Biochemical Systematics and Ecology 37 (2009) 234–236
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Phenolic compounds from Tragopogon porrifolius L. Vipaporn Sareedenchai a, Markus Ganzera a, Ernst P. Ellmerer b, Ulrike Lohwasser c, Christian Zidorn a, * a
¨t Innsbruck, Josef-Moeller-Haus, Innrain 52, A-6020 Innsbruck, Austria ¨ r Pharmazie, Universita Institut fu ¨t Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria ¨ r Organische Chemie, Universita Institut fu c ¨ r Pflanzengenetik und Kulturpflanzenforschung (IPK), Abt. Genbank, AG Ressourcengenetik und Reproduktion, Corrensstrasse 3, Institut fu D-06466 Gatersleben, Germany b
a r t i c l e i n f o Article history: Received 15 January 2009 Accepted 17 March 2009 Keywords: Tragopogon porrifolius L Asteraceae Chemosystematics Phenolic compounds
1. Subject and source Tragopogon porrifolius L. (Asteraceae) is an annual or biennial herb of 30–125 cm height with lilac to reddish-purple ligules. The taxon is native to the Eastern and Central Mediterranean region and Asia Minor. Commonly known as white salsify, it is also used as a vegetable (Richardson, 1976). Aerial parts used for this investigation were harvested from plants grown in the experimental fields of the IPK-Gatersleben (Saxony-Anhalt/Germany; voucher code: TRA 4, Herbarium GAT). Seeds were obtained from the Botanical Garden Beijing/PR China. 2. Previous work An early phytochemical investigation was focused on flavonoids from aerial parts of Tragopogon dubius, Scop. T. porrifolius, and T. pratensis L. and their allopolyploid hybrids T. mirus Ownbey (derived from T. porrifolius T. dubius) and T miscellus Ownbey (derived from T. dubius T. pratensis). Flavonoids and their glycosides were isolated by two-dimensional paper chromatography and identified by co-chromatography with authentic samples and UV spectral analyses (Kroschewsky et al., 1969). In T. porrifolius isoorientin, isovitexin, lucenin-1, luteolin, orientin, quercetin 3-O-b-D-gluoside, vicenin-1, vicenin-2, and vitexin were detected (Kroschewsky et al., 1969). Moreover, T. porrifolius L. yielded a number of acylated pentacyclic triterpene saponins, tragopogonsaponins A-R (Warashina et al., 1991). Various types of bibenzyls and dihydroisocoumarins were isolated from a methanolic extract of subaerial parts of T. porrifolius (Zidorn et al., 2005). Additionally, the ubiquitous quinic acid derivatives chlorogenic acid and 3,5-dicaffeoylquinic acid were identified by HPLC/DAD and HPLC/MS in crude extracts of subaerial parts of T. porrifolius (Zidorn et al., 2003).
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[email protected] (C. Zidorn). 0305-1978/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2009.03.004
V. Sareedenchai et al. / Biochemical Systematics and Ecology 37 (2009) 234–236
O HO HO
1: R = H 2: R = caffeoyl
OR
OH
OH
O O
O
HOOC
HO
HOH2C
HO
O
235
O
OH 3
H3CO
OH
OH
OH
OH
CH2OH CH2OH HO
HO
O
O
HO HO
OH
O
OH
O R 4: R = H 5: R = OH
OH
6
OH O
OH
O
O OH HO Fig. 1. Structures of phenolics from aerial parts of T. porrifolius L.
3. Present study Air-dried, ground aerial parts (1.03 kg) of T. porrifolius were exhaustively macerated with a mixture of MeOH/(CH3)2CO/ H2O (3/1/1, v/v/v) to yield 108 g of crude extract after evaporation of the solvent in vacuo. The crude extract was re-dissolved in a mixture of MeOH and H2O (1/1, v/v) and successively partitioned with petrol ether, EtOAc, and n-BuOH. The residue of the EtOAc layer (5.14 g) was fractionated by silica gel column chromatography using a step-wise gradient of CH2Cl2 and MeOH to give eight fractions. Chlorogenic acid 1 (2.8 mg), 4,5-dicaffeoylquinic acid 2 (5.6 mg), scopoletin 7-Oglucoside 3 (2.6 mg), vitexin 4 (4.0 mg), and orientin 5 (11.5) were concentrated in fraction 3 (3) (eluted with CH2Cl2/MeOH, 8/ 2–6/4, v/v) and fraction 7 (1, 2, 4, and 5) (eluted with CH2Cl2/MeOH, 3/7–2/8, v/v), respectively. Compounds 1–5 were isolated from enriched fractions by repeated Sephadex LH-20 column chromatography using MeOH as an eluant. Isoschaftoside 6 (7.1 mg) (Fig. 1) was isolated from the residue of the BuOH layer (26.8 g) by Sephadex LH-20 column chromatography using MeOH/(CH3)2CO/H2O (3/1/1, v/v/v) and successive Sephadex LH-20 column chromatography using MeOH/H2O (1:1, v/v) as an eluant. Compounds were identified on the basis of their UV, ESI-MS, 1D and 2D NMR data. Finally, results obtained were compared with literature data for 1 and 2 (Iwai et al., 2004), 3 (Bayoumi et al., 2008), 4 (Peng et al., 2008), 5 (Zhou et al., 2005), and 6 (Xie et al., 2003).
4. Chemotaxonomic significance From the six compounds characterized in this communication the caffeoyl derivative 4,5-dicaffeoylquinic acid 2, the coumarin scopoletin 7-O-glucoside 3, and the flavonoid isoschaftoside 6 are new for T. porrifolius and the genus Tragopogon. The C-flavonglycoside isoschaftoside 6 is the most interesting compound. Related C-flavonglycosides are already known from the genus Tragopogon (Kroschewsky et al., 1969). Within the Cichorieae tribe of the Asteraceae family C-flavonglycosides are relatively rare and have so far been also reported from the genera Catananche (Proliac and Raynaud, 1977), Launaea (Gupta and Ahmed, 1985), and Scolymus (Romussi and Ciarallo, 1978). The distribution of flavonoid aglyca and their O- and C-glycosides within the genus Tragopogon is the object of current studies.
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