• Archives of Pharmacal Research
• /
• 제29권7호
• /
• pp.570-576
• /
• 2006

Phytoestrogen biochanin A is an isoflavone derivative isolated from red clover Trifolium pratense with anticarcinogenic properties. This study examined the action of biochanin A with the carcinogen activation pathway that is mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 breast carcinoma cells. Treating the cells with biochanin A alone caused the accumulation of CYP1A1 mRNA and an increase in CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity in a dose dependent manner. A concomitant treatment with 7,12-dimethylbenz[a]anthracene (DMBA) and biochanin A markedly reduced the DMBA-inducible EROD activity and CYP1A1 mRNA level. In addition, the biochanin A treatment alone activated the DNA-binding capacity of the AhR for the dioxin-response element (DRE) of CYP1A1, as measured by the electrophoretic-mobility shift assay (EMSA). EMSA revealed that biochanin A reduced the level of the DMBA-inducible AhR-DRE binding complex. Furthermore, biochanin A competed with the prototypical AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), for binding to the AhR in an isolated rat cytosol. The biochanin A competitively inhibited the metabolic activation of DMBA, as measured by the formation of the DMBA-DNA adducts. These results suggest that biochanin A may thus be a natural ligand to bind on AhR. Therefore, biochanin A may be due to act an antagonist/agonist of the AhR pathway.

• Toxicological Research
• /
• 제23권1호
• /
• pp.55-63
• /
• 2007

Diethylnitrosamine (DEN) is a nitrosamine compound that can induce a variety of liver lesions including hepatic carcinoma, forming DNA-carcinogen adducts. In the present study, microarray analyses were performed with Affymetrix Murine Genome 430A Array in order to identify the gene-expression profiles for DEN and to provide valuable information for the evaluation of potential hepatotoxicity. C57BL/6NCrj mice were orally administered once with DEN at doses of 0, 3, 7 and 20 mg/kg. Liver from each animal was removed 2, 4, 8 and 24 hrs after the administration. The histopathological analysis and serum biochemical analysis showed no significant difference in DEN-treated groups compared to control group. Conversely, the principal component analysis (PCA) profiles demonstrated that a specific normal gene expression profile in control groups differed clearly from the expression profiles of DEN-treated groups. Within groups, a little variance was found between individuals. Student's t-test on the results obtained from triplicate hybridizations was performed to identify those genes with statistically significant changes in the expression. Statistical analysis revealed that 11 genes were significantly downregulated and 28 genes were upregulated in all three animals after 2 h treatment at 20 mg/kg. The upregulated group included genes encoding Gdf15, JunD1, and Mdm2, while the genes including Sox6, Shmt2, and SIc6a6 were largely down regulated. Hierarchical clustering of gene expression also allowed the identification of functionally related clusters that encode proteins related to metabolism, and MAPK signaling pathway. Taken together, this study suggests that match with a toxicant signature can assign a putative mechanism of action to the test compound if is established a database containing response patterns to various toxic compounds.

• 한국식품위생안전성학회지
• /
• 제13권3호
• /
• pp.243-251
• /
• 1998

백삼(Pampx ginseng C.A. Meyer, 4년근)을 가루로 한 다음 petroleum ether로 24시간 추출 후 감압 농축시켜 인삼 석유에텔추출물(GPE)로 하였다. 이때 GPE의 수율은 평균 2.24%였다. 또한 GPE를 petroleum ether 소량에 녹이고 petroleum ether:ether 용매계열로 silicagel column chromatography에 의한 partition을 실시하여 P1, P2, P3 , P4, P5의 5개의 분획을 얻었다. 본 실험에서는 소핵생성 물질인 N-methyl-N-nitrosourea(MNU) 및 benzo(a) pyrene[B(a)P]를 이용하여 소핵생성억제실험을 하였따. 상기의 5가지 분획 중에서 MNU에 대해서는 GPE, P1, P2에서 억제효과가 나타났다. 한편, B(a)P에 대해서는 GPE, P1, P2, P3 , P4, P5 모두에게 억제효과를 나타내었다. 그러나 여러 가지 활성을 보인 분획 중에서 여러 가지 양성대조물질들에 대해서 가장 두드러져 보이는 것은 P2였다. P2는 MNU, B(a)P 모두에 대해서 GPE와 유사한 억제경향을 보이면서 억제활성은 크게 나타난T다. EK라서 P2가 GPE가 보이는 소핵생성억제효과에 깊은 관련이 있는 물질로 판단되었다. 이와 같은 유전독성억제효과의 작용기전을 알기 위하여 B(a)P의 대사에 미치는 영향을 연구한 결과 GPE와 P2는 S-9 mix에 의해 유도된 B(a)P 대사를 억제시켰으며, DNA-B(a)P binding도 감소시켰다. 한편, MNU에 의한 DNA binding 과 O6-methyl guanine 및 7-methyl guanine 생성에 있어서도 억제적인 경향을 나타내었다. 따라서 GPE와 P2는 B(a)P와 같은 2차 발암 물질과 MNU와 같은 알킬화제에 의한 유전독성을 활성대사억제 및 methylation 억제 , DNA binding 억제 등의 기전으로 감소시키고 있는 것으로 판단되었다. 한편, 소핵생성억제 효과에서 가장 활성이 좋았던 P2를 NMR과 GC/MS결과, aliphatic ketone류의 혼합물로서 주성분은 분질량 330과 386의 두 개 물질이 함유되어 있는 혼합물이었으며 향후 계속적으로 분리 동정이 필요한 물질이다.