• Journal of Applied Biological Chemistry
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• 제42권2호
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• pp.66-70
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• 1999

Effects of the enhanced level of L-ascorbic acid (AA) on the water deficit-induced oxidative damage were studied in rice (Oryza sativa L.) seedlings. The seedlings sprayed with 20 to 80 mM L-galactono-${\gamma}$-lactone (GL), a putative precursor of AA, showed 2 to 5-fold higher levels of AA compared with controls. Pretreatment of the seedlings with GL prior to water stress imposition caused virtually no effect on dehydration of tissues during water deficit but substantially mitigated oxidative injury, as accessed by 2-thiobarbituric acid-reactive substances, ${\alpha}$-tocopherol, chlorophylls and ${\beta}$-carotene. Proline accumulation during water stress was also significantly lowered in the treated seedlings. In a complementary experiment, AA retarded photodegradation of ${\alpha}$-tocopherol in isolated thylakoids far more efficiently than glutathione. GL in itself did not show any noticeable reactivity toward ${\alpha}$-tocopheroxyl radical. The results demonstrate the antioxidative function of AA in rice seedlings encountering water-limited environments, suggesting a critical role of AA as a defense against oxidative stress in plants.

• Food Science and Biotechnology
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• 제18권1호
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• pp.1-11
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• 2009

Carotenoids being most important pigments among those occurring in nature, have received increased interest owing to their beneficial effects on human health. An effort is made to review marine carotenoids as important bioactive compounds with reference to their presence, chemical, and biofunctional benefits they afford. The potential beneficial effects of marine carotenoids were particularly focused on astaxanthin and fucoxanthin, major marine carotenoids found in marine animals and aquatic plants, respectively. Both carotenoids show strong antioxidant activity which is attributed to quenching singlet oxygen and scavenging free radicals. The potential role of the carotenoids as dietary antioxidants has been suggested as being one of the main mechanism by which they afford their beneficial health effects such as anticancer activity and anti-inflammatory effect. Only recently, antiobesity effect and antidiabetic effect have been noted as specific and novel bio-functions of fucoxanthin. Nutrigenomic study reveals that fucoxanthin induces uncoupling protein 1 (UCP1) expression in white adipose tissue (WAT) mitochondria to lead to oxidation of fatty acids and heat production in WAT. Fucoxanthin improves insulin resistance and decreases blood glucose level, at least in part, through the down-regulation of tumor necrosis factor $\alpha$ ($TNF{\alpha}$) in WAT of animals.

• 한국광학회지
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• 제16권2호
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• pp.146-151
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• 2005

PMMA에 pyrromethene 597(PM597) 색소를 주입하여 고체 색소를 제작한 후 그 레이저 출력특성을 분석하였다. 펌핑 광원으로 Q-스위치 Nd : YAG 레이저의 제 2 고조파를 사용하여 발진 중심파장 585 nm에서 최대 광 변환효율 $76\%$를 얻었다. 광안정성을 증가시키기 위해 단일항 에너지 상태의 산소 제거제인 DABCO(1,4-diazabicyclo [2,2,2]octane)를 주입하여 반복율 4 Hz, 출력에너지 250 mJ, 100,000번 이상의 펄스 출력을 얻었다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2007년도 Proceedings of The Convention
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• pp.93-114
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• 2007

Vaccinium uliginosum L. (VU) is a flowering plant in the genus Vaccinium has berry fruit. This study was performed to investigate the effect of water extract of Vaccinium uliginosum L. and fractions on inhibition of melanogenesis and wrinkle formation. One hundred grams of the Vaccinium uliginosum L. was extracted with 2,000 mL of water ($90^{\circ}C$, 16h, 2 times). The water extracts were lyophilized and stored at $4^{\circ}C$ until used. Vaccinium uliginosum L. extracts showed scavenger activities on DPPH radical, superoxide anion radical, hydroxyl radical, hydrogen peroxide and singlet oxygen radical, dose dependently. And VU extract and fractions reduced melanin contents on B16F10 melanoma and inhibited the expression of melanogenesis-related proteins, tyrosinase, tyrosinase-related protein (TRP-1) and dapachrometa utomerase (Dct, TRP-2). Moreover VU extract and fractions stimulated procollagen production and inhibited MMP-1 production in human fibroblast. And it decreased degree of wrinkle formation in hairless mouse skin that induced by DVB irradiation for 9 weeks. From the above results, it is possible that Vaccinium uliginosum L. may be developed to be the health functional food and functional cosmetics that have anti-melanogenesis and anti-wrinkle effect.

• Bulletin of the Korean Chemical Society
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• 제7권1호
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• pp.78-81
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• 1986

The photosensitized lysis of egg lecithin lipid membranes (liposomes) have been performed to UV-B light (270-320 nm) by L-tryptophan(L-Trp) and its peptide such as N-acetylphenylalanyl-L-tryptophan(NAPT) incorporated in the liposomes(ca. 0.1% by weight) or in the external buffer (0.1-0.3 mM). Requirement of oxygenation suggests that the lysis of liposomes is caused by the photosensitized oxidation of lipids. There was significant protection against lysis photosensitized by Trp in the external buffer by low concentration of ferricyanide (0.8 mM), but there was no effect on the lytic efficiency by $N_3^-$ which is singlet oxygen($^1O_2$) quencher, indicative of an electron transfer mechanism involved in the photosensitization. The small change of the lytic efficiency with increasing pH from 4 to 9 was interpreted by large target theory and subsequently indicates that superoxide($O_2^-$) may be an active intermediate for the oxidation. The efficiency of photosensitization of Trp was higher than that of NAPT under the same experimental condition. The weak lytic efficiency of liposomes photosensitized by NAPT was enhanced by incorporating NAPT in liposomes, but it was again quenched by ${\beta}$-carotene incorporated in the bilayer of liposomes. These results indicate that a portion of liposome lysis may be due to $^1O_2$ formation from the excited NAPT.

• Molecules and Cells
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• 제40권10호
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• pp.773-786
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• 2017

The loss of green coloration via chlorophyll (Chl) degradation typically occurs during leaf senescence. To date, many Chl catabolic enzymes have been identified and shown to interact with light harvesting complex II to form a Chl degradation complex in senescing chloroplasts; this complex might metabolically channel phototoxic Chl catabolic intermediates to prevent oxidative damage to cells. The Chl catabolic enzyme 7-hydroxymethyl Chl a reductase (HCAR) converts 7-hydroxymethyl Chl a (7-HMC a) to Chl a. The rice (Oryza sativa) genome contains a single HCAR homolog (OsHCAR), but its exact role remains unknown. Here, we show that an oshcar knockout mutant exhibits persistent green leaves during both dark-induced and natural senescence, and accumulates 7-HMC a and pheophorbide a (Pheo a) in green leaf blades. Interestingly, both rice and Arabidopsis hcar mutants exhibit severe cell death at the vegetative stage; this cell death largely occurs in a light intensity-dependent manner. In addition, 7-HMC a treatment led to the generation of singlet oxygen ($^1O_2$) in Arabidopsis and rice protoplasts in the light. Under herbicide-induced oxidative stress conditions, leaf necrosis was more severe in hcar plants than in wild type, and HCAR-overexpressing plants were more tolerant to reactive oxygen species than wild type. Therefore, in addition to functioning in the conversion of 7-HMC a to Chl a in senescent leaves, HCAR may play a critical role in protecting plants from high light-induced damage by preventing the accumulation of 7-HMC a and Pheo a in developing and mature leaves at the vegetative stage.

• 대한화학회지
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• 제29권4호
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• pp.426-436
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• 1985

몇가지 벤즈아닐리드류를 합성하여 광반응시킨 후 생성물을 분리하고 그 구조를 결정하였다. 벤즈아닐리드 자체는 광고리화 안되고 Photo-Fries형 생성물을 주었지만 2-chlorobenzaniline, 2-bromobenzanilide, 및 2-methoxybenzanilide는 질소기류하에서 광고리화하여 모두 phenanthridone을 생성하였다. 2-chloro-2-nitrobenzanilide는 광고리화되지 않았다. 니트로기가 페닐고리에 도입되니 들뜬상태의 에너지가 낮아서 광고리화 안되었다. 2,2'-dichlorobenzanilide가 광고리화 되어 8-chlorophenanthridone이 되는 것으로 보아 들뜬 부분은 카르보닐쪽의 페닐 부분인것을 알 수 있었다. 2'-위치에 Cl이 있는 경우에도 광고리화 되었다. 2-chlorobenzanilide나 2'-chlorobenzanilide에 대하여 몇가지 용매중에서 광고리화 양자수득률을 구하였는데, 2-chlorobenzaniline는 효과적으로, 2'-chlorobenzanilide는 비효과적으로 광고리화 되었다. 대체로 비극성용매중에서 또 저점성용매중에서 양자수득률이 좋았다. 2-chlorobenzaniline가 광고리화 될때 산소의 영향을 시험하였는데, 산소가 존재하는 데서 광고리화가 잘 안되었다. 따라서 이때 삼중상태가 상관하는 것을 알았으며 전이상태는 염소원자가 떨어져 나가고 이때 이웃 페닐고리가 도우는 메카니즘을 제안한다. 삼중상태의 2-chlorobenzaniline에서 카르보닐쪽의 페닐과 N-페닐의 도움으로 카르보닐쪽의 페닐에 붙은 염소원자 떨어져나가 중간체인 컨쥬게이션된 라디칼이 된다. 이 라디칼에서 수소원자가 떨어져 나가 phenanthridone이 되는데, 이 단계는 속도결정단계가 아니다. 왜냐하면, 이 광고리화 반응에서 수소대신 중수소를 치환해도 속도에는 영향이 없기 때문이다. 2-methoxybenzanilide가 광고리화 될때는 산소가 존재하니 반응이 빨라졌다. 이는 단일 상태가 상관하는 것 같으며 산소가 중간체를 산화하여 반응을 촉진하는 것 같다.

• Toxicological Research
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• 제33권1호
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• pp.43-48
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• 2017

With ultraviolet and visible light exposure, some pharmaceutical substances applied systemically or topically may cause phototoxic skin irritation. The major factor in phototoxicity is the generation of reactive oxygen species (ROS) such as singlet oxygen and superoxide anion that cause oxidative damage to DNA, lipids and proteins. Thus, measuring the generation of ROS can predict the phototoxic potential of a given substance indirectly. For this reason, a standard ROS assay (ROS assay) was developed and validated and provides an alternative method for phototoxicity evaluation. However, negative substances are over-predicted by the assay. Except for ultraviolet A (UVA), other UV ranges are not a major factor in causing phototoxicity and may lead to incorrect labeling of some non-phototoxic substances as being phototoxic in the ROS assay when using a solar simulator. A UVA stimulator is also widely used to evaluate phototoxicity in various test substances. Consequently, we identified the applicability of a UVA simulator to the ROS assay for photoreactivity. In this study, we tested 60 pharmaceutical substances including 50 phototoxins and 10 non-phototoxins to predict their phototoxic potential via the ROS assay with a UVA simulator. Following the ROS protocol, all test substances were dissolved in dimethyl sulfoxide or sodium phosphate buffer. The final concentration of the test solutions in the reaction mixture was 20 to $200{\mu}M$. The exposure was with $2.0{\sim}2.2mW/cm^2$ irradiance and optimization for a relevant dose of UVA was performed. The generation of ROS was compared before and after UVA exposure and was measured by a microplate spectrophotometer. Sensitivity and specificity values were 85.7% and 100.0% respectively, and the accuracy was 88.1%. From this analysis, the ROS assay with a UVA simulator is suitable for testing the photoreactivity and estimating the phototoxic potential of various test pharmaceutical substances.

• 한국식품영양과학회지
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• 제40권7호
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• pp.1053-1062
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• 2011

건강한 삶에 대한 현대인의 관심이 나날이 고조되고 있으며, 이에 따라 노화와 질병의 예방에 효과가 있는 항산화제의 연구가 활발히 이루어지고 있다. 특히 천연물이나 식품을 소재로 한 식이성 항산화제에 대한 연구는 꾸준히 증가하고 있는 추세이며, 천연물의 소재나 연구 분야의 폭이 매우 넓다. 따라서 다양한 식품 소재의 항산화능을 조사할 수 있는 측정법의 중요성이 크게 부각되고 있다. 현재 약용 식물이나 상용 채소, 과일을 시료로 하여 여러 가지 radical이나 target molecule에 대한 항산화능을 측정할 수 있는 다수의 생체외(in vitro) 측정법이 사용되고 있다. 이에 본 총설에서는 널리 사용되고 있는 항산화능 측정법의 특징을 분석하고 적용 사례를 검토하였다. 식품의 구성 성분은 단일물질이 아닌 복합체로 구성되어 있으므로 하나의 측정법으로 항산화능을 평가할 수가 없다. 그러므로 채소와 과일을 포함한 여러가지 식물성 식품 추출물의 항산화 활성을 정확히 측정하기 위해서는 각 실험에 사용되는 radical과 기전(mechanism), 실험 조건(온도, pH, 실험기기, 시료추출방법, 소요 시간, 비용) 등을 고려하여 적절히 수행되어야 할 것이다. 그러나 이들 측정법의 다양성과 사용 단위의 차이로 인해 각 시료의 항산화능을 객관적으로 비교하는데 어려움이 있는 실정이다. 따라서 향후 항산화능 측정법의 표준화와 표현 단위의 통일이 절실히 요구된다. 또한 in vitro에서 항산화능을 나타내는 채소, 과일 등의 생체 내 활성은 다양한 biomechanism과 polymerphism으로 인해 그 효과를 예측하기가 매우 어렵다. 따라서 in vitro에서의 항산화능 screening 결과를 바탕으로 in vivo에서의 그 효과를 검증하는 연구가 부가적으로 시행되어야 할 것이라 사료된다.

• 대한화학회지
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• 제42권2호
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• pp.203-208
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• 1998

할로겐화아렌이 다른 아렌에 etheral alkyl그룹에 의해 연결된 2-halobenzyl phenyl ether( 1과 2)를 합성하여 제조적인 광반응에서 생성물을 확인하고 또 속도론적 광반응에서 그 반응성을 시험하였다. 질소 기류 하에서 2-chlorobenzyl phenyl ether(1)은 페놀과 photo-Fries형 생성물이 나왔으며 Br치환 ether2는 페놀과 photo-Fries형 생성물 이외에 광고리화 및 광환원 생성물이 나왔다. 이것은 Cl이 benzyl고리에 강하게 붙어 있기 때문에 상대적으로 약한 $CH_{2}-O$결합의 파열이 생긴 결과이다. 또 Br유도체 2는 phenyl-bromine 사이의 결합이 phenyl-chlorine사이의 결합보다 약하니까 결국 그 결합의 광유발 파열이 $CH_{2}-O$결합 파열과 경쟁적으로 되었음이 분명하다. 산소 존재하에서 페놀의 생성은 큰 변화가 없고, photo-Fries형 생성물은 약간 감소하고 , 그리고 광고리화 생성물과 광환원 생성물은 큰 영향을 받는 것으로 보아 광고리화와 환원반응은 삼중상태가 상관하고 photo-fries형 반응은 단일상태와 삼중상태가 동시에 상관하는 것이다.