Leaf cuticular waxes of Tanaecium (Bignonieae, Bignoniaceae): Chemical composition and taxonomic implications

Tanaecium Sw. emend L.G. Lohmann (Bignonieae, Bignoniaceae, Lamiales) is a genus of Neotropical lianas comprising 21 species distributed from Mexico through Argentina. Despite the medicinal and economic importance of several species of the genus, little is still known about the phytochemistry and chemical composition of foliar cuticular waxes of members of Tanaecium. In this study, we extracted the lipophilic compounds of diverse specimens of seventeen species of Tanaecium and four species of the closely related genus Fridericia Mart. Derivatized compounds were identified by gas chromatography (CG) coupled with mass spectrometry (MS) and by comparison with standards. Relative abundances were estimated and investigated by statistical methods (multivariate and cluster analyses). Leaf cuticular waxes were composed by n-alkanes, fatty acids, primary alcohols, terpenoids, and steroids with n-alkanes C₂₉, C₃₁, and C₃₃ representing the major constituents in addition to octacosanol, β-sitosterol, ursolic, montanic, and palmitic acids. Multivariate analyses of surface compounds supported earlier morphological and molecular data, corroborating the recent placement of some species within Tanaecium and providing sufficient characters to clearly distinguish members of Tanaecium and Fridericia.