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Humans have been using plants in the treatment of various diseases for millennia. Currently, even with allopathic medicines available, numerous populations globally still use plants for therapeutic purposes. Although plants constitute a safer alternative compared to synthetic agents, it is well established that medicinal plants might also exert adverse effects. Thus, the present investigation aimed to assess the phytotoxic, cytotoxic, and genotoxic potential of two plants from the Brazilian Cerrado used in popular medicine, Davilla nitida (Vahl) Kubitzki, and Davilla elliptica (A. St.-Hil.). To this end, germination, growth, and cell cycle analyses were conducted using the plant model Lactuca sativa . Seeds and roots were treated with 0.0625 to 1 g/L for 48 hr under controlled conditions. The germination test demonstrated significant phytotoxic effects for both species at the highest concentrations tested, while none of the extracts produced significant effects in the lettuce growth test. In the microscopic analyses, the aneugenic and cytotoxic action of D. elliptica was evident. In the case of D. nitida greater clastogenic action and induction of micronuclei, (MN) were noted suggesting that the damage initiated by exposure to these extracts was not repaired or led to apoptosis. These findings indicated that the observed plant damage was transmitted to the next generation of cells by way of MN. These differences in the action of the two species may not be attributed to qualitative variations in the composition of the extracts as both are similar, but to quantitative differences associated with synergistic and antagonistic interactions between the compounds present in these extracts.

Natural products are usually considered harmless; however, these substances need to be consumed with caution. Biological assays with plant models are a suitable alternative for prospective studies to assess natural product-initiated toxicity. The aim of this study was to examine the toxic potential of leaf and flower extracts derived from Tropaeolum majus L. a widely used plant in traditional medicine. Seeds of Lactuca sativa L. were exposed to T. majus extracts and based upon the seedling growth curve values, the 50% Inhibition Concentration (IC 50 ) was calculated and applied for cell cycle analysis exposure. Both extracts contained organic acids, proteins, amino acids, and terpene steroids. Sesquiterpene lactones and depside were detected in leaf extracts. The higher concentration tested exhibited a marked phytotoxic effect. The extracts induced clastogenic, aneugenic cytotoxic, and potential mutagenic effects. The possible relationships between the classes of compounds found in the extracts and effects on cells and DNA were determined.