Abstract:
Tapura fischeri is a member of the family Dichapetalaceae and the only other member of
this family naturally occurring in South Africa is Dichapetalum cymosum. Poisoning by D.
cymosum results in the deaths of many domestic livestock each year due to the presence of
fluoroacetate. The aim of the study was to determine if monofluoroacetate or another
fluorinated compound is present in T. fischeri, and the possible role endophytes might play
in the production of these compounds. Through NMR and GCMS studies it was established
that trifluoroacetate is present in T. fischeri. Bacterial endophytes were isolated from plant
material and shown to produce a fluorinated compound other than mono and trifluoroacetate.
Since trifluoroacetic acid is extremely volatile, and evaporate from the plant
extract over time, column chromatography, together with NMR was employed to isolate and
identify other compounds responsible for antibacterial activity against the bacterium
Enterococcus faecalis previously observed on TLC plates. Two compounds were isolated,
and identified with NMR as a fatty acid and a fatty acid attached to glycerol. The names of
the compounds could not be established with GCMS due to insufficient derivatization of the
compounds. The antibacterial activity of the compounds were also analyzed using 96 well
microtitre plates in liquid media, where it was determined that the compounds do not have
antibacterial activity against E. faecalis. This indicated that previous results on TLC plates
were false positives due to the hydrophobic nature of the fatty acid compounds.
Transmission electron microscopy was done on leaf material to determine the presence of
bacterial endophytes in the intracellular spaces of plant material, but none was detected.
These results suggest a possitive correlation between the plant, its endophytes and the
production of the fluorinated compound.
