(3R,6R,12R,20S,24S)-3,6,12-Triacetyl-20,24-ep­oxy­dammarane-3,6,12,25-tetra­ol

Huan-Mei Guo; Liang Wang; Nan Wang; Jiang-Feng Zhang; Qing-Guo Meng

doi:10.1107/S1600536810050749

. 2010 Dec 11;67(Pt 1):o59. doi: 10.1107/S1600536810050749

(3R,6R,12R,20S,24S)-3,6,12-Triacetyl-20,24-epoxydammarane-3,6,12,25-tetraol

Huan-Mei Guo ^a, Liang Wang ^b, Nan Wang ^b, Jiang-Feng Zhang ^b, Qing-Guo Meng ^b,^*

PMCID: PMC3050417 PMID: 21522769

Abstract

The title compound, C₃₆H₅₈O₈, was prepared from 20(S)-protopanaxatriol, which was degraded from Panax quinquefolium saponin with sodium in glycerine, extracted and seperated by flash chromatography. Three six-membered rings are in chair conformations, the five-membered ring is in an envelope form and the tetrahydrofuran ring has a conformation intermediate between half-chair and envelope. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, and C—H⋯O contacts also occur. The absolute structure was assigned on the basis of the synthesis.

Related literature

For background to the medicinal uses of Araliaceae-type natural products, see: Shibata et al. (1985 ▶); Takano et al. (1999 ▶); Yu et al. (2007 ▶); Wang et al. (2010 ▶). For related structures, see: Iljin et al. (1982 ▶); Shi et al. (1992 ▶).

Experimental

Crystal data

C₃₆H₅₈O₈
M _r = 618.82
Orthorhombic,
a = 7.6936 (11) Å
b = 16.151 (2) Å
c = 28.439 (4) Å
V = 3533.7 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 298 K
0.41 × 0.20 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer
18696 measured reflections
3738 independent reflections
2746 reflections with I > 2σ(I)
R _int = 0.044

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.115
S = 1.04
3738 reflections
409 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: SMART (Bruker, 1997 ▶); cell refinement: SAINT (Bruker, 1997 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810050749/hb5749sup1.cif

e-67-00o59-sup1.cif^{(32.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810050749/hb5749Isup2.hkl

e-67-00o59-Isup2.hkl^{(183.3KB, 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
O1—H1⋯O8ⁱ	0.82	2.36	3.050 (4)	142
C8—H8⋯O8ⁱ	0.98	2.58	3.526 (4)	161
C35—H35C⋯O6ⁱⁱ	0.96	2.45	3.403 (5)	172

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

Acknowledgments

The authors thank Mr. Lian-dong Liu (College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University) for his invaluable support with the X-ray data collection. The authors would like to thank Shandong Provincial Natural Science Foundation, China (Y2007C138), and the Scientific Reasearch Foundation of the Higher Education Institutions of Shandong Province and China (J07WE26) for a research grant.

supplementary crystallographic information

Comment

Both Panax ginseng and Panax quinquefolium, belonging to the Araliaceae, are well known traditional medicinal herbs. They are used as tonics and the treatment for diseases, such as tumor and myocardial ischemia. Panax ginseng contains numbers of saponins, called ginsenoside, including an oleanolic acid-type saponin in addition to the major protopanaxadiol and protopanaxatriol-type saponins (Shibata et al.,1985). Panax quinquefolium contains an ocotillol-type (20S, 24R-epoxyside) saponin with high anti-tumor activity (Takano et al.,1999), as well as oleanolic acid-type saponin, protopanaxadiol and protopanaxatriol-type saponins. (3R,6R,12R,20S,24S)-20,24-epoxy-dammarane-3,6,12,25-tetraol and (3R,6R,12R,20S,24R)-20,24-epoxy-dammarane-3,12,25-triol are found to possess cardioprotective effect on myocardial injury induced by isoproterenol in rats (Yu et al.,2007; Wang et al.,2010). As part of our ongoing investigation of ocotillol-type compound and their cardioprotective effect on myocardial injury, we report here the crystal structure of the title compound, (I).

In the molecule, all bond lengths and angles are within normal ranges (Shi et al., 1992; Iljin et al., 1982) Rings A(C11,C13,C16,C17,C18,C19), B(C13,C15,C16,C22,C32,C33), and C(C22,C24,C25,C26,C29,C32)are in chair conformations. Ring D(8,C9,C10,C11,C19) has an envelope form with C11 as the out-of-plane atom. The tetrahydrofuran ring has a conformation intermediate between half-chair and envelope forms. In the crystal, O—H···O hydrogen bonds occur.

Experimental

20(S)-protopanaxatriol was degraded from Panax quinquefolium saponin with sodium in glycerine at about 200°C and seperated by flash chromatography. (3R,6R,12R,20S,24S)-3,6,12-acetyl-20,24-epoxy-dammarane- 3,6,12,25-tetraol was synthesized from 20(S)-protopanaxatriol in the presence of N,N-dimethylaminopyridine, pyridine and acetic anhydride. The esters were oxidized by m-CPBA and seperated by flash chromatography. Finally, the crystals were dried at room temperature. Colourless blocks of (I) were obtained by recrystallization from ethyl acetate and petroleum ether (60–90°C) at room temperature.