Synthesis and biological activity of novel 4-aminoquinoline/1,2,3-triazole hybrids against Leishmania amazonensis

Synthesis, biological evaluation and mechanism of action of benzothiazole derivatives with aromatic hydrazone moiety, a new class of antileishmanial compounds

Leishmaniasis is a disease caused by protozoa Leishmania spp., considered as a significant and urgent public health problem mainly in developing countries. In the absence of an effective vaccine, the treatment of infected people is one of the most commonly prophylactic measures used to control this disease. However, the therapeutic arsenal is reduced to a few drugs, with serious side effects and variability in efficacy. Attempting to this problem, in this work, a series of benzothiazole derivatives was synthetized and assayed against promastigotes and intracellular amastigotes of L. amazonensis, as well as the toxicity on macrophages. In addition, studies about the mechanism of action were also performed. Among the synthesized molecules, the substitution at position 4 of the aromatic ring appears to be critical for activity. The best compound exhibited IC50 values of 28.86 and 7.70 μM, against promastigotes and amastigotes of L. amazonensis, respectively, being more active than miltefosine, used as reference drug. The in silico analysis of physicochemical and pharmacokinetic (ADMET) properties of this compound suggested a good profile of oral bioavailability and safety. In conclusion, the strategy of using benzothiazole nucleous in the search for new antileishmanial agents was advantageous and preliminar data provide information about the mechanism of action as well as in silico parameters suggest a good profile for preclinical studies.

4-Quinolinylhydrazone analogues kill Leishmania (Leishmania) amazonensis by inducing apoptosis and mitochondria-dependent pathway cell death

Despite efforts, available alternatives for the treatment of leishmaniasis are still scarce. In this work we tested a class of 15 quinolinylhydrazone analogues and presented data that support the use of the most active compound in cutaneous leishmaniasis caused by Leishmania amazonensis. In general, the compounds showed activity at low concentrations for both parasitic forms (5.33-37.04 μM to promastigotes, and 14.31-61.98 μM to amastigotes). In addition, the best compound (MHZ15) is highly selective for the parasite. Biochemical studies indicate that the treatment of promastigotes with MHZ15 leads the loss of mitochondrial potential and increase in ROS levels as the primary effects, which triggers accumulation of lipid droplets, loss of plasma membrane integrity and apoptosis hallmarks, including DNA fragmentation and phosphatidylserine exposure. These effects were similar in the intracellular form of the parasite. However, in this parasitic form there is no change in plasma membrane integrity in the observed treatment time, which can be attributed to metabolic differences and the resilience of the amastigote. Also, ultrastructural changes such as vacuolization suggesting autophagy were observed. The in vivo effectiveness of MHZ15 in the experimental model of cutaneous leishmaniasis was carried out in mice of the BALB/c strain infected with L. amazonensis. The treatment by intralesional route showed that MHZ15 acted with great efficiency with significantly reduction in the parasite load in the injured paws and draining lymph nodes, without clinical signs of distress or compromise of animal welfare. In vivo toxicity was also evaluated and null alterations in the levels of hepatic enzymes aspartate aminotransferase, and alanine aminotransferase was observed. The data presented herein demonstrates that MHZ15 exhibits a range of favorable characteristics conducive to the development of an antileishmanial agent.

Design and Synthesis of Novel 3-Nitro-1H-1,2,4-triazole-1,2,3-triazole-1,4-disubstituted Analogs as Promising Antitrypanosomatid Agents: Evaluation of In Vitro Activity against Chagas Disease and Leishmaniasis

A series of 28 compounds, 3-nitro-1H-1,2,4-triazole, were synthesized by click-chemistry with diverse substitution patterns using medicinal chemistry approaches, such as bioisosterism, Craig-plot, and the Topliss set with excellent yields. Overall, the analogs demonstrated relevant in vitro antitrypanosomatid activity. Analog 15g (R1 = 4-OCF3-Ph, IC50 = 0.09 μM, SI = >555.5) exhibited an outstanding antichagasic activity (Trypanosoma cruzi, Tulahuen LacZ strain) 68-fold more active than benznidazole (BZN, IC50 = 6.15 μM, SI = >8.13) with relevant selectivity index, and suitable LipE = 5.31. 15g was considered an appropriate substrate for the type I nitro reductases (TcNTR I), contributing to a likely potential mechanism of action for antichagasic activity. Finally, 15g showed nonmutagenic potential against Salmonella typhimurium strains (TA98, TA100, and TA102). Therefore, 3-nitro-1H-1,2,4-triazole 15g is a promising antitrypanosomatid candidate for in vivo studies.

Synthetic product-based approach toward potential antileishmanial drug development

Leishmaniasis is a parasitic disease and is categorized as a tropically neglected disease (NTD) with no effective vaccines available. The available chemotherapeutics against leishmaniasis are associated with an increase in the incidence of toxicity and drug resistance. Consequently, targeting metabolic pathways and enzymes of parasites which differs from the mammalian host can be exploited to treat and overcome the resistance. The classical methods of identifying the structural fragments and the moieties responsible for the biological activities from the standard compounds and their modification are options for developing more effective novel compounds. Significant progress has been made in refining the development of potent non-toxic molecules and addressing the limitations of the current treatment available. Several examples of synthetic product-based approach utilizing their core heterocyclic rings including furan, pyrrole, thiazole, imidazole, pyrazole, triazole, quinazoline, quinoline, pyrimidine, coumarin, indole, acridine, oxadiazole, purine, chalcone, carboline, phenanthrene and metal containing derivatives and their structure-activity relationships are discussed in this review. It also analyses the groups/fragments interacting with the host cell receptors and will support the medicinal chemists with novel antileishmanial agents.

Quinoline as a Privileged Structure: A Recent Update on Synthesis and Biological Activities

Among heterocyclic compounds, quinoline is one of the best ubiquitous heterocyclic rings for medicinal chemistry purposes. Quinoline appears to be a powerful chemical structure to develop new drug entities. The quinoline derivatives own a wide array of biological activities such as anticancer, antimalarial, antimicrobial, anti-inflammatory, anti-leishmanial, etc. Because of the wide spectrum of bioactivities, the scientific communities are still looking for more efficient synthetic routes to form quinoline derivatives. Therefore, the primary focus of this review is to provide a thorough and inclusive, updated report on quinoline analogs that may pave the way for more efficient drug development.

Using Triazolobenzodiazepine as the Cyclic Imine in Various Types of Joullié-Ugi Reactions

The triazolobenzodiazepine as a cyclic imine was employed in a variety of Joullié-Ugi reactions, and three new families of unique triazolobenzodiazepine connected to carboxamide and tetrazole products were synthesized via a three-component reaction of the cyclic imine and isocyanides with each species of a carboxylic acid/water/TMSN3 under mild conditions in high yields. Furthermore, triazolobenzodiazepine imine was used in an interesting strategy based on the modified Ugi reaction (pseudo-Joullié-Ugi reaction) of cyclic imines with an isocyanide and acetylenedicarboxylates under catalyst-free conditions for the synthesis of triazolobenzodiazepine-fused pyrroles. Mechanistic investigation reveals that triazolobenzodiazepine-fused pyrroles have been generated via a surprising route. Significantly, the use of triazolobenzodiazepine in the Joullié-Ugi, azido-Joullié-Ugi, and pseudo-Joullié-Ugi reactions of a broad scope of biological scaffolds occurred under mild, simple conditions without any catalyst.

Synthesis of 1,2,3-Triazole-Containing Methoxylated Cinnamides and Their Antileishmanial Activity against the Leishmania braziliensis Species

Leishmaniasis is a group of infectious diseases caused by protozoan parasites that belong to the genus Leishmania. Currently, there is no human vaccine, and the available treatments are associated with toxicity, high cost, and the emergence of resistant strains. These factors highlight the need to identify new antileishmanial candidates. In this study, we synthesized twenty-four methoxylated cinnamides containing 1,2,3-triazole fragments and evaluated their antileishmanial activity against the Leishmania braziliensis species, which is the main etiological agent responsible for American Tegumentary Leishmaniasis (ATL). The cinnamides were synthetically prepared using nucleophilic acyl substitution and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. The compounds were characterized using infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. We performed preliminary studies to evaluate the biological activity of these compounds against L. braziliensis promastigotes and axenic amastigotes. Compound 28, N-((1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)-1H-1,2,3-triazole-4-yl) methyl)-3,4-dimethoxy cinnamide, demonstrated relevant antileishmanial activity with low toxicity in murine cells. The selectivity index values for this compound were superior compared with data obtained using amphotericin B. Furthermore, this cinnamide derivative reduced the infection percentage and number of recovered amastigotes in L. braziliensis-infected macrophages. It also induced an increase in reactive oxygen species production, depolarization of the mitochondrial potential, and disruption of the parasite membrane. Taken together, these findings suggest that this synthetic compound holds potential as an antileishmanial candidate and should be considered for future studies in the treatment of ATL.

In vitro evaluation of antileishmanial activity, mode of action and cellular response induced by vanillin synthetic derivatives against Leishmania species able to cause cutaneous and visceral leishmaniasis

The treatment against leishmaniasis presents problems, mainly due to their toxicity of the drugs, high cost and/or by the emergence of parasite resistant strains. In this context, new therapeutics should be searched. In this study, two novel synthetic derivatives from vanillin: [4-(2-hydroxy-3-(4-octyl-1H-1,2,3-triazol-1-yl)propoxy)-3-methoxybenzaldehyde] or 3s and [4-(3-(4-decyl-1H-1,2,3-triazol-1-yl)-2-hydroxypropoxy)-3-methoxybenzaldehyde] or 3t, were evaluated regarding their antileishmanial activity against distinct parasite species able to cause cutaneous and visceral leishmaniasis. Results showed that compounds 3s and 3t were effective against Leishmania infantum, L. amazonensis and L. braziliensis promastigote and amastigote-like forms, showing selectivity index (SI) of 25.1, 18.2 and 22.9, respectively, when 3s was used against promastigotes, and of 45.2, 7.5 and 15.0, respectively, against amastigote-like stage. Using the compound 3t, SI values were 45.2, 53.0 and 80.0, respectively, against promastigotes, and of 35.9, 46.0 and 58.4, respectively, against amastigote-like forms. Amphotericin B (AmpB) showed SI values of 5.0, 7.5 and 15.0, respectively, against promastigotes, and of 3.8, 5.0 and 7.5, respectively, against amastigote-like stage. The treatment of infected macrophages and inhibition of the infection upon pre-incubation with the molecules showed that they were effective in reducing the infection degree and inhibiting the infection in pre-incubated parasites, respectively, as compared to data obtained using AmpB. The mechanism of action of 3s and 3t was evaluated in L. infantum, revealing that both 3s and 3t altered the parasite mitochondrial membrane potential leading to reactive oxygen species production, increase in lipid corps and changes in the cell cycle, causing the parasite' death. A preliminary assay using the cell culture supernatant from treated and infected macrophages showed that 3s and 3t induced higher IL-12 and lower IL-10 values; suggesting the development of an in vitro Th1-type response in the treated cells. In this context, data indicated that 3s and 3t could be considered therapeutic agents to be tested in future studies against leishmaniasis.

Antibacterial, Antiparasitic, and Cytotoxic Activities of Chemical Characterized Essential Oil of Chrysopogon zizanioides Roots

This study aimed to investigate the chemical composition as well as the antibacterial, antiparasitic, and cytotoxic potentialities of the Brazilian Chrysopogon zizanioides root essential oil (CZ-EO) In addition, CZ-EO cytotoxicity to LLCMK₂ adherent epithelial cells was assessed. The major compounds identified in CZ-EO were khusimol (30.0 ± 0.3%), β-eudesmol (10.8 ± 0.3%), α-muurolene (6.0 ± 0.1%), and patchouli alcohol (5.6 ± 0.2%). CZ-EO displayed optimal antibacterial activity against Prevotella nigrescens, Fusobacterium nucleatum, Prevotella melaninogenica, and Aggregatibacter actinomycetemcomitans, with Minimum Inhibitory Concentration (MIC) values between 22 and 62.5 µg/mL and Minimum Bactericidal Concentration (MBC) values between 22 and 400 µg/mL. CZ-EO was highly active against the L. amazonensis promastigote and amastigote forms (IC₅₀ = 7.20 and 16.21 µg/mL, respectively) and the T. cruzi trypomastigote form (IC₅₀ = 11.2 µg/mL). Moreover, CZ-EO showed moderate cytotoxicity to LLCMK₂ cells, with CC₅₀ = 565.4 µg/mL. These results revealed an interesting in vitro selectivity of CZ-EO toward the L. amazonensis promastigote and amastigote forms (Selectivity Index, SI = 78.5 and 34.8, respectively) and the T. cruzi trypomastigote form (SI = 50.5) compared to LLCMK₂ cells. These results showed the promising potential of CZ-EO for developing new antimicrobial, antileishmanial, and antitrypanosomal drugs.