• Journal of Photoscience
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• 제11권2호
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• pp.77-81
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• 2004

Deoxygadusol (DO) and structurally related mycosporine-like amino acids, i.e. mycosporine glycine (MO) and mycosporine taurine (MT), were isolated from phytoplankton Prorocentrum micans and studied for the reactivity toward singlet oxygen. These water-soluble compounds with a cyclohexenone chromophore were all shown to be highly effective in quenching singlet oxygen ($^1$ $O_2$), with the efficiencies being significantly larger compared with histidine, a well-known $^1$ $O_2$ quencher. The $^1$ $O_2$ reaction rate constant ( $k_{Q}$) of DG was determined to be 5.4 ${\times}$ 10$^{7}$ $M^{-1}$ $s^{-1}$ by a steady state method based on competitive inhibition of rubrene oxidation. The feasibility of this method was confirmed by estimating the $k_{Q}$ values for MG and two other quenchers, furfuryl alcohol and 1,4-diazabicyclo [2,2,2]octane, and comparing with those values determined by the time-resolved $^1$ $O_2$ decay method in the previous work.ork.

• Journal of Ginseng Research
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• 제13권1호
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• pp.98-104
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• 1989

In order to determine the specific active oxygen species directly related to chlorophyll bleaching in the leaf-burning disease, we investigated the effects of singlet oxygen (1O2), superoxide radical (O2-), and hydrogen Peroxide (H2O2) on isolated chloroplast suspension and leaf discs from Panax ginseng C.A. Meyer. When the singlet oxygen was added to the chloroplast suspension, the chlorophyll and carotenoid contents were decreased by more than 809), similar to treatment with high light intensity (100 KLux). We assumed that the conversion of dioxygen (O2) produced either in photolysis or in breakdown of hydrogen peroxide to singlet oxygen resulted from photorespiration. On the basis of these experiments , :he inhibitory effects of active oxygen scavengers propylgallic acid (PGA), 2,5-ditetrabutyl hydroquinon (DBH), sodium pyrosulfate (SPS), and ascorbic acid (ABS) were examined. In chloroplast suspension all four scavengers inhibited chlorophyll bleaching by more than 75fl , and in the leaf discs the inhibition rates of SPS, PGA and ABS were 46%, 51%, and 96% respectively.

• Journal of Photoscience
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• 제9권2호
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• pp.63-65
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• 2002

This report concerns a putative role of mycosporine-like amino acids (MAA) as natural scavengers of singlet oxygen ($^1$O$_2$) in marine organisms. MAA prepared from the ascidian Lissoclinum patella were found to protect biological systems against detrimental effects of the type II photosensitization in vitro. L. patella MAA were resolved into five components, and the relative $^1$0$_2$ quenching efficiencies were measured for three major components in aqueous media. It turned out that they were all effective in scavenging $^1$0$_2$, to different degrees albeit. The results suggest that physiological relevance of MAA in marine organisms may be found in a 'built-in' defense against photooxidative effects of sunlight.

• Biomaterials and Biomechanics in Bioengineering
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• 제1권2호
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• pp.73-79
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• 2014

Covalent attachment of 1, 4-dimethylnaphthalene (DMN) based endoperoxide forming subunits to a polyvinyl butyral (PVB) backbone has been achieved. The functionalized polymer materials prepared and characterized here can serve as biocompatible carrier systems for studying cellular uptake, intermediate storage and delayed release of singlet oxygen, which opens up new doors for optimizing a variety of medical applications of photogenerated DMN-endoperoxides such as antiviral, antibacterial, antiplasmodial and antitumor activity.

• 대한화학회지
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• 제23권6호
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• pp.396-401
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• 1979

빌리루빈과 옥소디피로메텐들의 광산소화 분해 반응속도를 측정하던중 옥소디피로메텐들이 디페닐이소벤조퓨란보다 좋은 단일상태 산소의 트랩제라는 사실을 알게 되었다. 빌리루빈과 그 모델물질인 옥소디피로메텐들은 아주 빠른 속도로 단일상태 산소와 반응하거나 괜칭하였다. 한 새로운 옥소디피로메텐이 간단한 방법으로 합성되었다.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.281-285
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• 2002

The photophysical properties and the singlet oxygen generation efficiencies of meso-tetraphenyl-trithiasapphyrin $(S_3TPS)$ and meso-tetmkis(p-methoxy phenyl)-trithiasapphy rin ((p-MeO)-$S_3TPS$) have been investigated, utilizing steady-state and time-resolved spectroscopic methods to elucidate the possibility of their use as photosensitizers for photodynamic therapy (PDT). The observed photophysical properties were compared with those of other porphyrin-like photosensitizers in geometrical and electronic structural aspects, such as extended ${\pi}$ conjugation, structural distortion, and internal heavy atoms. The steady-state electronic absorption and fluorescence spectra were both red-shifted due to the extended ${\pi}$-conjugation. The fluorescence quantum yields were measured as very small. Even though intersystem crossing rates were expected to increase due to the increment of spin orbital coupling, the triplet quantum yields were measured as less than 0.15. Such characteristics can be ascribed to the more enhanced internal conversion rates compared with the intersystem crossing rates. Furthermore, the triplet state lifetimes were shortened to -1.0 ${\mu}s$ as expected. Therefore, the singlet oxygen quantum yields were estimated to be near zero due to the fast triplet state decay rates and the inefficient energy transfer to the oxygen molecule as well as the low triplet quantum yields. The low efficiencies of energy transfer to the oxygen molecule can be attributed to the lower oxidation potential and/or the energetically low lying triplet state. Such photophysical factors should be carefully evaluated as potential photosensitizers that have extended ${\pi}$-conjugation and heavy core atoms synthesized for red-shifted absorption and high triplet state quantum yields.

• Food Science and Biotechnology
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• 제18권2호
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• pp.526-532
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• 2009

Quenching mechanisms and kinetics of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol in photosensitized oxidation of lard were studied. Lard at 0.03, 0.07, 0.11, and 0.3 M in methylene chloride containing $4.4{\times}10^{-6}\;M$ chlorophyll and 0, 0.1, 0.3, and 0.6 mM $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol were stored under light for 4 hr, respectively. Oxidation was determined by headspace oxygen and peroxide value. Tocopherols prevented the photosensitized oxidation of lard (p<0.05). Steady state kinetic study showed that $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol prevented the photosensitized oxidation of lard by quenching singlet oxygen. Singlet oxygen quenching rates of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol by headspace oxygen depletion were 1.86, 2.39, 2.47, and $2.11{\times}10^7/M/sec$, respectively. The quenching rates of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol by peroxide value were 1.42, 1.11, 0.97, and $0.42{\times}10^7/M/sec$, respectively. The quenching rates of tocopherols were slightly different depending on the measurements of oxidation.

• Journal of Photoscience
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• 제9권2호
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• pp.174-177
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• 2002

Sugar-linked porphyrin and chlorin compounds have been synthesized. Phototoxicity of these compounds against the HeLa cell line was also examined. For the porphyrin derivatives, the higher activity was observed for a derivative having four OH-protected sugar moieties. For the chlorin derivatives, OH-unprotected free-base derivatives were generally effective. Singlet oxygen producing ability were examined to evaluate the activity on photodynamic therapy of the compounds.

• 한국식품과학회지
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• 제33권1호
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• pp.1-6
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• 2001

수용성 단백질을 첨가한 유화물을 형광 조명하에서 $5^{\circ}C$에서 8일간 저장하였을 때 POV(Peroxide value) 값의 변화를 측정한 결과 저장 초기에 유의적인 증가를 나타냈고 TBA(Thiobarbituric acid) 값의 변화에서도 저장 4일까지 상당량의 카르보닐 화합물이 발생하는 것으로 나타나서 일반적인 지방의 자동산화와는 다른 양상을 보였고 대두유 같은 유지에서 저장 초기에 나타나는 변향의 발생과 비슷한 결과를 나타냈다. 이러한 원인으로는 육색소인 myoglobin에 의한 산화로 사료되며 superoxide anion보다는 일중항 산소에 의한 산화일 가능성이 높은 것으로 사료된다. 빛을 차단하였을 때에도 전체적인 양상을 비슷했지만 산화생성물의 생성량이 빛을 쪼였을 때보다 약간 적었고 일중항 산소의 효과도 두드러지지 않았으며 유화물 제조과정 중에 생성된 일중항 산소가 저장 초기의 변향에 관여하였을 것으로 추정된다. 수용성 단백질을 첨가하지 않은 경우에는 과산화물의 생성량이 지속적인 증가를 나타내서 수용성 단백질 처리구와 차이를 보였는데 과산화물의 분해속도가 수용성 단백질 처리구에 비해 작은 것으로 사료되며 특히 저장 4일 이후에 카르보닐 화합물의 생성속도가 줄어드는 것으로 나타났다. 저장 중에 일중항 산소의 발생 가능성이 있는 것으로 나타났으나 대두유의 탈색과정에서 잔존하였을 식물성 감광체가 원인일 것으로 추정된다. 빛을 차단하였을 때에는 저장 초기의 산화생성물 발생량이 빛을 쪼였을 때보다 미미했고 소거제 처리에 대한 효과도 드러나지 않아서 지질의 산화에 대한 빛의 촉진효과를 나타내는 결과라고 사료된다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.3102-3102
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• 2001

Constituents of several .representative seaweeds, such as wakame Undaria pinnatifida; hijikia Hizikia fusifome; and kombu Laminaria japonica, were found to have fairly large reaction rates determined by quenching experiments of emission spectra in the near-infrared region (1max: 1270 nm) from singlet oxygen (102). Emission spectra of singlet oxygen generated from an aqueous solution of Rose Bengal under irradiation with a green laser (330 nm) were measured by a near-infrared (NIR) emission spectrometer constructed in our laboratory. The quenching experiments were as follows: Intensities of emission spectra were measured in the absence (I0) and in the presence of the seaweed constituents (I): Ratios of I0/I were plotted against every concentration of the quenchers (Stern-Volmer plots) which gives a straight line. The slope of each line gives a kqt value which gives a quenching constant kq value (an antioxidative constant against singlet oxygen) when the t value (half-life time of singlet oxygen in the solvent used) was given. The determined reaction rates are between 103-105 (g/l)-ls-1; the larger ones are as large as that of ascorbic acid, 8.4 ${\times}$ 104 (g/1)-ls-1. Most of these seaweed constituents also showed antioxidative activity against auto-oxidation and superoxide as well as their immunological enhancing activity. These results suggest a possibility that dietary fibers which are supposed to prevent the large-intestine cancer by their physical properties may prevent the cancer, at least in parts, by their chemical, antioxidative activity.