3,5,3′-Trihy­droxy-4′-meth­oxy-7-(3-methyl­but-2-en­yloxy)flavone

Sheng-Hua Zhu; Shao-Qian Liu

doi:10.1107/S1600536811005393

. 2011 Feb 19;67(Pt 3):o661. doi: 10.1107/S1600536811005393

3,5,3′-Trihydroxy-4′-methoxy-7-(3-methylbut-2-enyloxy)flavone

Sheng-Hua Zhu ^a,^*, Shao-Qian Liu ^b

PMCID: PMC3052086 PMID: 21522412

Abstract

The title compound pteleifolosin C, C₂₁H₂₀O₇, was isolated from the petroleum ether-soluble fraction of an indigenous Chinese tree Melicope pteleifolia (Rutaceae). The dihedral angle between the benzene rings is 2.7 (2)°. Intramolecular O—H⋯O hydrogen bonds occur. In the crystal, molecules are linked by intermolecular O—H—O hydrogen bonds.

Related literature

For the medicinal usage of M. pteleifolia in China, see: Chinese Pharmacopoeia (1977 ▶) and for folk use of M. pteleifolia in South East Asia, see: Gunawardana et al. (1987 ▶); Shaari et al. (2006 ▶). For related structures and background to pteleifolosin C, see: Smith et al. (2001 ▶); Sultana et al. (1999 ▶).

Experimental

Crystal data

C₂₁H₂₀O₇
M _r = 384.37
Triclinic,
a = 8.4073 (18) Å
b = 9.0343 (19) Å
c = 12.489 (3) Å
α = 79.371 (2)°
β = 83.519 (3)°
γ = 78.806 (3)°
V = 911.7 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 296 K
0.60 × 0.50 × 0.45 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.939, T _max = 0.954
8186 measured reflections
4103 independent reflections
3126 reflections with I > 2σ(I)
R _int = 0.019

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.114
S = 0.98
4103 reflections
259 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); 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 I, global. DOI: 10.1107/S1600536811005393/jh2258sup1.cif

e-67-0o661-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811005393/jh2258Isup2.hkl

e-67-0o661-Isup2.hkl^{(201.1KB, 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
O5—H5⋯O4	0.82	2.21	2.6682 (17)	115
O5—H5⋯O6ⁱ	0.82	2.04	2.7914 (16)	153
O6—H6⋯O7	0.82	2.19	2.6440 (16)	115
O2—H2⋯O4	0.82	1.88	2.6155 (17)	148

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Symmetry code: (i) Inline graphic .

Acknowledgments

We thank Professor Bing Chen for helpful discussions and assistance with the crystallization

supplementary crystallographic information

Comment

The title substance is a new compound named pteleifolosin C, which is from petroleum ether soluble fraction of an indigenous Chinese tree Melicope pteleifolia, Rutaceae. In the southern area of China and in the neighboring district of South East Asia, Melicope pteleifolia is a medical herb and an edible plant as well (Gunawardana et al., 1987; Shaari et al., 2006). As a staple material of Guang Dong herbal tea, it also serves as a medical herb for the treatment of injury, wounds, fester and eczema (Chinese Pharmacopoeia, 1977). Nowadays it is used as a constituent in many Chinese patent medicines. In order to find its bioactive ingredients we studied the chemical composition of its leaves and found pteleifolosin C among other flavones.

Experimental

The dried leaves powder (5 K g) of M. pteleifolia was percolated with 80% EtOH to yield crude extract which was fractionated in a Soxhlet to give petroleum ether, ethyl acetate, acetone and methanol soluble fraction successively. The petroleum ether fraction was subjected to column chromatography over silica gel using solvents of increasing polarity. The fraction obtained with 25% ethyl acetate in petroleum ether was subsequently subjected to gel filtration (Sephadex LH-20) eluting with CHCl₃ and CH₃OH (1:1) mixtures to give yellow powder, which was purified by prep. HPLC and yielded pteleifolosin C (25 mg). It is similar to the flavones found in the same genus with the O-prenylated side chain (Sultana et al., 1999; Smith et al., 2001). ¹HNMR (500 MHz, DMSO-d₆): δ 9.55 (1H, s, –OH), 12.43 (1H, s, –OH), 6.33 (1H, d, J=2.0 Hz), 6.72 (1H, d, J=2.0 Hz), 7.72 (1H, d, J=1.6 Hz), 9.31 (1H, s, –OH), 7.09 (1H, d, J=8.5 Hz), 7.68 (1H, d, J=1.6, 8.5 Hz), 4.64 (2H, d, J=6.5 Hz), 5.46 (1H, t, J=6.5 Hz), 1.76 (3H, s), 1.73 (3H, s), 3.85 (3H, s);

The dihedral angle between the benzene ring C6—C11 and the benzene ring C15—C20 is 2.7 (2)°. and the dihedral angle between the ring C8, C9, C12, C13, C14, O3 and the benzene ring C15—C20 is 2.2 (2) °. The C2—C4 (1.319 (2) Å) and C13—C14 (1.359 (2) Å) are double bands and are significantly shorter than the other C—C bond (e.g.The distance between the single band C1—C2 is 1.495 (3) Å)