• Natural Product Sciences
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• v.8 no.4
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• pp.162-164
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• 2002

The methanol extracts of 42 Korean indigenous plants were evaluated for the DNA strand-scission activity. As a result, the 17 extracts were found to be active in the criteria of $IC_{50}$}<$25\;{\mu}g/ml$. Among others, the MeOH extracts of Caesalpinia sappan and Mucuna birdwoodiana showed the most potent DNA strand-scission activity with $IC_{50}$ values of 5.9 and $4.9\;{\mu}g/ml$, respectively. Therefore, the partition and fractionation for C. sappan were performed and tested in the DNA strand-scission assay system for further bioassay-guided fractionation.

• Journal of Applied Biological Chemistry
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• v.43 no.3
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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.

• Natural Product Sciences
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• v.9 no.2
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• pp.105-108
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• 2003

During our research program to find DNA strand-scission agents from higher plants, the MeOH extracts of the stems of Mucuna birdwoodiana Tutcher. (Leguminosae) exhibited the most potent activity with an $IC_{50}$ value of $4.9\;{\mu}g/ml$. Thus, detailed laboratory investigation was performed, and led to the isolation of known compounds, $({\pm})$-catechin (1) and (-)-epicatechin(2) as active principles. Compounds 1 and 2 showed significant activity of DNA strand-scission with $IC_{50}$ values of 10.8 and $7.5\;{\mu}g/ml$, respectively (positive control, bleomycin: $IC_{50}\;3.3\;{\mu}g/ml$.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.307-312
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• 1997

As a preliminary experiment to investigate the antitumor activity of colored rice in vivo, inhibitory effect of solvent extracts from colored rice brans on DNA strand scission and tumor promotion was examined in vitro. Two colored rice cultivars, Sanghaehyanghyulla and Suwon 415 were compared with Chuchung as a control. The antimutagenic activity of each rice cultivars increased in order of Chuchung

• Archives of Pharmacal Research
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• v.26 no.2
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• pp.147-150
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• 2003

To find anticancer agents from higher plants, DNA strand-scission assay method was employed for bioassay-guided fractionation as well as for screening the crude extracts. During the screening, an ethyl acetate extracts of the heartwood of Caesalpinia sappan L. (Leguminosae) exhibited potent DNA strand-scission activity. Therefore, the ethyl acetate extracts of the dried heartwood of C. sappan was subjected to the bioassay-guided fractionation, which led to the isolation of a known compound, brazilin (1) as the active constituent. In addition, caesalpine J (2) was also isolated as an inactive constituent.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.964-969
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• 1998

To investigated the anticarcinogenic activity of 70% ethanol extracts from various cereal in vitro, antimutagenic activity, inhibitory effect of DNA strand scission and tumor promotion were examined. The antimutagenic activity of the beans such as black bean and small red bean was generally higher than that of cereals examined. However inhibitory activity of 70% ethanolic extracts against DNA strand scission induced mitomycin C showed that millet, job's tear, black bean and soy bean among cereals and beans tested in this study inhibited effectively the DNA strand scission. Antioxidative activity of some cereal extracts determined by using linoleic acid model system showed that Job's tear, millet and black bean were higher antioxidative activity than other cereals and beans. Conventional short-term antipromoter assay system using activation of Epstein Barr virus (EBV) clearly demonstrated that sorghum, buckwheat, black bean and small red bean have inhibitory effects on promotion in cellular carcinogenesis.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.255.1-255.1
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• 2003

During our research program to find DNA strand-scission agents from higher plants, the MeOH extracts of the wood bark of Mucunar birdwoodiana Tutcher. (Leguminosae) exhibited the most potent activity with an IC$\^$50/ value of 4.9 $\mu\textrm{g}$/$m\ell$. Thus, detailed laboratory investigation was performed, and led to the isolation of the known compounds, catechin(1) and epicatechin(2) as the active principles. (omitted)

• Archives of Pharmacal Research
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• v.26 no.2
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• pp.124-127
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• 2003

Four known prenylated flavonoids, artonins E (1) and O (2), artobiloxanthone (3), and cycloartobiloxanthone (4), were isolated from the stem bark of Artocarpus kemando by bioassayguided fractionation using the DNA strand-scission and the KB cytotoxicity assays as monitors. Compounds 1 and 3 exhibited strong DNA strand-scission activity, and all four compounds were found to be cytotoxic.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.222-227
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• 2005

To evaluate the antimutagenic activity of the specialty rices, a giant embryonic rice and a pigmented rice, we measured the inhibitory effect on the chemically induced mutagenesis in E. coli and V79 cultured cell system, as well as on DNA strand scission induced by oxidative damages in vitro. When the inhibitory activity to mitomycin C-induced mutagenesis using SOS chromotest in E. coli cell was measured, the activities decreased in the following order: germinated pigmented rice (40.4%) > germinated giant embryonic rice (37.1%) > pigmented rice (35.5%) > germinated brown rice (15.7%) > giant embryonic rice (14.0%) > brown rice (0.8%). The activities for inhibiting mitomycin C-induced DNA strand scission decreased in the order of pigmented rice > giant embryonic rice > germinated pigmented rice > germinated brown rice > brown rice > germinated giant embryonic rice. We also determined antimutagenic activities of the specialty rices using the suppressing effect on 6-TG resistant colony formation by 4-NQO in V79 cells as a mutagenicity index. The order of antimutagenicity was germinated giant embryonic rice (53.2%) > pigmented rice (40.0%) > brown rice (21.2%) > germinated brown rice (14.4%) > giant embryonic rice (0.23%); in contrast, germinated pigmented rice showed promoting effect on 4-NQO-induced mutagenesis.

• Biomedical Science Letters
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• v.15 no.1
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• pp.1-8
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• 2009

Human genomic DNA is continuously attacked by oxygen radicals originated from cellular metabolic processes and numerous environmental carcinogens. 2-deoxyribonolactone (dL) is a major type of oxidized abasic (AP) lesion implicated in DNA strand scission, mutagenesis, and formation of covalent DNA-protein crosslink (DPC) with DNA polymerase (Pol) ${\beta}$. We show here that human DNA polymerase (Pol)${\iota}$ and mitochondrial $Pol{\gamma}$ give rise to stable DNA-protein crosslink (DPC) formation that is specifically mediated by dL lesion. $Pol{\gamma}$ mediates DPC formation at the incised dL residue by its 5'-deoxyribose-5-phosphate (dRP) lyase activity, while $Pol{\gamma}$ cross links with dL thorough its intrinsic dRP lyase and AP lyase activities. Reactivity in forming dL-mediated DPC was significantly higher with $Pol{\gamma}$ than with $Pol{\iota}$. DPC formation by $Pol{\gamma}$, however, can be reduced by an accessory factor of $Pol{\gamma}$ holoenzyme that may attenuate deleterious effects of crosslink adducts on mitochondrial DNA. Comparative kinetic analysis of DPC formation showed that the rate of DPC formation with either $Pol{\iota}$ or $Pol{\gamma}$ was lower than that with $Pol{\beta}$. These results revealed that the activity of catalytic lyase in DNA polymerases determine the efficiency of DPC formation with dL damages. Irreversible crosslink formation of such DNA polymerases by dL lesions may result in a prolonged strand scission and a suicide of DNA repair proteins, both of which could pose a threat to the genetic and structural integrity of DNA.