A quimica das interações ecologicas de Clusia e seus polinizadores

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

The research project we are about to describe has the particular aspect of approaching the Clusia ecosystem from the chemical point of view investigating the composition of the floral resins and oils and its importance in the life their pollinators (bees). Chemical investigations on the floral resins of Clusia species revealed that they are mainly constituted of polyisoprenylated benzophenones. We have isolated ten benzophenones from C. spiritu-sanctensis male, C. renggerioides male with pistillodeum, C. weddelliana male and C. lanceolata male floral resins, eight of which have not been mentioned in the literature before. The isolated compounds were used in qualitative and quantitative analyses of the benzophenones present in 11 Clusia species using high performance liquid chromatography. This evaluation revealed that in the eight Clusia species belonging to the section Cordylandra (C. burchellii male, C. spiritu-sanctensis male e female, C. fluminensis male, C. pana-panari male, C. paralicola male, C. pernambucensis male, C. renggerioides male with e sem pistillodeum, C. renggerioides female, C. weddelliana male) clusianone e benzophenone possessing the bicyclic [3.3.1]nonene moiety was the major component, while in the two Clusia species belonging to the section Phloianthera (C. lanceolata male e C. hilariana male) the profile was rather complex and compounds with the bicyclic [3.3.1]nonen moiety were not major components. The gas chromatography associated with mass spectrometry analysis (GC/MS) revealed that the fluid staminal floral oils main constituents are fatty acids. These oils would act as a natural solvent reducing the viscosity of the Clusia floral resins belonging to the section Cordylandra, thus allowing enough mobility to the pollen grains mixed this section with resin + oil in order to reach the stigma papillae where conditions for germination are found. In section Chlamydoclusia, where staminal oil and resins are well separated within a male flower, the oil serves to improve the adherence of the dry pollen grains to the smooth body of the pollinating bees. Although the chemistry of the floral resins and oils were interesting we were rather intrigued by their role in the pollinators´ life (bees). It was observed that the bees would collect resins too build their nest and would keep on collecting constantly new resin. This field observation was the starting point for the second part of our investigation which involved the unquestionable confirmation that the Clusia floral resins were used in the bees´ nest building process. Thus material of a Trigona nest close to several Clusia specimens was collected and analysed by HPLC and by GC/MS. Among the several components we have indeed confirmed the presence of polyisoprenylated benzophenones thus confirming the floral resins as one of the nest constructing materials. The constant harvesting of the resins was taken as indicative of an possiby additional function of the floral resins in the bees life, like biological activity e.g. protecting larvae and nest from infestation microorganisms. Bioautography tests confirmed that the polyisoprenylated benzophenones do have an inhibitory activity in the growth of several microorganisms (Bacillus subtilis, Staphylococcus aureus, Candida albicans). Bioautography tests using nest extracts also revealed that these were active against the microorganisms and that this activity was mainly related to the benzophenones present in the extrats. Finally the interdisciplinary concerted effort of botanists, microbiologists and chemists allowed to uncover the ecological interactions of Clusia floral resins, fluid oils and the pollinating bees in our part of the world.

ASSUNTO(S)

clusia quimica compostos aromaticos ecologia polinização interação animal-planta

ACESSO AO ARTIGO

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