Resumen de Epicuticular components from pseudognaphalium robustum (asteraceae): Chemosystematic considerations
Alejandro Urzúa, Leonora Mendoza
Surface compounds were obtained by a methylene chloride extraction of fresh aerial parts of Pseudognaphalium robustum. The methylene chloride extract was fractionated by CC and the fractions were analyzed by GC-MS. Since flavonoids and terpenes are present only in small amounts in the epicuticular exúdate of P. robustum, 80% of the surface compounds actually correspond to a complex mixture of saturated fatty acid esters, unsaturated fatty acid esters, alcohols, aldehydes, fatty acids, alkenes, triglycerides and monoglycerides. A minor hydrocarbon fraction of n-alkanes from C23 to C37 was also identified. On the contrary, in P. vira vira, P. cheiranthifolium, and P. heterotrichium, the epicuticular extracts contain from 70% to 80% of a mixture of diterpenoids and n-alkanes. These results show a remarkable distance between P. robustum and other species of the genus, which share the same ecosystem, when the whole pool of epicuticular compounds is taken into account. Also, these considerable differences in chemical composition are in agreement with authors that consider Pseudognaphalium as a heterogeneous taxonomic group
