The title compound, 4-methoxy-2-[(1
S,2
R,3
S,4
S,5
R)-3,4,5,6-tetrahydro-3,4,5-trihydroxy-6-(hydroxymethyl)-2
H-pyran-2-yl]-
-resorcylic acid
-lactone monohydrate, C
14H
16O
9·H
2O, is a
C-glucoside of 4-
O-methylgallic acid which has antiasthmatic, antitussive, anti-inflammatory, antifungal, anti-HIV and antihepatotoxic activity. The molecule is composed of three six-membered rings: an aromatic ring, a glucopyranose ring and an annellated
-lactone ring. The glucopyranose ring exhibits only small deviations from an ideal chair conformation. The annellated
-lactone ring possesses the expected half-chair conformation. There is one intra- and six intermolecular hydrogen bonds which form an extensive hydrogen-bonding network within the crystal.
Supporting information
CCDC reference: 243598
The rhizomes of A. chinensis were collected in Anji county, Zhejiang province, China, in August 2001. The plants were identified as A. chinensis (Maxim.) Franch. et Savat. by Professor Xiang-Ji Xue, College of Pharmaceutical Science, Zhejiang University. A voucher specimen (No. 200120) was deposited in the Laboratory of Nature and Biochemistry, Zhejiang University. The rhizomes of Astilbe Chinensis were dried in the dark, in a ventilated hood, and ground. The material (5.0 kg) was extracted with MeOH (3 × 25 l) at room temperature to give 366 g of extract. The MeOH extract was suspended in H2O, and sequentially partitioned with petroleum ether and EtOAc. The EtOAc extract (90.9 g) was absorbed onto silica gel and chromatographied on a silica-gel column eluted successively with CHCl3, CHCl3/MeOH (9:1), CHCl3/MeOH (4:1) and CHCl3/MeOH (1:1), to yield five fractions. The third fraction was subjected to column chromatography on Sephadex LH-20 and eluted with MeOH to afford 15.342 g of the pure title compound, (I). Crystals suitable for X-ray structure analysis were obtained by slow evaporation from an MeOH/H2O (1:1) solution at room temperature (m.p. 443–445 K But 413 K given in CIF data block). Spectroscopic analysis: 13C NMR (125 MHz, DMDO-d6, δ, p.p.m): 163.3 (C1), 150.9 (C6), 148.1 (C7), 140.8 (C8), 118.1 (C5), 116.1 (C10), 109.7 (C9), 81.9 (C13), 80.0 (C3), 74.0 (C11), 72.4 (C4), 71.0 (C12), 61.3 (C14), 60.0 (C15).
After location of H atoms in difference density maps, all H atoms were geometrically fixed and allowed to ride on their attached atoms using SHELXL97 (Sheldrick, 1997) defaults. The structure was refined using the absolute stereochemistry established through chemical synthesis (Frick & Schmidt, 1991).
Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL/PC (Siemens, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC; software used to prepare material for publication: SHELXTL/PC.
4-methoxy-2-[tetrahydro-3,4,5-trihydroxy-6-(hydroxymethyl) pyran-2-yl]-
α-resorcylic acid
δ-lactone monohydrate
top
Crystal data top
C14H16O9·H2O | Dx = 1.542 Mg m−3 |
Mr = 346.28 | Melting point: 413(1) K |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.497 (1) Å | Cell parameters from 34 reflections |
b = 13.930 (2) Å | θ = 3.2–14.7° |
c = 14.282 (2) Å | µ = 0.13 mm−1 |
V = 1491.5 (4) Å3 | T = 288 K |
Z = 4 | Prism, colourless |
F(000) = 728 | 0.56 × 0.52 × 0.50 mm |
Data collection top
Siemens P4 diffractometer | Rint = 0.010 |
Radiation source: normal-focus sealed tube | θmax = 29.2°, θmin = 2.0° |
Graphite monochromator | h = 0→10 |
ω scans | k = 0→19 |
2523 measured reflections | l = −1→19 |
2330 independent reflections | 3 standard reflections every 97 reflections |
1787 reflections with I > 2σ(I) | intensity decay: 3.5% |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.036 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.088 | w = 1/[σ2(Fo2) + (0.049P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.96 | (Δ/σ)max < 0.001 |
2330 reflections | Δρmax = 0.27 e Å−3 |
232 parameters | Δρmin = −0.19 e Å−3 |
3 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0135 (19) |
Crystal data top
C14H16O9·H2O | V = 1491.5 (4) Å3 |
Mr = 346.28 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.497 (1) Å | µ = 0.13 mm−1 |
b = 13.930 (2) Å | T = 288 K |
c = 14.282 (2) Å | 0.56 × 0.52 × 0.50 mm |
Data collection top
Siemens P4 diffractometer | Rint = 0.010 |
2523 measured reflections | 3 standard reflections every 97 reflections |
2330 independent reflections | intensity decay: 3.5% |
1787 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.036 | 3 restraints |
wR(F2) = 0.088 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.96 | Δρmax = 0.27 e Å−3 |
2330 reflections | Δρmin = −0.19 e Å−3 |
232 parameters | |
Special details top
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) top | x | y | z | Uiso*/Ueq | |
O1 | 0.0940 (2) | 0.54515 (13) | 0.70349 (13) | 0.0474 (5) | |
O2 | 0.2351 (2) | 0.46012 (10) | 0.59816 (11) | 0.0324 (4) | |
O3 | 0.6459 (2) | 0.50246 (10) | 0.46516 (10) | 0.0264 (3) | |
O4 | 0.7915 (2) | 0.66373 (12) | 0.53087 (13) | 0.0409 (5) | |
H4O | 0.7938 | 0.6112 | 0.5050 | 0.049* | |
O5 | 0.7156 (2) | 0.83886 (10) | 0.60465 (12) | 0.0326 (4) | |
O6 | 0.4244 (2) | 0.86799 (11) | 0.70672 (13) | 0.0409 (5) | |
H6O | 0.3372 | 0.8684 | 0.7414 | 0.049* | |
O7 | 0.2102 (2) | 0.31910 (11) | 0.45466 (12) | 0.0303 (4) | |
H7O | 0.1542 | 0.3601 | 0.4258 | 0.036* | |
O8 | 0.5575 (2) | 0.25522 (10) | 0.38740 (11) | 0.0310 (4) | |
H8O | 0.5946 | 0.2283 | 0.4346 | 0.037* | |
O9 | 0.9834 (2) | 0.45263 (12) | 0.37981 (13) | 0.0386 (4) | |
H9O | 0.9927 | 0.5076 | 0.3599 | 0.046* | |
C1 | 0.2193 (3) | 0.54124 (16) | 0.64929 (17) | 0.0314 (5) | |
C3 | 0.3551 (3) | 0.46160 (15) | 0.51905 (15) | 0.0244 (4) | |
H3 | 0.3044 | 0.5011 | 0.4689 | 0.029* | |
C4 | 0.5357 (3) | 0.50095 (15) | 0.54730 (14) | 0.0234 (4) | |
H4 | 0.5896 | 0.4593 | 0.5949 | 0.028* | |
C5 | 0.5106 (3) | 0.60018 (15) | 0.58636 (15) | 0.0238 (4) | |
C6 | 0.6355 (3) | 0.67383 (15) | 0.57784 (15) | 0.0256 (5) | |
C7 | 0.6017 (3) | 0.76364 (15) | 0.61761 (16) | 0.0271 (5) | |
C8 | 0.4457 (3) | 0.77830 (15) | 0.66983 (16) | 0.0285 (5) | |
C9 | 0.3232 (3) | 0.70564 (16) | 0.68016 (16) | 0.0299 (5) | |
H9 | 0.2206 | 0.7154 | 0.7154 | 0.036* | |
C10 | 0.3537 (3) | 0.61736 (15) | 0.63750 (16) | 0.0257 (5) | |
C11 | 0.3756 (3) | 0.35838 (15) | 0.48548 (15) | 0.0238 (4) | |
H11 | 0.4173 | 0.3198 | 0.5385 | 0.029* | |
C12 | 0.5171 (3) | 0.35300 (14) | 0.40864 (15) | 0.0241 (4) | |
H12 | 0.4683 | 0.3830 | 0.3521 | 0.029* | |
C13 | 0.6891 (3) | 0.40618 (14) | 0.43521 (15) | 0.0245 (5) | |
H13 | 0.7486 | 0.3720 | 0.4864 | 0.029* | |
C14 | 0.8144 (3) | 0.41411 (17) | 0.35295 (17) | 0.0308 (5) | |
H14A | 0.8317 | 0.3510 | 0.3256 | 0.037* | |
H14B | 0.7613 | 0.4551 | 0.3056 | 0.037* | |
C15 | 0.8762 (4) | 0.8319 (2) | 0.6577 (2) | 0.0574 (9) | |
H15A | 0.8477 | 0.8258 | 0.7229 | 0.069* | |
H15B | 0.9466 | 0.8887 | 0.6482 | 0.069* | |
H15C | 0.9425 | 0.7767 | 0.6377 | 0.069* | |
O10 | 0.8437 (2) | 0.39252 (13) | 0.67747 (14) | 0.0377 (4) | |
H10A | 0.898 (3) | 0.3449 (12) | 0.660 (2) | 0.064 (11)* | |
H10B | 0.916 (3) | 0.4374 (14) | 0.685 (2) | 0.072 (11)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0431 (10) | 0.0396 (10) | 0.0596 (11) | −0.0141 (9) | 0.0279 (10) | −0.0178 (9) |
O2 | 0.0320 (9) | 0.0247 (8) | 0.0405 (9) | −0.0081 (7) | 0.0149 (8) | −0.0071 (7) |
O3 | 0.0255 (8) | 0.0202 (7) | 0.0334 (8) | −0.0003 (6) | 0.0074 (7) | −0.0026 (7) |
O4 | 0.0311 (9) | 0.0381 (10) | 0.0535 (11) | −0.0112 (8) | 0.0166 (9) | −0.0148 (9) |
O5 | 0.0320 (8) | 0.0250 (8) | 0.0409 (9) | −0.0087 (7) | −0.0016 (8) | 0.0028 (7) |
O6 | 0.0415 (11) | 0.0205 (7) | 0.0607 (12) | −0.0008 (8) | 0.0175 (10) | −0.0066 (8) |
O7 | 0.0259 (8) | 0.0239 (7) | 0.0410 (9) | −0.0041 (7) | −0.0029 (8) | 0.0003 (7) |
O8 | 0.0339 (9) | 0.0224 (7) | 0.0368 (8) | 0.0036 (7) | −0.0013 (8) | −0.0044 (7) |
O9 | 0.0240 (8) | 0.0306 (9) | 0.0612 (11) | 0.0008 (7) | 0.0004 (9) | 0.0101 (8) |
C1 | 0.0302 (12) | 0.0266 (11) | 0.0373 (12) | −0.0047 (11) | 0.0058 (11) | −0.0053 (10) |
C3 | 0.0220 (10) | 0.0216 (10) | 0.0295 (11) | −0.0014 (9) | 0.0037 (9) | 0.0001 (9) |
C4 | 0.0216 (10) | 0.0218 (9) | 0.0267 (10) | 0.0004 (9) | 0.0024 (9) | −0.0005 (9) |
C5 | 0.0240 (10) | 0.0225 (10) | 0.0248 (10) | −0.0022 (9) | 0.0002 (9) | −0.0015 (9) |
C6 | 0.0229 (10) | 0.0264 (11) | 0.0274 (11) | −0.0016 (9) | 0.0019 (9) | −0.0021 (9) |
C7 | 0.0266 (11) | 0.0226 (10) | 0.0320 (11) | −0.0039 (9) | −0.0025 (10) | 0.0027 (9) |
C8 | 0.0291 (12) | 0.0222 (10) | 0.0341 (12) | 0.0018 (10) | 0.0023 (11) | −0.0016 (9) |
C9 | 0.0285 (12) | 0.0278 (11) | 0.0334 (12) | −0.0003 (10) | 0.0058 (11) | −0.0018 (10) |
C10 | 0.0242 (11) | 0.0215 (10) | 0.0315 (11) | −0.0036 (9) | 0.0030 (10) | −0.0011 (9) |
C11 | 0.0229 (10) | 0.0193 (9) | 0.0291 (11) | −0.0009 (8) | −0.0012 (9) | 0.0004 (9) |
C12 | 0.0258 (11) | 0.0194 (9) | 0.0271 (10) | 0.0008 (9) | −0.0023 (10) | 0.0008 (8) |
C13 | 0.0220 (10) | 0.0208 (10) | 0.0306 (11) | 0.0039 (9) | −0.0013 (9) | 0.0002 (9) |
C14 | 0.0263 (12) | 0.0318 (12) | 0.0342 (12) | 0.0009 (10) | 0.0045 (10) | −0.0028 (10) |
C15 | 0.0461 (18) | 0.0574 (19) | 0.069 (2) | −0.0238 (16) | −0.0226 (16) | 0.0127 (16) |
O10 | 0.0294 (9) | 0.0332 (9) | 0.0504 (11) | −0.0004 (8) | 0.0042 (9) | 0.0003 (9) |
Geometric parameters (Å, º) top
O1—C1 | 1.219 (3) | C4—H4 | 0.9800 |
O2—C1 | 1.351 (3) | C5—C6 | 1.395 (3) |
O2—C3 | 1.444 (3) | C5—C10 | 1.404 (3) |
O3—C4 | 1.435 (2) | C6—C7 | 1.397 (3) |
O3—C13 | 1.444 (2) | C7—C8 | 1.402 (3) |
O4—C6 | 1.356 (3) | C8—C9 | 1.374 (3) |
O4—H4O | 0.8200 | C9—C10 | 1.391 (3) |
O5—C7 | 1.365 (3) | C9—H9 | 0.9300 |
O5—C15 | 1.426 (3) | C11—C12 | 1.528 (3) |
O6—C8 | 1.365 (3) | C11—H11 | 0.9800 |
O6—H6O | 0.8200 | C12—C13 | 1.535 (3) |
O7—C11 | 1.425 (3) | C12—H12 | 0.9800 |
O7—H7O | 0.8200 | C13—C14 | 1.508 (3) |
O8—C12 | 1.428 (2) | C13—H13 | 0.9800 |
O8—H8O | 0.8200 | C14—H14A | 0.9700 |
O9—C14 | 1.428 (3) | C14—H14B | 0.9700 |
O9—H9O | 0.8200 | C15—H15A | 0.9600 |
C1—C10 | 1.473 (3) | C15—H15B | 0.9600 |
C3—C4 | 1.516 (3) | C15—H15C | 0.9600 |
C3—C11 | 1.523 (3) | O10—H10A | 0.82 (2) |
C3—H3 | 0.9800 | O10—H10B | 0.83 (2) |
C4—C5 | 1.502 (3) | | |
| | | |
C1—O2—C3 | 117.75 (16) | C8—C9—H9 | 120.2 |
C4—O3—C13 | 110.94 (15) | C10—C9—H9 | 120.2 |
C6—O4—H4O | 109.5 | C9—C10—C5 | 121.1 (2) |
C7—O5—C15 | 113.87 (19) | C9—C10—C1 | 118.3 (2) |
C8—O6—H6O | 109.5 | C5—C10—C1 | 120.64 (19) |
C11—O7—H7O | 109.5 | O7—C11—C3 | 111.83 (18) |
C12—O8—H8O | 109.5 | O7—C11—C12 | 111.31 (16) |
C14—O9—H9O | 109.5 | C3—C11—C12 | 110.01 (17) |
O1—C1—O2 | 116.6 (2) | O7—C11—H11 | 107.8 |
O1—C1—C10 | 124.6 (2) | C3—C11—H11 | 107.8 |
O2—C1—C10 | 118.7 (2) | C12—C11—H11 | 107.8 |
O2—C3—C4 | 110.69 (16) | O8—C12—C11 | 110.28 (17) |
O2—C3—C11 | 107.18 (16) | O8—C12—C13 | 109.57 (17) |
C4—C3—C11 | 109.58 (17) | C11—C12—C13 | 112.45 (17) |
O2—C3—H3 | 109.8 | O8—C12—H12 | 108.1 |
C4—C3—H3 | 109.8 | C11—C12—H12 | 108.1 |
C11—C3—H3 | 109.8 | C13—C12—H12 | 108.1 |
O3—C4—C5 | 111.25 (16) | O3—C13—C14 | 107.58 (17) |
O3—C4—C3 | 107.58 (16) | O3—C13—C12 | 109.48 (16) |
C5—C4—C3 | 108.62 (17) | C14—C13—C12 | 111.48 (17) |
O3—C4—H4 | 109.8 | O3—C13—H13 | 109.4 |
C5—C4—H4 | 109.8 | C14—C13—H13 | 109.4 |
C3—C4—H4 | 109.8 | C12—C13—H13 | 109.4 |
C6—C5—C10 | 118.83 (19) | O9—C14—C13 | 111.77 (19) |
C6—C5—C4 | 124.05 (19) | O9—C14—H14A | 109.3 |
C10—C5—C4 | 117.07 (18) | C13—C14—H14A | 109.3 |
O4—C6—C5 | 123.12 (19) | O9—C14—H14B | 109.3 |
O4—C6—C7 | 116.79 (19) | C13—C14—H14B | 109.3 |
C5—C6—C7 | 120.1 (2) | H14A—C14—H14B | 107.9 |
O5—C7—C6 | 121.3 (2) | O5—C15—H15A | 109.5 |
O5—C7—C8 | 118.85 (19) | O5—C15—H15B | 109.5 |
C6—C7—C8 | 119.88 (19) | H15A—C15—H15B | 109.5 |
O6—C8—C9 | 123.7 (2) | O5—C15—H15C | 109.5 |
O6—C8—C7 | 115.9 (2) | H15A—C15—H15C | 109.5 |
C9—C8—C7 | 120.5 (2) | H15B—C15—H15C | 109.5 |
C8—C9—C10 | 119.6 (2) | H10A—O10—H10B | 109 (2) |
| | | |
C3—O2—C1—O1 | 166.0 (2) | O6—C8—C9—C10 | 178.0 (2) |
C3—O2—C1—C10 | −15.0 (3) | C7—C8—C9—C10 | −0.7 (4) |
C1—O2—C3—C4 | 50.0 (3) | C8—C9—C10—C5 | 2.0 (3) |
C1—O2—C3—C11 | 169.4 (2) | C8—C9—C10—C1 | −179.5 (2) |
C13—O3—C4—C5 | 172.40 (17) | C6—C5—C10—C9 | −0.8 (3) |
C13—O3—C4—C3 | −68.8 (2) | C4—C5—C10—C9 | 176.8 (2) |
O2—C3—C4—O3 | −178.63 (16) | C6—C5—C10—C1 | −179.2 (2) |
C11—C3—C4—O3 | 63.4 (2) | C4—C5—C10—C1 | −1.6 (3) |
O2—C3—C4—C5 | −58.1 (2) | O1—C1—C10—C9 | −10.0 (4) |
C11—C3—C4—C5 | −176.11 (17) | O2—C1—C10—C9 | 171.1 (2) |
O3—C4—C5—C6 | −29.5 (3) | O1—C1—C10—C5 | 168.5 (2) |
C3—C4—C5—C6 | −147.8 (2) | O2—C1—C10—C5 | −10.4 (3) |
O3—C4—C5—C10 | 153.01 (17) | O2—C3—C11—O7 | 62.0 (2) |
C3—C4—C5—C10 | 34.8 (2) | C4—C3—C11—O7 | −177.78 (17) |
C10—C5—C6—O4 | 179.2 (2) | O2—C3—C11—C12 | −173.71 (16) |
C4—C5—C6—O4 | 1.8 (3) | C4—C3—C11—C12 | −53.5 (2) |
C10—C5—C6—C7 | −1.7 (3) | O7—C11—C12—O8 | −64.7 (2) |
C4—C5—C6—C7 | −179.1 (2) | C3—C11—C12—O8 | 170.75 (18) |
C15—O5—C7—C6 | −74.6 (3) | O7—C11—C12—C13 | 172.67 (16) |
C15—O5—C7—C8 | 107.2 (3) | C3—C11—C12—C13 | 48.1 (2) |
O4—C6—C7—O5 | 3.9 (3) | C4—O3—C13—C14 | −176.29 (17) |
C5—C6—C7—O5 | −175.3 (2) | C4—O3—C13—C12 | 62.4 (2) |
O4—C6—C7—C8 | −177.9 (2) | O8—C12—C13—O3 | −174.63 (16) |
C5—C6—C7—C8 | 3.0 (3) | C11—C12—C13—O3 | −51.6 (2) |
O5—C7—C8—O6 | −2.3 (3) | O8—C12—C13—C14 | 66.5 (2) |
C6—C7—C8—O6 | 179.5 (2) | C11—C12—C13—C14 | −170.53 (18) |
O5—C7—C8—C9 | 176.5 (2) | O3—C13—C14—O9 | 67.3 (2) |
C6—C7—C8—C9 | −1.7 (3) | C12—C13—C14—O9 | −172.68 (17) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···O3 | 0.82 | 1.96 | 2.668 (2) | 144 |
O6—H6O···O10i | 0.82 | 1.81 | 2.625 (2) | 169 |
O7—H7O···O9ii | 0.82 | 1.93 | 2.737 (2) | 167 |
O8—H8O···O7iii | 0.82 | 1.92 | 2.733 (2) | 171 |
O9—H9O···O6iv | 0.82 | 2.04 | 2.823 (2) | 159 |
O10—H10B···O1v | 0.83 (2) | 2.03 (2) | 2.860 (3) | 179 (4) |
O10—H10A···O8iii | 0.83 (2) | 1.95 (2) | 2.768 (2) | 171 (3) |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) x+1/2, −y+1/2, −z+1; (iv) x+1/2, −y+3/2, −z+1; (v) x+1, y, z. |
Experimental details
Crystal data |
Chemical formula | C14H16O9·H2O |
Mr | 346.28 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 288 |
a, b, c (Å) | 7.497 (1), 13.930 (2), 14.282 (2) |
V (Å3) | 1491.5 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.56 × 0.52 × 0.50 |
|
Data collection |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2523, 2330, 1787 |
Rint | 0.010 |
(sin θ/λ)max (Å−1) | 0.687 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.088, 0.96 |
No. of reflections | 2330 |
No. of parameters | 232 |
No. of restraints | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.27, −0.19 |
Selected geometric parameters (Å, º) topO1—C1 | 1.219 (3) | O2—C1 | 1.351 (3) |
| | | |
C3—O2—C1—O1 | 166.0 (2) | O4—C6—C7—O5 | 3.9 (3) |
C3—O2—C1—C10 | −15.0 (3) | O5—C7—C8—O6 | −2.3 (3) |
C1—O2—C3—C4 | 50.0 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4O···O3 | 0.82 | 1.96 | 2.668 (2) | 144 |
O6—H6O···O10i | 0.82 | 1.81 | 2.625 (2) | 169 |
O7—H7O···O9ii | 0.82 | 1.93 | 2.737 (2) | 167 |
O8—H8O···O7iii | 0.82 | 1.92 | 2.733 (2) | 171 |
O9—H9O···O6iv | 0.82 | 2.04 | 2.823 (2) | 159 |
O10—H10B···O1v | 0.83 (2) | 2.03 (2) | 2.860 (3) | 179 (4) |
O10—H10A···O8iii | 0.83 (2) | 1.95 (2) | 2.768 (2) | 171 (3) |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) x+1/2, −y+1/2, −z+1; (iv) x+1/2, −y+3/2, −z+1; (v) x+1, y, z. |
Bergenin has been isolated from the roots of Bergenia crassifolia (Hua et al., 1998), B. purpurascens and Casesalpinia digyna, from the bark of Corylopsis spicata and Mallotus japonicus (Yoshida et al., 1982), from the heartwood of Shorea leprosula and Macaranga peltatathe, and from the rhizhome of Astilbe chinensis (Sun et al., 2002). Pharmacological experiments have indicated that it possesses significant antiasthmatic, antitussive, anti-inflammatory, antifungal (Prithiviraj et al., 1997), in vitro anti-HIV (Piacente et al., 1996) and antihepatotoxic activity (Kim et al., 2000; Lim Kim Chung & Kim, 2000; Lim Kim Choi et al., 2000). The first structures of bergenin proposed by Tschitschibabin et al. (1929) and Shimokoriyama (1950) were revised independently by Hay & Haynes (1958) and Posternak & Dürr (1958). The structure of bergenin, which involves an aryl β-C-glucoside and an aryl δ-lactone ring, was unequivocally confirmed by synthesis of bergenin-type C-glucosylarenes (Frick & Schmidt, 1991) and an X-ray analysis of 3,4,8,10,11-penta-O-acetylbergenin (Frick et al., 1991). Meanwhile, the chemical structure of the natural product bergenin from plants was determined on the basis of two-dimensional NMR data (Zhou et al., 1999). The chemical structure of bergenin as the title monohydrate, (I), has now been confirmed by single-crystal X-ray diffraction analysis. \sch
The structure of (I), with the atom-numbering scheme, is shown in Fig. 1. The molecule is composed of three six-membered rings, viz. A (C5—C10, an aromatic ring), B (C1/O2/C3—C5/C10, an annellated δ-lactone ring) and C (C3—C4/C11—C13/O3, a glucopyranose ring). Ring B possesses the expected half-chair conformation, while ring C exhibits only small deviations from an ideal chair conformation. The B/C junction is trans fused. The hydroxyl and hydroxymethyl substituents at the other chiral centres (atoms C11, C12 and C13) adopt equatorial conformations with respect to the glucopyranose ring. The structure of (I) is consistent with the conformation found for 3,4,8,10,11-penta-O-acetylbergenin by Frick et al. (1991) through an X-ray analysis.
All hydroxyl groups, except for C6—OH, serve as simultaneous hydrogen-bond donors and acceptors (Table 2), resulting in one intra- and six intermolecular O—H···O hydrogen bonds. The intramolecular O—H···O hydrogen bond is formed between atom H4 of the C6 hydroxyl group and the O3 ring atom of the glucopyranose moiety. The water atom, O10, acts as an acceptor, with the O6 hydroxyl atom as donor, to form O6—H6O···O10 hydrogen bonds between the solvent and bergenin.
In the solid state, the screw-related molecules are linked by O7—H7O···O9, O8—H8O···O7 and O9—H9O···O6 hydrogen bonds, to form molecular chains along the a axis. The chain formation is further stabilized by the solvent water through O10—H10B···O1 and O10—H10A.·O8 hydrogen bonds.