Contribuição ao estudo fitoquímico e quimiotaxonômico do gênero Unonopsis da região Amazônica

Abstract

In the present work are presented phytochemicals and chemotaxonomic data from five species of the Unonopsis genus (U. guatterioides, U. stipitata, U. duckei, U. floribunda and U. rufescens) commonly found in the Amazon region. Leaves, twigs and trunk barks from each species were collected in different locations in the Amazonas State, being the leaves submitted to hydrodistillation and acid-base treatment. The obtained essential oils and alkaloidal fractions were subjected to analysis by GC-MS and ESI-MS, respectively, verifying after chemometric data processing (PCA and HCA), significant difference between investigated species and their collection points. Through the essential oils analysis by GC-MS were identified 57 constituents, observing the predominance of the sesquiterpenes spathulenol and caryophyllene oxide in practically all investigated species. Analysis by ESI-MS of the alkaloidal fractions evidenced aporphine, proaporphine and tetrahydroprotoberberine alkaloids as responsible for the segregation of the studied species, which are tentatively identified by ESI-MSn. Due to the medicinal use of leaves of U. stipitata and trunk barks of U. floribunda, their respective alkaloidal fractions, FASF and FAFC, were investigated by ESI-MSn and HPLC-DAD-MS. The chromatographic fractionation of FASF resulted in the isolation of the alkaloids norisocorydine, norglaucine, nornatenine, oxoglaucine and N-formyl-norglaucine, while the fractionation of FAFC resulted in the isolation of the alkaloids pallidine, asimilobine, liriodenine, norushinsunine, nornuciferine, isopiline, anonaine, lysicamine, oxoxylopine and O-methylisopiline. All the structures were determined from the spectroscopic data analysis and comparison with literature data. N-formyl-norglaucine is reported for the first time as natural products. Pallidine, norisocorydine, nornantenine, isolipine, oxoxylopine and O-methylisopiline are described for the first time in Unonopsis genus. In addition, the recurrent lanostane-type triterpene polycarpol was confirmed by TLC and MS in the aerial parts (twigs and trunk barks) of U. duckei, U. floribunda, U. rufescens and U. stipitata, reinforcing its significance as chemical marker of the genus.