Ecosystem of microorganisms, bees and Clusia floral resins and oils from the chemistry point of view

Chemical investigations concerning the floral resins of the genus Clusia revealed that they are mainly constituted of polyisoprenylated benzophenones. We have isolated ten benzophenones from C. spiritu-sanctensis (male), C. renggerioides (male with pistilodium), C. weddelliana (male) and C. lanceolata (male) floral resins, eight of which have not been mentioned in the literature before. The islated compounds were used in qualitive and quantitative analyses of the benzophenones present in eleven Clusia species using high performance liquid chromatography. This evaluation revealed that in the eight Clusia species belonging to the section Cordylandra clusianone, a benzophenone possessing the bicyclic [3.3.1] nonene moiety, was the major component, while in the two Clusia species belonging to the section Phloianthera the profile was rather complex and compounds with the bicyclic [3.3.1] nonene moiety were not predominant. The GC/MS analyses revealed that fatty acids are the main constituents of the staminal floral oil. 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, which are mixed with the resins and oils, to reach the stigma papillae where the 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. Bioautography tests confirmed that the resins and the polyisoprenylated benzophenones do have an inhibitory activity in the growth of several microorganisms (Bacillus subtillis, Staphylococcus aureus, Candida albicans). Bioautography tests using nest extracts also revealed that they were active against these microorganisms and that this activity was mainly related to the benzophenones present in the mixture. To complete the study of the Clusia ecosystem we have isolated the microorganisms carried by the Trigona bees and submitted to autobiography tests with Clusia resins. The concerted interdisciplinary effort of botanists, microbiologists and chemist revealed the ecological interactions of Clusia floral resins, fluid oils and some pollinating bees in our part of the World.