steroids 74 ( 2 0 0 9 ) 73–80 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/steroids 5,8-Epidioxysterols from the gorgonian Eunicella cavolini and the ascidian Trididemnum inarmatum: Isolation and evaluation of their antiproliferative activity Efstathia Ioannou a , Ayman F. Abdel-Razik a,b , Maria Zervou c , Dimitrios Christofidis a , Xanthippi Alexi d , Constantinos Vagias a , Michael N. Alexis d , Vassilios Roussis a,* a Department of Pharmacognosy & Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece b Natural Products Chemistry Department, National Research Center, Dokki 12622, Cairo, Egypt c Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, Vas. Constantinou 48, Athens 11635, Greece d Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Vas. Constantinou 48, Athens 11635, Greece article info Article history: Received 23 July 2008 Received in revised form 6 September 2008 Accepted 12 September 2008 Published on line 21 September 2008 Keywords: Eunicella cavolini Trididemnum inarmatum 5,8-Epidioxysterols Structure elucidation Antiproliferative activity abstract Three new (1, 4, 9) and nine previously reported (2, 3, 5–8, 10–12)5,8-epidioxysterols were isolated from the organic extracts of the gorgonian Eunicella cavolini and the ascidian Trididemnum inarmatum. The structures and relative configurations of 1–12 were established on the basis of detailed NMR spectroscopic analyses and comparison with the literature. The growth inhibitory effects of 1–12 were evaluated against MCF-7 human breast cancer cells. Compound 1, bearing a cyclopropyl moiety in the side chain, exhibited the highest antiproliferative activity. © 2008 Elsevier Inc. All rights reserved. 1. Introduction Marine organisms are considered to be a prolific source of often structurally complex steroids, possessing unusual nuclei or functionalized side chains. Oxygenation of the basic carbon skeleton, as well as of the side chain, extensive modification of the latter, or bond cleavage in the rings of the tetracyclic nucleus are frequently observed in steroids isolated from marine invertebrates. Steroids of marine origin have exhib- ∗ Corresponding author. Tel.: +30 210 7274592; fax: +30 210 7274592. E-mail address: roussis@pharm.uoa.gr (V. Roussis). ited a diverse array of pharmacological activities, such as antimicrobial, cytotoxic, antifouling, ichthyotoxic, and anti- inflammatory [1,2]. As part of our ongoing research towards the isolation and structural characterization of bioactive natural products from marine organisms of the Greek Seas [3–5], we focused our attention on the gorgonian Eunicella cavolini and the ascid- ian Trididemnum inarmatum, since the organic extracts of both species showed interesting and complex steroidal profiles, in 0039-128X/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.steroids.2008.09.007