Cynaratriol, a sesquiterpene lactone from Centaurea musimomum

Matías López-Rodríguez; Victor P García; Hanêne Zater; Samir Benayache; Fadila Benayache

doi:10.1107/S1600536809026701

. 2009 Jul 15;65(Pt 8):o1867–o1868. doi: 10.1107/S1600536809026701

Cynaratriol, a sesquiterpene lactone from Centaurea musimomum

Matías López-Rodríguez ^a, Victor P García ^b, Hanêne Zater ^c, Samir Benayache ^d, Fadila Benayache ^c,^*

PMCID: PMC2977309 PMID: 21583563

Abstract

The title compound [systematic name: 3,8-dihydroxy-3-(hydroxymethyl)-9-methyl-6-methylenedecahydroazuleno[4,5-b]furan-2(3H)-one], C₁₅H₂₂O₅, is a sesquiterpene lactone showing the typical tricyclic guaianolide skeleton which has been isolated, together with other related metabolites, from the plant Centaurea musimomum. The present study confirms the molecular structure, assigned by ¹H NMR and MS spectroscopy, as well as the the 11β-hydroxymethyl, 3β-hydroxy and 4α-methyl stereochemistry. The crystal structure is built through a network of O—H⋯O hydrogen bonds involving the three hydroxyl groups that are present in the molecular skeleton.

Related literature

For the ethyl acetate soluble extract of Centaurea musimomum, an endemic specie from Algeria, see: Quezel & Santa (1963 ▶). For the structures of several guaianolide type sesquiterpene lactones isolated from the chloroform-soluble part of Centaurea musimomum, see: Medjroubi et al. (1997 ▶, 2003 ▶, 2005 ▶); González-Platas et al. (1999 ▶). Cynaratriol was previously isolated from Cynara species, see: von Heinz et al. (1979 ▶). For related structures, see: Oksuz et al. (1993 ▶); González-Platas et al. (1999 ▶).

Experimental

Crystal data

C₁₅H₂₂O₅
M _r = 282.33
Orthorhombic,
a = 8.417 (4) Å
b = 9.919 (3) Å
c = 17.187 (8) Å
V = 1434.9 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 293 K
0.40 × 0.30 × 0.25 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: none
8829 measured reflections
2054 independent reflections
1847 reflections with I > 2σ(I)
R _int = 0.038

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.101
S = 1.11
2054 reflections
194 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809026701/bx2222sup1.cif

e-65-o1867-sup1.cif^{(21.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809026701/bx2222Isup2.hkl

e-65-o1867-Isup2.hkl^{(99KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H4O⋯O1ⁱ	0.84 (3)	1.93 (3)	2.756 (2)	169 (3)
O5—H5O⋯O3ⁱⁱ	0.86 (3)	1.99 (3)	2.844 (2)	176 (3)
O1—H1O⋯O3ⁱⁱⁱ	0.76 (4)	2.26 (4)	2.978 (3)	159 (4)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors wish to thank Professor N. Khalfallah of the Nature and Life Sciences Department, Mentorui University of Constantine, Algerie, for the identification of the plant material.

supplementary crystallographic information

Comment

The Centaurea genus plants are a natural source of various type of sesquiterpenic lactones, many of which have been shown to be biologically active: Medjroubi, Benayache & Bermejo. In connection with a systematic study of this genus, we have investigated the ethyl acetate soluble extract of Centaurea musimomum, an endemic specie from Algeria: Quezel & Santa, (1963). Our previous phytochemical study of the chloroform soluble part led to the isolation an molecular structure determination of several guaianolide type sesquiterpene lactones: Medjroubi et al., 1997; González-Platas et al. 1999; Medjroubi et al., 2003. Cynaratriol was previously isolated from Cynara species (Heinz, Thiele & Pretsch, 1979). In this work we report the isolation and the molecular and crystal structure determination of the title compound, which it is described for the first time as a metabolite for the Centaurea genus. The lack of suitable anomalous scatters did not allow us to reliably determine the absolute structure and that shown was chosen to be the same as that the, close related, 4β,15-Dihydro-3-dehydrosolstiatilin A (González-Platas et al., 1999) and its acetate (Oksuz, Clark & Herz, 1993).