Flavonoids of Bignoniaceae from the "cerrado" and their possible taxonomic significance

Flavones and glycosides of flavones and flavonols were obtained from leaves of five species of Bignoniaceae from the "cerrado", a savanna ecosystem of Central and Southeast Brazil. A predominance of flavonol glycosides was observed in all samples investigated. Flavones were often found in species of tribe Tecomeae and rarely in Bignonieae. The species of the former yielded derivatives of 6-hydroxyluteolin. No 6-oxygenated compounds were found in species of Bignonieae. The results point to the flavonoid chemistry evolution of Bignoniaceae following a path of simplification. More complex chemical profiles characterize the more woody Tecomeae rather than the more advanced Bignonieae.