• Bulletin of the Korean Chemical Society
• /
• v.35 no.9
• /
• pp.2704-2710
• /
• 2014

Catalase (CAT) decomposes hydrogen peroxide that is toxic to the body. In this study, simple and sensitive detector has been developed for observing catalase activity using liquid crystal droplet system. Microscale LC droplet patterns are formed by spreading aldehyde-doped nematic liquid crystal on pre-treated glass slides. When hydrogen peroxide is added, aldehyde is oxidized and amphiphiles are formed. Dodecanoates cause the pattern to transit from bright to dark as they self-assemble to form a carboxyalte monolayer at the interface. When a drop of pre-incubated CAT and hydrogen peroxide mixture is placed onto the pattern, bright fan-shape is observed. This planar optical appearance indicates that catalase has decomposed hydrogen peroxide. Compared to the detectors that have been previously developed, this system is more sensitive with detection limit of 1fM. This research suggests further studies to be on LC droplet patterning to develop highly sensitive and methodologically simple sensors for various chemicals.

• The Korea Journal of Herbology
• /
• v.38 no.4
• /
• pp.11-19
• /
• 2023

Objectives : The aim of this study was to investigate the effect of baicalein (BA) on the production of hydrogen peroxide and nitric oxide (NO) in RAW 264.7 mouse macrophages stimulated with polyinosinic-polycytidylic acid (poly-IC) and lipoteichoic acid. Methods : RAW 264.7 co-stimulated with poly-IC and lipoteichoic acid were incubated with baicalein at concentrations of 25 and 50 μM. Incubation time is 16 h, 18 h, 20 h, 22 h, and 24 h. After incubation, The production of hydrogen peroxide in RAW 264.7 was measured with dihydrorhodamine 123 assay. Chrysin was used as a comparative material. NO production was evaluated by griess assay. Results : For 16 h, 18 h, 20 h, 22 h, and 24 h incubation, BA at the concentration of 25 and 50 μM significantly inhibited the production of hydrogen peroxide in RAW 264.7 stimulated by poly-IC and lipoteichoic acid (p <0.001). In details, production of hydrogen peroxide in 'poly-IC and lipoteichoic acid'-stimulated RAW 264.7 treated for 16 h with BA at concentrations of 25 and 50 μM was 82.36% and 77.24% of the control group treated with poly-IC and lipoteichoic acid only, respectively; the production of hydrogen peroxide for 18 h was 83.15% and 77.91%, respectively;production of hydrogen peroxide for 20 h was 82.88% and 77.82%, respectively; production of hydrogen peroxide for 22 h was 83.27% and 78.17%, respectively; production of hydrogen peroxide for 24 h was 83.54% and 78.35%, respectively. Additionally, BA at the concentration of 50 and 100 μM significantly inhibited NO production in lipoteichoic acid-induced RAW 264.7 (p <0.001). Conclusions : BA might have anti-oxidative activity related to its inhibition of hydrogen peroxide production in 'poly-IC and lipoteichoic acid'-stimulated RAW 264.7 macrophages.

• Journal of dental hygiene science
• /
• v.8 no.4
• /
• pp.255-260
• /
• 2008

The purposes of this study were to examine the effect of 35% hydrogen peroxide (HP) bleaching agent on the changes in physical and chemical characteristics of tooth. The bleached teeth showed an apparent color changes. The whiteness increased linearly within the tested period as the period of bleaching increased. The microhardness between bleached groups after bleaching showed any statistically significant difference according to the paried t-test. The bleached enamel surface showed any apparent morphological changes compared to the enamel which was stored in distilled water only. The difference of the total mineral contents for the distilled water and hydrogen peroxide did not show statistical significance. These results demonstrated that bleaching using 35% hydrogen peroxide were adversely affects application time of experimental group and may confirm the safety of using these agents for a short time in dentist-monitored bleaching.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.629-630
• /
• 2014

• Restorative Dentistry and Endodontics
• /
• v.19 no.1
• /
• pp.114-123
• /
• 1994

The purpose of this study was to examine the shear bond strength of resin-enamel bond formed at specific time intervals after the termination ov vital bleaching. A total of 72 human extracted maxillary premolars were divided into nine groups : untreated control (group 1) ; enamel treated with 35% hydrogen peroxide(group 2, 3, 4, 5) ; and enamel reated with 15% carbamide peroxide gel (group 6, 7, 8, 9). After the treatment with 35% hydrogen peroxide for 2 hours and 15% carbamide peroxide for 24 hours, adhesion of a resin to bleached enamel was formed at 1 hour (group 2, 6) and 24 hours(group 3, 7) ; 3days(group 4, 8) and 7 days(group 5, 9) post-termination of bleaching treatment. A $3{\times}3mm$ mold was filled with Scotchbond Multi-Purpose and Z100. After 24 hours later, the specimens were shear-tested at crosshead speed 1mm/min and analyzed statistically. Fractured specimens from group 1,2, 6 were gold-coated with Eiko ion coater and observed under Scanning electron microscope at 25KV. The following results results were obtained : 1. Bonds formed at 1 hour post-termination of 35 % hydrogen peroxide(P<0.01) and 15 % carbamide peroxide bleaching treatment groups(P<0.05) showed significantly lower shear bond strength than untreated group. 2. Bonds formed at 24 hours, 3 days and 7 days post-termination of 35% hydrogen peroxide and 15 % carbamide peroxide bleaching treatment groups showed no significant differences in shear bond strength with untreated group(p>0.05). 3. SEM examinations of the untreated fracture specimen indicated cohesive fracture within enamel and exposed enamel prisms, but the bleached fracture specimens indicated adhesive fracture.

• The Korea Journal of Herbology
• /
• v.36 no.5
• /
• pp.117-123
• /
• 2021

Objectives : The aim of this study is to investigate the effect of wogonin on the production of hydrogen peroxide in polyinosinic:polycytidylic acid (poly I:C)-stimulated TM4 mouse sertoli cells. Methods : TM4 were treated with poly I:C (50 ug/mL) and wogonin at concentrations of 5, 10, 25, and 50 µM for 30 min, 2 hr, 12 hr, 18 hr, and 24 hr. The production of intracellular hydrogen peroxide was measured by dihydrorhodamine 123 assay. Results : For 30 min, 2 hr, 12 hr, 18 hr, and 24 hr treatment, wogonin significantly inhibited intracellular hydrogen peroxide productions of TM4 at the concentration of 5, 10, 25, and 50 µM (p<0.05). In details, production of hydrogen peroxide in poly I:C-stimulated TM4 treated for 30 min with wogonin at concentrations of 5, 10, 25, and 50 µM was 95.67%, 92.69%, 92.05%, and 91.97% of the control group treated with poly I:C only, respectively; the production of hydrogen peroxide for 2 hr was 94.44%, 94.41%, 93%, and 92.98%, respectively; production of hydrogen peroxide for 12 hr was 96.78%, 95.32%, 94.33%, and 93.17%, respectively; production of hydrogen peroxide for 18 hr was 94.7%, 93.4%, 93.38%, and 93.35%, respectively; and production of hydrogen peroxide for 24 hr was 95.75%, 94.77%, 94.58%, and 92.8%, respectively. Conclusions : Wogonin might have anti-viral property related with its inhibition of intracellular hydrogen peroxide production in poly I:C-stimulated TM4 cells.

• Journal of dental hygiene science
• /
• v.11 no.4
• /
• pp.375-380
• /
• 2011

This study evaluated whether fluoride treatment can affect recovery of the irregularity of enamel surface after tooth whitening with a high concentration of hydrogen peroxide (HP) activated by plasma arc light. A total of 36 bovine teeth stained with coke were used in this experiment. The specimens were classified into following three groups (two different commercial plasma arc groups and a control group without light curing source): (1) 35% HP gel only, (2): 35% HP gel and Plasma arc A, and (3) 35% HP gel and Plasma arc B. To measure color changes and surface morphologies before and after the bleaching, colorimeter and scanning electron microscopy were used, respectively. When the specimens were bleached with hydrogen peroxide and plasma arc lights, the bleaching effect was greater than when only hydrogen peroxide gels were used (Kruskal-Wallis test, p<0.05). In addition, plasma arc B showed the more color changes than plasma arc A (Bonferroni post-hoc test, p<0.05). The surfaces of the teeth treated with fluoride gel after the whitening treatment came to be smooth. Therefore, the results of this study suggested that the fluoride application for patients who got tooth whitening therapy with a high concentration of hydrogen peroxide gels activated by plasma arc light will be effective to recover rough enamel surfaces.

• The Korean Journal of Food And Nutrition
• /
• v.35 no.4
• /
• pp.259-267
• /
• 2022

The purpose of this study was to evaluate the antioxidative activities of jeolpyun containing Cnidium officinale M extract (2%, 4%, 6%, 8%) by total polyphenol contents, electron donating ability on 2,2-diphenyl-1-picrylhydrazyl (DPPH), scavenging ability of superoxide anion radical and decomposing ability of hydrogen peroxide. In chromaticity analysis, the brightness significantly decreased with increasing Cnidium officinale M extract content. Jeolpyun containing 8% Cnidium officinale M extract revealing the highest value for the redness and the yellowness, 1.07, 12.70, respectively. The total polyphenol contents of jeolpyun containing 8% Cnidium officinale M extract were the highest content of 4,213 ㎍ gallic acid equivalent (GAE)/mL. The total polyphenol contents revealed significant difference (p<0.05). Jeolpyun containing 8% Cnidium officinale M extract revealing the highest electron donating ability (83.55%). The electron donating abilities were significantly related at p<0.05. The scavenging abilities of superoxide anion radical for jeolpyun containing 4% Cnidium officinale M extract revealed the highest ability (0.01676). There was no significant difference. The hydrogen peroxide decomposing ability for jeolpyun containing 8% Cnidium officinale M extract revealed the most hydrogen peroxide decomposing ability (-0.193) and the hydrogen peroxide decomposing ability revealed a significant difference (p<0.05).

• Korean Journal of Microbiology
• /
• v.31 no.2
• /
• pp.166-174
• /
• 1993

Streptomyces coeUc%r (Muller) cells were treated with $100 \mu$M hydrogen peroxide for I hour and proteins synthesized during hydrogen peroxide stress were labeled with L-[$^{35}S$]-methionine. Total cellular proteins were extracted and analyzed by two-dimensional polyacrylamide gel electrophoresis. In exponential growth phase, synthesis of about 100 proteins was increased by hydrogen peroxide treatment. These proteins were named as Pin (£eroxide-inducib]e) proteins and classified into 4 subgroups according to their induction time after hydrogen peroxide treatment. About 60 of them were found to be induced within 20 minutes and maintained throughout I hour of treatment. In stationary growth phase. synthesis of 62 proteins was increased by hydrogen peroxide and 21 of them were the same Pins found in exponential growth phase. Proteins from the mutants which are resistant to hydrogen peroxide were obtained in exponential growth phase and compared with those from the wild type on two-dimensional gel. The three mutants, N7, N9. and N24, were found to have higher constitutive leve]s of ]5, 17, and 15 Pin proteins respectively, than the wild type. 9 of these Pin proteins (D74.7a, E76.0c, E23.3. F50.7, F47.2a. F25.5, G39.6b, G24.0, H39.6a) increased in two of the three mutants and 3 proteins (F39.7, H6I.7. 120.8) increased in all of the three mutants. These proteins might play important roles in the response of S. coelic%r to hydrogen peroxide.

• YAKHAK HOEJI
• /
• v.56 no.6
• /
• pp.390-394
• /
• 2012

A series of new pyridazinyl sulfoxides 3a~e and pyridazinyl sulfones 4a were synthesized for development of candidates to retain anticancer activity. The utility of sulfoxides and sulfones in both laboratory and industrial practice was quickly recognized, and these species have been extensively utilized, including as pharmaceutical intermediates and anticancer agents. Alkylthiopyridazines 2a~e were prepared from the 3,6-dichloropyridazine using allylthiolation with alkyl mercaptan. Sulfides could be oxidized to sulfoxides or sulfones using 1~3 equivalents of hydrogen peroxide as an oxidant. The oxidation of sulfoxides to sulfones was also accomplished with aqueous hydrogen peroxide. Formation of 3a~e and 4a was undertaken with stirring using 35% hydrogen peroxide at room temperature in acetic acid for 18~72 h. Synthetic compounds were identified using NMR spectrum.