J. Chil. Chem. Soc, 53, N° 4 (2008) págs: 1732-1733

 

X-RAY CRYSTALLOGRAPHIC STRUCTURAL STUDY ON A CINNAMOLIDE-CLASS SESQUITERPENE LACTONE FROM DRIMYS WINTERIFORST. VAR. CHILENSIS

 

IVÁN BRITO*¹, ALEJANDRO CÁRDENAS², MIGUEL ZÁRRAGA³, CRISTIAN PAZ³, CLAUDIA PÉREZ⁴ AND MATÍAS LÓPEZ-RODRÍGUEZ⁵

¹Departamento de Química, Facultad de Ciencias Básicas, Universidad de Antofagasta, Casilla 170, Antofagasta-Chile.
²Departamento de Física, Facultad de Ciencias Básicas, Universidad de Antofagasta, Casilla 170, Antofagasta-Chile.
³Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad de Concepción, Casilla 160-C, Concepción-Chile.
⁴Laboratorio de Fitoquímica, Facultad de Ciencias Biológicas, Universidad de Concepción y Centro de Investigación de Ecosistemas de la Patagonia (CIEP). Bilbao 449, Coyhaique-Chile.
⁵Instituto de Bio-Orgánica 'Antonio González', Universidad de La Laguna, Astrofísico Francisco Sánchez N" 2, La Laguna, Tenerife, España.

---

ABSTRACT

In order to ascertain the structure and secure the assignment of the stereochemistry of the title compound an X-ray analysis was performed, the absolute configuration was not determined by this analysis.

Keywords: X-ray diffraction, cinnamolide - class sesquiterpene.

---

INTRODUCTION

Drimys winteri J.R. Forst is a plant used in folk medicine of the many Latinoamerican countries. In Chile , Drimys winteri (canelo) is used by the indigenous Mapuche in the treatment of several stomachal diseases, ulcers and hemorrhages¹. Chemical studies has shown the presence of a variety of sesquiterpenes with drimano skeleton² and flavonoids. Some of these structures have shown significant antibacterial, antifungi, antitumor and insecticide properties ^3,4. The extract of Drimys winteri leaves afforded Cinnamolide and Drimenin two lactones with drimano skeleton. Cinnamolide have not been previuosly reported for these specie. Recently it has been reported that the title compound was also isolated of Cinnamosma macrocarpa ⁵. In order to ascertain the structure and secure the assignment of the stereochemistry of the title compound an X-ray analysis was performed, the absolute configuration was not determined by this analysis. The X-ray crystallographic analysis confirms the previously proposed molecular structure, including the molecular conformation. The molecular structure is shown in Fig. 1 and selected geometric parameters are given in Table I. The structure consists of a drimane skeleton.

The methyl group at C9a is seen to be ß-oriented. The cyclohexene ring A and cyclohexane ring B exist in a half-chair and a chair conformation, respectively [Q_T = 0.538(3) Å, φ₂ = 227.4(4) °, q₂ = 0.428 (3) Å for ring A; Q_T = 0.556(4) Å , φ₂ = 21 (4)°, q₂ = 0.060 (4) Å for ring B], and the lactone ring an envelope on C3a conformation⁶. The A and B rings are trans-fused. Bond lengths are within expected ranges⁷. There are no unusually short contacts between the molecules and the crystal packing is controlled by weak van der Waals interactions.

Source of material

Drimys winteri was collected from the Estuary of Reloncaví, X^th Región, Chile in November 2005. 2 kg of bark was extracted in dichloromethane and concentrated under vacuum, to yield 180 g. 30 grams of crude extract was subjected to flash chromatography on silicagel G, 70-200 mesh with hexane-ethyl acetate mixtures of increasing polarity as elution solvents. Pure components were obtained by further chromatography on silicagel of the fraction 10% hexane-ethyl acetate (11 g) and recrystallization from methanol, at room temperature afforded colorless crystals of Drimenin (0.02g) suitable for X-ray diffraction analysis.

ACKNOWLEDGEMENTS

We thank the Spanish Research Council (CSIC) for providing us with a free-of-charge licence for the CSD system. M. Z. recognises support provided by the Center for Ecosystem Research in Patagonia (CIEP), under grant

REFERENCES

1.     A. T. Almeida, R. Lacerda & H. Kloos. Mem. Inst. Oswaldo Cruz, 831, (2001)

2.     H. H. Appel, R. P. M. Bond & K. H. Overton..Tetrahedron, 19, 635, (1963)

3.     A. Cruz, M. Silva & P. G. Sammmes. Phytochemistry, 12, 2549, (1973)

4.     J. Sierra, J. López, & M. Cortés. Phytochemistry, 25, 253. (1986).

5.     L. Harinanteaina, Y. Asakawa & E. De Clercq. J. Nat. Prod. 70, 277, (2007)

6.     D. Cremer & J. A. Pople. J. Am. Chem. Soc. 97, 1354, (1975)

7.     F. H. Alien, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen & R. Taylor. J. Chem. Soc. Perkin Trans. 2, pp. Sl-19, (1987)

8.     A. Alternare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori & R. Spagna. J. Appl. Cryst. 32,115,(1999).

9.     G. M. Sheldrick. Acta Cryst. A64, 112, (2008)

10.  L. J. Farrugia. ORTEP-3 for Windows. J. Appl. Cryst. 30, 565. (1997)

 

(Received: April 25, 2008 - Accepted: August 1, 2008)

*e-mail: ibrito@vantof.cl