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Acta Crystallogr Sect E Struct Rep Online. 2008 February 1; 64(Pt 2): o371.
Published online 2008 January 4. doi:  10.1107/S1600536807067864
PMCID: PMC2960471

2-Hydr­oxy-1,6,7,8-tetra­meth­oxy-3-methyl­anthraquinone

Abstract

The title compound, C19H18O7, also known as chrysoobtusin, was isolated from Cassia tora L. (Leguminosae). The anthraquinone ring system is almost planar, the dihedral angle between the two benzene rings being 4.27 (4)°. The structure is stabilized by intra- and inter­molecular O—H(...)O and C—H(...)O hydrogen bonds, and by weak π–π stacking inter­actions along the b axis, with a centroid–centroid distance between related benzene rings of 3.800 (4) Å.

Related literature

For related literature, see: Boonnak et al. (2005 [triangle]); Hao et al. (1995 [triangle]); Jia et al. (2007 [triangle]); Ng et al. (2005 [triangle]); Patil et al. (2004 [triangle]); Wu & Yen (2004 [triangle]); Allen et al. (1987 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-0o371-scheme1.jpg

Experimental

Crystal data

  • C19H18O7
  • M r = 358.33
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o371-efi1.jpg
  • a = 12.2960 (3) Å
  • b = 7.8545 (2) Å
  • c = 18.3361 (5) Å
  • β = 106.581 (2)°
  • V = 1697.24 (8) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.11 mm−1
  • T = 296 (2) K
  • 0.30 × 0.28 × 0.26 mm

Data collection

  • Bruker APEXII area-detector diffractometer
  • Absorption correction: none
  • 13295 measured reflections
  • 3871 independent reflections
  • 2527 reflections with I > 2σ(I)
  • R int = 0.032

Refinement

  • R[F 2 > 2σ(F 2)] = 0.046
  • wR(F 2) = 0.133
  • S = 1.02
  • 3871 reflections
  • 241 parameters
  • H-atom parameters constrained
  • Δρmax = 0.19 e Å−3
  • Δρmin = −0.21 e Å−3

Data collection: APEX2 (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: SHELXTL (Bruker, 2004 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807067864/rz2185sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807067864/rz2185Isup2.hkl

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

Acknowledgments

The authors acknowledge the Ministry of Science and Technology of China (fund No. 2006BAD27B03) for financial support, and South China University of Technology and South China Normal University for supporting this work.

supplementary crystallographic information

Comment

Anthraquinone derivatives extracted from the seeds of Cassia tora L. (most common familiar name in China: Juemingzi) have been used traditionally to improve visual acuity. Recent studies have demonstrated that they have multiple pharmacological actions such as antimicrobial, diuretic, antidiarrhoic, antioxidant, antihepatotoxic and antimutagenic activities (Wu & Yen, 2004). One component found in Cassia tora L., 2-hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone, is known as chrysoobusin and exhibits a variety of potent biological effects such as suppression of mutagenicity of mycotoxins (Hao et al., 1995), antioxidant activity (Jia et al., 2007) and hypolipidemic activity (Patil et al., 2004). We report here the structure of the title compound.

In the title compound (Fig. 1), the C—C bond lengths show normal values (Allen et al., 1987), and the C—O and C=O bond lengths are comparable to those observed in similar structures (Ng et al., 2005; Boonnak et al., 2005). The anthraquinone ring system is substantially planar, the dihedral angle between the two benzene rings being 4.27 (4)°. The molecules are self-assembled by intra- and intermolecular C—H···O and O—H···.O hydrogen bonding interactions (Table 1) into a superamolecular network. The crystal structure is further stabilized by weak π-π stacking interactions along the b axis (Fig. 2) occurring between centrosymmetrically related anthraquinone ring systems. The centroid-to-centriod distances between related benzene rings of the stacked molecules is 3.800 (4) Å.

Experimental

The seeds of Cassia tora L. (800 g) were shattered to powder (about 30 mesh) and extracted with 60% ethanol (3000 ml) for 40 min by microwave irradiation at 333 K. The extraction procedure was repeated three times. The extracts were combined and evaporated to dryness under reduced pressure at 333 K, the residue was redissolved in water (600 ml) and was added 400 ml light petroleum to remove low-polar substaces three times. Then the enriched extracts were extracted with chloroform four times (500 ml for each time), the chlorofrom solution were combined and evaporated to dryness under reduced pressure at 333 K, 4.52 g crude extracts was obtained. The crude extracts were separated with n-hexane-ethyl acetate-methanol-water (11: 90: 10: 10, v/v) using high-speed counter-current chromatography (HSCCC) to obtain 2-hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone (yield 46.2 mg). Single crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

Refinement

All H atoms were placed at calculated positions and were treated as riding on the parent C atoms with C—H = 0.93–0.97 and O—H = 0.82 Å, and with Uiso(H) = 1.2 or 1.5 Ueq(C, O).

Figures

Fig. 1.
The molecular structure of the title compound showing the atomic-numbering scheme and displacement ellipsoids drawn at the 50% probability level.
Fig. 2.
The molecular packing of the title compound showing the intra- and intermolecular hydrogen bonding interactions as broken lines.

Crystal data

C19H18O7F000 = 752
Mr = 358.33Dx = 1.402 Mg m3
Monoclinic, P21/nMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 3645 reflections
a = 12.2960 (3) Åθ = 1.4–28.0º
b = 7.8545 (2) ŵ = 0.11 mm1
c = 18.3361 (5) ÅT = 296 (2) K
β = 106.581 (2)ºBlock, yellow
V = 1697.24 (8) Å30.30 × 0.28 × 0.26 mm
Z = 4

Data collection

Bruker APEXII area-detector diffractometer2527 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.032
Monochromator: graphiteθmax = 27.5º
T = 296(2) Kθmin = 1.8º
f and ω scansh = −15→15
Absorption correction: nonek = −10→10
13295 measured reflectionsl = −23→23
3871 independent reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.133  w = 1/[σ2(Fo2) + (0.0598P)2 + 0.2883P] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
3871 reflectionsΔρmax = 0.19 e Å3
241 parametersΔρmin = −0.21 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
C10.12772 (16)0.3847 (2)−0.08053 (10)0.0478 (4)
C20.23670 (15)0.3514 (2)−0.03234 (10)0.0479 (4)
C30.25066 (14)0.2624 (2)0.03525 (9)0.0417 (4)
C40.15663 (13)0.2073 (2)0.05800 (9)0.0391 (4)
C50.04861 (13)0.2443 (2)0.00932 (9)0.0394 (4)
C60.03506 (15)0.3313 (2)−0.05891 (9)0.0452 (4)
H6−0.03760.3536−0.09020.054*
C7−0.05610 (14)0.1888 (2)0.02762 (9)0.0419 (4)
C8−0.04420 (13)0.10489 (19)0.10100 (9)0.0391 (4)
C90.06335 (13)0.07377 (19)0.15239 (9)0.0385 (4)
C100.16909 (14)0.1101 (2)0.12996 (9)0.0420 (4)
C110.06680 (13)−0.0001 (2)0.22235 (9)0.0404 (4)
C12−0.03346 (14)−0.0496 (2)0.23820 (9)0.0447 (4)
C13−0.14001 (14)−0.0222 (2)0.18680 (9)0.0459 (4)
C14−0.14247 (14)0.0570 (2)0.11918 (9)0.0444 (4)
H14−0.21240.07930.08440.053*
C150.01444 (17)0.4980 (3)−0.19883 (11)0.0645 (5)
H15A−0.02230.3913−0.21570.097*
H15B0.02360.5600−0.24180.097*
H15C−0.03110.5634−0.17440.097*
C160.3571 (2)0.5740 (3)−0.04686 (16)0.0795 (7)
H16A0.29510.6370−0.07940.119*
H16B0.42460.5946−0.06190.119*
H16C0.36900.60980.00490.119*
C170.41092 (17)0.0855 (3)0.06199 (13)0.0682 (6)
H17A0.3652−0.01080.06660.102*
H17B0.48550.07290.09670.102*
H17C0.41630.09200.01090.102*
C180.21311 (19)0.1135 (3)0.32189 (12)0.0727 (6)
H18A0.24430.18580.29070.109*
H18B0.27230.07900.36600.109*
H18C0.15590.17450.33750.109*
C19−0.24641 (16)−0.0758 (3)0.20556 (12)0.0666 (6)
H19A−0.3114−0.03110.16800.100*
H19B−0.2450−0.03270.25480.100*
H19C−0.2507−0.19780.20580.100*
O10.12327 (11)0.46722 (18)−0.14620 (7)0.0641 (4)
O20.33123 (11)0.39758 (17)−0.05315 (8)0.0617 (4)
O30.36000 (9)0.23760 (15)0.07962 (6)0.0495 (3)
O40.26068 (10)0.05769 (19)0.16791 (7)0.0642 (4)
O5−0.14949 (10)0.21417 (18)−0.01744 (7)0.0581 (4)
O60.16389 (10)−0.03329 (16)0.27947 (6)0.0510 (3)
O7−0.02886 (10)−0.12633 (19)0.30522 (7)0.0599 (4)
H70.0376−0.14340.32910.090*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0551 (11)0.0446 (9)0.0446 (9)0.0084 (8)0.0161 (8)0.0035 (8)
C20.0478 (10)0.0460 (9)0.0522 (10)0.0032 (8)0.0180 (8)−0.0028 (8)
C30.0395 (9)0.0421 (9)0.0407 (9)0.0039 (7)0.0069 (7)−0.0082 (7)
C40.0396 (9)0.0387 (8)0.0363 (8)0.0037 (7)0.0064 (7)−0.0053 (7)
C50.0412 (9)0.0371 (8)0.0367 (8)0.0034 (7)0.0061 (7)−0.0039 (7)
C60.0450 (9)0.0420 (9)0.0455 (9)0.0075 (7)0.0080 (7)0.0007 (8)
C70.0409 (9)0.0399 (9)0.0401 (8)0.0051 (7)0.0038 (7)−0.0022 (7)
C80.0399 (9)0.0369 (8)0.0368 (8)0.0029 (7)0.0047 (7)−0.0036 (7)
C90.0396 (8)0.0349 (8)0.0376 (8)0.0017 (7)0.0056 (7)−0.0034 (7)
C100.0388 (9)0.0431 (9)0.0392 (9)0.0036 (7)0.0032 (7)−0.0049 (7)
C110.0386 (8)0.0389 (8)0.0379 (8)0.0025 (7)0.0017 (7)−0.0031 (7)
C120.0474 (10)0.0459 (9)0.0379 (8)0.0022 (8)0.0078 (7)0.0005 (7)
C130.0426 (9)0.0484 (10)0.0450 (9)0.0006 (8)0.0098 (7)−0.0017 (8)
C140.0368 (8)0.0475 (9)0.0435 (9)0.0043 (7)0.0026 (7)−0.0019 (8)
C150.0741 (14)0.0684 (13)0.0482 (10)0.0172 (11)0.0129 (10)0.0118 (10)
C160.0717 (15)0.0681 (14)0.1065 (19)−0.0097 (12)0.0382 (14)0.0046 (14)
C170.0536 (11)0.0765 (14)0.0700 (13)0.0212 (10)0.0104 (10)−0.0125 (11)
C180.0665 (13)0.0868 (16)0.0526 (11)−0.0165 (12)−0.0026 (10)−0.0160 (11)
C190.0477 (11)0.0890 (15)0.0636 (12)−0.0002 (10)0.0165 (9)0.0115 (11)
O10.0621 (8)0.0764 (9)0.0543 (8)0.0081 (7)0.0177 (7)0.0207 (7)
O20.0554 (8)0.0657 (9)0.0712 (9)0.0024 (7)0.0298 (7)0.0041 (7)
O30.0375 (6)0.0581 (7)0.0487 (7)0.0028 (5)0.0056 (5)−0.0093 (6)
O40.0424 (7)0.0934 (11)0.0526 (7)0.0150 (7)0.0069 (6)0.0189 (7)
O50.0399 (7)0.0773 (9)0.0495 (7)0.0038 (6)0.0005 (6)0.0141 (7)
O60.0447 (7)0.0585 (7)0.0411 (6)−0.0002 (6)−0.0016 (5)0.0051 (6)
O70.0489 (7)0.0822 (10)0.0461 (7)0.0018 (7)0.0096 (6)0.0156 (7)

Geometric parameters (Å, °)

C1—O11.355 (2)C13—C141.380 (2)
C1—C61.374 (2)C13—C191.505 (2)
C1—C21.403 (2)C14—H140.9300
C2—O21.372 (2)C15—O11.429 (2)
C2—C31.390 (2)C15—H15A0.9600
C3—O31.3723 (19)C15—H15B0.9600
C3—C41.405 (2)C15—H15C0.9600
C4—C51.403 (2)C16—O21.419 (2)
C4—C101.494 (2)C16—H16A0.9600
C5—C61.393 (2)C16—H16B0.9600
C5—C71.485 (2)C16—H16C0.9600
C6—H60.9300C17—O31.428 (2)
C7—O51.2245 (19)C17—H17A0.9600
C7—C81.468 (2)C17—H17B0.9600
C8—C141.394 (2)C17—H17C0.9600
C8—C91.409 (2)C18—O61.425 (2)
C9—C111.397 (2)C18—H18A0.9600
C9—C101.499 (2)C18—H18B0.9600
C10—O41.2144 (19)C18—H18C0.9600
C11—O61.3699 (18)C19—H19A0.9600
C11—C121.400 (2)C19—H19B0.9600
C12—O71.355 (2)C19—H19C0.9600
C12—C131.395 (2)O7—H70.8200
O1—C1—C6125.14 (16)C13—C14—C8122.57 (15)
O1—C1—C2115.97 (16)C13—C14—H14118.7
C6—C1—C2118.88 (16)C8—C14—H14118.7
O2—C2—C3118.82 (16)O1—C15—H15A109.5
O2—C2—C1120.56 (16)O1—C15—H15B109.5
C3—C2—C1120.52 (16)H15A—C15—H15B109.5
O3—C3—C2116.80 (15)O1—C15—H15C109.5
O3—C3—C4122.02 (15)H15A—C15—H15C109.5
C2—C3—C4121.13 (15)H15B—C15—H15C109.5
C5—C4—C3117.20 (15)O2—C16—H16A109.5
C5—C4—C10120.50 (14)O2—C16—H16B109.5
C3—C4—C10122.29 (14)H16A—C16—H16B109.5
C6—C5—C4121.45 (15)O2—C16—H16C109.5
C6—C5—C7117.22 (14)H16A—C16—H16C109.5
C4—C5—C7121.32 (15)H16B—C16—H16C109.5
C1—C6—C5120.80 (16)O3—C17—H17A109.5
C1—C6—H6119.6O3—C17—H17B109.5
C5—C6—H6119.6H17A—C17—H17B109.5
O5—C7—C8121.37 (16)O3—C17—H17C109.5
O5—C7—C5120.42 (15)H17A—C17—H17C109.5
C8—C7—C5118.21 (14)H17B—C17—H17C109.5
C14—C8—C9120.37 (15)O6—C18—H18A109.5
C14—C8—C7118.30 (14)O6—C18—H18B109.5
C9—C8—C7121.33 (15)H18A—C18—H18B109.5
C11—C9—C8117.57 (15)O6—C18—H18C109.5
C11—C9—C10121.97 (14)H18A—C18—H18C109.5
C8—C9—C10120.37 (14)H18B—C18—H18C109.5
O4—C10—C4121.60 (15)C13—C19—H19A109.5
O4—C10—C9120.89 (15)C13—C19—H19B109.5
C4—C10—C9117.48 (13)H19A—C19—H19B109.5
O6—C11—C9124.92 (15)C13—C19—H19C109.5
O6—C11—C12114.54 (14)H19A—C19—H19C109.5
C9—C11—C12120.53 (14)H19B—C19—H19C109.5
O7—C12—C13118.00 (15)C1—O1—C15118.27 (15)
O7—C12—C11120.03 (14)C2—O2—C16115.05 (15)
C13—C12—C11121.98 (15)C3—O3—C17113.79 (13)
C14—C13—C12116.89 (15)C11—O6—C18113.88 (14)
C14—C13—C19122.28 (16)C12—O7—H7109.5
C12—C13—C19120.83 (16)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C18—H18A···O40.962.533.074 (3)116
C17—H17A···O40.962.603.046 (3)109
C16—H16A···O10.962.503.049 (3)116
O7—H7···O60.822.192.6482 (17)116
O7—H7···O3i0.822.022.7221 (16)144

Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2185).

References

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  • Bruker (2004). APEX2 (Version 7.23A), SAINT (Version 7.23A) and SHELXTL (Version 6.10). Bruker AXS Inc., Madison, Wisconsin, USA.
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  • Ng, S.-L., Razak, I. A., Fun, H.-K., Boonsri, S., Chantrapromma, S. & Prawat, U. (2005). Acta Cryst. E61, o3656–o3658.
  • Patil, U. K., Saraf, S. & Dixit, V. K. (2004). J. Ethnopharmacol.90, 249–252. [PubMed]
  • Sheldrick, G. M. (1997). SHELXS97 and SHELXL97 University of Göttingen, Germany.
  • Wu, C. H. & Yen, G. C. (2004). Life Sci.76, 85–101. [PubMed]

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