Synthesis and anti-Trypanosoma cruzi activity of new 3‐phenylthio-nor-β-lapachone derivatives

A comprehensive review on potential candidates for the treatment of chagas disease

Twenty different infectious disorders induced by bacteria, viruses, and parasites are categorized as neglected tropical diseases (NTDs) by WHO. The severity of chagas disease remains a major concern in endemic areas and an emerging public health hazard in nonendemic countries. Trypanosoma cruzi, the etiological agent of this NTD, is mostly transmitted by triatomine vectors and comprises a range of epidemiologically significant variants. Current chemotherapeutics are obsolete, and one of the primary reasons for treatment cessation is their poor safety and effectiveness. Due to the aforementioned challenges, researchers are now focusing on discovering alternative novel safe, and economically reachable therapies for the treatment of trypanosomiasis. Certain target-based drugs that target specific biochemical processes of the causative parasites have been described as potential antichagasic agents that possesses various types of heterocyclic scaffolds. These flexible molecules have a wide range of biological actions, and various synthesized compounds with strong activity have been documented. This review aims to discuss the available literature on synthetic anti-T. cruzi drugs that will give a food for thought to medicinal chemists thriving to design and develop such drugs. Furthermore, some of the studies discussed herein are concerned with the potential of novel drugs to block new viable sites in T. cruzi.

Chemoselective Synthesis of Mannich Adducts from 1,4-Naphthoquinones and Profile as Autophagic Inducers in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a worldwide public health problem, accounting for approximately 90% of all oral cancers, and is the eighth most common cancer in men. Cisplatin and carboplatin are the main chemotherapy drugs used in the clinic. However, in addition to their serious side effects, such as damage to the nervous system and kidneys, there is also drug resistance. Thus, the development of new drugs becomes of great importance. Naphthoquinones have been described with antitumor activity. Some of them are found in nature, but semi synthesis has been used as strategy to find new chemical entities for the treatment of cancer. In the present study, we promote a multiple component reaction (MCR) among lawsone, arylaldehydes, and benzylamine to produce sixteen chemoselectively derivated Mannich adducts of 1,4-naphthoquinones in good yield (up to 97%). The antitumor activities and molecular mechanisms of action of these compounds were investigated in OSCC models and the compound 6a induced cytotoxicity in three different tumor cell lines (OSCC4, OSCC9, and OSCC25) and was more selective (IS > 2) for tumor cells than the chemotropic drug carboplatin and the controls lapachol and shikonin, which are chemically similar compounds with cytotoxic effects. The 6a selectively and significantly reduced the amount of cell colony growth, was not hemolytic, and tolerable in mice with no serious side effects at a concentration of 100 mg/kg with a LD50 of 150 mg/kg. The new compound is biologically stable with a profile similar to carboplatin. Morphologically, 6a does not induce cell retraction or membrane blebs, but it does induce intense vesicle formation and late emergence of membrane bubbles. Exploring the mechanism of cell death induction, compound 6a does not induce ROS formation, and cell viability was not affected by inhibitors of apoptosis (ZVAD) and necroptosis (necrostatin 1). Autophagy followed by a late apoptosis process appears to be the death-inducing pathway of 6a, as observed by increased viability by the autophagy inhibitor (3-MA) and by the appearance of autophagosomes, later triggering a process of late apoptosis with the presence of caspase 3/7 and DNA fragmentation. Molecular modeling suggests the ability of the compound to bind to topoisomerase I and II and with greater affinity to hPKM2 enzyme than controls, which could explain the mechanism of cell death by autophagy. Finally, the in-silico prediction of drug-relevant properties showed that compound 6a has a good pharmacokinetic profile when compared to carboplatin and doxorubicin. Among the sixteen naphthoquinones tested, compound 6a was the most effective and is highly selective and well tolerated in animals. The induction of cell death in OSCC through autophagy followed by late apoptosis possibly via inhibition of the PKM2 enzyme points to a promising potential of 6a as a new preclinical anticancer candidate.

Natural naphthoquinones and their derivatives as potential drug molecules against trypanosome parasites

Over the past decades, a number of 1,4-naphthoquinones have been isolated from natural resources and several of naphthoquinone derivatives with diverse structural motif have been synthesized; they possess a multitude of biochemical properties and modulate numerous pharmacological roles that offer new targets for addressing the challenges pertaining to novel drug developments. Among natural naphthoquinones, lapachol, α-lapachone, β-lapachone, lawsone, juglone, and plumbagin have been evaluated for its potential as antitrypanosomal activities. The chemotherapeutic drugs available for combating human trypanosomiasis, that is, American trypanosomiasis and African trypanosomiasis caused by Trypanosoma cruzi and Trypanosoma brucei, respectively, and animal tripanosomosis caused by Trypanosoma evansi have a problem of drug resistance and several toxic effect. Therefore, search of alternative effective drug molecules, without toxic effects, have enthused the researchers for searching new drug entity with potential clinical efficacy. In the search for new antitrypanosomal compound, this review focuses on different natural quinones and their synthetic derivatives associated with antitrypanosomal studies. In this context, this review will be useful for the development of new antitrypanosomal drugs mainly based on different structural modification of natural and synthetic naphthoquinones.

Hybrid-Compounds Against Trypanosomiases

Neglected tropical diseases (NTDs) are a global public health problem associated with approximately 20 conditions. Among these, Chagas disease (CD), caused by Trypanosoma cruzi, and human African trypanosomiasis (HAT), caused by T. brucei gambiense or T. brucei rhodesiense, affect mainly the populations of the countries from the American continent and sub- Saharan Africa. Pharmacological therapies used for such illnesses are not yet fully effective. In this context, the search for new therapeutic alternatives against these diseases becomes necessary. A drug design tool, recently recognized for its effectiveness in obtaining ligands capable of modulating multiple targets for complex diseases, concerns molecular hybridization. Therefore, this review aims to demonstrate the importance of applying molecular hybridization in facing the challenges of developing prototypes as candidates for the treatment of parasitic diseases. Therefore, studies involving different chemical classes that investigated and used hybrid compounds in recent years were compiled in this work, such as thiazolidinones, naphthoquinones, quinolines, and others. Finally, this review covers several applications of the exploration of molecular hybridization as a potent strategy in the development of molecules potentially active against trypanosomiases, in order to provide information that can help in designing new drugs with trypanocidal activity.

1,4-Naphthoquinone (CNN1) Induces Apoptosis through DNA Damage and Promotes Upregulation of H2AFX in Leukemia Multidrug Resistant Cell Line

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Potential of sulfur-selenium isosteric replacement as a strategy for the development of new anti-chagasic drugs

Current treatment for Chagas disease is based on only two drugs: benznidazole and nifurtimox. Compounds containing sulfur (S) in their structure have shown promising results in vitro and in vivo against Trypanosoma cruzi, the parasite causing Chagas disease. Notably, some reports show that the isosteric replacement of S by selenium (Se) could be an interesting strategy for the development of new compounds for the treatment of Chagas disease. To date, the activity against T. cruzi of three Se- containing groups has been compared with their S counterparts: selenosemicarbazones, selenoquinones, and selenocyanates. More studies are needed to confirm the positive results of Se compounds. Therefore, we have investigated S compounds described in the literature tested against T. cruzi. We focused on those tested in vivo that allowed isosteric replacement to propose their Se counterparts as promising compounds for the future development of new drugs against Chagas disease.

IgE antibodies against Trypanosoma cruzi arginine kinase in patients with chronic Chagas disease

Arginine kinase (AK) is an enzyme present in various invertebrates, as well as in some trypanosomatids such as T. cruzi, the etiological agent that causes Chagas disease. In invertebrates, this protein acts as an allergen inducing an IgE-type humoral immune response. Since AK is a highly conserved protein, we decided to study whether patients with chronic Chagas disease (CCD) produce specific antibodies against T. cruzi AK (TcAK). Plasma from patients with CCD, with and without cardiac alterations and non-infected individuals were evaluated for the presence of anti-TcAK IgG and IgE antibodies by ELISA, including detection of specific IgG subclasses. Our results showed that the levels of specific anti-TcAK IgG and IgE were different between infected and non-infected individuals, but comparable between those with different clinical manifestations. Interestingly, anti-TcAK IgG4 antibodies associated with IgE-mediated allergenic processes were also increased in CCD patients. Finally, we found that several of the predicted B cell epitopes in TcAK matched allergenic peptides previously described for its homologues in other organisms. Our results revealed for the first time a parasite's specific IgE antibody target and suggest that TcAK could contribute to delineate an inefficient B cell response by prompting a bias towards a Th2 profile. These findings also shed light on a potential allergenic response in the context of T. cruzi infection.

Naphthoquinones and Derivatives for Chemotherapy: Perspectives and Limitations of their Anti-trypanosomatids Activities

Chagas disease, Sleeping sickness and Leishmaniasis, caused by trypanosomatids Trypanosoma cruzi, Trypanosoma brucei and Leishmania spp., respectively, are considered neglected tropical diseases, and they especially affect impoverished populations in the developing world. The available chemotherapies are very limited, and a search for alternatives is still necessary. In folk medicine, natural naphthoquinones have been employed for the treatment of a great variety of illnesses, including parasitic infections. This review is focused on the anti-trypanosomatid activity and mechanistic analysis of naphthoquinones and derivatives. Among all the series of derivatives tested in vitro, naphthoquinone-derived 1,2,3-triazoles were very active on T. cruzi infective forms in blood bank conditions, as well as in amastigotes of Leishmania spp. naphthoquinones containing a CF₃ on a phenyl amine ring inhibited T. brucei proliferation in the nanomolar range, and naphthopterocarpanquinones stood out for their activity on a range of Leishmania species. Some of these compounds showed a promising selectivity index (SI) (30 to 1900), supporting further analysis in animal models. Indeed, high toxicity to the host and inactivation by blood components are crucial obstacles to be overcome to use naphthoquinones and/or their derivatives for chemotherapy. Multidisciplinary initiatives embracing medicinal chemistry, bioinformatics, biochemistry, and molecular and cellular biology need to be encouraged to allow the optimization of these compounds. Large scale automated tests are pivotal for the efficiency of the screening step, and subsequent evaluation of both the mechanism of action in vitro and pharmacokinetics in vivo is essential for the development of a novel, specific and safe derivative, minimizing adverse effects.

Design, synthesis, and biological evaluation of 3-(1-benzotriazole)-nor-β-lapachones as NQO1-directed antitumor agents

A series of novel 3-(1-benzotriazole)-nor-β-lapachones 5a-5l were synthesized as the NQO1-targeted anticancer agents. Most of these compounds displayed good antiproliferative activity against the breast cancer MCF-7, lung cancer A549 and hepatocellular carcinoma HepG2 cells in agreements with their NQO1 activity. Among them, compound 5k was identified as a favorable NQO1 substrate. It could activate the ROS production in a NQO1-dependent manner, arrest tumor cell cycle at G0/G1 phase, promote tumor cell apoptosis, and decrease the mitochondrial membrane potential. In HepG2 xenograft models, 5k significantly suppressed the tumor growth with no influences on animal body weights. Therefore, 5k could be a good lead for further anticancer drug developments.

Characterization and trypanocidal activity of a β-lapachone-containing drug carrier

The treatment of Chagas disease (CD), a neglected parasitic condition caused by Trypanosoma cruzi, is still based on only two drugs, nifurtimox (Nif) and benznidazole (Bz), both of which have limited efficacy in the late chronic phase and induce severe side effects. This scenario justifies the continuous search for alternative drugs, and in this context, the natural naphthoquinone β-lapachone (β-Lap) and its derivatives have demonstrated important trypanocidal activities. Unfortunately, the decrease in trypanocidal activity in the blood, high toxicity to mammalian cells and low water solubility of β-Lap limit its systemic administration and, consequently, clinical applications. For this reason, carriers as drug delivery systems can strategically maximize the therapeutic effects of this drug, overcoming the above mentioned restrictions. Accordingly, the aim of this study is to investigate the in vitro anti-T. cruzi effects of β-Lap encapsulated in2-hydroxypropyl-β-cyclodextrin (2HP-β-CD) and its potential toxicity to mammalian cells.

Chagas Disease Chemotherapy: What Do We Know So Far?

Chagas disease is a Neglected Tropical Disease (NTD), and although endemic in Latin America, affects around 6-7 million people infected worldwide. The treatment of Chagas disease is based on benznidazole and nifurtimox, which are the only available drugs. However, they are not effective during the chronic phase and cause several side effects. Furthermore, BZ promotes cure in 80% of the patients in the acute phase, but the cure rate drops to 20% in adults in the chronic phase of the disease. In this review, we present several studies published in the last six years, which describes the antiparasitic potential of distinct drugs, from the synthesis of new compounds aiming to target the parasite, as well as the repositioning and the combination of drugs. We highlight several compounds for having shown results that are equivalent or superior to BZ, which means that they should be further studied, either in vitro or in vivo. Furthermore, we stand out the differences in the effects of BZ on the same strain of T. cruzi, which might be related to methodological differences such as parasite and cell ratios, host cell type and the time of adding the drug. In addition, we discuss the wide variety of strains and also the cell types used as a host cell, which makes it difficult to compare the trypanocidal effect of the compounds.

A comprehensive review on β-lapachone: Mechanisms, structural modifications, and therapeutic potentials

β-Lapachone (β-lap, 1), an ortho-naphthoquinone natural product isolated from the lapacho tree (Tabebuia avellanedae) in many regions of South America, has received extensive attention due to various pharmacological activities, such as antitumor, anti-Trypanosoma cruzi, anti-Mycobacterium tuberculosis, antibacterial, and antimalarial activities. Related mechanisms of β-lap have been widely investigated for a full understanding of its therapeutic potentials. Numerous derivatives of β-lap have been reported with aims to generate new chemical entities, improve the corresponding biological potency, and overcome disadvantages of its physical and chemical properties and safety profiles. This review will give insight into the pharmacological mechanisms of β-lap and provide a comprehensive understanding of its structural modifications with regard to different therapeutic potentials. The available clinical trials related to β-lap and its derivatives are also summarized.

Synthesis of new N,S-acetal analogs derived from juglone with cytotoxic activity against Trypanossoma cruzi

A series of 11 new N,S-acetal juglone derivatives were synthesized and evaluated against T. cruzi epimastigote forms. These compounds were obtained in good to moderate yields using a microwave irradiation protocol. Among all compounds, two N,S-acetal analogs, showed significant trypanocidal activity. Notably, one compound 11g exhibited selectivity index 10-fold higher than the reference drug benznidazole for epimastigote. The compound 11h was more effective for amastigote forms. Both prototypes exhibited S.I. higher than the benznidazole description. Thus, both compounds proving to be useful candidate molecules to further studies in infected animals.

Synthesis and biological evaluation of β-lapachone and nor-β-lapachone complexes with 2-hydroxypropyl-β-cyclodextrin as trypanocidal agents

We study βLAP and its derivative nor-β-Lapachone (NβL) complexes with 2-hydroxypropyl-β-cyclodextrin to increase the solubility and bioavailability. The formation of true inclusion complexes between βLAP or NβL in 2-HP-β-CD in solid solution was characterization by FT-IR, DSC, powder X-ray was and was confirmed by one- and two-dimensional ¹H NMR experiments. Additionally, the biological activities of βLAP, NβL, ICβLAP, and ICNβL were investigated through trypanocidal assays with T. cruzi and cytotoxicity studies with mouse peritoneal macrophages. Originally, we tested these complexes against T. cruzi viability and observed higher biological activities and lower cytotoxicity when compared to βLAP and NβL. Thus, the complexation of βLAP and NβL with 2-HP-β-CD increases the drug solubility, in addition vectorization was observed, increasing the biological activity against epimastigotes and trypomastigotes T. cruzi forms. Reduced the toxicity of the compounds against mammalian cells. In addition, the selectivity indices higher of the inclusion complexes comparing to substance free and those of benznidazole.

Synthesis of quinones with highlighted biological applications: A critical update on the strategies towards bioactive compounds with emphasis on lapachones

Naphthoquinones are of key importance in organic synthesis and medicinal chemistry. In the last few years, various synthetic routes have been developed to prepare bioactive compounds derived or based on lapachones. In this sense, this review is mainly focused on the synthetic aspects and strategies used for the design of these compounds on the basis of their biological activities for the development of drugs against the neglected diseases leishmaniases and Chagas disease and also cancer. Three strategies used to develop bioactive quinones are discussed and categorized: (i) C-ring modification, (ii) redox centre modification and (iii) A-ring modification. Framed within these strategies for the development of naphthoquinoidal compounds against T. cruzi. Leishmania and cancer, reactions including copper-catalyzed azide-alkyne cycloaddition (click chemistry), palladium-catalysed cross couplings, C-H activation reactions, Ullmann couplings and heterocyclisations reported up to July 2019 will be discussed. The aim of derivatisation is the generation of novel molecules that can potentially inhibit cellular organelles/processes, generate reactive oxygen species and increase lipophilicity to enhance penetration through the plasma membrane. Modified lapachones have emerged as promising prototypes for the development of drugs against leishmaniases, Chagas disease and cancer.

Synthesis, Stability Studies, and Antifungal Evaluation of Substituted α- and β-2,3-Dihydrofuranaphthoquinones against Sporothrix brasiliensis and Sporothrix schenckii

Sporotrichosis is a neglected fungal infection caused by Sporothrix spp., which have a worldwide distribution. The standard antifungal itraconazole has been recommended as a first-line therapy. However, failure cases in human and feline treatment have been reported in recent years. This study aimed to synthesize several α- and β-2,3-dihydrofuranaphthoquinones and evaluate them against Sporothrix schenckii and Sporothrix brasiliensis—the main etiological agents of sporotrichosis in Brazil. The stability of these compounds was also investigated under different storage conditions for 3 months. The samples were removed at 0, 60, and 90 days and assessed by ¹H-NMR, and their in vitro antifungal susceptibility was tested. Furthermore, we evaluated the superficial changes caused by the most effective and stable compounds using scanning electron microscopy and determined their effects when combined with itraconazole. Nine dihydrofuranaphthoquinones showed good antifungal activity and stability, with MIC values of 2–32 µM. Compounds 6 and 10 were the most active dihydrofuranaphthoquinones in vitro for both species; in fungi, these compounds induced yeast–hyphae conversion and alteration in the hyphae and conidia structures. Compound 10 also exhibited a synergistic activity with itraconazole against S. schenckii, with a ΣFIC index value of 0.3. Our results indicate that Compounds 6 and 10 are potential candidates for the development of new antifungal agents for the treatment of sporotrichosis.

An efficient cyclization of lapachol to new benzo[h]chromene hybrid compounds: a stepwisevs.one-pot esterification-click (CuAAC) study

Comparison of one-potvs.stepwise esterification of lapachol to obtain highly diversified heterocycles. Whereas the one-pot esterification leads to mono esterified lapachol, the tandem approach generated benzo[h]chromene.

Efficient Catalytic Oxidation of 3-Arylthio- and 3-Cyclohexylthio-lapachone Derivatives to New Sulfonyl Derivatives and Evaluation of Their Antibacterial Activities

New sulfonyl-lapachones were efficiently obtained through the catalytic oxidation of arylthio- and cyclohexylthio-lapachone derivatives with hydrogen peroxide in the presence of a Mn(III) porphyrin complex. The antibacterial activities of the non-oxidized and oxidized lapachone derivatives against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus were evaluated after their incorporation into polyvinylpyrrolidone (PVP) micelles. The obtained results show that the PVP-formulations of the lapachones 4b–g and of the sulfonyl-lapachones 7e and 7g reduced the growth of S. aureus.

Design and synthesis of a new series of 3,5-disubstituted isoxazoles active against Trypanosoma cruzi and Leishmania amazonensis

Chagas disease and leishmaniasis are neglected tropical diseases (NTDs) endemic in developing countries. Although there are drugs available for their treatment, efforts on finding new efficacious therapies are continuous. The natural lignans grandisin (1) and veraguensin (2) show activity against trypomastigote T. cruzi and their scaffold has been used as inspiration to design new derivatives with improved potency and chemical properties. We describe here the planning and microwave-irradiated synthesis of 26 isoxazole derivatives based on the structure of the lignans 1 and 2. In addition, the in vitro evaluation against culture trypomastigotes and intracellular amastigotes of T. cruzi and intracellular amastigotes of L. amazonensis and L. infantum is reported. Among the synthesized derivatives, compounds 17 (IC₅₀ = 5.26 μM for T. cruzi), 29 (IC₅₀ = 1.74 μM for T. cruzi) and 31 (IC₅₀ = 1.13 μM for T. cruzi and IC₅₀ = 5.08 μM for L. amazonensis) were the most active and were also evaluated against recombinant trypanothione reductase of T. cruzi in a preliminary study of their mechanism of action.

Synthesis, characterization and biological activities of 3-aryl-1,4-naphthoquinones – green palladium-catalysed Suzuki cross coupling

Antifungal and trypanocidal aryl-1,4-naphthoquinones were prepared through an aqueous Suzuki protocol with reflux or microwave irradiation.

Lawsone in organic synthesis

Lawsone has been used as the starting material for the synthesis of a variety of biologically active compounds and materials.