Original Article

Assessment of the estrogenic activities of chickpea (Cicer arietinum L) sprout isoflavone extract in ovariectomized rats

Authors: Hai-rong Ma, Jie Wang, Hong-xue Qi, Yan-hua Gao, Li-juan Pang, Yi Yang, Zhen-hua Wang, Ming-jun Duan, Hua Chen, Xu Cao, Haji Akber Aisa
DOI: 10.1038/aps.2012.160

Abstract

Hai-rong MA1, Jie WANG1, 2, Hong-xue QI1, Yan-hua GAO1, Li-juan PANG3, Yi YANG1, Zhen-hua WANG2, Ming-jun DUAN4, Hua CHEN1, Xu CAO5, Haji Akber AISA1, *
Xinjiang Key Laboratory of Plant Resources and Natural Products Chemistry, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, China; 2Key Laboratory of Xinjiang Endemic Phytomedicine Resources, Ministry of Education, College of Pharmacy, Shihezi University, Shihezi 832002, China; 3School of Medicine, Shihezi University, Shihezi 832002, China; 4Animal Experimental Center, The First Teaching Hospital of Xinjiang Medical University, Urumqi 830011, China; 5Department of Orthopaedic Surgery, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA

Aim: Benzothiophene compounds are selective estrogen receptor modulators (SERMs), which are recently found to activate antioxidant signaling. In this study the molecular mechanisms of antioxidant signaling activation by benzothiophene compound BC-1 were investigated.
Methods: HepG2 cells were stably transfected with antioxidant response element (ARE)-luciferase reporter (HepG2-ARE cells). The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in HepG2-ARE cells was suppressed using siRNA. The metabolites of BC-1 in rat liver microsome incubation were analyzed using LC-UV and LC-MS.

Results: Addition of BC-1 (5 μmol/L) in HepG2-ARE cells resulted in a 17-fold increase of ARE-luciferase activity. Pretreatment with the estrogen receptor agonist E2 (5 μmol/L) or antagonist ICI 182,780 (5 μmol/L) did not affect BC-1-induced ARE-luciferase activity. However, transfection of the cells with anti-Nrf2 siRNA suppressed this effect by 79%. Addition of BC-1 in rat microsome incubation resulted in formation of di-quinone methides and o-quinones, followed by formation of GSH conjugates. BC-1 analogues with hydrogen (BC-2) or fluorine (BC-3) at the 4' position did not form the di-quinone methides. Both BC-2 and BC-3 showed comparable estrogenic activity with BC-1, but did not induce ARE-luciferase activity in HepG2-ARE cells.

Conclusion: Benzothiophene compound BC-1 activates ARE signaling via reactive metabolite formation that is independent of estrogen receptors.


Keywords: selective estrogen receptor modulator; benzothiophene compound; E2; ICI 182,780; antioxidant response element (ARE); reactive metabolites; quinoid formation; nuclear factor erythroid 2-related factor 2 (Nrf2); siRNA

We thank Ying-qin LI, Hai-qing ZHAO, Yan-hong LI, Chun-fang LU, and Mei MA at the Animal Experimental Center, First Teaching Hospital Xinjiang Medical University for their assistance with rat surgery. We thank Prof Yiu-fai CHEN of the University of Alabama for language revision of the manuscript. This work was supported in part by grants from the China National Funds for Distinguished Young Scientists (Grant No 30925045), National Natural Science Foundation of China (Grant No 81102890), CAS/SAFEA International Partnership Program for Creative Research Teams (Grant No KGCX2-YW-503) and Natural Science Foundation of Xinjiang Province, China (Grant No 2010211A58).
* To whom correspondence should be addressed.
E-mail haji@ms.xjb.ac.cn (Haji Akber AISA); xcao11@jhmi.edu (Xu CAO)
Received 2012-08-01 Accepted 2012-10-21
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