Constituents from Moghat, the Roots of Glossostemon bruguieri (Desf.)

The new biflavone moghatin (3″′-hydroxycupressuflavone) was isolated from Moghat, the dried peeled roots of Glossostemon bruguieri (Desf.), together with five known compounds: 4′-methoxyisoscutellargin, sesamin, chrysophanol, emodin and methoxyemodin (physcion). The structures of these compounds were assigned on the basis of spectroscopic data. Occurrence of these compounds in Moghat is reported here for the first time.


Introduction
Plants of the cacao family (Sterculiaceae) are trees, shrubs, or herbs comprising about 65 genera and 1,000 species that are further characterized by the presence of stellate hairs and, in most cases, mucilaginous sap [1]. Glossostemon bruguieri (Desf.), family Sterculiaceae, is a shrub with thick long tapering dark colored roots (70-100 cm in length and 5-8 cm in breadth) [1,2]. G. bruguieri is native to Iraq and Iran, and was cultivated in Egypt for its edible roots a long time ago. The dried peeled roots of G. bruguieri (Desf.) (known in Arabic as Moghat) are used in folk medicine for the treatment of gout and spasms, and as a tonic and nutritive agent [3]. After childbirth, women have especially used hot drinks of powdered Moghat as a general tonic and lactagogue. Due to its high content of mucilage (up to 27% based on dry weight) [2,[4][5][6], Moghat is also prescribed as a demulcent agent. Previous work  on the chemistry of the compounds produced from Moghat indicated the presence of oestrone [2,7], scopoletin, phytosterols (a mixture of β-sitosterol, stigmasterol and campesterol) [2,8], α-amyrin, and glucosides of flavone and chalcone [2]. In addition, amino acids and fatty acids were identified [2,4]. We report herein the isolation and structure elucidation of six compounds from Moghat roots.

Results and Discussion
Fractionation and repeated chromatography of the MeOH extract of Moghat roots has led to the isolation of six compounds (16) (Figure 1).
Compound 1 was obtained as a yellow amorphous powder that gave a positive magnesiumhydrochloric acid reaction for flavonoids. Its UV spectrum showed absorption bands at 262 and 332 nm, characteristic for flavones. The IR spectrum showed absorptions for hydroxyl (3440 cm -1 ), α,βunsaturated C=O (1640 cm -1 ) and aromatic (1610 and 1580 cm -1 ) functions. Compound 1 was assigned the molecular formula C 30 H 18   Data marked # are taken from ref. [15] and those marked * from ref. [16].
Assignments with the same superscript in the same column may be reversed.
When the 13 C-NMR shift values of 1 were compared with those of related biflavones [15] and flavones [16], the involvement of C-8 and C-8″ in the interflavone linkage of the two asymmetric moieties in 1 was suggested (Table 1). Thus, when compared with monomeric flavones with a 5,7-dihydroxy substitution [15], the C-8 carbons in both moieties were found to be shifted downfield (+ 10.0 ppm), whereas the carbon atoms C-6 and C-6″ in 1 resonate at almost identical chemical shift values (δ 99.8 and 99.7, respectively) for the respective carbon atoms as seen in monomers. Involvement of C-8 and C-8″ in an interflavonoid linkage was previously reported for cupressuflavone (Table 1), a symmetrical C-8, C-8″ biapigenin, previously isolated from Cupressus obtusa [15]. This finding was further supported by a HMBC experiment. Long-range correlation between the 1 H signals at δ 6.27 and 6.28 (H-6 and H-6″, respectively) and the 13 C signal at δ 104.2 was observed. This 13 C signal showed also long range correlation with 1 H signals at δ 6.67 and 6.79 (H-3″ and H-3, respectively). The structure of 1 was, therefore, determined to be a 3″′-hydroxy derivative of cupressuflavone and was given the name moghatin.

Conclusions
In addition to mucilage, oestrone and phytosterol, the present study provides the first report on the presence of biflavones, methoxylated flavones, anthraquinones and lignans in Moghat. These constituents exhibit a variety of biological effects. Besides, sesamin has been found to be good for the liver, and has antihypertensive effects [17]. This broad spectrum of constituents suggests the possible utilization of Moghat as a valuable crude drug.

Acknowledgments
The author is grateful to Prof. Dr. Samia Abdel-Wahab, Professor of Applied Pharmacognosy,

Plant Material
The air-dried peeled roots of G. bruguieri (Desf.), family Sterculiaceae, were purchased from Harraz drugstore in Cairo in March 2001. The plant material was kindly identified by Prof. Dr. El-Sayed A. Aboutabl, Professor of Pharmacognosy, Faculty of Pharmacy, Cairo University, and a voucher specimen was deposited in the museum of the Department of Pharmacognosy of this university.

Extraction and Isolation
Commercially available Moghat (900 g) was pulverized and extracted with portions of MeOH under reflux (2L x 4, 2h each). The MeOH solutions were combined and evaporated under reduced pressure to give 75 g of a viscous residue. This residue was again dissolved in MeOH (500 mL) under sonication and H 2 O (500 mL) was added. The organic solvent was evaporated under reduced pressure and the suspension was applied to a column of Diaion HP-20 (1 L). The column was washed with H 2 O (4 L), MeOH (3 L) and finally with CHCl 3 (3 L). The MeOH and CHCl 3 eluates were separately evaporated to dryness to give 37.5 g and 20 g of oily residues, respectively. The residue from the MeOH eluate was suspended in MeCN-H 2 O (9:1 v/v, 500 mL) and partitioned with n-hexane (500 mL Compound 2 (83 mg) was obtained as a light yellow amorphous powder from fractions 5-11 after crystallization of the crude isolate (120 mg) from MeOH.