Callyaerin G, a new cytotoxic cyclic peptide from the marine sponge Callyspongia aerizusa

Callyaerin G, a new cytotoxic cyclic peptide from the marine sponge Callyspongia aerizusa Sabrin R. M. Ibrahim,a RuAngelie Edrada-Ebel,b Gamal A. Mohamed,c Diaa T. A. Youssef,d Victor Wray,e and Peter Proksch*,f aPharmacognosy Department, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt bStrathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, The John Arbuthnott Building, 27 Taylor Street, Glasgow G4 0NR, United Kingdom cPharmacognosy Department, Faculty of Pharmacy, Al-Azhar University, Assiut branch, Assiut 71524, Egypt dDepartment of Pharmacognosy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt e Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany fInstitute für Pharmazeutische Biologie und Biotechnologie, Heinrich-Heine Universität, Universitätsstrasse 1, Geb. 26.23, D-40225 Düsseldorf, Germany E-mail: [email protected] Abstract From the ethyl acetate fraction of the Indonesian sponge Callyspongia aerizusa extract, a new cyclic peptide named callyaerin G was isolated. Its structure was elucidated by extensive 1D and 2D NMR (1H NMR, TOCSY and ROESY) studies and mass spectrometric data (ESI- and FAB- MS). The stereochemistry was determined by Marfey`s analysis. Callyaerin G was found to exhibit cytotoxic activity when tested against different cancer cell lines. Keywords: Callyspongia aerizusa, Callyaerin G, Marfey’s analysis, cytotoxicity Introduction Sponges belonging to the genus Callyspongia have been reported to yield unusual secondary metabolites with pronounced biological activities. Examples of these secondary metabolites are polyacetylenic compounds with different chain lengths,1-5 depsipeptides,6 and cyclic peptides.7, a,b Our ongoing research for biologically active metabolites from marine organisms led to the isolation of a new cyclic peptide from the Indonesian sponge Callyspongia aerizusa, for which we propose the name callyaerin G. In this paper, we describe the isolation and structural elucidation of this new cyclic peptide, together with its cytotoxic activity.