FLAVONOIDS OF BIGNONIACEAE FROM THE CERRADO AND THEIR POSSIBLE TAXONOMIC SIGNIFICANCE

Flavones and glycosides of flavones and flavonols were obtained from l eaves 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 oft en found in species of tribe Tecomeae and rarely in Bignonieae. The sp ecies of the former yielded derivatives of 6-hydroxyluteolin. No 6-oxy genated compounds were found in species of Bignonieae. The results poi nt to the flavonoid chemistry evolution of Bignoniaceae following a pa th of simplification. More complex chemical profiles characterize the more woody Tecomeae rather than the more advanced Bignonieae.