Chagas disease (CD) is a neglected tropical parasitic disease caused by the protozoan Trypanosoma cruzi. Unfortunately, the current etiological treatment for CD is unsatisfactory, due to the high toxicity and low cure efficacy of compounds, mainly during the chronic phase of this disease. Thus, the discovery of new drugs for the treatment of CD is urgent. In the present study, we report the synthesis of a series of guanidines and its evaluation in in vitro assays to determine the trypanocidal effects on the Tulahuen T. cruzi strain, transfected with a β-galactosidase reporter gene, in comparison to the cytotoxic effects on vertebrate cells. The most potent and selective compounds LQOF-G1 and LQOF-G29 were considered good drug prototypes and candidates for in vivo tests using mice. Both compounds possess an electron withdrawing group on the aniline moiety, namely a NO2 and Br group, respectively, which effectively decrease the electron density. LQOF-G29 stands out among the investigated compounds due to the replacement of the benzyl group by methyladamantane.

In this paper is described the obtention of fourteen derivatives from four natural labdane diterpenes isolated from Copaifera oleoresin, named ent-copalic acid (1), ¬ent-3beta-acetoxy copalic acid (2), ent-3beta-hydroxy copalic acid (3) and ent-agathic acid (4). All eighteen compounds were assayed against promastigote form of Leishmania amazonensis and trypomastigote forms of Trypanosoma cruzi, revealing two promising compounds related to leishmanicidal activity (IC50 = 5.94 micromolar and 5.31 micromolar) and three promising compounds with trypanocidal activity, two of them (IC50 = 13.31micromolar and IC50 = 15.05micromolar) displaying similar activity as the reference drug (IC50 = 13.12micromolar) and one of them even more potent with IC50 = 0.425micromolar.

Parthenium incanum (Mariola) is used in Mexico to treat stomach and liver disorders. Reports have shown that the genus Parthenium contains biologically active metabolites. This work aimed to isolate and identify biologically active compounds with trypanocidal activity. The extracts were obtained through static maceration and extraction with successive reflux using different solvents. After that, they were fractionated with column chromatography, and the obtained fractions were compared by TLC; similar fractions were pooled and concentrated. A bioguided assay was performed with S. aureus ATCC 25923, using agar diffusion techniques and bioautography to determine preliminary biological activity. Active fractions were obtained and purified from a preparative TLC plate. The obtained compounds were identified as parthenin and coronopolin by TLC, FT-IR, and HPLC-MS. Finally, they were evaluated against the Ninoa strain of Trypanosoma cruzi, obtaining an IC50 of up to 45±2.5 ppm. It was concluded that P. incanum contains compounds with trypanocidal activity.