• YAKHAK HOEJI
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• v.47 no.3
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• pp.125-129
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• 2003

A series of 2-phenyl-5-nitrobenzimidazoles substituted at the para positon of the 2-phenyl moiety was synthesized ＆ evaluated for their activity to inhibit topoisomerase I. The structure-activity relationship study revealed that neither the electronic nor lipophilic parameters were related to the topoisomerase I inhibition. A strict spatial requirement seems to be present for retention of topoisomerase I inhibition activity.

• Journal of Microbiology and Biotechnology
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• v.8 no.1
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• pp.89-91
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• 1998

Cryptotanshinone induced topoisomerase I-mediated DNA cleavage in vitro as strongly as camptothecin, whereas topoisomerase II-mediated DNA cleavage was not induced by this agent. In DNA relaxation assay using calf thymus DNA topoisomerase I and supercoiled pBR322 DNA, cryptotanshinone inhibited topoisomerase I-mediated DNA relaxation in a dose-dependent manner. In unwinding assay, cryptotanshinone ($50{\mu}M$) did not shift the topoisomers of DNA. These results suggest that cryptotanshinone exerted a preferential inhibition of topoisomerase I without intercalating into DNA.

• YAKHAK HOEJI
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• v.44 no.4
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• pp.358-361
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• 2000

Parameter focusing on the DNA topoisomerase-Iinhibition with X-substituted phenyl substituents in 1-(2-furyl)-3-phenylpropenone derivatives as inhibition material were analyzed. From the basis on the results the inhibition on DNA topoisomerase I suggested that the inhibition activities of X-substituted phenyl substitutents would depend largely on the net charge of $\beta$-carbon atom, LUMO energy (e.v.) and STERIMOL parameter B$_{5}$ (width) of X. Among them, non-substituent (X=H), 1 and 2,2-dichloro substituent, 4 showed the highest DNA topoisomerase-I inhibition activity.y.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.1013-1016
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• 2002

Cyclo(L-prolyl-L-phenylalanyl) [cyclo(pro-phe)] was isolated from Streptomyces sp. AMLK-335 and found to inhibit DNA topoisomerase I activity. In a DNA relaxation assay using supercoiled pBR322 DNA, cyclo(pro-phe) inhibited the DNA topoisomerase activity more strongly than camptothecin, a known topoisomerase inhibitor. However, at a concentration of $10{\mu}M$, cyclo(pro-phe) produced a lower degree of DNA relaxation than camptothecin, therefore, the inhibition of topoisomerase I activity by cyclo(pro-phe) was also found to be dose dependent. Accordingly, the current results suggest that cyclo(pro-phe) may be a novel inhibitor of topoisomerase I.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.228-230
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• 2000

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.917-921
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• 2000

This study was carried out to investigate the effects on the mutagenicity and activity of DNA topoisomerase I of Sarcodon aspratus. Using an Ames mutagenicity test, which has been used to assess both mutagenic and antimutagenic effects of various molecules, it was observed that the methanol extracted fraction and other fractions (prepared in water or ethylacetate) of Sarcodon aspratus showed a significant antimutagenic activity against a mutagenecity induced by both a direct mutagenic agent such as MNNG and an indirect mutagenic agents such as B(a)P and AFB$_1$in Salmonella typhimurium TA98, TA100. Also, the extract and fractions of Sarcodon aspratus were found to have an inhibitory activity on the relaxation process of DNA topoisomerase I.

• Journal of Microbiology and Biotechnology
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• v.6 no.5
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• pp.366-367
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• 1996

Dibutyl phthalate induced topoisomerase Ⅰ mediated DNA relaxation comparable to that of camptothecin, and topoisomerase Ⅱ mediated DNA relaxation equipotent to that of 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA). The relaxation activities of dibutyl phthalate were dose-de-pendent and nearly as potent as those of camptothecin and m-AMSA.

• Archives of Pharmacal Research
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• v.22 no.5
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• pp.507-514
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• 1999

6-(1-azidoalkyl)-DMNQ derivatives compared to 2-(1-azidoalkyl)-DMNQ isomers, exhibited higher cytotoxic activity against L1210 mouse leukemia cells and stronger inhibition of DNA topoisomerase-I (TOPO-I), suggesting involvement of steric hindrance. However, similar antitumor activity against mice bearing S-180 cell was shown by 2-an 6-(1-azidoalkyl)-DMNQ derivatives.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.236.2-237
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• 2003

Several studies of terbenzimidazoles and bibenzimidazoles suggested that benzimidazoles, especially 5-nitro-2-(para-methoxyphenyl)benzimidazole. possess topoisomerase I inhibition activities. In order to find out the structure activity relationship of 5-nitro-2-phenyl-benzimidazoles. eight derivatives that are substituted at the para position of 2-phenyl moiety were selected, synthesized ＆ evaluated considering their electronic or lipophilic parameters. (omitted)

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1829-1832
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• 2005