• Journal of Applied Biological Chemistry
• /
• v.60 no.2
• /
• pp.185-190
• /
• 2017

Antioxidative ability of 50% ethanol extract from leaves of Leucaena leucocephala (Lam.) de Wit was investigated. The extraction yield, total polyphenols and total flavonoids of the ethanol extract were $18.3{\pm}0.40%$, $121.3{\pm}11.04{\mu}g$ gallic acid equivalents/mg and $105.2{\pm}2.77{\mu}g$ quercetin equivalents/mg, respectively. The ethanol extract possessed the antioxidative activities such as free radical, cation radical, and nitrite scavenging activities as well as reducing power and lipid peroxidation inhibitory activity. These antioxidative activities of the ethanol extract increased in proportion to the extract concentration. $EC_{50}$ values for free radical scavenging, cation radical scavenging nitrite scavenging, and reducing power were $133.51{\mu}g/mL$, $667.22{\mu}g/mL$, 2.58 mg/mL, and $250.00{\mu}g/mL$, respectively. Polyphenols and flavonoids are suggested to be the key contributors for the antioxidative ability of the ethanol extract from Leucaena leucocephala leaves.

• Korean journal of food and cookery science
• /
• v.32 no.3
• /
• pp.299-306
• /
• 2016

Purpose: Curcuma aromatica Salisb., commonly known as turmeric, has long been used as a powerful health-promoting anti-inflammatory or antioxidant that supports cellular health of the human body. The objective of this study was to compare the antioxidant and antimicrobial activities of the samples with or without fermentation. Methods: Antioxidant activities of the samples were compared using total phenol, flavonoid contents, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging activity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Antimicrobial activities were also examined using the paper disc method and minimum inhibitory concentration (MIC). Results: Organic acid content of the C. aromatica Salisb. fermented with Aspergillus oryzae (FCAS) showed a significantly higher value of 0.41% than that of the typical sample without fermentation (CAS) which showed a value of 0.27% (p<0.001). Total phenol and flavonoid contents of the CAS and FCAS did not show significant differences. However, ABTS cation radical scavenging activity and DPPH radical scavenging activity were significantly increased in the samples with fermentation (p<0.001, p<0.01), respectively. The samples of the disc showed inhibited growth of gram positive Bacillus cereus (FCAS 3.70 cm and CAS 2.73 cm) and Staphylococcus aureus (FCAS 2.70 cm and CAS 1.97 cm). MIC of the FCAS (0.25-0.50, 0.5-1.00 mg/mL) was higher than that of the CAS (1.00-2.00, 2.00-3.00 mg/mL), respectively. Conclusion: C. aromatica Salisb. with fermentation showed higher antioxidant and antimicrobial activities in this study. Thus we conclude that fermentation can be a helpful process for more effective application of C. aromatica Salisb. with fermentation in the health-promoting food industry.

• Journal of Applied Biological Chemistry
• /
• v.62 no.2
• /
• pp.167-172
• /
• 2019

In vitro antioxidant effect of 50% ethanol extract from Napier grass (Penninsetum purpureum) was investigated. The yield and polyphenol content of the Napier grass extract were $6.3{\pm}0.35%$ and $79.6{\pm}3.65{\mu}g$ gallic acid equivalents/mg-extract, respectively. Antioxidant ability of the Napier grass extract such as fee radical and cation radical scavenging activities, reducing power, nitrite scavenging activity, and lipid peroxidation inhibitory activity proportionally increased as concentration of the extract increased. $EC_{50}$ values of the Napier grass extract for free radical scavenging, cation radical scavenging, reducing power, and nitrite scavenging were 1,930.0, 350.0, 840.0, and $1,470.0{\mu}g/mL$, respectively. In the presence of $85.0{\mu}g/mL$ of the Napier grass extract, lipid peroxidation was potently inhibited by 74.6%.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2019.04a
• /
• pp.105-105
• /
• 2019

Dendropanax morbifera H.Lev is an evergreen tree that lives in subtropical climates. About 75 species of D. morbifera live in East Asia, but only one species live in Korea(Korean dendropanax). D. morbifera belonging to Aralicacae family 98% of D. morbifera are distributed in Jeollanam-do in the Korea and the grow wild in Gyeongsangnam-do and Jeju Island. The harvest time and usage of D. morbifera were recorded in traditional medicinal books. The roots and stems of D. morbifera had been used for traditional medicine to treat migraine, menstrual irregularity and skin disease. And D. morbifera leaves are contain flavonoids and polyacetylene compounds. In this study, we were investigated the physiological activity of D. morbifera by different areas collected at the same time, and compared to characteristics of plants. D. morbifera collected from Jeollanam-do (Goheung-gun), Gyeongsangnam-do (Namhae-gun) and Jeju Island, and dried at $50^{\circ}C$ for three days. We used dried D. morbifera powder for antioxidant tests. Each sample was extracted with hot water under the same conditions. The contents of total polyphenols and total flavonoids from D. morbifera were identified. Also, we performed to DPPH radical scavenging activity, ABTS cation radical scavenging activity and Superoxide anion scavenging activity efficacy for antioxidant activity determination. The contents of total polyphenols and total flavonoids in hot water extract of D. morbifera harvested from Gyeongsangnam-do and Jeollanam-do were higher than Jeju. However, D. morbifera harvested from Gyeongsangnam-do and Jeollanam-do showed no significant difference those content of total polyphenols and total flavonoids. And the antioxidant capacity was showed the similar patterns in antioxidant activity.

• Journal of the Korean Chemical Society
• /
• v.40 no.8
• /
• pp.34-585
• /
• 1996

• Journal of the Korean Chemical Society
• /
• v.8 no.1
• /
• pp.25-29
• /
• 1964

Benzhydryl azide 類에 Benzhydrol 類를 混合하여 Schmidt 反應을 逐行할 때에 Benzhydryl 基 間에 完全한 Radical exchange 現象이 일어남을 알았다. 故로 Benzhydrol 類의 Schmidt 反應에 있어서는 一但 生成된 Benzhydryl azide가 濃硫酸存在下에서 Benzhydryl cation과 Hydrazoic acid로 分離되어 完全平衡狀態에 있음을 確認할 수 있었다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2008.02a
• /
• pp.319-320
• /
• 2008

• Journal of Applied Biological Chemistry
• /
• v.43 no.3
• /
• pp.156-160
• /
• 2000

The possible mechanism of the DNA strand breaking activity of the hot-water extract of Fructus Chaenomelis (dried fruit of Chaenomeles sinensis) in a closed circular duplex replica form DNA (RFI DNA) was studied through agarose gel electrophresis under various conditions. Induction of DNA strand scission by the hot-water extract of C. sinensis occurred in dose and time-dependent manners. $Cu^{2+}$ was indispensable for the induction of DNA strand breakage. Exogeneous chelating agents inhibited the DNA breaking activity, conforming the catalytic action of $Cu^{2+}$ on generation of free radicals responsible for oxidative damage. Antioxidant enzymes and some radical scavengers were used to investigate the major radical species triggering the DNA strand scission, demonstrating that a highest inhibitory activity was found in the presence of catalase, while less in the presence of tiron (a scavenger for superoxide radical), 2-aminoethyl-isothiuroniumbromide-HBr, cysteamine (scavengers for hydroxyl radical), and 1,4-diazabicyclo [2,2,2] octane (a scavenger for singlet oxygen) in decreasing order. The findings implied that oxygen radical species generated in presence of transition divalent cation during the oxidation of some compounds contained in the hot-water extract of C. sinensis is mainly responsible for inducing genotoxicity.

• Journal of Electrochemical Science and Technology
• /
• v.4 no.2
• /
• pp.71-80
• /
• 2013

The study of methyl viologen ($MV^{2+}$) mediated oxygen reduction in electrolytic ethanol media possesses potential application in the electrochemical synthesis of hydrogen peroxide mainly due to the advantages of the much increased solubility of molecular oxygen ($O_2$) and high degree of reversibility of $MV^{2+/{\bullet}+}$ redox couple. The diffusion coefficients of both $MV^{2+}$ and $O_2$ were investigated via electrochemical techniques. For the first time, $MV^{2+}$ mediated $O_2$ reduction in electrolytic ethanol solution has been proved to be feasible on both boron-doped diamond and micro-carbon disc electrodes. The electrocatalytic response is demonstrated to be due to the radical cation, $MV^{{\bullet}+}$. The homogeneous electron transfer step is suggested to be the rate determining step with a rate constant of $(1{\pm}0.1){\times}10^5M^{-1}s^{-1}$. With the aid of a simulation program describing the EC' mechanism, by increasing the concentration ratio of $MV^{2+}$ to $O_2$ electrochemical catalysis can be switched from a partial to a 'total catalysis' regime.

• Journal of the Korean Chemical Society
• /
• v.40 no.11
• /
• pp.686-691
• /
• 1996

Several kind of viologen derivatives were synthesized and the electrochromic property of these compounds was examined by cyclovoltametric and chronoamperometric method, relating to the mechanisum of coloring reaction. The electrochromic properties of 1,1'-diethyl-4,4'-bipyridinium dibromide(EV), 1,1'-dipropyl-4,4'-bipyridinium dibromide(PV), 1,1'-dibuthyl-4,4'-bipyridinium dibromide(BV) and 1-ethyl-1'-butyl-4,4'-bipyridinium dibromide(EBV) are studied by using an propylenecarbonate/methanol solution with $Bu_4NBF_4$ as supporting electrolyte. A monomer-dimer equilibrium was proposed to explain the related observation that EV and EBV cation radical solutions are violet at an applied voltage of 1.7∼3.0V but become blue in open-circuit condition.