• Environmental Mutagens and Carcinogens
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• v.19 no.2
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• pp.112-115
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• 1999

The action mechanism of the inhibitory effect of some natural products on the DNA strand break and DNA damage was investigated in vitro and in vivo. In the E. coli chromosomal DNA strand break experiment in vitro, three mushroom water extracts were effective on the DNA strand breaking by daunorubicin. Phellinus linteus water extract inactivated daunorubicin, a DNA strand breaking agent, but did not protect DNA from daunorubicin-induced DNA strand breaking. Agaricus blazei water extract inhibited DNA strand breaking action of daunorubicin not only by daunorubicin inactivation, but also by DNA protection from daunorubicin. An inhibitory effect of Ganoderma lucidum water extract on the DNA strand break was based on the DNA protection rather than daunorubicin inactivation. In vivo mutagen assay system (SOS-chromotest), among three mushroom water extracts Phellinus linteus water extract was the most effective one on the inhibition of DNA damage by 4-NQO. The results suggest that all three mushroom water extracts inhibit daunorubicin-induced DNA damage and in vivo DNA damaging action of 4-NQO by the reaction of mutagen inactivation or DNA protection from the mutagen.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.110-114
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• 1987

To correlate the conformational changes of DNA (Calf Thymus) with entrapment of DNA into liposomes, the effect of ions ($Na^+$, $Mg^{++}$on the entrapment of calf thymus DNA into liposomes was investigated. The effect of divalent ion ($Mg^{++}$ on the structural changes of DNA indicated by decrease of observed ellipticity at 274 nm and nonspecific binding of DNA to lipid bilayers was greater than monovalent ion ($\Na^+$). But the efficiency of DNA encapsulated was not altered. These results show that entrapment of DNA into liposomes is not due to nonspecific binding and structural changes because of electrostatic forces but to mechanical capture of DNA by the internal aqueous space of liposomes although divalent ion contributes large structural changes and more nonspecific association of DNA with liposomes due to strong charges.

• The Korea Journal of Herbology
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• v.26 no.4
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• pp.95-99
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• 2011

Objective : In this study, we demonstrate the protective effect on oxidative DNA damage of leaf extracts from Abeliophylli distichi Folium via its antioxidant activity for the establishment of new value for the herbal medicine. Methods : Abeliophylli distichi Folium leaves were extracted with hot-water and ethylacetate (EtOAC). The 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical and hydroxyl scavenging assay and $Fe^{2+}$ chelating assay were performed for antioxidative effect and ${\varphi}$X-174 RF I DNA cleavage assay and intracellular DNA damage assay were used for inhibitory effect of intracellular DNA damage. Results : In DPPH, Hydroxyl radical scavenging activity and $Fe^{2+}$ chelating activity of EtOAC extracts were 94.72%, 62.88%, 41.13%, and hot-water extracts were 88.86%, 56.7%, 37.4% at 200 ${\mu}g/m{\ell}$, respectively. Also, those extracts showed protective effect of DNA damage against the oxidative stress. Conclusion : These results indicated that the leaf extracts of Abeliophylli distichi Folium can be used as a natural antioxidants, which effectively inhibits the oxidative DNA damage.

• Journal of Radiation Protection and Research
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• v.42 no.1
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• pp.63-68
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• 2017

Background: The combined effect of the low energy electron (LEE) irradiation and $Cu^{2+}$ ion on DNA damage was investigated. Materials and Methods: Lyophilized pBR322 plasmid DNA films with various concentrations (1-15 mM) of $Cu^{2+}$ ion were independently irradiated by monochromatic LEEs with 5 eV. The types of DNA damage, single strand break (SSB) and double strand break (DSB), were separated and quantified by gel electrophoresis. Results and Discussion: Without electron irradiation, DNA damage was slightly increased with increasing Cu ion concentration via Fenton reaction. LEE-induced DNA damage, with no Cu ion, was only 6.6% via dissociative electron attachment (DEA) process. However, DNA damage was significantly increased through the combined effect of LEE-irradiation and Cu ion, except around 9 mM Cu ion. The possible pathways of DNA damage for each of these different cases were suggested. Conclusion: The combined effect of LEE-irradiation and Cu ion is likely to cause increasing dissociation after elevated transient negative ion state, resulting in the enhanced DNA damage. For the decrease of DNA damage at around 9-mM Cu ion, it is assumed to be related to the structural stabilization due to DNA inter- and intra-crosslinks via Cu ion.

• Korean Journal of Microbiology
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• v.27 no.1
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• pp.16-20
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• 1989

The effect of E. coli plasmid DNA sequences contained by chimeric vectors on plasmid replication was investigated. We constructed YRp7- or 2.$\mu$m circle-based plasmids containing E. coli plasmid DNA sequences and those not containing it. By examining their maintenance in yeast, we showed that plasmid without E. coli plasmid DNA sdquences was nore stable and presented higher copy number, and espressed higher level of hepatitis B viral surface antigen as a foreign gene. This result suggested that E. coli plasmid DNA sequences within chimeric plasmid somehow inhibited plasmid replication in yeast.

• BMB Reports
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• v.44 no.5
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• pp.341-346
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• 2011

The single-stranded DNA binding activity of the Escherichia coli RecA protein is crucial for homologous recombination to occur. This and other biochemical activities of ssDNA binding proteins may be affected by various factors. In this study, we analyzed the effect of $CaCl_2$, NaCl and $NH_4NO_3$ salts in combination with the pH and nucleotide cofactor effect on the ssDNA-binding activity of RecA. The studies revealed that, in addition to the inhibitory effect, these salts exert also a stimulatory effect on RecA. These effects occur only under very strict conditions, and the presence or absence and the type of nucleotide cofactor play here a major role. It was observed that in contrast to ATP, ATP${\gamma}$S prevented the inhibitory effect of NaCl and $NH_4NO_3$, even at very high salt concentration. These results indicate that ATP${\gamma}$S most likely stabilizes the structure of RecA required for DNA binding, making it resistant to high salt concentrations.

• Environmental Mutagens and Carcinogens
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• v.11 no.2
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• pp.107-117
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• 1991

The effect of 3-aminobenzamide (3AB), an inhibitor of poly (ADP-ribose) polymerase, on ethyl methanesulfonate (EMS)-or bleomycin (BLM)-induced DNA repair synthesis and chromosome aberrations was examined during the cell cycle of Chinese hamster ovary (CHO)-K$_1$ cells. The synchronized cells were obtained by using thymidine double block method and mitotic selection method. Three assays were employed in this study: unscheduled DNA synthesis, alkaline elution and chromosome aberrations. 3AB alone did not induce DNA repair and chromosome aberrations in all phases. The post-treatment with 3AB inhibited DNA repair synthesis induced by EMS or BLM in G$_2$ phase, whereas 3AB did not affect chromosome aberrations induced by EMS or BLM in all phases. These results suggest that 3AB aggravates the cell cycle disturbance which occur after DNA damage, and leads to an accumulation of cells at G$_2$ phase, and inhibits DNA repair synthesis, while the effect 3AB on chromosome aberrations may need reevaluated.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.46-51
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• 1993

The inactivating effect of iron(II)-ascorbate complex (Fe-Asc) on various phages was previously reported. This paper describes the molecular target in the phage virion attacked by Fe-Asc. The effect of Fe-Asc on protein was investigated with bovine serum albumin and the structural protein of phage J1. There were no differences in the SDS-polyacrylamide gel electrophoresis (patterns of these two proteins when either they were treated) with Fe-Asc or not. Also, there were no changes in the amino acid composition and ultraviolet spectrum of the proteins. The effects of Fe-Asc on DNA was investigated with pUC18 DNA, M13mpB DNA and ${\lambda}$ DNA as well as DNA from phage J1. Fe-Asc caused initially nicking of the subsequently form of pUC18 DNA to yield the open circular form and then subsequently the linear form. Strand breaks were also confirmed with M13mp8 DNA and ${\lambda}$ DNA as well as J1 DNA. The results indicate that the strand breaks in phage DNA could be responsible for the inactivation of phages by Fe-Asc.

• The Korea Journal of Herbology
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• v.33 no.5
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• pp.105-110
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• 2018

Objectives : We tried to observe the fluorescence anisotropy and intensity of ethidium ion in the intercalating binding interaction between DNA and ethidium ions in the presence of berberine, and then tried to explain the effect of berberine on the intercalating interaction of ethidium ion with DNA. Methods : DNA(calf thymus DNA), berberine and ethidium bromide(EtBr) were purchased from Sigma-Aldrich Co. Proper amount of each compound was dissolved in 20 mM sodium phosphate buffer(pH 7.0) containing 100 mM of NaCl to prepare stock solutions. Collections of the fluorescence anisotropy and intensity data were performed on JASCO FP-8300 spectrofluorometer equipped with a polarizer and a Peltier temperature controller. The excitation of ethidium ion was done at 550 nm and the emission data were collected at 600 nm. For Stern-Volmer plot, the fluorescence data were collected at $18^{\circ}C$ and $30^{\circ}C$. Results : According to the results of this research, the weak competitive binding pattern between ethidium ion and berberine appeared in binding with DNA at low ratio of DNA to ethidium ion. But at high ratio of DNA to ethidium ion, this weak competition disappeared. Instead, berberine might bind to DNA by intercalating way. In other words, berberine could de-intercalate ethidium ion from DNA at low concentration of DNA relative to ethidium ion, but could not at high concentration of DNA relative to ethidium ion. In addition, the mechanism of fluorescence quenching of ethidium ion could also proceed differently, depending on the ratio of the amount of DNA to that of ethidium ion. Conclusions : The effect of berberine on the DNA-ethidium ion intercalating interaction could work differently, depending on the relative ratio of the amount of DNA to that of ethidium ion. This study also showed that fluorescence anisotropy analysis is very useful method to obtain detailed information for investigation of the complex binding interactions. In order to fully understand the mechanism of action of the pharmacological effect by berberine, studies on the effect of berberine on the action of proteins such as various enzymes closely related to berberine-induced medicinal effects should be continued.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.533-538
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• 1985

To investigate the importance of the hydrophobic interaction in the spermine-induced collapse of DNA to a compact structure, the effect of urea on the anomalous absorbance-temperature profile of calf thymus DNA has been investigated. With the increase of the urea concentration, the trough phase of the anomalous absorbance-temperature profile was eliminated eventually. The cooperativity, enthalpy, and the midpoint of the transition to the trough region are more sensitive to urea than those of the Tm-region transition. The present data of the adverse effect of urea, a hydrophobic environmental reagent, on the thermal stabilization of the condensed state of DNA, suggest that hydrophobic interaction may play an important role in the stabilization of the tertiary structure of the collapsed state of DNA.