Aim of the study: Despite the extensive traditional use of Croton gratissimus Burch. var. gratissimus for
medicinal purposes, scientific studies validating the therapeutic properties of this indigenous plant are
lacking. As the bark, roots and leaves of C. gratissimus are used separately as well as in combination, this
study focused on determining antimicrobial efficacies of the plant parts independently and in combination
to assess possible pharmacological interactions (e.g. synergy, antagonism).
Material and Methods: The hydro-distilled leaf essential oil and extracts of bark, root and leafwere comparatively
assessed for antimicrobial activity by means of microdilution minimum inhibitory concentration
(MIC). The fractional inhibitory concentrations (FIC) were determined for the leaf and root (1:1), bark
and root (1:1), leaf and bark (1:1) combination. Isobolograms were plotted to demonstrate interactions
between various ratios of the roots and leaves.
Results: The MIC and FIC results indicated variable efficacies for the various plant part combinations,
the greatest of which was noted for Cryptococcus neoformans in the root and leaf combination (MIC 0.4
mg/ml and FIC of 0.4). Isobolograms indicated the greatest synergy for Bacillus cereus, Candida albicans
and Cryptococcus neoformans.
Conclusion: The observed synergistic interactions clearly indicate that the reductionist approach may
often be short-sighted and that biological activity may be improved through combination therapy, where
different complex metabolic pools collectively contribute to the enhanced effect.
van Vuuren, SF
0314354450697863-van Vuuren and Viljoen.pdf
Journal of Ethnopharmacology
In vitro evidence of phyto-synergy for plant part combinations of Croton
gratissimus (Euphorbiaceae) used in African traditional healing