Eucalyptus spp e Trigona spinipes Fabricius: fitoquímica e contribuição ao conhecimento químico da interação inseto/planta

Abstract

This work reports the study on the volatile chemical constituents of leaves of two Eucalyptus species (Myrtaceae): Eucalyptus citriodora Hook and Eucalyptus tereticornis Smith, collected from the Medicinal Plants Garden Francisco José de Abreu Matos, of the Universidade Federal do Ceará. The circadian and seasonal chemical variation was determined for both plants specimens. Citronelal and 1,8-cineol were major constituents for E. citriodora and E. tereticornis, respectively. Attempting to establish the ecological link between Trigona spinipes Fabricius ("arapuá") and the trees visited by them, particularly E. citriodora Hook, a chromatographic study was performed with the kino (the exudate - resin from several Eucalyptus species originary from Australia) and the ethanol extract from the bees' colony. Thought adequate chromatographic techniques applied to the fractions obtained from the solubilized kino the flavonols: sakuranetin, naringenin, aromadendrin 7-methyl ether, aromadendrin, kaempferol 7-methyl ether, and two news flavonols 6-[1-(phydroxyphenyl)-ethyl]-3,5,4'-trihydroxy-7-methoxy-flavanone and the 6-[1-(p-hydroxyfenil)- ethyl]-3,5,7,4'-tetrahydroxy-flavanone and the heterosides 1-O-cinnamoyl-6-O-(pcoumaroyl)-(3-D-glucopyranoside and 7-methylaromadendrin-4'-O-(6"-trans p-coumaroil)-(3- D-glucopyranoside were obtained from the CHC13 fraction. From the ethyl acetate fraction were isolated the gallic acid, 6-0-(p-coumaroyl)-D-glucopyranose and the tannin 1,0-2,0- digaloyl-6-0-(p-coumaroyl)-13-D-glucopyranoside. From the ethanol extract of the T spinipes Fabricius colony a mixture of the triterpenes magniferolic acid and 3 (3-hydroxi-24 methylenccyclopropan-26-oic, and five flavonoids 3'-methyl-quercetin, sakuranetin, kaempferol 7-methyl ether, tricetin e aromadendrin 7-methyl ether. The volatile components were identified by GC/MS analysis and comparison of the Kovats Indices and mass spectra from a computer library, as well as by visual comparison to literature date. The non-volatile constituents were characterized by spectroscopic and derivatives techniques such IR, MS, iH and 13C NMR, including 2D NMR COSY, HMQC and HMBC.