• 제목/요약/키워드: cytochrome P450 1A1

검색결과 538건 처리시간 0.037초

Heterologous Expression of Rhizopus Oryzae CYP509C12 Gene in Rhizopus Nigricans Enhances Reactive Oxygen Species Production and 11α-Hydroxylation Rate of 16α, 17-Epoxyprogesterone

  • Shen, Chaohui;Gao, Xiyang;Li, Tao;Zhang, Jun;Gao, Yuqian;Qiu, Liyou;Zhang, Guang
    • Mycobiology
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    • 제47권3호
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    • pp.301-307
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    • 2019
  • The $11{\alpha}$-hydroxylation of $16{\alpha}$, 17-epoxyprogesterone (EP) catalyzed by Rhizopus nigricans is crucial for the steroid industry. However, lower conversion rate of the biohydroxylation restricts its potential industrial application. The $11{\alpha}$-steroid hydroxylase CYP509C12 from R. oryzae were reported to play a crucial role in the $11{\alpha}$-hydroxylation in recombinant fission yeast. In the present study, the CYP509C12 of R. oryzae (RoCYP) was introduced into R. nigricans using the liposome-mediated mycelial transformation. Heterologous expression of RoCYP resulted in increased fungal growth and improved intracellular reactive oxygen species content in R. nigricans. The $H_2O_2$ levels in RoCYP transformants were approximately 2-folder that of the R. nigricans wild type (RnWT) strain, with the superoxide dismutase activities increased approximately 45% and catalase activities decreased approximately 68%. Furthermore, the $11{\alpha}$-hydroxylation rates of EP in RoCYP transformants (C4, C6 and C9) were 39.7%, 38.3% and 38.7%, which were 12.1%, 8.2% and 9.4% higher than the rate of the RnWT strain, respectively. This paper investigated the effect of heterologous expression of RoCYP in R. nigricans, providing an effective genetic method to construct the engineered strains for steroid industry.

Brassinosteroid의 대사공학 (Metabolic Engineering of the Brassinosteroid Biosynthetic Pathways)

  • 이미옥;송기홍;이현경;정지윤;최빛나리;최성화
    • Journal of Plant Biotechnology
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    • 제29권2호
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    • pp.139-144
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    • 2002
  • Sterols play two major roles in plants: a bulk component in biological membranes and precursors of plant steroid hormones. Physiological effects of plant steroids, brassinosteroids (BRs), include cell elongation, cell division, stress tolerance, and senescence acceleration. Arabidopsis mutants that carry genetic defects in BR biosynthesis or its signaling display characteristic phenotypes, such as short robust inflorescences, dark-green round leaves, and sterility. Currently there are more than 100 dwarf mutants representing 7 genetic loci in Arabidopsis. Mutants of 6 loci, dwf1/dim1/cbb1, cpd/dwf3, dwf4, dwf5, det2/dwf6, dwf7 are rescued by exogenous application of BRs, whereas bri1/dwf2 shares phenotypes with the above 6 loci but are resistant to BRs. These suggest that the 6 loci are defective in BR biosynthesis, and the one locus is in BR signaling. Biochemical analyses, such as intermediate feeding tests, examining the levels of endogenous BR, and molecular cloning of the genes revealed that dwf7, dwf5, and dwf1 are defective in the three consecutive steps of sterol biosynthesis, from episterol to campesterol via 5-dehydroepisterol. Similarly, det2/dwf6, dwf4, and cpd /dwf3 were shown to be blocked in D$^4$reduction, 22a-hydroxylation, and 23 a-hydroxylation, respectively. A signaling mutant bril/dwf2 carries mutations in a Leucine-rich repeat receptor kinase. Interestingly, the bri1 mutant was shown to accumulate significant amount of BRs, suggesting that signaling and biosynthesis are dynamically coupled in Arabidopsis. Thus it is likely that transgenic plants over-expressing the rate-limiting step enzyme DWF4 as well as blocking its use by BRIl could dramatically increase the biosynthetic yield of BRs. When applied industrially, BRs will boost new sector of plant biotechnology because of its potential use as a precursor of human steroid hormones, a novel lead compound for cholesterol-lowering effects, and a various application in plant protection.

The Role of CYP2B6*6 Gene Polymorphisms in 3,5,6-Trichloro-2-pyridinol Levels as a Biomarker of Chlorpyrifos Toxicity Among Indonesian Farmers

  • Liem, Jen Fuk;Suryandari, Dwi A.;Malik, Safarina G.;Mansyur, Muchtaruddin;Soemarko, Dewi S.;Kekalih, Aria;Subekti, Imam;Suyatna, Franciscus D.;Pangaribuan, Bertha
    • Journal of Preventive Medicine and Public Health
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    • 제55권3호
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    • pp.280-288
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    • 2022
  • Objectives: One of the most widely used pesticides today is chlorpyrifos (CPF). Cytochrome P450 (CYP)2B6, the most prominent catalyst in CPF bioactivation, is highly polymorphic. The objective of our study was to evaluate the role of CYP2B6*6, which contains both 516G>T and 785A>G polymorphisms, in CPF toxicity, as represented by the concentration of 3,5,6-trichloro-2-pyridinol (TCPy), among vegetable farmers in Central Java, Indonesia, where CPF has been commonly used. Methods: A cross-sectional study was conducted among 132 vegetable farmers. Individual socio-demographic and occupational characteristics, as determinants of TCPy levels, were obtained using a structured interviewer-administered questionnaire and subsequently used to estimate the cumulative exposure level (CEL). TCPy levels were detected with liquid chromatography-mass spectrometry. CYP2B6*6 gene polymorphisms were analyzed using a TaqMan® SNP Genotyping Assay and Sanger sequencing. Linear regression analysis was performed to analyze the association between TCPy, as a biomarker of CPF exposure, and its determinants. Results: The prevalence of CYP2B6*6 polymorphisms was 31% for *1/*1, 51% for *1/*6, and 18% for *6/*6. TCPy concentrations were higher among participants with CYP2B6*1/*1 than among those with *1/*6 or *6/*6 genotypes. CYP2B6*6 gene polymorphisms, smoking, CEL, body mass index, and spraying time were retained in the final linear regression model as determinants of TCPy. Conclusions: The results suggest that CYP2B6*6 gene polymorphisms may play an important role in influencing susceptibility to CPF exposure. CYP2B6*6 gene polymorphisms together with CEL, smoking habits, body mass index, and spraying time were the determinants of urinary TCPy concentrations, as a biomarker of CPF toxicity.

리팜핀이 와파린의 항응고 효과에 미치는 영향 (Interaction of Rifampin and Warfarin)

  • 오연목
    • Tuberculosis and Respiratory Diseases
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    • 제47권6호
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    • pp.768-774
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    • 1999
  • 연구배경: 리팜핀(rifampin)은 간의 시토크폼 P-450 효소를 유도하여 이 효소에 의해서 대사되는 와파린(warfarin)의 항응고 효과를 감소시킨다. 이와 같은 리팜핀과 와파린의 약제 상호작용에 대해서 건강한 지원자가 아닌 환자를 대상으로 아래의 문제를 해결하고자 본 연구를 수행하였다. 첫째 와파린을 투여하는 환자에게 리팜핀을 추가할 경우 리팜핀 투여 전, 중, 후에 항응고 효과를 적절히 유지하기 위한 와파린 용량, 둘째 리팜핀 추가 후 적절한 와파린 증량 방법(시간 계획), 셋째 와파린과 리팜핀을 함께 투여하는 경우 합병증등을 살펴 보았다. 방 법: 1995년 1월부터 1999년 8월까지 부천 세종병원에 입원한 환자 중 와파린과 리팜핀을 동시에 투여한 환자를 찾아서 질병 기록을 후향적으로 확인하였다. 리팜핀 투여 전, 중, 후의 와파린 필요량을 '적절한 항응고' 상태를 유지한 환자를 대상으로 조사하였다. 그리고, 리팜핀 추가 시 와파린 증량 방법(시간 계획)을 리팜핀 투여 후 prothrombin time 이 INR 1.1이하로 떨어지는데 걸리는 시간을 측정하여 간접적으로 평가하였다. 마지막으로 리팜핀과 와파린 동시 투여시 합병증을 조사하였다. 결 과: 라팜핀과 와파린을 동시에 투여한 환자는 모두 12명이었고 이 중 리팜핀 투여 기간 중에 '적절한 항응고' 상태를 유지한 환자는 6명이었다. 이 6명환자의 와파린 용량은 리팜핀 투여 중에 증가하여(p<0.05) 리팜핀 투여 전과 비교하여 $2.4{\pm}0.6$(평균${\pm}$표준편차) 배이었다. 그라고, 리팜핀을 중지한 후의 와파린 용량은 다시 감소하여 거의 리팜핀 사용 전의 용량으로 돌아갔다. 리팜핀 투여 후 prothrombin time이 INR 1.1이하로 떨어지는데 걸리는 시간은 $5.8{\pm}2.9$ (평균$\pm$표준편차) 일이었다. 2명이 리팜핀과 와파린 동시 투약과 관련되어 합병증이 발생하였다. 한 명은 낮은 항응고 상태 때문에 뇌색전증이 발생하였고, 다른 한명은 높은 항응고 상태 때문에 뇌출혈이 발생하여 사망하였다. 결 론: 와파린과 리팜핀을 동시에 투약하는 경우, 적절한 항응고 효과를 유지하기 위해서 리팜핀 추가 시 와파린을 약 1주에 걸쳐서 단계적으로 약 2배 증량하고 리팜핀 중단 시 리팜핀 투여 전의 와파린 용량으로 감량하는 방법을 시도해 불 수 있겠고, 이를 향후 전향적 연구를 통해서 확인하는 것이 필요하다. 또한, 리팜핀을 추가하거나 중단할 때 합병증이 발생하지 않도록 항응고 상태를 자주 감시하는 것이 필요하리라 생각된다.

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Selection signature reveals genes associated with susceptibility loci affecting respiratory disease due to pleiotropic and hitchhiking effect in Chinese indigenous pigs

  • Xu, Zhong;Sun, Hao;Zhang, Zhe;Zhang, Cheng-Yue;Zhao, Qing-bo;Xiao, Qian;Olasege, Babatunde Shittu;Ma, Pei-Pei;Zhang, Xiang-Zhe;Wang, Qi-Shan;Pan, Yu-Chun
    • Asian-Australasian Journal of Animal Sciences
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    • 제33권2호
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    • pp.187-196
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    • 2020
  • Objective: Porcine respiratory disease is one of the most important health problems causing significant economic losses. To understand the genetic basis for susceptibility to swine enzootic pneumonia (EP) in pigs, we detected 102,809 single nucleotide polymorphisms in a total of 249 individuals based on genome-wide sequencing data. Methods: Genome comparison of susceptibility to swine EP in three pig breeds (Jinhua, Erhualian, and Meishan) with two western lines that are considered more resistant (Duroc and Landrace) using cross-population extended haplotype homozygosity and F-statistic (FST) statistical approaches identified 691 positively selected genes. Based on quantitative trait loci, gene ontology terms and literature search, we selected 14 candidate genes that have convincible biological functions associated with swine EP or human asthma. Results: Most of these genes were tested by several methods including transcription analysis and candidate genes association study. Among these genes: cytochrome P450 1A1 and catenin beta 1 (CTNNB1) are involved in fertility; transforming growth factor beta receptor 3 plays a role in meat quality traits; Wnt family member 2, CTNNB1 and transcription factor 7 take part in adipogenesis and fat deposition simultaneously; plasminogen activator, urokinase receptor (completely linked to AXL receptor tyrosine kinase, r2 = 1) plays an essential role in the successful ovulation of matured oocytes in pigs; colipase like 2 (strongly linked to SAM pointed domain containing ETS transcription factor, r2 = 0.848) is involved in male fertility. Conclusion: These adverse genes susceptible to swine EP may be selected while selecting for economic traits (especially reproduction traits) due to pleiotropic and hitchhiking effect of linked genes. Our study provided a completely new point of view to understand the genetic basis for susceptibility or resistance to swine EP in pigs thereby, provides insight for designing sustainable breed selection programs. Finally, the candidate genes are crucial due to their potential roles in respiratory diseases in a large number of species, including human.

오이 발효음료가 만성적으로 에탄올을 급여한 흰쥐의 에탄올 대사와 항산화방어계에 미치는 영향 (Effect of Fermented Cucumber Beverage on Ethanol Metabolism and Antioxidant Activity in Ethanol-treated Rats)

  • 이해인;서권일;이진;이점숙;홍성민;이주혜;김명주;이미경
    • 한국식품영양과학회지
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    • 제40권8호
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    • pp.1099-1106
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    • 2011
  • 본 연구는 다량으로 폐기되는 오이를 이용하기 위하여 개발한 오이 발효원액을 주원료로 제조한 숙취해소 음료의 간보호 효능을 검증하기 위하여 만성적으로 에탄올을 섭취시킨 흰쥐에서 에탄올 대사, 항산화 방어계, 간독성 관련지표 및 지질함량 변화를 살펴보았다. 실험동물은 4주령의 수컷 SD계 흰쥐 24마리를 1주간 고형식이로 적응시킨 후 난괴법에 의하여 에탄올대조군(Control) 및 에탄올 섭취 흰쥐에게 헛개열매 추출물을 주원료로 하여 개발한 숙취해소 물질인 SKM 급여군(SKM) 또는 SKM을 함유한 오이 발효음료 급여군(CF+SKM)으로 나누었다. SKM과 CF+SKM은 사람의 하루 섭취량을 기준으로 체중 kg당 7 mL씩 매일 일정시각에 경구투여 하였다. SKM과 CF+SKM은 체중과 식이섭취에는 영향을 미치지 않았으며, CF+SKM군의 신장무게가 대조군보다 낮았다. 혈장 중 에탄올 함량은 대조군에 비하여 CF+SKM군에서 유의적으로(p<0.05) 낮았으며, SKM군은 낮은 경향을 보였다. 혈장 중의 아세트알데히드 함량은 대조군에 비하여 SKM과 CF+SKM군 모두 각각 40.6%와 48.4% 유의적인(p<0.05) 개선 효과를 보였다. 간조직 중의 ADH 활성은 실험군간 유의적인 변화가 없었으나 CYP2E1 활성은 SKM과 CF+SKM 모두 대조군에 비하여 유의적으로 (p<0.05) 낮았다. 간조직의 CYP2E1 활성은 혈장 중의 아세트알데히드 함량과 양의 상관관계(r=0.566, p<0.01)였다. 간조직의 ALDH 활성은 SKM과 CF+SKM 모두 대조군에 비하여 유의적으로(p<0.05) 높았으며 혈장의 아세트알데히드 농도와 유의적 음의 상관관계(r=-0.564, p<0.01)를 보였다. SKM군과 CF+SKM군의 간조직내 SOD와 CAT 활성과 GSH 함량이 대조군에 비하여 유의적으로 높았다. 반면, SKM과 CF+SKM은 간조직 중의 지질과산화물 생성을 대조군에 비하여 각각 유의적으로 낮추었다. SKM과 CF+SKM 급여 시 에탄올대조군에 비하여 각각 AST 활성은 29%와 44% 낮았으며, ALT 활성은 42%와 34% 낮았다. 혈장의 총 콜레스테롤과 간조직의 콜레스테롤 함량은 대조군에 비하여 SKM과 CF+SKM군에서 유의적으로(p<0.05) 낮았으며 특히, CF+SKM의 간조직내 중성지질 함량은 대조군에 비하여 유의적으로(p<0.05) 낮았다. SKM군과 CF+SKM군의 간조직 중 지방축적이 대조군에 비하여 감소되었다. 이와 같이 SKM과 CF+SKM은 간조직의 CYP2E1 활성을 억제하고 ALDH 활성과 항산화 방어계를 향상시킴으로써 에탄올로 인한 간독성을 보호할 수 있을 것으로 사료된다.

Mechanism of Relaxation of Rat Aorta by Scopoletin; an Active Constituent of Artemisia Capillaris

  • Kwon Eui Kwang;Jin Sang Sik;oChoi Min H;Hwang Kyung Taek;Shim Jin Chan;Hwang Il Taek;Han Jong Hyun
    • 동의생리병리학회지
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    • 제16권2호
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    • pp.389-396
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    • 2002
  • In the present work, we examined the mechanism of vasorelaxant effect of scopoletin, an active constituent of Artemisia capillaris on rat thoracic descending aortic rings. Scopoletin induced a concentration-dependent relaxation in rat thoracic descending aortic rings pre-contracted with phenylephrine (EC/sub 50/ = 238.94±37.4 μM), while it was less effective in rat thoracic descending aortic rings precontracted with high potassium solution (KCI 30 mM). Vasorelaxation by scopoletin was significantly inhibited after endothelial removal, but recovered at high concentration. Pretreatment of rat thoracic descending aortic rings with N/sup G/-nitro-L-arginine (100 μM), a nitric oxide synthase inhibitor, and atropine (1 μM), a muscarinic receptor antagonist, significantly inhibited scopoletin-induced relaxation of rat thoracic descending aortic rings. Neither indomethacin (3 μM), an inhibitor of cydooxygenase, nor propranolol (1 μM), a β -adrenoceptor antagonist, modified the effect of scopoletin. The combination of N/sup G/ -nitro-L-arginine (100 μ M) and miconazole (10 μ M), an inhibitor of cytochrome P 450, did not modify the effect of scopoletin, when compared with pretreatment with N/sup G/-nitro-L-arginine(100 μM) alone. Vasorelaxant effect of scopoletin was inverted by pretreatment with diltiazem (10 μM), a Ca/sup 2+/-channel blocker, at low concentration, while restored at high concentration. Apamin (K/sub ca/-channel blocker, 1 μM), 4-aminopyridine (4-AP, K/sub v/-channel blocker, 1 mM), and tetrodotoxin (TTX, Na/sup +/-channel blocker 1 μM) potentiated the vasorelaxant effect of scopoledn, but glibendamide (K/sub ATP/-channel blocker, 10 μM), tetraetylammonium(TEA, non-selective K-channel blocker, 10 mM) did not affect the relaxation of scopoletin. Free radical scavengers (TEMPO, catalase, mannitol) did not modify vascular tone. These results suggest that nitric oxide, Ca/sup 2+/ -channels play a role in endothelium-dependent relaxations to scopoletin in rat aortas, that apamin, 4-AP, TTX but not glibenclamide, TEA potentiated relaxation to scopoletin mediated by these channels, and that free radicals do not concern to the vasorelaxant effect of scopoletin.

Fermented Protaetia brevitarsis Larvae Ameliorates Chronic Ethanol-Induced Hepatotoxicity in Mice via AMPK and TLR-4/TGF-β1 Pathways

  • Hyo Lim Lee;Jong Min Kim;Min Ji Go;Seung Gyum Joo;Tae Yoon Kim;Han Su Lee;Ju Hui Kim;Jin-Sung Son;Ho Jin Heo
    • Journal of Microbiology and Biotechnology
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    • 제34권3호
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    • pp.606-621
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    • 2024
  • This study evaluated the hepatoprotective effect of fermented Protaetia brevitarsis larvae (FPB) in ethanol-induced liver injury mice. As a result of amino acids in FPB, 18 types of amino acids including essential amino acids were identified. In the results of in vitro tests, FPB increased alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities. In addition, FPB treatment increased cell viability on ethanol- and H2O2-induced HepG2 cells. FPB ameliorated serum biomarkers related to hepatoxicity including glutamic oxaloacetic transaminase, glutamine pyruvic transaminase, total bilirubin, and lactate dehydrogenase and lipid metabolism including triglyceride, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Also, FPB controlled ethanol metabolism enzymes by regulating the protein expression levels of ADH, ALDH, and cytochrome P450 2E1 in liver tissue. FPB protected hepatic oxidative stress by improving malondialdehyde content, reduced glutathione, and superoxide dismutase levels. In addition, FPB reversed mitochondrial dysfunction by regulating reactive oxygen species production, mitochondrial membrane potential, and ATP levels. FPB protected ethanol-induced apoptosis, fatty liver, and hepatic inflammation through p-AMP-activated protein kinase and TLR-4/NF-κB signaling pathways. Furthermore, FPB prevented hepatic fibrosis by decreasing TGF-β1/Smad pathway. In summary, these results suggest that FPB might be a potential prophylactic agent for the treatment of alcoholic liver disease via preventing liver injury such as fatty liver, hepatic inflammation due to chronic ethanol-induced oxidative stress.

The Roles of Arachidonic Acid and Calcium in the Angiotensin II-induced Inhibition of $Na^+$ Uptake in Renal Proximal Tubule Cells

  • Park, Soo-Hyun;Koh, Hyun-Joo;Lee, Yeun-Hee;Son, Chang-Ho;Park, Min-Kyoung;Lee, Young-Jae;Han, Ho-Jae
    • The Korean Journal of Physiology and Pharmacology
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    • 제3권1호
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    • pp.83-91
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    • 1999
  • Angiotensin II (ANG II) has a biphasic effect on $Na^+$ transport in proximal tubule: low doses of ANG II increase the $Na^+$ transport, whereas high doses of ANG II inhibit it. However, the mechanisms of high dose ANG II-induced inhibition on $Na^+$ uptake are poorly understood. Thus the aim of the present study was to investigate signal transduction pathways involved in the ANG II-induced inhibition of $Na^+$ uptake in the primary cultured rabbit renal proximal tubule cells (PTCs) in hormonally defined serum-free medium. ANG II $(10^{-9}\;M)-induced$ inhibition of $Na^+$ uptake was blocked by losartan $(10^{-8}\;M,\;AT_1\;antagonist),$ but not by PD123319 $(10^{-8}\;M,\;AT_2\;antagonist)$ (P<0.05). ANG II-induced inhibition of $Na^+$ uptake was also completely abolished by neomycin $(10^{-4}\;M,$ PLC inhibitor), W-7 $(10^{-4}\;M,$ calmodulin antagonist), and $AACOCF_3\;(10^{-6}\;M,\;PLA_2\;inhibitor)$ (P<0.05). ANG II significantly increased $[^3H]arachidonic$ acid (AA) release compared to control. The ANG II-induced $[^3H]AA$ release was blocked by losartan, $AACOCF_3,$ neomycin, and W-7, but not by PD123319. ANG II-induced $[^3H]AA$ release in the presence of extracellular $Ca^{2+}$ was greater than in $Ca^{2+}-free$ medium, and it was partially blocked by TMB-8 $(10^{-4}\;M,$ intracelluar $Ca^{2+}$ mobilization blocker). However, in the absence of extracellular $Ca^{2+},$ it was completely blocked by TMB-8. In addition, econazole $(10^{-6}\;M,$ cytochrome P-450 monooxygenase inhibitor) and indomethacin $(10^{-6}\;M,$ cyclooxygenase inhibitor) blocked ANG II-induced inhibition of $Na^+$ uptake, but NGDA $(10^{-6}\;M,$ lipoxygenase inhibitor) did not affect it. In conclusion, $PLA_2-mediated$ AA release is involved in ANG II-induced inhibition of $Na^+$ uptake and is modulated by $[Ca^{2+}]_i$ in the PTCs.

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The effects of the standardized extracts of Ginkgo biloba on steroidogenesis pathways and aromatase activity in H295R human adrenocortical carcinoma cells

  • Kim, Mijie;Park, Yong Joo;Ahn, Huiyeon;Moon, Byeonghak;Chung, Kyu Hyuck;Oh, Seung Min
    • Environmental Analysis Health and Toxicology
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    • 제31권
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    • pp.10.1-10.8
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    • 2016
  • Objectives Aromatase inhibitors that block estrogen synthesis are a proven first-line hormonal therapy for postmenopausal breast cancer. Although it is known that standardized extract of Ginkgo biloba (EGb761) induces anti-carcinogenic effects like the aromatase inhibitors, the effects of EGb761 on steroidogenesis have not been studied yet. Therefore, the effects of EGb761 on steroidogenesis and aromatase activity was studied using a H295R cell model, which was a good in vitro model to predict effects on human adrenal steroidogenesis. Methods Cortisol, aldosterone, testosterone, and $17{\beta}$-estradiol were evaluated in the H295R cells by competitive enzyme-linked immunospecific assay after exposure to EGb761. Real-time polymerase chain reaction were performed to evaluate effects on critical genes in steroid hormone production, specifically cytochrome P450 (CYP11/ 17/19/21) and the hydroxysteroid dehydrogenases ($3{\beta}$-HSD2 and $17{\beta}$-HSD1/4). Finally, aromatase activities were measured with a tritiated water-release assay and by western blotting analysis. Results H295R cells exposed to EGb761 (10 and $100{\mu}g/mL$) showed a significant decrease in $17{\beta}$-estradiol and testosterone, but no change in aldosterone or cortisol. Genes (CYP19 and $17{\beta}$-HSD1) related to the estrogen steroidogenesis were significantly decreased by EGb761. EGb761 treatment of H295R cells resulted in a significant decrease of aromatase activity as measured by the direct and indirect assays. The coding sequence/Exon PII of CYP19 gene transcript and protein level of CYP19 were significantly decreased by EGb761. Conclusions These results suggest that EGb761 could regulate steroidogenesis-related genes such as CYP19 and $17{\beta}$-HSD1, and lead to a decrease in $17{\beta}$-estradiol and testosterone. The present study provides good information on potential therapeutic effects of EGb761 on estrogen dependent breast cancer.