Turrianes from Kermadecia rotundifolia as new acetylcholinesterase inhibitors Mehdi A. Beniddir, Anne-Laure Simonin, Marie-The ´ re ` se Martin, Vincent Dumontet, Cyril Poullain, Franc ¸oise Gue ´ ritte, Marc Litaudon * Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles, CNRS, 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France 1. Introduction In the course of automated screening for small-molecules for acetylcholinesterase inhibitory activity, a significant activity was observed for kermadecin D (7), a cyclophane-type compound isolated from the bark of Kermadecia elliptica (Jolly et al., 2008). With the aim to discover analogues of kermadecin D, we performed a chemical investigation of Kermadecia rotundifolia Brongniart & Gris, an endemic species to New Caledonia with very similar morphological characteristics to K. elliptica. The genus Kermadecia (Proteaceae), contains twelve species, of which four are endemic to New Caledonia (Virot, 1968). No report is mentioned regarding their utilisation by traditional healers. K. rotundifolia, may reach 20 m in height, possesses large orbiculate to ovalate leaves, and white to yellowish small flowers are organized in branched racemes 15–40 cm long. This rare species is mainly distributed in the Northern part of the main highland. Until now K. elliptica is the only species that has been investigated chemically and biologically (Jolly et al., 2008). The isolated compounds are new bisresorcinol derivatives having a 20-membered-o,-p-cyclophane skeleton or a biaryl-ether containing macrocycle in their structure. We wish to report in this paper the isolation and characterization of four new kermadecins (1–4) together with their acetylcholinesterase inhibitory activities and those of three other known kermadecins (5–7). 2. Results and discussion This study was accomplished with the aid of HPLC, LC–APCI-MS and NMR analysis, and led to the isolation and identification of four new kermadecins (1–4) together with the known kermadecins A, B and D (5–7). In order to determine the presence of common fragments in this chemical series, we applied the LC/MS–MS method developed in our previous study on K. elliptica (Jolly et al., 2008). In APCI positive-ion mode, LC/MS–MS analysis of com- pounds 1–4 indicated the presence of ions resulting from the systematic loss of fragments 182 (C 13 H 26 )(1, 2 and 4) or 180 (C 13 H 24 for compound 3), mass units in favour of a 14 carbons aliphatic chain, with an additional double bond in the case of 3. In negative-ion mode, LC/MS–MS analyses of the quasimolecular peak [MH]  of 2 and 3 showed the presence of an ion at m/z = 369 corresponding to the loss of a fragment of 108 mass units, suggesting the loss of a dimethylpyran ring. Kermadecins A, B and D (5–7), previously isolated from K. elliptica (Jolly et al., 2008) were identified by comparison of their spectroscopic data (HR-MS, 1 H and 13 C NMR). The HRESIMS of compound 1 indicated an ion peak m/z 491.2789 [MH]  (calcd. for 491.2797) giving the molecular formula C 31 H 40 O 5 . The IR spectrum of 1 showed absorption bands at 3600 cm 1 for hydroxyl groups, 1608 and 1424 cm 1 for an Phytochemistry Letters 3 (2010) 75–78 ARTICLE INFO Article history: Received 20 November 2009 Received in revised form 11 December 2009 Accepted 17 December 2009 Available online 29 December 2009 Keywords: Kermadecia rotundifolia Proteaceae Kermadecin Turriane Cyclophane Acetylcholinesterase ABSTRACT Four new kermadecins, together with the known kermadecins A, B and D have been isolated from the Kermadecia rotundifolia ethyl acetate bark extract. These compounds are derivatives of the (20- membered-o,-p)cyclophane skeleton and belong to the turriane family. The structures were elucidated by mass spectrometry, extensive one- and two-dimensional NMR spectroscopy and through comparison with data reported in the literature. Isokermadecin D (2) and kermadecins D and J (7 and 4) possess significant inhibitory effect on acetylcholinesterase. ß 2009 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +33 1 69 82 30 85; fax: +33 1 69 07 72 47. E-mail address: litaudon@icsn.cnrs-gif.fr (M. Litaudon). Contents lists available at ScienceDirect Phytochemistry Letters journal homepage: www.elsevier.com/locate/phytol 1874-3900/$ – see front matter ß 2009 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.phytol.2009.12.003