Constituents, antileishmanial activity and toxicity profile of volatile oil from berries of Croton macrostachyus

The chemical composition of the volatile oil from berries of Croton macrostachyus Hochst. ex Del. was determined by GC and GC/MS. The oil was tested for its in vitro antileishmanial activity on two Leishmania strains, and its toxicity on the human monocytic leukemia (THP-1) cell line and erythrocytes from sheep blood. The main constituents of the oil were benzyl benzoate (51.8%), linalool (10.1%), gamma-muurolene (9.3%), (E,E)-alpha-farnesene (3.2%), delta-cadinene (2.8%) and alpha-curcumene (2.7%). The oil was effective against L. donovani and L. aethiopica promastigotes (MIC = 0.08 microL/mL and 0.16 microL/mL, respectively) and axenic amastigote stages (EC50 = 20.00 nL/mL and 6.66 nL/mL, respectively). The CC50 value for the oil was 10.00 nL/mL on THP-1 cells with selectivity index values of 0.5 for L. donovani and 1.5 for L. aethiopica. The median lethal concentration (LC50) of the oil was 2.45 microL/mL. Thus the observed high efficacy and moderate toxicity of the volatile oil from C. macrostachyus, makes the plant a promising source of new lead compounds in the search for safe and effective antileishmanial drugs.