Secondary metabolites are essential for plant survival and reproduction. Wild undomesticated and tropical plants are expected to harbor highly diverse metabolomes. We investigated the metabolomic diversity of two morphologically similar trees of tropical Africa, Erythrophleum suaveolens and E. ivorense, known for particular secondary metabolites named the cassaine-type diterpenoids. To assess how the metabolome varies between and within species, we sampled leaves from individuals of different geographic origins but grown from seeds in a common garden in Cameroon. Metabolites were analyzed using reversed phase LC-HRMS(/MS). Data were interpreted by untargeted metabolomics and molecular networks based on MS/MS data. Multivariate analyses enabled us to cluster samples based on species but also on geographic origins. We identified the structures of 28 cassaine-type diterpenoids among which 19 were new, 10 were largely specific to E. ivorense and five to E. suaveolens. Our results showed that the metabolome allows an unequivocal distinction of morphologically-close species, suggesting the potential of metabolite fingerprinting for these species. Plant geographic origin had a significant influence on relative concentrations of metabolites with variations up to eight (suaveolens) and 30 times (ivorense) between origins of the same species. This shows that the metabolome is strongly influenced by the geographical origin of plants (i.e., genetic factors).

Background. Cutaneous leishmaniasis causes physical disfigurement and impairment on affected individuals, however, little attention has been paid to it eradication. The situation of this neglected disease is complicated with the expansion of the non-human pathogenic Leishmania enriettii complex causing infection in humans. We have previously shown that the extract from Erythrophleum ivorense has leishmanicidal activity against promastigote stages of the L. enriettii complex isolate from Ghana and L eishmania donovani. The extract of E. ivorense has shown to have anti-inflammatory, wound-healing ability, antiallergic, antimalarial and antischistosomal activity. However, the concentration threshold of E. ivorense extract required for leishmanicidal activity against the emerging human pathogenic L. enriettii complex isolates is not clear. Aim. To test for the concentration threshold of E. ivorense extract required to obtain ideal leishmanicidal activity against the promastigote stage of human pathogenic L. enriettii complex isolates from Ghana. Method. The ethanolic leaf extract of E. ivorense was serially diluted and tested against the promastigote stage of the L. enriettii complex. Parasite inhibition was measured at 590 nm using a spectrophotometer after staining parasites with trypan blue. To select the threshold concentration for maximum inhibition of the promastigote stage of the L. enriettii complex, the concentration cut-off statistic was used. Results. The MIC of E. ivorense extract for L. enriettii promastigote inhibition was 62.3 μg ml−1. The highest promastigote inhibition was observed at 72 h. Conclusion. We show that a MIC of 62.3 μg ml−1 of E. ivorense leaf extract exhibits an ideal leishmanicidal activity against the promastigote stage of L. enriettii complex isolates.

The extract of different species of Euphorbia has been successfully used as a remedy for treatment of cutaneous leishmaniasis. The aim of this study was to assess the in vitro leishmanicidal effect of Euphorbia petiolata (E. petiolata) extract. Ethanolic percolated and methanolic Soxhlet extract of E. petiolata on promastigotes of L. major at different concentrations of extracts, one positive control group and one negative control group as well as 1 solvent control were prepared and placed in 24-well plates that contained 40,000 parasites/well. Afterwards, plates were incubated at 25 ˚C for six days and number of parasites in each well were determined on days 2, 4 and 6 of the experiment. Both percolated and Soxhlet extracts in methanol and DMSO solvents had significant effects (equal to that of amphotericin B) on promastigote form of parasite at the concentration of 1 mg/ml. At lower concentrations, the extracts of E. petiolata had favorable leishmanicidal activity and killed L. major promastigotes dose-dependently. Our results support the possibility of E. petiolata extracts application as an anti-leishmanial agent with similar effects to amphotericin B.