A series of fifty arylideneketones and thiazolidenehydrazines was evaluated against Leishmania infantum and Leishmania braziliensis. Furthermore, new simplified thiazolidenehydrazine derivatives were evaluated against Trypanosoma cruzi. The cytotoxicity of the active compounds on non-infected fibroblasts or macrophages was established in vitro to evaluate the selectivity of their anti-parasitic effects. Seven thiazolidenehydrazine derivatives and ten arylideneketones had good activity against the three parasites. The IC₅₀ values for T. cruzi and Leishmania spp. ranged from 90 nM–25 µM. Eight compounds had multi-trypanocidal activity against T. cruzi and Leishmania spp. (the etiological agents of cutaneous and visceral forms). The selectivity of these active compounds was better than the three reference drugs: benznidazole, glucantime and miltefosine. They also had low toxicity when tested in vivo on zebrafish. Trying to understand the mechanism of action of these compounds, two possible molecular targets were investigated: triosephosphate isomerase and cruzipain. We also used a molecular stripping approach to elucidate the minimal structural requirements for their anti-T. cruzi activity.

The currently available treatments for Chagas disease show limited therapeutic potential and are associated with serious side effects. Attempting to find alternative drugs isolated from Nature as agents against Trypanosoma cruzi has been our goal. Recently, we have demonstrated the in vitro anti-T. cruzi activities of two secondary metabolites isolated from the hydro-ethanolic extract of the aerial parts of Aristeguietia glutinosa (Lam.), (family Asteraceae). These active principles displayed poor hemolytic activity, low toxicity against murine macrophages, and absence of mutagenicity. Herein, proof of concept in vivo studies of the whole hydro-ethanolic extract of the aerial parts of Aristeguietia glutinosa and of the most active component isolated from the hydro-ethanolic extract, i.e., (+)-15-hydroxy-7-labden-17-al, was done in a murine acute model of Chagas disease. Both treatments caused a decrease in the animals’ parasitemia. Metabolomic mechanism of action studies were done by ¹H-NMR, both on the extract and on the active compounds, examining the effects of the metabolites both on membrane sterol biosynthesis and mitochondrial dehydrogenases, whereby we found that one of the metabolites inhibited the activity of the parasite mitochondrial dehydrogenases and the other inhibited the biosynthesis of parasite membrane sterols. The results are interesting in the context of popular use of plants for the treatment of Chagas disease.

Background: Multiple therapeutic properties have been attributed to Cannabis sativa. However, further research is required to unveil the medicinal potential of Cannabis and the relationship between biological activity and chemical profile. Objectives: The primary objective of this study was to characterize the chemical profile and antioxidant properties of three varieties of Cannabis sativa available in Uruguay during progressive stages of maturation. Methods: Fresh samples of female inflorescences from three stable Cannabis sativa phenotypes, collected at different time points during the end of the flowering period were analyzed. Chemical characterization of chloroform extracts was performed by ¹H-NMR. The antioxidant properties of the Cannabis sativa extracts, and pure cannabinoids, were measured in a Cu²⁺-induced LDL oxidation assay. Results: The main cannabinoids in the youngest inflorescences were tetrahydrocannabinolic acid (THC-A, 242 ± 62 mg/g) and tetrahydrocannabinol (THC, 7.3 ± 6.5 mg/g). Cannabinoid levels increased more than twice in two of the mature samples. A third sample showed a lower and constant concentration of THC-A and THC (177 ± 25 and 1 ± 1, respectively). The THC-A/THC rich cannabis extracts increased the latency phase of LDL oxidation by a factor of 1.2–3.5 per μg, and slowed down the propagation phase of lipoperoxidation (IC₅₀ 1.7–4.6 μg/mL). Hemp, a cannabidiol (CBD, 198 mg/g) and cannabidiolic acid (CBD-A, 92 mg/g) rich variety, also prevented the formation of conjugated dienes during LDL oxidation. In fact, 1 μg of extract was able to stretch the latency phase 3.7 times and also to significantly reduce the steepness of the propagation phase (IC₅₀ of 8 μg/mL). Synthetic THC lengthened the duration of the lag phase by a factor of 21 per μg, while for the propagation phase showed an IC₅₀ ≤ 1 μg/mL. Conversely, THC-A was unable to improve any parameter. Meanwhile, the presence of 1 μg of pure CBD and CBD-A increased the initial latency phase 4.8 and 9.4 times, respectively, but did not have an effect on the propagation phase. Conclusion: Cannabis whole extracts acted on both phases of lipid oxidation in copper challenged LDL. Those effects were just partially related with the content of cannabinoids and partially recapitulated by isolated pure cannabinoids. Our results support the potentially beneficial effects of Cannabis sativa whole extracts on the initial phase of atherosclerosis.

The current pharmacological Chagas disease treatments, using Nifurtimox or Benznidazole, show limited therapeutic results and are associated with potential side effects, like mutagenicity. Using random screening we have identified new chemotypes that were able to inhibit relevant targets of the Trypanosoma cruzi. We found 3H-[1,2]dithioles with the ability to inhibit Trypanosoma cruzi triosephosphate isomerase (TcTIM). Herein, we studied the structural modifications of this chemotype to analyze the influence of volume, lipophilicity and electronic properties in the anti-T. cruzi activity. Their selectivity to parasites vs. mammalian cells was also examined. To get insights into a possible mechanism of action, the inhibition of the enzymatic activity of TcTIM and cruzipain, using the isolated enzymes, and the inhibition of membrane sterol biosynthesis and excreted metabolites, using the whole parasite, were achieved. We found that this structural framework is interesting for the generation of innovative drugs for the treatment of Chagas disease.

Chagas disease, caused by Trypanosoma cruzi, is considered an endemic disease that affects millions of people causing generating health, economic and social problems. This study provides a review on research and development of new therapies for Chagas based in natural products of plant origin. We observed that there are more than 400 plant species that have been evaluated against different models of Chagas disease, and in some cases, there are interesting results. Challenge that hinders research work is the purification of the active compound and standardization of the chemical profile of whole extracts. The principal common factor that delays clinical testing is the lack of investment for the development of these products at the clinical phase. In the search of a natural, low cost and available drug for Chagas disease, we propose the use of new methodologies to overcome the existing challenges. The use of plant metabolomic technique is proposed as an option with high potential for the identification of biomarkers that could allow the standardization of chemical profiles. Furthermore, we describe the importance of applying good agricultural and manufacturing practices for reaching a successful development of quality phytotherapeutic products.