Variability in potency is usually ascribed to differences in
the relative amount and composition of phenolic compounds
extracted with specific solvents. Some plant tissues yield
fractions of comparatively simple composition and the source
of antimicrobial activity can be deduced with some certainty. In
contrast, mangosteen tissues contain heterogeneous mixtures
of molecules belonging to several major groups of phenolic
compounds.5 Chemical analysis was therefore carried out with
a view to identifying differences in the major classes of phenolic
compounds recovered with the two solvents. Table 5 shows
the concentrations of total phenolics, tartaric esters, flavonols and
tannins in the waterandmethanol extracts. Anthocyaninswere not
detected in the samples. The method used for these analyses can
only provide estimates of tannin concentration due to interference
by non-phenolic compounds during absorbance measurements.
It was therefore not possible to calculate accurate percentages
of each class of phenolics. Nevertheless the results indicated that
extraction of pericarp with methanol yielded the highest relative
concentrations of tartaric esters and flavonols, followed by bark
extract. These classes of phenolics were also present in aqueous
extract prepared from pericarp, although in comparatively lower
concentrations, and aqueous bark extract contained the lowest