Scutellarein 4′-methyl ether glycosides as taxonomic markers in Teucridium and Tripora (Lamiaceae, Ajugoideae)
The flavone glycosides scutellarein 4′-methyl ether 7-O-rutinoside and scutellarein 4′-methyl ether 7-O-glucuronide have been isolated from Teucridium parvifolium and Tripora divaricata, respectively. Their value as chemical characters in the taxonomy of the Ajugoideae is described.
Introduction
The taxonomic treatment of Teucridium parvifolium Hook.f. and Tripora divaricata (Maxim.) P.D.Cantino (=Caryopteris divaricata Maxim.) has changed many times during the last decade. Teucridium parvifolium is one of only four species of Lamiaceae native to New Zealand, which are all endemic (Allan, 1961). It is a woody shrub up to 2 m tall, with interlacing branches, small leaves and very small flowers, and is the only species in the genus Teucridium. Tripora is also a monotypic genus with a name derived from the triporate pollen of T. divaricata, a unique character in the Lamiaceae. Tripora, a tall herb native to China, Japan and Korea, was recently removed from Caryopteris, because this genus was found to be paraphyletic (Cantino et al., 1999). Teucridium and Caryopteris including Tripora were formerly classified in the family Verbenaceae, but later transferred to the newly created Lamiaceae subfamily Teucrioideae, together with a number of other genera (Cantino et al., 1992). Recently all the genera of the Teucrioideae were transferred to the subfamily Ajugoideae (Cantino et al., 1997), which now comprises ca. 850 species in 24 genera. These include Clerodendrum (500 spp.), Aegiphila (150 spp.), Teucrium (100 spp.), Ajuga (50 spp.), Oxera (23 spp.), Caryopteris (7 spp.), Faradaya (3 spp.) and the monotypic Huxleya, Oncinocalyx, Teucridium and Tripora. Evidence from chloroplast DNA sequences suggests that Teucridium is sister to the Australian genus Oncinocalyx and that these form a clade with the cosmopolitan genus Teucrium. Clerodendrum, Caryopteris, Tripora and Ajuga form a sister group to this clade (Wagstaff et al., 1998). To the best of our knowledge Teucridium parvifolium and Tripora divaricata have not yet been investigated for their flavonoid constituents. This paper describes the isolation and identification of flavonoids from these species and discusses their use in the chemosystematics of the Ajugoideae.
Section snippets
Results and discussion
Aqueous methanol extracts of Teucridium parvifolium and Tripora divaricata were analyzed by 2-D PC, HPLC with diode array detection and LC–MS using atmospheric pressure chemical ionisation (APCI). The flavonoids from the extracts of Teucridium parvifolium (1a, 2a, 3, 4a, 5) and Tripora divaricata (1b, 2b, 3, 4b, 6, 7) were isolated by means of preparative PC and semi-preparative HPLC. The short wavelength UV band of 1a (λmax=285 nm) was typical of that of a flavone with hydroxylation at C-6 (
General
1H NMR (500 MHz) and 13C NMR (125 and 67.8 MHz) spectra were recorded in DMSO-d6 with the residual solvent resonances used as internal references at δ 2.50 and 39.5, respectively. ROE connectivities were measured using the 1D XSROESY pulse sequence (Gradwell et al., 1997). High-resolution ESI-MS (positive mode) were obtained on a Bruker Apex II instrument using internal calibrants. Positive ion first-order APCI-MS were obtained with a quadrupole ion-trap instrument (Finnigan LCQ) using a
Acknowledgements
Access to high field NMR facilities was kindly provided by the Medical Research Council, Biomedical NMR Centre, National Institute for Medical Research, Mill Hill, London, UK. We thank chemiSPEC (North of England Business and Innovation Centre, Sunderland Enterprise Park East, Sunderland, UK) for high-resolution MS data.
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