Pergamon 7'e‘pirahedron Vol. 51. No. 45. pp. 12453-12462. 1995 Copyright 0 1995 Elsevier Science Ltd Printed in Great Bntain. All rights reserved Ctl40-4020/95 $9.50+0.00 0040.4020~ 95)00X0 I -2 Lignans from Ochroma lagopus Swartz Vanderlicia F. Paula@), Luiz C. A. Barbosata)*v Oliver W. Eowarthcb)*y AntBnio J. Demunerca), Quezia B. Cash) and Ivo J. C. Vieira@) (a) Departamento de Quimtca, Unrverstdade Federal de Vicosa. 36571-000. Vipsa-MG - Braztl (b) Department of Chemistry, Umversity of Warwck, Coventry, CV4 7AL - England-UK (c) Deprtamento de Quimrca, Umversuiade Federal de S&o Carlos, 13565-905, Sb Carlos-SP Abstract: An mvesttgatton of the chemrcal constrtuents of the ethanohc extract of the hearhvood of Ochroma fagopus Swxtz led to the rsolatron of rune new hgnans named boehmenan B-D and carol&pan A-F Then chemtcal structures have been deduced on the basts of ‘H, 13C, ‘H-homonuclear COSY, HETCOR. NOEDIFF and DEFT nmr spectral studies INTRODUCTION Ochroma fugopus Swartz, 6om the Bombacaceae family. is a tree widely distributed from southern Mexico through the West Indies to Bolivia’, including the Amazon region in Brazil. Due to the low density of its wood (0.12 g.cm-‘) it is widely used in the Guianas and the Amazon state in Brad in the manufacture of raft floats and coBins2. An infusion born its bark is also given to cows postpartum3. Previous studies on this plant have lead to the isolation and identification of the fatty acids pahnitic, stearic, oleic, linoleic and linolenic: the steroids B-sitosterol and stigmasterol; the coumarins scopoletin and cleomiscosin A and the ligrtans boehmenan and secoisolariciresinoyl diferulate4. A continuation of our phytochemical investigation of Ochroma lugopus wood ethanolic extract has led to the isolation and structural elucidation of nine new lignans designated as boehmenan B-D and caroJignan A-F. The structures of these new compounds have been elucidated by detailed NMR spectroscopic studies. RESULTS AND DlSClJSSION The ethanolic extract of the heartwood of Ochroma fugopus was submitted to repeated column chromatography on silica gel. and finally to preparative-scale recycling HPLC. This led to the separation of fractions A-J. AU these fractions were very viscous oils. some of which solidified on standing, after some time. Fractions A. B, E and J consisted of the pure compounds 1, 2, 5 and 7 respectively. Fractions C, D and I consisted of an isomeric mixture of compounds (3a + 3b - 2), (4a + 4b + 5) and (6a + 6b) respectively. Fractions F, G and H showed JR and tH-NMR spectra very similar to all the other fractions, but they were ah very complex mixtures and therefore it was not possible to identify any compounds Born them. FRACTION E (Compound 5): The ‘H-NMR spectrum revealed that this fraction consisted of a pure compound 5. This compound. boehmenan, has previously been isolated horn Boehmeria tricuspiss and from Ochroma Ingo& A detailed discussion of its structural ehmidation is given by Paula4. In the present paper, its ‘H-NMR and r3C-NMR data are reproduced in tables I and 3 for purposes of comparison.