ORIGINAL PAPER Absolute Configuration of Two Eudesmane Derivatives from Verbesina turbacensis H.B.K. Julia Bruno-Colmena ´rez Æ Juan M. Amaro-Luis Æ Irama Ramı ´rez Æ Paulino Delgado-Me ´ndez Æ Graciela Dı ´az de Delgado Received: 6 January 2009 / Accepted: 8 August 2009 / Published online: 23 August 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Two compounds isolated from the aerial parts of Verbesina turbacensis H.B.K, are reported in this work. Both compounds crystallize in the orthorhombic system, space group P2 1 2 1 2 1 . Compound (1), 6b-[cinnamoyloxy]- 3b,4a-dihydroxyeudesmane, formula C 24 H 34 O 4, has unit cell parameters a = 9.6234(2), b = 12.3137(3) and c = 18.6277(5) A ˚ , V = 2207.38(9) A ˚ 3 , Z = 4. On the other hand, 6b-[cinnamoyloxy]-eudesman-15-oic acid (2), formula C 24 H 32 O 4, has cell parameters a = 8.7035(3), b = 14.2020(4), c = 17.1590(5) A ˚ , V = 2120.97(11) A ˚ 3 , Z = 4. Keywords Verbesina derivatives  Eudesmane  Sesquiterpenes  Crystal structure Introduction Species of the genus Verbesina (family: Compositae; Helintheae) and derivatives have great importance as pro- moters of vegetal growth and germination. Additionally, many species have shown antibacterial, fungicidal, antivi- ral, and antitumoral activity. As part of a continuous effort to characterize medicinal plants commonly used in the Venezuelan Andes, two cin- namate substituted eudesmane compounds were isolated, among other compounds, from the aerial parts of Verbesina turbacensis H.B.K: compound (1) 6b-[cinnamoyloxy]- 3b,4a-dihydroxyeudesmane and compound (2)6b-[cinna- moyloxy]-eudesman-15-oic acid [1]. Even though Verbesina turbacensis H.B.K. is widely distributed throughout Mexico, Central America, Colom- bia, and Venezuela, it has not been studied in detail. V. turbacensis as well as V. caracasana Fries (which contains the dose-dependent hypotensive agent Caraca- sanamide) are frequently used in Venezuela in folk medi- cine against a variety of diseases. A search performed in the Cambridge Structural Data- base (CSD) Version 5.29 [2] indicated that compound (1) had not been reported before. A structural study for Julia Bruno-Colmena ´rez: J. Chem. Cryst. Poster Prize at the 2007 ACA meeting, Salt Lake City. J. Bruno-Colmena ´rez  G. Dı ´az de Delgado (&) Laboratorio de Cristalografı ´a-LNDRX, Departamento de Quı ´mica, Facultad de Ciencias, Universidad de Los Andes, Apdo. 40 La Hechicera, Me ´rida 5251, Venezuela e-mail: diaz@ula.ve J. M. Amaro-Luis  I. Ramı ´rez  P. Delgado-Me ´ndez Laboratorio de Productos Naturales, Departamento de Quı ´mica, Facultad de Ciencias, Universidad de Los Andes, Me ´rida, Venezuela 123 J Chem Crystallogr (2010) 40:110–115 DOI 10.1007/s10870-009-9610-4