Outlining the Molecules Tested In Vivo for Chagas Disease, Malaria, and Schistosomiasis Over the Last Six Years - A Literature Review Focused on New Synthetic Drug Identities and Repurposing Strategies.

BACKGROUND: COVID-19 disrupted NTD programs in 60% of countries, impairing public health goals. Thus, boosting NTD's research knowledge is demanding, and in vivo screening of candidates allows for the prospect of promising options based on their overall profile. OBJECTIVE: In this work, we highlighted the relevant research done between 2015-2021 in the fields of synthetic and repurposed drugs that were tested in vivo for Chagas disease, malaria, and schistosomiasis. METHODS: MEDLINE, PUBMED, CAPES PERIODIC, and ELSEVIER databases were used for a comprehensive literature review of the last 6 years of research on each area/disease. RESULTS: Overall, research focused on nitro heterocyclic, aromatic nitro, nucleoside, and metal-based scaffolds for analogue-based drug generation. Repurposing was widely assessed, mainly with heterocyclic drugs, their analogues, and in combinations with current treatments. Several drug targets were aimed for Chagas treatment, specific ones such as iron superoxide dismutase, and more general ones, such as mitochondrial dysfunction. For malaria, hemozoin is still popular, and for schistosomiasis, more general structural damage and/or reproduction impairment were aimed at in vitro analysis of the mechanism of action. CONCLUSION: Latest in vivo results outlined trends for each disease - for Chagas Disease, heterocyclics as thiazoles were successfully explored; for Malaria, quinoline derivatives are still relevant, and for schistosomiasis, repurposed drugs from different classes outstood in comparison to synthetic compounds. This study uprises the continuous development of Chagas disease, malaria, and schistosomiasis drugs, providing researchers with tools and information to address such unmet therapeutic needs.

Identification of Novel Zika Virus Inhibitors: A Screening using Thiosemicarbazones and Thiazoles Templates.

BACKGROUND: Zika virus (ZIKV) remains an important cause of congenital infection, fetal microcephaly, and Guillain-Barré syndrome in the population. In 2016, WHO declared a cluster of microcephaly cases and other neurological disorders reported as a global public health emergency in Brazil. There is still no specific treatment for Zika virus fever, only palliative care. Therefore, there is a need for new therapies against this disease. According to the literature, thiosemicarbazone, phthalimide and thiazole are privileged structures with several biological activities, including antiviral activity against various viruses. OBJECTIVE: Based on this, this work presents an antiviral screening using previously synthesized compounds derived from thiosemicarbazone, phthalimide, and thiazole as new hits active against ZIKV. METHODS: After synthesis and characterization, all compounds were submitted to Cytotoxicity by MTT and Antiviral activity against ZIKV assays. RESULTS: Compounds 63, 64, 65, and 73 exhibited major reductions in the ZIKV title from this evaluation. Compounds 63 (99.74%), 64 (99.77%), 65 (99.92%), and 73 (99.21%) showed a higher inhibition than the standard 6MMPr (98.74%) at the CC20 dose. These results revealed new chemical entities with anti-ZIKV activity. CONCLUSION: These derivatives are promising candidates for further assays. In addition, the current approach brings a new privileged scaffolding, which may drive future drug discovery for ZIKV.

An Overview of the Compounds Tested In Vivo for Leishmania spp. of the Last 5 Years.

BACKGROUND: Leishmaniasis, a still important public health problem, exhibits environmental risk factors such as massive migrations, urbanization, and deforestation. WHO research for Leishmaniasis is mainly focused on the development of new tools, such as diagnostic tests, drugs, and vaccines. During the drug development strategy, only a few compounds were promising and call for further study after the in vitro and in vivo preclinical tests. OBJECTIVE: In this review, our group aimed to highlight the utmost research done during 2014 to 2019 in the fields of natural and synthetic compounds, as well as repurposed drugs and new formulations tested in vivo for Leishmania spp. METHOD: Based on the literature search, we used the databases MEDLINE, PUBMED, CAPES PERIODIC and ELSEVIER to delineate an interval of the last 5 years of research on each field. RESULTS: Among the natural compounds tested, allicin and a fraction of potato tuber extract showed the most promising antileishmanial activity. Concerning synthetic compounds, quinolines, bornyl ester, thymol, benzoxaborole and nitroimidazole derivatives exhibited encouraging results. Moreover, repositioned alternatives involved combinations with known drugs and monotherapy protocols as well. In these years, new formulations were widely assessed as drug delivery systems, such as nanoparticles, micelles and liposomes in polymer conjugations. CONCLUSION: Drug repurposing and new formulations of already-known drugs are worthwhile approaches to promptly introduce new treatment schemes to Leishmaniasis. Nevertheless, the interest in new synthetic compounds and new formulations brings light to new treatment proposals and are notable lines of research.

Dual Parasiticidal Activities of Phthalimides: Synthesis and Biological Profile against Trypanosoma cruzi and Plasmodium falciparum.

Chagas disease and malaria are two neglected tropical diseases (NTDs) that prevail in tropical and subtropical regions in 149 countries. Chagas is also present in Europe, the US and Australia due to immigration of asymptomatic infected individuals. In the absence of an effective vaccine, the control of both diseases relies on chemotherapy. However, the emergence of parasite drug resistance is rendering currently available drugs obsolete. Hence, it is crucial to develop new molecules. Phthalimides, thiosemicarbazones, and 1,3-thiazoles have been used as scaffolds to obtain antiplasmodial and anti-Trypanosoma cruzi agents. Herein we present the synthesis of 24 phthalimido-thiosemicarbazones (3 a-x) and 14 phthalimido-thiazoles (4 a-n) and the corresponding biological activity against T. cruzi, Plasmodium falciparum, and cytotoxicity against mammalian cell lines. Some of these compounds showed potent inhibition of T. cruzi at low cytotoxic concentrations in RAW 264.7 cells. The most active compounds, 3 t (IC50 =3.60 µM), 3 h (IC50 =3.75 µM), and 4 j (IC50 =4.48 µM), were more active than the control drug benznidazole (IC50 =14.6 µM). Overall, the phthalimido-thiosemicarbazone derivatives were more potent than phthalimido-thiazole derivatives against T. cruzi. Flow cytometry assay data showed that compound 4 j was able to induce necrosis and apoptosis in trypomastigotes. Analysis by scanning electron microscopy showed that T. cruzi trypomastigote cells treated with compounds 3 h, 3 t, and 4 j at IC50 concentrations promoted changes in the shape, flagella, and surface of the parasite body similar to those observed in benznidazole-treated cells. The compounds with the highest antimalarial activity were the phthalimido-thiazoles 4 l (IC50 =1.2 µM), 4 m (IC50 =1.7 µM), and 4 n (IC50 =2.4 µM). Together, these data revealed that phthalimido derivatives possess a dual antiparasitic profile with potential effects against T. cruzi and lead-like characteristics.

Phthalimido-thiazole as privileged scaffold: activity against immature and adult worms of Schistosoma mansoni.

Phthalimide, 1,3-thiazole, and thiazolidinone cores are considered privileged scaffolds and represent an attractive starting point to design new bioactive compounds for neglected tropical disease (NTD). Schistosomiasis is a NTD, caused by Schistosoma worms which praziquantel (PZQ) is the only drug used to treat humans, but the decrease in the effect after treatment has been reported. Recently, some phthalimide-thiazole derivatives exhibited in vitro antischistosomal activity against adult worms with significant ultrastructural changes and a lower cytotoxic effect on splenocytes. This new biological phthalimido-thiazole profile has motivated us to evaluate a new generation of such molecules in immature and adult worms. Thus, a phthalimido-thiazolidinone derivative, (3c), and three phthalimido-thiazoles (6c, 7a, and 7h) were evaluated concerning their in vitro activity on schistosomulae and adult worms. The results showed that these compounds brought a significant reduction on the mortality, inhibited oviposition, and then induced mortality in immature and adult worms alike. According to scanning electron microscopy, the tegument was the principal target for 7a and 7h and revealed gradual damage to the tegument surface, inducing destruction and decomposition of the tegument in the same areas and exposition of subtegumental tissue and of muscle tissue. Furthermore, they caused less toxicity in splenocytes than PZQ. Compounds 7a and 7h revealed to possess promising activity against larval forms. According to the present study, the privileged structure phthalimido-thiazoles act as a molecular framework that has antischistosomal activity and most form the basis to the next pre-clinical tests. Graphical abstract.