Crystal and molecular structure of lancerodiol-p-hydroxybenzoate.

Lancerodiol-p-hydroxybenzoate was isolated from the leaves of Ferula sinaica L. (Apiaceae) as light needle crystals. This work reports for the first time the molecular structure and relative configuration of compound 1, established by X-ray analysis.

INTRODUCTION

The genus Ferula presents interesting phytochemical features. Ferula sinaica L. (Apiaceae) is widespread in Sinai peninsula, Egypt. The gum resins of the genus Ferula have been used in folklore medicine for treatment of various diseases.[1] Thus, Ferula communis L., its subspecies and varieties have been used as agents against hysteria and to treat dysentery,[2] Ferula jaeschkeana vatke has been applied to wounds and bruises,[3] and Ferula tingitana L. has proved to be a good source of ammoniac, an oleo-gum resin used in medicine.[4] The widespread sesquiterpene compounds in this genus are characteristic dauicanes, humulanes, himachalanes, germacranes, eudesmanes, and guainanes.[5] Chemically, the resin of the species is characterized by the presence of sesquiterpenes,[5-8] sesquiterpene coumarines,[7-9] and monoterpenes.[9-12] Investigation of the CH2Cl2:MeOH (1:1) extract of the leaves of F. sinaica led to the isolation of lancerodiol–p–hydroxybenzoate 1. Herein, we describe the relative stereochemistry and the molecular structure of 1 by X–ray diffraction.

MATERIALS AND METHODS

General

Compound 1 [Figure 1], with a molecular formula C22H28O5, was isolated from CH2Cl2:MeOH (1:1) extract of the leaves of F. sinaica and was recrystallized from CDCl3. A colorless needle was mounted on glass fiber at room temperature. Preliminary examination and data collection were performed on Siemens P4 (oriented graphite monochromator; Mo–Kα radiation) at 293 K. Cell parameters were calculated from the least-squares fitting for 25 high angle reflections (2Θ > 15). Omega scans for several intense reflections indicated acceptable crystal quality. Crystallographic data for the structural analysis [Figure 2] have been deposited with the Cambridge Crystallographic data center (CCDC) and allocated the deposition number CCDC 207262. These data can be obtained free of charge through the website www.ccdc.Cam.ac.uk/cants/retrieving html/or from the CCDC, 12 union Road, Cambridge CB2 1 EZ, UK; fax: +44–1223–336033; email: deposit@ccdc.cam.ac.uk.

Figure 1

Symmetry transformations used to generate equivalent atoms

Figure 2

X-ray structure of compound 1

Plant material

F. sinaica was collected in 2005 from El-Minia, Egypt. A voucher specimen of the collection was identified by Prof. Mohamed Jaber and was deposited at the Department of Botany, Aswan–Faculty of Science, Egypt.

Extraction and isolation

Air-dried and powdered leaves (200 g) of F. sinaica were extracted with CH2Cl2: MeOH (1:1) at room temperature for 24 h. The extract was concentrated in vacuo to give a residue (15 g) that was chromatographed by using flash column chromatography on a silica gel eluted with n–hexane–CH2Cl2 step–gradient up to CH2Cl2 and CH2Cl2–MeOH up to 15% MeOH (2 l each of the solvent mixture). The n–hexane–CH2Cl2 fraction (1:3) was carefully chromatographed on a Sephadex LH–20 column eluted with n–hexane–CH2Cl2–MeOH (7:4:0.25) with increasing polarity to give compound 1 (21 mg).

RESULTS AND DISCUSSION

Colorless needle crystals suitable for X–ray diffraction were grown by slow evaporation of CDCl3 solution. The crystal data [Tables 1–3] for lancerodiol–p–hydroxybenzoate were as follows: orthorhombic, space group P212121 with a = 8.179 (2) Å, b = 14.165 (3) Å, c = 17.408 (3) Å, V = 2080.9 (8) Å, Z = 4. The structure refined to R(F) = 0.0 725 [I > 2σ(I)] and wR(F2) = 0.1934 [I > 2σ(I)] for 2102 observed reflections with Mo–Kα radiation (λ = 0.71073 Å). The scanning speed was varied according to the intensity, from a minimum of 1 to a maximum of 11/min.

Table 1

Crystal data and structure refinement for lancerodiol p–hydroxybenzoate

Table 3

Bond lengths (Å) and angles (°) of compound 1

Table 2

Functional atomic coordination and equivalent isotropic displacement parameters (Å × 103)