4,5,7,8,17-Pentahydroxy-14,18-dimethyl-6-methylene-3,10-dioxapentacyclo[9.8.0.01,7.04,19.013,18]nonadec-14-ene-9,16-dione methanol solvate dihydrate

The title quassinoid compound, C20H24O9·CH3OH·2H2O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The molecules contain a fused five-ring system, with one tetrahydrofuran ring adopting an envelope conformation, one tetrahydropyran-2-one ring in a screw boat conformation, one cyclohexenone ring in a half-chair conformation and two cyclohexane rings in chair conformations. Intramolecular C—H⋯O interactions generate S(5) ring motifs and an O—H⋯O interaction generates an S(7) ring motif. In the crystal, molecules are linked via intermolecular O—H⋯O interactions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

The title quassinoid compound, C 20 H 24 O 9 ÁCH 3 OHÁ2H 2 O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The molecules contain a fused five-ring system, with one tetrahydrofuran ring adopting an envelope conformation, one tetrahydropyran-2-one ring in a screw boat conformation, one cyclohexenone ring in a half-chair conformation and two cyclohexane rings in chair conformations. Intramolecular C-HÁ Á ÁO interactions generate S(5) ring motifs and an O-HÁ Á ÁO interaction generates an S(7) ring motif. In the crystal, molecules are linked via intermolecular O-HÁ Á ÁO interactions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

Comment
Eurycoma longifolia Jack is a tall, slender shrub-tree, commonly found in lowland forests below 500 meters above sea level in Southeast Asia. The roots of this Simaroubaceae plant are used in folk medicine for intermittent fever (malaria), dysentery, glandular swelling and aphrodisiac properties. Various classes of chemical constituents , Chan et al., 1992, Kardono et al., 1991 have been identified and some have shown antiulcer (Tada et al., 1991), cytotoxic (Kardono et al., 1991 and antimalarial (Ang et al., 1995, Chan et al., 2004 activities. In our continuing search for the bioactive compounds from E. longifolia, we have isolated eurycomanone (1), a quassinoid in crystalline form.

Experimental
The air-dried powdered roots of E. longifolia (11.6 kg) were extracted with MeOH. The MeOH extract on evaporation to dryness yielded 485 g of dark brown residue which was next chromatographed on a Diaion HP 20 column using H 2 O-MeOH (1:0 -0:1) gradient mixtures to afford 4 fractions (Fr 1 -4). Fr 2 was concentrated under vacuum to give 52.2 g of residue.

Refinement
The H atoms bound to O1W and O2W were located from the difference Fourier map and constrained to ride with the parent atom with U iso (H)= 1.5 U eq (O). The H atoms of the hydroxy groups were positioned by a freely rotating O-H bond and constrained with a fixed distance of 0.82 Å. The rest of the hydrogen atoms were positioned geometrically with a riding model approximation with C-H = 0.93-0.98 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating-group model was used for the hydrogen of the methyl groups. As there are not enough anomalous dispersion to determine the aboslute configuration, 2770 Friedel pairs were merged before final refinement. The absolute stereochemistry of eurycomanone was inferred following those reported (Tada et al., 1991) for its analogues.
Figures Fig. 1. The molecular structure of the title compound with atom labels and 50% probability ellipsoids for non-H atoms. Intramolecular hydrogen bonds are shown as dashed lines.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.