• Journal of Applied Biological Chemistry
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• 제43권3호
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• pp.156-160
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• 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.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제45차 학술발표회
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• pp.41-41
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• 2011

The aims of this study were to examine the efficacy of phytochemicals of Rumex crispus as anti-oxidant and anti-browning agent. The bioactive properties of Rumex crispus as natural colorants were studied by total phenolic contents, DPPH radical scavenging, ABTS radical scavenging,lipid peroxidation, cell viability, singlet oxygen quenching and photoprotection effect. Among all of the results ($IC_{50}$: the concentration of various extracts required to exert 50% reducing effect), the higher activity of the extract was found in the ethyl acetate and butanol extracts. Anti-browning activity was evaluated by monitoring the change $L^*$, $a^*$, $b^*$ values and total color differences(${\Delta}E$). It was found that ethyl acetate and butanol extracts effectively inhibited browning in apple juice at a concentration below 0.3 mg/ml. Rumex crispus extracts used natural colorants could be of good resources as anti-oxidant and anti-browning agents. The results suggest that our study may contribute to the development of natural and functional materials with potential application to reduce oxidative damage.

• Journal of Photoscience
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• 제9권3호
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• pp.41-43
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• 2002

PDT-mediated cyototoxicity basically depends on the penetrated light-dose into the tumor tissue. This limits the efficiency of PDT to the superficial tumor region typically less than 1 cm. The localized photochemical generation of reactive oxygen species, including singlet oxygen is known to increase expression of assortment of early response genes including heat shock protein. In order to increase PDT cytotoxicity in the treatment of solid tumor, it is desirable to combine PDT with other therapeutic effects. In this preliminary study we evaluated enhanced cytotoxicity from the PDT-mediated expression of thymidine kinase in a transfected tumor cell line. Two types of photo sensitizers, a hematoporphyrin derivative(Photogem, Russia) and aluminium sulphonated phthalocyanine(Photosense, Russia) were used to evaluate the overexpression of hsp-70 in PDT-treated cell. Transient increase of hsp-70 was observed at 6-8 hrs later following irradiation in the photosense-treated cell whereas it was not observed in Photogem-treated cell. In the presence of ganciclovia, transfected cell showed a 17％ increase in the cytotoxicity compared to the PDT only cell.

• 한국식품영양과학회지
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• 제19권6호
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• pp.565-570
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• 1990

Plasmid pBR322 DNA와 Maillard 반응생성물중 카르보닐화합물인 glyoxal, methyl glyoxal, dihydroxyacetone, diacetyl, glyceraldehyde, glycolaldehyde 및 furfural 등과 각각 37$^{\circ}C$에서 반응시켰을때 나타나는 DNA 손상능과 활성산소소거제에 의한 DNA손상억제 작용을 agarose gel 전기영동을 통하여 살펴보았다. 카르보닐화합물을 37$^{\circ}C$에서 6시간 동안 반응시켰을 경우, furfural을 제외한 모든 카르보닐화합물에 DNA 손상능이 나타났는데, 그 중에서도 glyoxal, methyl glyoxal 및 dihyd-roxyacetone 이 diacetyl, glyceraldehyde 및 glyco-laldehyde보다 BNA의 손상능이 크게 나타났다. 또한 plasmid DNA와 카르보닐화합물의 반응계에 각종 활성산소소거제의 첨가를 통하여 이들 카르보닐화합물에 대한 DNA의 손상을 검토한 결과 일중항산소, 과산화수소, superoxide anion 등이 주요원인물질로 밝혀졌으며, hydroxyl radical은 그 작용이 미약하거나 거의 영향을 나타내지 않는 것으로 나타났다.

• 생체재료학회지
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• 제22권4호
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• pp.303-310
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• 2018

Background: Photodynamic therapy (PDT) is photo-treatment of malignant or benign diseases using photosensitizing agents, light, and oxygen which generates cytotoxic reactive oxygens and induces tumour regressions. Several photodynamic treatments have been extensively studied and the photosensitizers (PS) are key to their biological efficacy, while laser and oxygen allow to appropriate and flexible delivery for treatment of diseases. Introduction: In presence of oxygen and the specific light triggering, PS is activated from its ground state into an excited singlet state, generates reactive oxygen species (ROS) and induces apoptosis of cancer tissues. Those PS can be divided by its specific efficiency of ROS generation, absorption wavelength and chemical structure. Main body: Up to dates, several PS were approved for clinical applications or under clinical trials. $Photofrin^{(R)}$ is the first clinically approved photosensitizer for the treatment of cancer. The second generation of PS, Porfimer sodium ($Photofrin^{(R)}$), Temoporfin ($Foscan^{(R)}$), Motexafin lutetium, Palladium bacteriopheophorbide, $Purlytin^{(R)}$, Verteporfin ($Visudyne{(R)}$), Talaporfin ($Laserphyrin^{(R)}$) are clinically approved or under-clinical trials. Now, third generation of PS, which can dramatically improve cancer-targeting efficiency by chemical modification, nano-delivery system or antibody conjugation, are extensively studied for clinical development. Conclusion: Here, we discuss up-to-date information on FDA-approved photodynamic agents, the clinical benefits of these agents. However, PDT is still dearth for the treatment of diseases in specifically deep tissue cancer. Next generation PS will be addressed in the future for PDT. We also provide clinical unmet need for the design of new photosensitizers.

• Journal of Photoscience
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• 제7권4호
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• pp.135-138
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• 2000

The photochemical behavior of haloarene tethered to alkyl by an amide bone(1,2) was studied. The photoreaction of N-(2-bromophenyl) cyclohexanecarboxamide (1b) in basic medium afforded intramolecular substitute product, 2-cyclohexylbenzoxazole (4) and reduced product, N-phenylcyclohexanecarboxamide (5)in 33 and 26% yield, respectively. The chloro analogue(1a) produced photo-Fries type and photosubstituted products(6,4), whereas the iodo analogue produced extensively photoreduced product 5. N-(2-bromophenyl)-N-methylcyclohexanecarboxamide (2), which can not exist as imidol form, produced a photocyclized product, supporting as imidol form is involved in the intramolecular photosubstitution. since the photoreduction but the photosubstitution reaction is retarded by the presence of oxygen, a trilpet state for the photoreduction and a singlet state for the photosubstitution are involved.

• Journal of Photoscience
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• 제10권1호
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• pp.1-7
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• 2003

The results of recent work on the dye-sensitized photooxygenation of sulfides is discussed. In the case of dialkyl sulfides, the weakly bonded adduct initially formed with singlet oxygen (the persulfoxide) decays unproductively unless protonation by an acid (an alcohol or a carboxylic acid) facilitates its conversion to the sulfoxide. The effect is proportional to the strength of the acid (eg., less than 0.1 % chloroacetic acid in benzene is sufficient for maximal efficiency) and corresponds to general acid catalysis, suggesting that protonation of the persulfoxide occurs. On the other hand, with sulfides possessing an activated hydrogen in ${\alpha}$ position (eg., benzyl and allyl sulfides), hydrogen transfer becomes an efficient process in aprotic media and yields a S-hydroperoxysulfoniumm ylide, possibly arising from a conformation of the persulfoxide that is different from the one protonated in the presence of acids. Calculations on some substituted sulfides support this hypothesis. This process, which leads to C-S bond fragmentation with formation of an aldehyde, may be viewed as a general method for the preparation of aryl and heteroaryl aldehydes. In this effort, mechanistic studies offered new hints on the structure of the intermediate persulfoxide.

• Journal of Photoscience
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• 제10권1호
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• pp.127-148
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• 2003

Zeolite is a porous highly interactive matrix. Zeolitic cations help to generate triplets from molecules that possess poor intersystem crossing efficiency. Certain zeolites act as electron acceptors and thus can spontaneously generate radical cations. Zeolites also act as proton donors and thus yield carbocations without any additional reagents. These reactive species, radical cations and carbocations, have long lifetime within a zeolite and thus lend themselves to be handled as ‘regular’ chemicals. Internal structure of zeolites is studded with cations, the counter-ions of the anionic framework. The internal constrained structure and the cations serve as handles for chemists to control the behavior of guest molecules included within zeolites.

• 한국식품영양학회:학술대회논문집
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• 한국식품영양학회 2000년도 춘계학술심포지엄
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• pp.13-20
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• 2000

Melatonin, a chemical mediator produced in the mammalian pineal gland and several other organ, is a ubiquitously acting antioxidant. It has been shown to scavenge the hydroxyl radical (ㆍOH), singlet oxygen ($^1$O$_2$) and the peroxynitrite anion (ONOO-). In addition, melatonin reportedly stimulates a number of antioxidative enzymes including glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase. Antioxidative effect of melatonin in pharmacological and physiological level was investigated using hepatocarcinogen 2-nitropropane (2-NP) and pinealectornized (Px) rats, respectively. Lipid peroxidation (LPO) as indicated by malondialdehyde and 4-hydroxyalkenals and DNA damage as indicated by 8-hydroxydeoxyguanosine (8-OH-dG) induced by 2-NP were prevented by melatonin. The degree of LPO and DNA damage in Px rats were higher than those of intact old and young ones suggesting the removal of pineal gland resulted in higher accumulation of oxidative damage.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2315-2318
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• 2007

Epinephrine was determined using a lab-made chemiluminescence (CL) system with air pump. Luminolsodium IO4? chemiluminescence system was employed to produce the luminescence of epinephrine. In the reaction, epinephrine was oxidized to produce superoxide or singlet oxygen by periodate in alkaline solution, which enhanced CL of luminol. For optimization, various buffers, such as phosphate, borate, and tris, were studied in this experiment. Compared to NaOH, the phosphate and borate buffer showed better reproducibility with similar sensitivity. Small amount of sample, 22 μL, was required for a measurement. The limit of quantification for epinephrine was obtained to be ~10?9 g/mL after optimization.