Jatropha curcas L. (Euphorbiaceae) is important for biofuel production and as a feed ingredient for animal. However, the presence of phorbol esters in the oil and cake renders the seeds toxic. The toxicity ofJ. curcas oil is currently assessed by testing in animals, leading to their death. The identification of toxic and nontoxic improved varieties is important for the safe use of J. curcas seeds and byproducts to avoid their environmental toxicity. Hence, the aim of this study was to propose a short-term bioassay using a plant as a model to screen the toxicity of J. curcas oil without the need to sacrifice any animals. The toxicity of J. curcas oil was evident in germination, root elongation and chromosomal aberration tests in Lactuca sativa. It was demonstrated that J. curcas seeds contain natural compounds that exert phyto-, cyto- and genotoxic effects on lettuce, and that phorbol esters act as aneugenic agents, leading to the formation of sticky chromosomes and c-metaphase cells. In conclusion, the tests applied have shown reproducibility, which is important to verify the extent of detoxification and to determine toxic doses, thus reducing the numbers of animals that would be used for toxicity tests.

The intensive application of agrochemicals in crops has negatively impacted the environment and other organisms. The use of naturally occurring compounds may be an alternative to mitigate these effects. Plants are secondary metabolite reservoirs and may present allelopathic activity, which is potentially interesting to be used in bioherbicide formulations. In this context, the present work aimed to evaluate the phytotoxic and cytotoxic effects of essential oils extracted from leaves of Sparattanthelium botocudorum and Sparattanthelium tupiniquinorum in bioassays with the plant models Lactuca sativa L. and Sorghum bicolor L. Moench. The essential oils were applied at concentrations of 3,000, 1,500, 750, 375 and 187.5 ppm. Chemical characterization of the oils was performed, and their impact on the percentage of germinated seeds, initial development of L. sativa and S. bicolor seedlings, and changes in the mitotic cycle of meristematic cells from L. sativa roots was evaluated. The major compound of the essential oils was germacrene D, followed by bicyclogermacrene, β-elemene and germacrene A. The phytotoxicity assay showed that the essential oils of both species reduced the root and shoot growth in L. sativa and decreased the germination and shoot growth in S. bicolor. Inhibition was dependent on the tested oil concentration. In the cytotoxicity assay, a decrease in mitotic index and chromosomal and nuclear alterations were observed, which resulted from aneugenic and clastogenic action.