Biochemical Systematics and Ecology 29 (2001) 113}115
Emodin and syringaldehyde from
Rhamnus pubescens
(Rhamnaceae)
Hazel Sharp
!
, Zahid Latif
!
, Barbara Bartholomew
!
,
David Thomas
!
, Bob Thomas
"
, Satyajit D. Sarker
#
,
*
,
Robert J. Nash
$
!Molecular Nature Limited, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK
"Biotics Limited, University of Sussex, Brighton, UK
#Pharmaceutical Sciences Section, School of Pharmacy, The Robert Gordon University, Schoolhill, Aberdeen AB10 1FR, UK
$Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK Received 4 January 2000; accepted 28 February 2000
Keywords: Rhamnus pubescens; Rhamnaceae; Anthraquinone; Emodin; Syringaldehyde; Chemotaxonomy
1. Subject and source
Rhamnus pubescensSibth. & Sm. non Poir., originally from Greece, is a European species of Rhamnaceae (PANDORA Taxonomic Database System, 1999). Plant material was collected from San Jose, Costa Rica during August 1991 by Polybiotika, Costa Rica. A voucher specimen (MNL10067) has been maintained at the herbarium of the Institute of Grassland and Environmental Research, Aberystwyth, UK.
2. Previous work
Tocopherols have previously been reported fromR. pubescens(Demo et al., 1998).
*Corresponding author. Tel.:#44-1224-262547; fax:#44-1224-262555. E-mail address:s.sarker@rgu.ac.uk (S.D. Sarker).
3. Present study
BiotageTM 75 #ash chromatography (silica gel, eluting with a step gradient of increasing polarity: n-hexane}EtOAc}MeOH) of the CH
2Cl2 extract of leaves and
stems ofR. pubescens (0.97 kg) provided 9 fractions (1000 ml each). Flash fractions 2 (10% EtOAc inn-hexane) and 5 (40% EtOAc inn-hexane), respectively, a!orded emodin (1, 1.9 mg) (SDBS database, 1999; Coskun et al., 1990; Pouchert, 1983) and syringaldehyde (1.6 mg) (SDBS database, 1999) upon reverse phase HPLC puri" ca-tion (C
18 preparative column, for 1, eluted isocratically with a mobile phase,
water : acetonitrile : 0.1% TFA in acetonitrile"30 : 60 : 10, and for syringaldehyde, eluted with a gradient, water : acetonitrile : 0.1% TFA in acetonitrile"60 : 30 : 10, 55 ml/min. to 00 : 90 : 10 in 15 min, #ow rate"55 ml/min, detection at 210 nm). Structures of these compounds were determined on the basis of UV, LC-MS and NMR data, and also by direct comparison with the respective literature data.
4. Chemotaxonomic signi5cance
Anthraquinones, especially emodin (1) and its glycosides, are also found in other species of the genusRhamnus, and they have also been reported from few other plant families (Dictionary of Natural Products, 1999; BIDS database, 1999). Chemotaxonomic signi"cance of emodin within the genusRhamnusdeserves consid-eration. Syringaldehyde is one of the common plant secondary metabolites found in woody plants (Dictionary of Natural Products, 1999).
Acknowledgements
We thank Colin Bright, Felicity Currie, and Julia Turnock for pre-HPLC prepara-tion of plant material. BBSRC is thanked for partial"nancial support for purchasing the BRUKER DRX500 NMR spectrometer.
References
Dictionary of Natural Products (DNP) in CD-ROM (1999) Version 8:1, Chapman & Hall, Boca Raton, Florida, USA.
Demo, A., Petrakis, C., Kefalas, P., Boskou, D., 1998. Food Research International 31, 351.
PANDORA Taxonomic Database System, 1999. Flora Europaea. Royal Botanic Garden Edinburgh, UK. Available on line at: http://www.rbge.org.uk/research/pandora.home
Pouchert, C. J., 1983. The Aldrich Library of NMR Spectra, 2nd edition. Aldrich Chemical, Milwaukee, WI, USA. p. 91D.
SDBS, Integrated Spectral Database System for Organic Compounds, 1999. National Institute of Materials and Chemical Research Tsukuba, Ibaraki 305-8565, Japan. Available on-line at: http://www/aist.go.jp/RIODB/SDBS/menu-e.html.
