be conducted via biological or thermochemical methods. In this study, a 30 Nm³/h thermochemical CO₂ methanation process consisting of an isothermal reactor and an adiabatic reactor was used. The CO₂ conversion rate and methane concentration according to the temperature measurement results at the center and outside of the adiabatic reactor were analyzed. The gas flow into the adiabatic reactor was found to reach equilibrium after about 1.10 seconds or more by evaluating the residence time. Furthermore, experimental and analysis results were compared to evaluate performance of the reactor.

• Journal of Biomedical Engineering Research
• /
• v.44 no.6
• /
• pp.465-475
• /
• 2023

In this study, we demonstrated a silica nanofibrous membrane based on the electrospinning process and evaluated its DNA isolation and purification performance in PCR pretreatment. Generally, silica membranes made of non-woven fabric are used for PCR pretreatment, but this study aimed to improve the efficiency of the pretreatment process by developing a nanofiber-type silica membrane with high specific surface area and porosity. In order to manufacture a nanofiber-shaped silica film while maintaining the original physical properties of silica, nanofiber membranes produced by adding various concentrations of PEO (5 wt%, 8 wt%, and 10 wt%) to silica prepared by the sol-gel method were compared. In terms of nanofiber membrane production, the higher the PEO concentration, the more effective it was in producing nanofiber membranes. The produced silica nanofiber membrane was inserted to a pretreatment device used in commercial PCR equipment, and the pretreatment performance was compared and verified using Salmonella bacteria. When Salmonella was used, samples containing 5 wt% PEO showed superior PCR efficiency compared to samples containing 8 wt% and 10 wt% PEO. These results show that adding 5 wt% of PEO can effectively improve DNA purification and separation by producing a nanofiber-shaped silica film while maintaining the physical properties of silica. We expect that this study will contribute to the development of effective PCR pretreatment technology essential for various molecular biology applications.

• Journal of Microbiology and Biotechnology
• /
• v.33 no.12
• /
• pp.1563-1575
• /
• 2023

Acyl-coenzyme A (CoA):diacylglycerol acyltransferase 2 (DGAT2) catalyzes the last stage of triacylglycerol (TAG) synthesis, a process that forms ester bonds with diacylglycerols (DAG) and fatty acyl-CoA substrates. The enzymatic role of Dgat2 has been studied in various biological species. Still, the full description of how Dgat2 channels fatty acids in skeletal myocytes and the consequence thereof in glucose uptake have yet to be well established. Therefore, this study explored the mediating role of Dgat2 in glucose uptake and fatty acid partitioning under short interfering ribonucleic acid (siRNA)-mediated Dgat2 knockdown conditions. Cells transfected with Dgat2 siRNA downregulated glucose transporter type 4 (Glut4) messenger RNA (mRNA) expression and decreased the cellular uptake of [1-¹⁴C]-labeled 2-deoxyglucose up to 24.3% (p < 0.05). Suppression of Dgat2 deteriorated insulin-induced Akt phosphorylation. Dgat2 siRNA reduced [1-¹⁴C]-labeled oleic acid incorporation into TAG, but increased the level of [1-¹⁴C]-labeled free fatty acids at 3 h after initial fatty acid loading. In an experiment of chasing radioisotope-labeled fatty acids, Dgat2 suppression augmented the level of cellular free fatty acids. It decreased the level of re-esterification of free fatty acids to TAG by 67.6% during the chase period, and the remaining pulses of phospholipids and cholesteryl esters were decreased by 34.5% and 61%, respectively. Incorporating labeled fatty acids into beta-oxidation products increased in Dgat2 siRNA transfected cells without gene expression involving fatty acid oxidation. These results indicate that Dgat2 has regulatory function in glucose uptake, possibly through the reaction of TAG with endogenously released or recycled fatty acids.

• Journal of Microbiology and Biotechnology
• /
• v.34 no.5
• /
• pp.1154-1163
• /
• 2024

Glucosylation is a well-known approach to improve the solubility, pharmacological, and biological properties of flavonoids, making flavonoid glucosides a target for large-scale biosynthesis. However, the low yield of products coupled with the requirement of expensive UDP-sugars limits the application of enzymatic systems for large-scale. C. glutamicum is a Gram-positive and generally regarded as safe (GRAS) bacteria frequently employed for the large-scale production of amino acids and biofuels. Due to the versatility of its cell factory system and its non-endotoxin producing properties, it has become an attractive system for the industrial-scale biosynthesis of alternate products. Here, we explored the cell factory of C. glutamicum for efficient glucosylation of flavonoids using apigenin as a model flavonoid, with the heterologous expression of a promiscuous glycosyltransferase, YdhE from Bacillus licheniformis and the endogenous overexpression of C. glutamicum genes galU1 encoding UDP-glucose pyrophosphorylase and pgm encoding phosphoglucomutase involved in the synthesis of UDP-glucose to create a C. glutamicum cell factory system capable of efficiently glucosylation apigenin with a high yield of glucosides production. Consequently, the production of various apigenin glucosides was controlled under different temperatures yielding almost 4.2 mM of APG1(apigenin-4'-O-β-glucoside) at 25℃, and 0.6 mM of APG2 (apigenin-7-O-β-glucoside), 1.7 mM of APG3 (apigenin-4',7-O-β-diglucoside) and 2.1 mM of APG4 (apigenin- 4',5-O-β-diglucoside) after 40 h of incubation with the supplementation of 5 mM of apigenin and 37℃. The cost-effective developed system could be used to modify a wide range of plant secondary metabolites with increased pharmacokinetic activities on a large scale without the use of expensive UDP-sugars.

• Development and Reproduction
• /
• v.28 no.2
• /
• pp.47-54
• /
• 2024

In eukaryotes, RNA splicing, an essential biological process, is crucial for precise gene expression. Inaccurate RNA splicing can cause aberrant mRNA production, disrupting protein synthesis. To regulate splicing efficiency, some splicing factors are reported to undergo Ubiquitin-like Modifier (SUMO)ylation. Our data indicate that in Saccharomyces cerevisiae, the SUMO protease, Ulp2, is involved in splicing. In the ulp2Δ mutant, some ribosomal protein (RP) transcripts exhibited a significant increase in the levels of intron-containing pre-mRNA because of improper splicing. Moreover, we confirmed Ulp2 protein binding to the intronic regions of RP genes. These findings highlight a critical Ulp2 role in RP transcript splicing.