12.

Phenolics from Phaleria nisidai with Estrogenic Activity

Christopher Kitalong, Ali M. El-Halawany, RihamSalah El-Dine, Chao-mei Ma and Masao Hattori

The Graduate Center, City University of New York, Lehman College Campus Bronx, NY, USA

Institute of Natural Medicine, University of Toyama; 2630 Sugitani, Toyama 930-0194, Japan

Faculty of Pharmacy, Department of Pharmacognosy, Cairo University, Kasr El-Aini St. 11562, Cairo, Egypt.

Abstract: The methanol extract of P. nisidai leaves yielded a benzophenone rhamnoside , iriflophenone 2-O-α-L-rhamnopyranoside (1) in addition to g enkwanin 5-O-β-D-primeveroside (2) and mangiferin (3). The isolated compounds as well as the derived aglycones of 1 and 2 assigned as compounds 4 and 5, respectively, were tested for their estrogenic activity on ERα using an estrogen receptor competitive binding screen. Compounds 1 , 4 and 5 showed almost the same binding ability to ERα with IC 50 of 630 µM, 700 µM and 800 µM, respectively. Virtual docking with ERα revealed that compound 1, 4 and 5 strongly hydrogen bond with amino acids Glu353, Arg349, Gly521 and His524, in the estrogen receptor ligand binding domain, similar to that of mammalian estrogen 17β-estradiol.

Keywords: Phaleria nisidai; estrogenic activity; ER; benzophenone; mangiferin.