Chemistry aids conservation
Scientists at Kew have discovered that a chemical present in Brazilian rosewood (Dalbergia nigra) can be used to identify imports of timber from this species that contravene international regulations, so aiding conservation.
01 Mar 2011
A radial longitudinal section of the heartwood of Dalbergia nigra viewed under a microscope (Image: P.Gasson/RBG Kew)
Dalbergia nigra (Brazilian rosewood) is a timber species from the Atlantic forests of Brazil that has become threatened in the wild due to overexploitation in the past for use in furniture, flooring and musical instruments. Since 1992, to help protect the species, international trade in the wood has been regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
One problem with enforcing the CITES regulations has been distinguishing Brazilian rosewood from some other similar timbers traded as ‘rosewoods’ that are not subject to regulation. Now a team of scientists at Kew have discovered a way to uniquely identify the wood.
Firstly the team examined the microscopic characteristics of wood from D. nigra and similar rosewoods. They identified certain characteristics that could be used to suggest that a wood may be from D. nigra. Such microscopic examination could quickly eliminate a timber that was not D. nigra but it could not positively distinguish the wood of D. nigra from some very similar woods of other Dalbergia species.
A chemical test
Woods of Dalbergia are rich in phenolic compounds, so the team then decided undertake chemical analyses to see if the anatomically-similar species differed in their chemistry. This involved soaking small fragments of timber in methanol and then analysing the compounds that the methanol had extracted. The analysis used a mass spectrometer coupled to a liquid chromatograph to separate the extracted compounds and determine their molecular masses and formulae.
The chemical analyses showed that one of the main phenolic compounds extracted from wood of D. nigra was not present in any of the other species having similar wood anatomy. The team then set about isolating this compound to find out what it was. To their surprise they discovered that it was a compound new to science (albeit a variation of a previously known compound) and they named it dalnigrin.
Using this combination of microscopic and chemical analyses, scientists at Kew can help the UK Border Agency and other enforcement officers to identify illegal imports of this timber.
Item from Dr Geoffrey Kite (Phytochemist, RBG Kew)
Originally published in Kew Scientist, issue 38
Gasson, P.,Miller, R, Stekel, D.J., Whinder, F. and Zieminska, K. (2010). Wood identification of Dalbergia nigra (CITES Appendix I) using quantitative wood anatomy, principal components analysis and naıve Bayes classification. Annals of Botany 105, 45–56.
Kite, G.C., Green, P.W.C, Veitch, N.C, Groves, M.C., Gasson, P.E. & Simmonds, M.S.J. (2010). Dalnigrin, a neoflavonoid marker for the identification of Brazilian rosewood (Dalbergia nigra) in CITES enforcement. Phytochemistry 71: 1122–1131.
Scientific Research and Data
- CITES-Listed Timbers (Kew Science Project)
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