X-ray, 1 H/ 13 C 2D and 3D NMR Studies of the Structures of Davallene and Adipedatol, Two Triterpenes Isolated from American Adiantum capillus-veneris by C.K. Jankowski *1 , A. Aumelas 1 , P. Thuéry 2 , R. Reyes-Chilpa 3 , M. Jimenez-Estrada 3 , H. Barrios 3 and E. Diaz 3 1 Département de Chimie et Biochimie, Université de Moncton, Moncton, Nouveau-Brunswick, Canada, E1A 3E9 2 CEA/Saclay, DSM/DRECAM/SCM (URA 331), Bât. 125, 91191 Gif-sur-Yvette, France 3 Instituto de Quimica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan 04510 Mexico D.F., Mexico (Received November 25th, 2003) Two triterpenic compounds, Davallene 1 and Adipedatol 2 were isolated from the roots of Mexican Adiantum capillus-veneris L. (Adiantaceae). The structures of both compounds are discussed on the basis of new 2D and 3D NMR spectroscopic and single crystal X-ray diffraction data. Key words: triterpenes from Adiantum, NMR 1D and 2D of triterpenes, X-rays – 2D, 3D NMR of triterpenes Adiantum capillus-veneris is one of the most widely-distributed fern species in the world. It can be found in Asia, Africa, Europe and the Americas [1]. Previous phytochemical studies of A. capillus-veneris have reported the presence of a number of hopane and oleane triterpenoids [2,3]. Differences in chemical composition have been found in samples from Asia and Africa [4,5], but less is known about the specimens from the Americas. A. capillus-veneris is also widely spread in Mexico, where it is commonly used in traditional folk medicine. Infusions of the fern are used in many applications for a variety of ailments, such as against cough, after childbirth, as a remedy for excessive menstrual flux and as a soft abortifacient. The infusion is also administered for minor liver and spleen disorders [6]. To our knowledge this is the first time that Davallene 1 and Adipedatol 2 (Scheme 1) have been isolated from Mesoamerican A. capillus-veneris. Davallene is widely found in ferns [3], while Adipedatol has previously been obtained only from Japanese Adiantum pedatum [4]. Its structure was determined spectroscopically and through chemical transformations [5], with the exception of the stereochemistry of C-20. Although structures of both triterpenes were proposed several years ago [4,7], the reported features of their NMR spectra have offered only limited structural infor- mation, since their proton-NMR spectra were recorded at <300 MHz frequencies. Polish J. Chem., 78, 389–408 (2004) * Author to whom correspondence may be addressed. Email: jankowc@umoncton.ca