• 한국식품과학회지
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• 제39권2호
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• pp.133-137
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• 2007

유지의 산화안정도 측정을 위해 개발된 DPPH법의 최적화를 위해 시료의 양에 따른 유지의 산화변화를 분석하였고, 결정도니 조건을 사용하여 시중에서 튀김유로 사용되는 4종류 식용유지의 열산화안정성을 측정하였다. CDA와 p-AV는 산화반응이 진행될수록 증가하였으며 시료간의 상대적인 산화안정성 차이를 확인할 수 있었다. 반면에 DPPH법은 유지의 산화라디칼과의 반응성을 이용하며 흡광도의 증가와 감소를 반복하는 경향을 나타냈고 이로부터 유지산화라디칼의 변화를 측정 할 수 있었다. 또한 유지의 초기 전자 혹은 수소공여능을 확인할 수 있었고, DPPH 흡광도 증가를 통해 산화방지물질의 소진속도 및 산화라디칼의 생성속도를 계산할 수 있었으며, 산화방지물질의 소진시점을 결정할 수 있었다. 따라서 DPPH법을 기존의 산화도 측정방법과 병용한다면 유지의 산화도는 물론 산화반응 단계를 측정 할 수 있고, 산화안정성을 예측하는데 도움이 될 것으로 기대된다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.317-320
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• 2002

10 가지 식물추출물에서 항산화활성을 측정하여 가장 효과가 높았던 오미자를 선택하여 순차적으로 층분리 후, 각 유기용매층에 따라 분리된 추출물의 항산화 활성을 측정하였다. 그 결과 Ethyl acetate층 추출물 (DPPH 51.6%. SOD 66.2%)과 Butanol층추추물 (DPPH 60.7%, SOD 67.4%) 에서 가장 높은 항산화활성을 나타내었으며 총 polyphenol 함량 또한 Ethyl acetate층 (30000 mg/kg) 과 Butanol층 (30000 mg/kg)에서 높게 나타났으며, 특이한 점은 항산화 활성이 낮았던 water층 (39400 mg/kg) 에서 총polyphenol함량이 높았다.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2557-2560
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• 2010

To assay for antioxidant capacity of natural products considered important in producing human health benefits, a practical and economical method using pellet techniques was developed. A standard visualizing reagent, 1,1diphenyl-2-picryl-hydrazyl (DPPH), was mixed with a water-miscible polyvinyl alcohol (PVA), serving as a solid phase support for the DPPH reagent. A DPPH pellet was prepared by dropping a small volume of the DPPH solution onto PET film, and drying in an oven. The PVA-based DPPH pellet was dissolved into water, in which the water-miscible PVA plays as a non-ionic surfactant to help the DPPH reagent to be dissolved into the solvent. Using the DPPH assay, the antioxidant capacity of water-soluble extracts of black soybean, barley, green tea, and green gram was examined. Among the natural products tested, green tea showed the highest antioxidant capacity. This PVA-based DPPH antioxidant assay can be further applied in the natural food, raw plant material, and health product inspection field.

• 동아시아식생활학회지
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• 제20권1호
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• pp.54-59
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• 2010

Basil is known to contain six types of polyphenols that engage in physiological activation; protocateuic acid, caffeic acid, chlorogenic acid, courmaric acid, rosmarinic acid and quercetin. In this study, the antioxidants in eight types of basil were evaluated. Specifically, the antioxidative activation of basil was evaluated based on the relationship between active oxygen scavenging (DPPH radical-scavenging), which was used as an index showing the content and functionality of the polyphenol compounds in basil, and $Fe^{2+}$/ascorbate (FTC) and 2-thiobarbituric acid (TBA). The total polyphenol content of the different types basil occurred in the following order: Dark-opal> Lettuce> Bush> Greek> Lemon> Sweet> Geno> Holy. The highest content Dark-opal was 173.3 mg, which was about three times greater than the lowest content Holy, which was 49.85 mg. In addition, DPPH radical-scavenging by Dark-opal 51%, which was the highest scavenging activity occurred in the folling order: Dark-opal> Lettuce> Bush> Greek> Lemon> Sweet> Geno> Holy. The antioxidative activation values measured using the FTC and TBA were the same as the value obtained using the DPPH method. Finally, the level of antioxidative activation measured using FTC, TBA and DPPH methods showed that the higher the content of polyphenol substance was, the stronger the antioxidative activation became.

• 한국산림과학회지
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• 제102권4호
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• pp.566-570
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• 2013

정금나무의 기능성 품종을 육성하기 위하여 정금나무 선발 5개체의 열매에 대한 항산화 활성을 측정하였으며, 항산화 성분인 총 페놀 함량을 측정하였다. 총 페놀 함량은 gallic acid를 기준물질로 하여 분석한 결과 15.8~19.9 mg/g 범위로 전체 평균 17.9 mg/g을 나타냈으며, DPPH free radical 소거활성은 400 ppm의 농도에서 69.1~91.4% 범위로 전체평균 84.2%를 나타내었다. 환원력은 0.56~0.96 범위로 전체 평균 0.79를 나타내었다. 상관분석 결과 DPPH free radical 소거활성과 환원력에서 상관계수가 0.969로 매우 높은 정의 상관관계를 나타내었다.

• BMB Reports
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• 제37권5호
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• pp.629-633
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• 2004

NADPH-cytochrome P450 reductase (CPR) transfers electrons from NADPH to cytochrome P450, and catalyzes the one-electron reduction of many drugs and foreign compounds. Various forms of spectrophotometric titration have been performed to investigate the electron-accepting properties of CPR, particularly, to examine its ability to reduce cytochrome c and ferricyanide. In this study, the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) by CPR was assessed as a means of monitoring CPR activity. The principle advantage of DPPH is that its reduction can be assayed directly in the reaction medium by a continuous spectrophotometry. Thus, electrons released from NADPH by CPR were transferred to DPPH, and DPPH reduction was then followed spectrophotometrically by measuring $A_{520}$ reduction. Optimal assay concentrations of DPPH, CPR, potassium phosphate buffer, and NADPH were first established. DPPH reduction activity was found to depend upon the strength of the buffer used, which was optimal at 100 mM potassium phosphate and pH 7.6. The extinction coefficient of DPPH was $4.09\;mM^{-1}\;cm^{-1}$. DPPH reduction followed classical Michaelis-Menten kinetics ($K_m\;=\;28\;{\mu}M$, $K_{cat}\;=\;1690\;min^{-1}$). This method uses readily available materials, and has the additional advantages of being rapid and inexpensive.

• 동아시아식생활학회지
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• 제19권3호
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• pp.375-383
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• 2009

This study was conducted to measure the total polyphenol contents and DPPH radical scavenging activities of different potato plants parts, varieties, and grades, and by distribution and different cooking conditions. The results were as follows. For the plant parts, total phenolic content and DPPH radical scavenging activity were highest in the flowers followed by leaves and stems, respectively. Among 5 potato varieties, 'Jasim' had the highest DPPH radical scavenging activity and the activity of its pulp was lower than that of its cortex(peel). Regardless of potato grade, the cortexes(peel) of samples had two-fold higher DPPH radical scavenging activity than pulp, and the Grade SS potato had the highest phenolic content. It was also found that the bud ends and stem ends had comparably larger amounts of phenolic compounds in horizontally cut potatoes. Finally, the descending order for DPPH radical scavenging activity, according to different cooking conditions, was as follows: gas oven range-baking, frying, microwave-heating, sauteing, boiling in 1% saline solution, steaming, and boiling in 3% saline solution.

• Natural Product Sciences
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• 제22권1호
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• pp.64-69
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• 2016

A method for simultaneously identifying antioxidative compounds was developed using time-based LC-MS coupled with DPPH assay regardless of the time consuming process. The methanolic extract of Polygonum aviculare (Polygonaceae) showed significant DPPH radical scavenging activity. Time-based DPPH assay for simultaneous identification of active compounds from the extracts of P. aviculare was used. Major peaks of ethyl acetate fraction of P. aviculare showed high DPPH radical scavenging activity. A simple phenolic compound (1) and six flavonoids (2-7) were isolated from the ethyl acetate fraction of P. aviculare by silica gel and sephadex LH-20 column chromatography. The structures of seven compounds were determined to be protocatechuic acid (1), catechin (2), myricitrin (3), epicatechin-3-O-gallate (4), avicularin (5), quercitrin (6), and juglanin (7) based on the analysis of the $^1H$-NMR, $^{13}C$-NMR and ESI-MS data. All compounds exhibited significant antioxidant activity on DPPH assay and active compounds were well correlated with predicted one.

• Natural Product Sciences
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• 제25권2호
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• pp.122-129
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• 2019

The roots of Phlomis umbrosa (Turcz.) (Phlomidis Radix) have been traditionally used to treat cold, reduce swelling and staunch bleeding. Four iridoids (1 - 3 and 5) and six phenylethanoid derivatives (4, and 6 - 10) were isolated from the roots of P. umbrosa. A simple, sensitive, and reliable analytical HPLC/PDA method was developed, validated, and applied to determine 10 marker compounds in Phlomidis Radix. Furthermore, the isolates were evaluated for cytotoxic and anti-oxidant activities as well as DPPH-HPLC method. Among them, compounds 4 and 6 - 9 displayed potent anti-oxidant capacities using DPPH assay with $IC_{50}$ values of $27.7{\pm}2.4$, $10.2{\pm}1.1$, $18.0{\pm}0.8$, $19.1{\pm}0.3$, and $19.9{\pm}0.6{\mu}M$, and compounds 6, 8, and 9 displayed significant cytotoxic activity against HL-60 with $IC_{50}$ values of $35.4{\pm}3.1$, $18.6{\pm}2.0$, and $42.9{\pm}3.0{\mu}M$, respectively.

• 한국식품영양과학회지
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• 제30권3호
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• pp.547-551
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• 2001

The comparative activities of acetone, ethanol, and aqueous fractions extracted from fruit powder of Cudrania tricuspidata by different temperature were tested by in vitro experimental models; peroxidation of linoleic acid and autooxidation of rat hepatic and renal microsomes by using thiobarbituric acid (TBA) for assay of free malondialdehyde production, and scavenging activities of free radicals by DPPH (α, α'-diphenyl-β-picrylhydrazyl). In DPPH method, acetone fraction extracted at 30℃ showed the highest free radical scavenging activities and acetone fractions extracted at 30℃ and 60℃ and ethanol fraction extracted at 30℃ showed stronger than BHT (butylated hydroxitoluene) although used ten-fold lower concentrations. In thiocyanate method used linoleic acid an inhibitory effects of all fractions showed higher than control treatment. TBA method used linoleic acid showed the highest antioxidative activity in acetone fraction extracted at 30℃ and 60℃. an inhibition activity against lipid peroxidation in hepatic microsomes of rats showed the highest at acetone faction extracted at acetone fraction among extracted fractions was shown to be the most potent antioxidative properties and this action was more potent in fractions extracted at 30℃ than those extracted at 60℃.