Objective: To compare the in vitro antiparasitic activity of aqueous extracts from Ziziphus joazeiro leaves and stem bark against Trypanosoma cruzi, Leishmania braziliensis, and Leishmania infantum, as well as to evaluate its cytotoxicity in mammalian cells, in addition to identifying the chemical composition of the extracts. Methods: Ziziphus joazeiro leaf and stem bark aqueous extracts were prepared by cold extraction maceration and subjected to ultra-efficient liquid chromatography coupled to a quadrupole/time of flight system. The susceptibility assays used Trypanosoma cruzi CL-B5 strains and promastigote forms of Leishmania braziliensis and Leishmania infantum for antiparasitic activity of the extracts. Moreover, mammalian fibroblasts NCTC clone 929 were used for cytotoxicity analysis. Results: Terpenoid compounds, flavonoids and phenolic acid were identified in extracts. The stem bark aqueous extracts presented more significant results in terms of antiparasitic activity compared with the leaf aqueous extracts, especially against Leishmania braziliensis and Leishmania infantum promastigote forms with an IC50 < 500 μg/mL. The cytotoxicity evaluation showed moderate toxicity of the stem bark aqueous extracts, which is relevant information for the rational use of this plant part since it is widely used by the population. Conclusions: These preliminary results may contribute to the formulation of new therapeutic agents against this group of neglected diseases, so further investigations are required to delineate the mechanisms of action mainly of the aqueous extract of stem bark of Ziziphus joazeiro.

Objective To identify the main chemical classes of compounds from aqueous extract of Enterolobium contortisiliquum (E. contortisiliquum) seed bark and to evaluate its antibacterial activity, as well as its potential to increase the activity of antibiotics against strains of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. Methods Different classes of compounds in the aqueous extract of E. contortisiliquum were evaluated based on the visual changes in the coloration and the formation of precipitate after the addition of specific reagents. The antibacterial activity of the extract and its potential to increase of antibiotic activity of antibiotics drugs, gentamicin and norfloxacin was determined by using the microdilution method. Results Our results demonstrated that the following secondary metabolites were presented in E. contortisiliquum seed bark: flavones, flavonols, xanthones, flavononols, chalcones, aurones, flavones and catechins. The extract itself had very low antibacterial activity against all bacterial strains tested (MIC ≥ 1 024 μg/mL), but there was an increase in the antibiotic activity of gentamicin and norfloxacin when combined in the sub-inhibitory concentration (i.e., MIC/8). Conclusions Our data suggests that E. contortisiliquum seed bark may be an alternative source for new drugs with the potential to increase antibiotic activity against different strains of bacteria.