Chemotaxonomy of the genus Aquilaria (Thymelaeaceae)
C Zaremski, N Amusant, C Andary, M Ducousso, S Hul, G Michaloud, A Zaremski
The genus Aquilaria Lam. (Thymelaeaceae) comprises 21 tree species and is mostly found in Southeast Asia. When the tree is infected (fungi, bacteria, etc.), its wood turns brownish or blackish (called agarwood) due to the secretion of an oleoresin in reaction to the infection. The resin is very fragrant and has been sought after and used for centuries by Buddhists, Hindus and Muslims to make incense for religious ceremonies. This oleoresin is mainly found in species of the genus Aquilaria, but also in a few species of the genera Gyrinops Gaertner and Gonystylus Teijsmann & Binnendijk. It is difficult to distinguish between these species and this lack of taxonomic knowledge has led to over-use of the trees, endangering these endemic species listed in CITES Appendix II. We used chemotaxonomy as a discrimination tool to analyse polyphenolic molecules, secondary metabolites, which are known to act as taxonomic markers in other plants.
This work showed the possibility of using some very old herbarium samples, which revealed good conservation of its phenolic profile. It is interesting to note that mangiferin, through its high concentration and constant presence in all the species of the genus Aquilaria analysed, constitutes a chemical marker for this genus. Comparative analysis of these phenolic molecules can therefore be very useful when seeking chemotaxonomic markers.