The ecosystem of microorganisms, bees and Clusia
floral resins and oils, from the chemistry point of view*
A. J. Marsaioli,
A.L.M. Porto, R.A.C. Goncalves, C.M.A. de Oliveira, G.P. Manfio,
and V. Bittrich
Instituto de Quimica, UNICAMP, CP 6154, Campinas
13083-970 S.Paulo, Brazil
E-mail: [email protected]
Abstract: The research that 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 their importance in the life of their
pollinators.
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 sanctenis (male), C. reggerioides
(male with pistilodium), 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 eleven Clusia species using high performance liquid
chromatography. This evaluation revealed that in the eight Clusia
species belonging to the 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
Ploianthera 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. The 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.
With the elucidation of the floral resin and oil chemistry
we focused our attention on this particular ecosystem involving
Clusia floral resins and oils and their pollinators (bees).
It was observed that the bees would constantly collect resins to
build their nests. To confirm that Clusia floral resins were
indeed used in the bees’ nest building process we have collected
a Trigona nest close to several Clusia specimens and
analysed by HPLC and GC/MS. Among several components we have 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
additional function of the floral resins in the bees’ life,
like biological activity and protecting larvae and nest from microorganisms
infestation.
Bioautography tests confirmed that the resins and the polyisoprenylated
benzophenones do have an inhibitory activity in the growth of several
microorganisms (Bactillus subtillis, Staphylococcus aureus, Candida
albicans). Bioautography tests using the 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 bioautography tests with Clusia resins.
The concerted interdisciplinary effort of botanists, microbiologists
and chemists revealed the ecological interactions of Clusia
floral resins, fluid oils and some pollinating bees in our part
of the World.
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