organic compounds
1,3,6-Trihydroxy-7-methoxy-2,8-bis(3-methylbut-2-enyl)-9H-xanthen-9-one
aDepartment of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
*Correspondence e-mail: gwen@science.upm.edu.my
The title compound (trivial name α-mangostin), C24H26O6, isolated from Cratoxylum glaucum, is characterized by a xanthone skeleton of three fused six-membered rings and two 3-methylbut-2-enyl side chains. The three rings in the structure are nearly coplanar, with an r.m.s. deviation for the tricyclic ring system of 0.0014 Å. The two 3-methylbut-2-enyl side chains are in (+)-synclinal and (-)-anticlinal conformations. Intramolecular O—H⋯O and C—H⋯O interactions occur. The is stabilized by intermolecular O—H⋯O, C—H⋯O and C—H⋯π interactions.
Related literature
For standard bond lengths, see Allen et al. (1987). For related structures, see: Marek et al. (2003); Ndjakou et al. (2007); Boonnak et al. (2007). For the biological activity of Cratoxylum species, see: Boonnak et al. (2006); Bennett et al. (1993); Nguyen & Harrison (1998); Boonsri et al. (2006); Reutrakul et al. (2006).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: CRYSTALS.
Supporting information
https://doi.org/10.1107/S1600536810049123/kp2293sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810049123/kp2293Isup2.hkl
The stem bark (3.75 kg) of Cratoxylum glaucum was ground and extracted with n-hexane, ethyl acetate and methanol. Fractionation of the ethyl acetate extract with vacuum
over Merck 7731 silica gel produced 25 fractions. Fraction 8 was subjected to further purification by (Merck Kieselgel No. 1.09385.1000). These columns were eluted with hexane, hexane/ethyl acetate, ethyl acetate/methanol in a step-wise gradual increment in polarity. The yellow amorphous powder obtained from fraction 6 was dissolved in chloroform and left for a month before orange crystals were obtained. The melting point was 452-453 K.The H atoms were all observed in a difference map, but those attached to carbon atoms were positioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H in the range 0.93–0.98, N—H in the range 0.86–0.89 N—H to 0.86 O—H = 0.82 Å) and Uiso(H) (in the range 1.2–1.5 times Ueq of the parent atom), after which the positions were refined with riding constraints.
Cratoxylum is a small genus which comprises of six species indigenous to Southeast Asia (Boonnak et al., 2006). The stem bark of the species has been applied in traditional medicine in Malaysia (Bennett et al., 1993). Reports indicated that the bark, roots and leaves have been used in folk medicine to treat fevers, cough, diarrhoea, itches, ulcers and abdominal complaints (Nguyen & Harrison, 1998). Antibacterial, cytotoxic and anti-HIV constituents have also been reported in recent studies on Cratoxylum species (Boonsri et al., 2006; Reutrakul et al., 2006). In this report, the X-ray crystallographic structure for the title compound 1,3,6-trihydroxy-7-methoxy-2,8-bis(3-methylbut-2-enyl)-4aH-xanthen-9(9aH)-one, α-mangostin (I) isolated from Cratoxylum glaucum is reported.
Bond distances and angles in the title compound (Fig. 1) are in a normal range (Allen et al., 1987) and are comparable with those for closely related structures (Marek et al., 2003; Ndjakou et al., 2007; Boonnak et al., 2007). The tricyclic ring system (rings A, B and C) is nearly planar (r. m. s. deviation of 0.0014 Å). Atoms O10, O18, O21 and O30 deviate from this plane by 0.045, 0.056, 0.025 and 0.071 Å, respectively. The dihedral angle between the rings A and B is 1.51°, and between the rings B and C is 1.73°.
The orientations of two 3-methylbut-2-enyl side chains are defined by their respective torsion angles: the first side chain towards the ring A with the atom sequence C11—C12—C13—C14 of 80.19° [116.4° in similar compound (Ndjakou et al., 2007)] indicating a (+)-synclinal conformation; the second side chain towards the ring C with the atom sequence C20—C22—C23—C24 of -87.62°, indicating a (-)-anticlinal conformation. The average value of C—O1 bond lengths in pyranoid ring B is 1.368 Å. The ═C15 (H301···Cg A= 2.384 Å, O30···Cg A=3.227 Å and O30—H301···Cg A = 166.2.
is stabilised by intra- and intermolecular O—H···O and C—H···O hydrogen bonding (Table 1, Figs. 2 and 3). In addition to classical hydrogen bonds, there is a contact from hydroxyl group O30—H301 to centroid (Cg A) of the C14For standard bond lengths, see Allen et al. (1987). For related structures, see: Marek et al. (2003); Ndjakou et al. (2007); Boonnak et al. (2007). For the biological activity of Cratoxylum species, see: Boonnak et al. (2006); Bennett et al. (1993); Nguyen & Harrison (1998); Boonsri et al. (2006); Reutrakul et al. (2006).
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell
CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).C24H26O6 | Dx = 1.303 Mg m−3 |
Mr = 410.47 | Melting point: 452 K |
Orthorhombic, Pbcn | Cu Kα radiation, λ = 1.54184 Å |
Hall symbol: -P 2n 2ab | Cell parameters from 5947 reflections |
a = 14.6818 (3) Å | θ = 3.0–71.2° |
b = 9.53505 (19) Å | µ = 0.77 mm−1 |
c = 29.8893 (6) Å | T = 150 K |
V = 4184.24 (14) Å3 | Plate, yellow |
Z = 8 | 0.11 × 0.10 × 0.04 mm |
F(000) = 1744 |
Oxford Diffraction Gemini E diffractometer | 4032 independent reflections |
Radiation source: sealed x-ray tube | 2812 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
ω/2θ scans | θmax = 71.4°, θmin = 4.2° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2006) | h = −17→17 |
Tmin = 0.926, Tmax = 0.970 | k = −11→11 |
13773 measured reflections | l = −36→29 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.041 | H-atom parameters constrained |
wR(F2) = 0.113 | Method = Modified Sheldrick w = 1/[σ2(F2) + (0.08P)2 + 0.0P], where P = [max(Fo2,0) + 2Fc2]/3 |
S = 0.88 | (Δ/σ)max = 0.0003346 |
4018 reflections | Δρmax = 0.34 e Å−3 |
271 parameters | Δρmin = −0.27 e Å−3 |
0 restraints |
C24H26O6 | V = 4184.24 (14) Å3 |
Mr = 410.47 | Z = 8 |
Orthorhombic, Pbcn | Cu Kα radiation |
a = 14.6818 (3) Å | µ = 0.77 mm−1 |
b = 9.53505 (19) Å | T = 150 K |
c = 29.8893 (6) Å | 0.11 × 0.10 × 0.04 mm |
Oxford Diffraction Gemini E diffractometer | 4032 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2006) | 2812 reflections with I > 2σ(I) |
Tmin = 0.926, Tmax = 0.970 | Rint = 0.034 |
13773 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 0.88 | Δρmax = 0.34 e Å−3 |
4018 reflections | Δρmin = −0.27 e Å−3 |
271 parameters |
Refinement. (sinθ X)2 was set to > 0.01 to eliminate reflection measured near the vicinity of the beam stop. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.87635 (7) | 0.30339 (12) | 0.25523 (4) | 0.0309 | |
C2 | 0.82099 (10) | 0.22222 (17) | 0.28118 (5) | 0.0276 | |
C3 | 0.72644 (10) | 0.23373 (17) | 0.27827 (5) | 0.0279 | |
C4 | 0.68351 (10) | 0.32642 (17) | 0.24630 (5) | 0.0285 | |
O5 | 0.59844 (7) | 0.32795 (13) | 0.24258 (4) | 0.0368 | |
C6 | 0.74439 (10) | 0.41346 (17) | 0.21923 (5) | 0.0274 | |
C7 | 0.83874 (10) | 0.39435 (17) | 0.22495 (5) | 0.0274 | |
C8 | 0.90312 (10) | 0.46582 (18) | 0.19999 (6) | 0.0307 | |
C9 | 0.87454 (10) | 0.55982 (17) | 0.16816 (6) | 0.0307 | |
O10 | 0.93348 (7) | 0.63408 (13) | 0.14256 (4) | 0.0361 | |
C11 | 0.78053 (10) | 0.58382 (17) | 0.16158 (5) | 0.0292 | |
C12 | 0.71573 (10) | 0.51369 (18) | 0.18686 (5) | 0.0286 | |
C13 | 0.61617 (10) | 0.55256 (18) | 0.17851 (6) | 0.0305 | |
C14 | 0.58048 (10) | 0.47960 (19) | 0.13754 (6) | 0.0329 | |
C15 | 0.54434 (11) | 0.5383 (2) | 0.10128 (6) | 0.0416 | |
C16 | 0.52901 (15) | 0.6929 (3) | 0.09490 (8) | 0.0574 | |
C17 | 0.51697 (14) | 0.4474 (3) | 0.06219 (7) | 0.0634 | |
O18 | 0.75300 (8) | 0.68622 (13) | 0.13202 (4) | 0.0356 | |
C19 | 0.76973 (12) | 0.6541 (2) | 0.08604 (6) | 0.0444 | |
C20 | 0.67452 (10) | 0.14669 (17) | 0.30706 (5) | 0.0291 | |
O21 | 0.58222 (7) | 0.15647 (13) | 0.30532 (4) | 0.0349 | |
C22 | 0.71415 (10) | 0.05261 (18) | 0.33651 (5) | 0.0302 | |
C23 | 0.65776 (11) | −0.03859 (19) | 0.36731 (6) | 0.0337 | |
C24 | 0.63628 (11) | 0.0336 (2) | 0.41077 (6) | 0.0370 | |
C25 | 0.65495 (12) | −0.0099 (2) | 0.45188 (7) | 0.0441 | |
C26 | 0.62764 (17) | 0.0757 (3) | 0.49190 (8) | 0.0589 | |
C27 | 0.7041 (2) | −0.1435 (3) | 0.46259 (9) | 0.0688 | |
C28 | 0.81001 (11) | 0.04585 (18) | 0.33691 (6) | 0.0309 | |
C29 | 0.86367 (10) | 0.12942 (18) | 0.30953 (6) | 0.0311 | |
O30 | 0.84808 (8) | −0.04872 (13) | 0.36537 (4) | 0.0388 | |
H81 | 0.9656 | 0.4502 | 0.2049 | 0.0363* | |
H131 | 0.6130 | 0.6516 | 0.1755 | 0.0361* | |
H132 | 0.5811 | 0.5267 | 0.2037 | 0.0360* | |
H141 | 0.5857 | 0.3795 | 0.1381 | 0.0387* | |
H161 | 0.5550 | 0.7236 | 0.0664 | 0.0850* | |
H163 | 0.5558 | 0.7469 | 0.1192 | 0.0852* | |
H162 | 0.4643 | 0.7120 | 0.0934 | 0.0857* | |
H171 | 0.4551 | 0.4673 | 0.0536 | 0.0945* | |
H173 | 0.5552 | 0.4712 | 0.0368 | 0.0938* | |
H172 | 0.5250 | 0.3454 | 0.0687 | 0.0952* | |
H191 | 0.7492 | 0.7303 | 0.0678 | 0.0666* | |
H193 | 0.8329 | 0.6388 | 0.0802 | 0.0658* | |
H192 | 0.7357 | 0.5710 | 0.0777 | 0.0666* | |
H231 | 0.6891 | −0.1275 | 0.3725 | 0.0390* | |
H232 | 0.6016 | −0.0609 | 0.3524 | 0.0393* | |
H241 | 0.6065 | 0.1214 | 0.4085 | 0.0447* | |
H261 | 0.6799 | 0.1001 | 0.5095 | 0.0886* | |
H263 | 0.5951 | 0.1616 | 0.4833 | 0.0880* | |
H262 | 0.5893 | 0.0198 | 0.5113 | 0.0878* | |
H271 | 0.7562 | −0.1207 | 0.4801 | 0.1025* | |
H273 | 0.7216 | −0.1943 | 0.4357 | 0.1020* | |
H272 | 0.6645 | −0.2019 | 0.4808 | 0.1027* | |
H291 | 0.9267 | 0.1242 | 0.3103 | 0.0351* | |
H211 | 0.5707 | 0.2133 | 0.2842 | 0.0526* | |
H101 | 0.9842 | 0.6299 | 0.1553 | 0.0544* | |
H301 | 0.9064 | −0.0397 | 0.3648 | 0.0578* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0172 (5) | 0.0397 (6) | 0.0357 (6) | 0.0002 (4) | 0.0001 (4) | 0.0033 (5) |
C2 | 0.0216 (7) | 0.0330 (9) | 0.0283 (8) | −0.0023 (6) | 0.0008 (6) | −0.0033 (7) |
C3 | 0.0220 (7) | 0.0323 (8) | 0.0295 (8) | −0.0012 (6) | −0.0005 (6) | −0.0042 (7) |
C4 | 0.0207 (7) | 0.0344 (8) | 0.0303 (8) | −0.0001 (6) | 0.0005 (6) | −0.0060 (7) |
O5 | 0.0177 (5) | 0.0478 (7) | 0.0447 (7) | −0.0010 (5) | −0.0011 (5) | 0.0055 (6) |
C6 | 0.0213 (7) | 0.0333 (8) | 0.0277 (8) | −0.0005 (6) | 0.0000 (6) | −0.0045 (6) |
C7 | 0.0215 (7) | 0.0320 (8) | 0.0288 (8) | 0.0007 (6) | −0.0009 (6) | −0.0023 (7) |
C8 | 0.0171 (6) | 0.0392 (9) | 0.0357 (9) | −0.0008 (6) | −0.0007 (6) | −0.0030 (7) |
C9 | 0.0242 (7) | 0.0370 (9) | 0.0309 (8) | −0.0037 (6) | 0.0018 (6) | −0.0036 (7) |
O10 | 0.0231 (5) | 0.0468 (7) | 0.0385 (7) | −0.0043 (5) | −0.0014 (5) | 0.0069 (5) |
C11 | 0.0255 (7) | 0.0330 (8) | 0.0290 (8) | 0.0002 (6) | −0.0016 (6) | −0.0030 (7) |
C12 | 0.0215 (7) | 0.0351 (9) | 0.0292 (8) | 0.0012 (6) | −0.0009 (6) | −0.0053 (7) |
C13 | 0.0209 (7) | 0.0373 (9) | 0.0335 (8) | 0.0041 (6) | −0.0001 (6) | 0.0011 (7) |
C14 | 0.0191 (7) | 0.0415 (9) | 0.0381 (9) | 0.0006 (6) | 0.0003 (6) | −0.0012 (8) |
C15 | 0.0220 (7) | 0.0669 (13) | 0.0358 (9) | 0.0017 (7) | −0.0005 (7) | 0.0024 (9) |
C16 | 0.0424 (10) | 0.0754 (15) | 0.0545 (13) | 0.0110 (10) | −0.0030 (9) | 0.0238 (12) |
C17 | 0.0384 (10) | 0.111 (2) | 0.0411 (12) | −0.0001 (11) | −0.0084 (9) | −0.0129 (13) |
O18 | 0.0296 (5) | 0.0420 (6) | 0.0351 (6) | 0.0015 (5) | −0.0008 (5) | 0.0037 (5) |
C19 | 0.0322 (9) | 0.0691 (13) | 0.0319 (9) | −0.0004 (8) | −0.0003 (7) | 0.0081 (9) |
C20 | 0.0205 (7) | 0.0361 (8) | 0.0309 (8) | −0.0021 (6) | 0.0009 (6) | −0.0076 (7) |
O21 | 0.0185 (5) | 0.0470 (7) | 0.0391 (7) | −0.0024 (4) | 0.0005 (4) | 0.0046 (5) |
C22 | 0.0272 (7) | 0.0342 (9) | 0.0292 (8) | −0.0025 (6) | 0.0003 (6) | −0.0042 (7) |
C23 | 0.0267 (7) | 0.0386 (9) | 0.0357 (9) | −0.0044 (6) | −0.0003 (6) | 0.0009 (8) |
C24 | 0.0295 (8) | 0.0401 (10) | 0.0413 (10) | −0.0016 (7) | 0.0025 (7) | 0.0018 (8) |
C25 | 0.0381 (9) | 0.0531 (11) | 0.0410 (10) | −0.0053 (8) | 0.0000 (8) | −0.0002 (9) |
C26 | 0.0679 (14) | 0.0683 (15) | 0.0405 (11) | −0.0041 (11) | 0.0055 (10) | −0.0038 (11) |
C27 | 0.0864 (18) | 0.0722 (17) | 0.0479 (13) | 0.0185 (13) | −0.0092 (12) | 0.0084 (12) |
C28 | 0.0278 (7) | 0.0343 (9) | 0.0305 (8) | 0.0011 (6) | −0.0035 (6) | −0.0018 (7) |
C29 | 0.0190 (7) | 0.0389 (9) | 0.0354 (9) | 0.0008 (6) | −0.0015 (6) | −0.0028 (7) |
O30 | 0.0273 (5) | 0.0451 (7) | 0.0439 (7) | 0.0007 (5) | −0.0033 (5) | 0.0092 (6) |
O1—C2 | 1.3644 (19) | C17—H171 | 0.962 |
O1—C7 | 1.370 (2) | C17—H173 | 0.972 |
C2—C3 | 1.395 (2) | C17—H172 | 0.999 |
C2—C29 | 1.376 (2) | O18—C19 | 1.429 (2) |
C3—C4 | 1.446 (2) | C19—H191 | 0.957 |
C3—C20 | 1.418 (2) | C19—H193 | 0.954 |
C4—O5 | 1.2540 (19) | C19—H192 | 0.969 |
C4—C6 | 1.464 (2) | C20—O21 | 1.3594 (17) |
C6—C7 | 1.408 (2) | C20—C22 | 1.385 (2) |
C6—C12 | 1.424 (2) | O21—H211 | 0.849 |
C7—C8 | 1.384 (2) | C22—C23 | 1.513 (2) |
C8—C9 | 1.373 (2) | C22—C28 | 1.409 (2) |
C8—H81 | 0.941 | C23—C24 | 1.503 (3) |
C9—O10 | 1.3550 (19) | C23—H231 | 0.977 |
C9—C11 | 1.413 (2) | C23—H232 | 0.961 |
O10—H101 | 0.837 | C24—C25 | 1.326 (3) |
C11—C12 | 1.387 (2) | C24—H241 | 0.947 |
C11—O18 | 1.377 (2) | C25—C26 | 1.503 (3) |
C12—C13 | 1.5284 (19) | C25—C27 | 1.499 (3) |
C13—C14 | 1.503 (2) | C26—H261 | 0.959 |
C13—H131 | 0.950 | C26—H263 | 0.982 |
C13—H132 | 0.944 | C26—H262 | 0.969 |
C14—C15 | 1.330 (3) | C27—H271 | 0.952 |
C14—H141 | 0.957 | C27—H273 | 0.974 |
C15—C16 | 1.503 (3) | C27—H272 | 0.972 |
C15—C17 | 1.509 (3) | C28—C29 | 1.388 (2) |
C16—H161 | 0.979 | C28—O30 | 1.360 (2) |
C16—H163 | 0.972 | C29—H291 | 0.928 |
C16—H162 | 0.968 | O30—H301 | 0.860 |
C2—O1—C7 | 119.65 (12) | H171—C17—H173 | 107.0 |
O1—C2—C3 | 120.84 (14) | C15—C17—H172 | 112.2 |
O1—C2—C29 | 116.34 (13) | H171—C17—H172 | 110.8 |
C3—C2—C29 | 122.82 (15) | H173—C17—H172 | 108.1 |
C2—C3—C4 | 121.52 (14) | C11—O18—C19 | 114.47 (14) |
C2—C3—C20 | 116.82 (14) | O18—C19—H191 | 109.2 |
C4—C3—C20 | 121.63 (13) | O18—C19—H193 | 112.0 |
C3—C4—O5 | 119.99 (14) | H191—C19—H193 | 108.6 |
C3—C4—C6 | 116.46 (13) | O18—C19—H192 | 109.6 |
O5—C4—C6 | 123.55 (15) | H191—C19—H192 | 108.1 |
C4—C6—C7 | 117.42 (14) | H193—C19—H192 | 109.2 |
C4—C6—C12 | 125.15 (13) | C3—C20—O21 | 118.21 (14) |
C7—C6—C12 | 117.41 (14) | C3—C20—C22 | 122.61 (14) |
C6—C7—O1 | 123.98 (14) | O21—C20—C22 | 119.18 (14) |
C6—C7—C8 | 122.89 (15) | C20—O21—H211 | 105.7 |
O1—C7—C8 | 113.13 (13) | C20—C22—C23 | 121.94 (14) |
C7—C8—C9 | 119.11 (14) | C20—C22—C28 | 117.05 (15) |
C7—C8—H81 | 120.3 | C23—C22—C28 | 121.00 (15) |
C9—C8—H81 | 120.6 | C22—C23—C24 | 112.16 (14) |
C8—C9—O10 | 122.51 (14) | C22—C23—H231 | 109.8 |
C8—C9—C11 | 120.06 (14) | C24—C23—H231 | 111.0 |
O10—C9—C11 | 117.42 (15) | C22—C23—H232 | 108.3 |
C9—O10—H101 | 106.6 | C24—C23—H232 | 108.8 |
C9—C11—C12 | 121.07 (15) | H231—C23—H232 | 106.7 |
C9—C11—O18 | 119.40 (14) | C23—C24—C25 | 127.89 (18) |
C12—C11—O18 | 119.33 (13) | C23—C24—H241 | 116.0 |
C6—C12—C11 | 119.42 (13) | C25—C24—H241 | 116.1 |
C6—C12—C13 | 123.81 (14) | C24—C25—C26 | 120.8 (2) |
C11—C12—C13 | 116.76 (14) | C24—C25—C27 | 124.3 (2) |
C12—C13—C14 | 110.75 (13) | C26—C25—C27 | 114.9 (2) |
C12—C13—H131 | 107.6 | C25—C26—H261 | 110.8 |
C14—C13—H131 | 111.4 | C25—C26—H263 | 112.1 |
C12—C13—H132 | 109.2 | H261—C26—H263 | 109.3 |
C14—C13—H132 | 109.7 | C25—C26—H262 | 109.4 |
H131—C13—H132 | 108.1 | H261—C26—H262 | 105.7 |
C13—C14—C15 | 127.45 (17) | H263—C26—H262 | 109.4 |
C13—C14—H141 | 114.8 | C25—C27—H271 | 108.1 |
C15—C14—H141 | 117.7 | C25—C27—H273 | 111.9 |
C14—C15—C16 | 125.16 (19) | H271—C27—H273 | 110.9 |
C14—C15—C17 | 119.7 (2) | C25—C27—H272 | 108.6 |
C16—C15—C17 | 115.16 (19) | H271—C27—H272 | 107.7 |
C15—C16—H161 | 110.2 | H273—C27—H272 | 109.6 |
C15—C16—H163 | 111.4 | C22—C28—C29 | 122.40 (15) |
H161—C16—H163 | 109.5 | C22—C28—O30 | 116.51 (15) |
C15—C16—H162 | 109.7 | C29—C28—O30 | 121.09 (14) |
H161—C16—H162 | 106.6 | C28—C29—C2 | 118.29 (13) |
H163—C16—H162 | 109.4 | C28—C29—H291 | 121.4 |
C15—C17—H171 | 110.1 | C2—C29—H291 | 120.3 |
C15—C17—H173 | 108.5 | C28—O30—H301 | 109.3 |
CgA is the mid-point of the C14═C15 double bond. |
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H132···O5 | 0.94 | 2.24 | 2.885 (3) | 125 |
C14—H141···O10i | 0.96 | 2.36 | 3.304 (3) | 168 |
O21—H211···C4 | 0.85 | 2.28 | 2.820 (3) | 122 |
O21—H211···O5 | 0.85 | 1.71 | 2.499 (3) | 155 |
O10—H101···O21ii | 0.84 | 1.88 | 2.691 (3) | 164 |
O30—H301···C14iii | 0.86 | 2.56 | 3.424 (3) | 178 |
O30—H301···C15iii | 0.86 | 2.38 | 3.160 (3) | 150 |
O30—H301···CgA | 0.86 | 2.38 | 3.227 (3) | 166 |
Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) x+1/2, y+1/2, −z+1/2; (iii) x+1/2, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C24H26O6 |
Mr | 410.47 |
Crystal system, space group | Orthorhombic, Pbcn |
Temperature (K) | 150 |
a, b, c (Å) | 14.6818 (3), 9.53505 (19), 29.8893 (6) |
V (Å3) | 4184.24 (14) |
Z | 8 |
Radiation type | Cu Kα |
µ (mm−1) | 0.77 |
Crystal size (mm) | 0.11 × 0.10 × 0.04 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini E |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2006) |
Tmin, Tmax | 0.926, 0.970 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13773, 4032, 2812 |
Rint | 0.034 |
(sin θ/λ)max (Å−1) | 0.615 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.113, 0.88 |
No. of reflections | 4018 |
No. of parameters | 271 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.27 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SIR92 (Altomare et al., 1994), CRYSTALS (Betteridge et al., 2003), Mercury (Macrae et al., 2006).
CgA is the mid-point of the C14═C15 double bond. |
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H132···O5 | 0.94 | 2.24 | 2.885 (3) | 125 |
C14—H141···O10i | 0.96 | 2.36 | 3.304 (3) | 168 |
O21—H211···O5 | 0.85 | 1.71 | 2.499 (3) | 155 |
O10—H101···O21ii | 0.84 | 1.88 | 2.691 (3) | 164 |
O30—H301···CgA | 0.86 | 2.38 | 3.227 (3) | 166 |
Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) x+1/2, y+1/2, −z+1/2. |
Acknowledgements
The author would like to acknowledge the Ministry of Science, Technology and Innovation (MOSTI) for e-science funding.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Cratoxylum is a small genus which comprises of six species indigenous to Southeast Asia (Boonnak et al., 2006). The stem bark of the species has been applied in traditional medicine in Malaysia (Bennett et al., 1993). Reports indicated that the bark, roots and leaves have been used in folk medicine to treat fevers, cough, diarrhoea, itches, ulcers and abdominal complaints (Nguyen & Harrison, 1998). Antibacterial, cytotoxic and anti-HIV constituents have also been reported in recent studies on Cratoxylum species (Boonsri et al., 2006; Reutrakul et al., 2006). In this report, the X-ray crystallographic structure for the title compound 1,3,6-trihydroxy-7-methoxy-2,8-bis(3-methylbut-2-enyl)-4aH-xanthen-9(9aH)-one, α-mangostin (I) isolated from Cratoxylum glaucum is reported.
Bond distances and angles in the title compound (Fig. 1) are in a normal range (Allen et al., 1987) and are comparable with those for closely related structures (Marek et al., 2003; Ndjakou et al., 2007; Boonnak et al., 2007). The tricyclic ring system (rings A, B and C) is nearly planar (r. m. s. deviation of 0.0014 Å). Atoms O10, O18, O21 and O30 deviate from this plane by 0.045, 0.056, 0.025 and 0.071 Å, respectively. The dihedral angle between the rings A and B is 1.51°, and between the rings B and C is 1.73°.
The orientations of two 3-methylbut-2-enyl side chains are defined by their respective torsion angles: the first side chain towards the ring A with the atom sequence C11—C12—C13—C14 of 80.19° [116.4° in similar compound (Ndjakou et al., 2007)] indicating a (+)-synclinal conformation; the second side chain towards the ring C with the atom sequence C20—C22—C23—C24 of -87.62°, indicating a (-)-anticlinal conformation. The average value of C—O1 bond lengths in pyranoid ring B is 1.368 Å. The crystal structure is stabilised by intra- and intermolecular O—H···O and C—H···O hydrogen bonding (Table 1, Figs. 2 and 3). In addition to classical hydrogen bonds, there is a contact from hydroxyl group O30—H301 to centroid (Cg A) of the C14═C15 (H301···Cg A= 2.384 Å, O30···Cg A=3.227 Å and O30—H301···Cg A = 166.2.