Aminoquinoline compounds: Effect of 7-chloro-4-quinolinylhydrazone derivatives against Leishmania amazonensis

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.

Targeting the Schistosoma mansoni nutritional mechanisms to design new antischistosomal compounds

The chemical classes of semicarbazones, thiosemicarbazones, and hydrazones are present in various compounds, each demonstrating diverse biological activities. Extensive studies have revealed their potential as schistosomicidal agents. Thiosemicarbazones, in particular, have shown inhibitory effects on Schistosoma mansoni's cathepsin B1 enzyme (SmCB1), which plays a crucial role in hemoglobin degradation within the worm's gut and its nutrition processes. Consequently, SmCB1 has emerged as a promising target for novel schistosomiasis therapies. Moreover, chloroquinoline exhibits characteristics in its aromatic structure that hold promise for developing SmCB1 inhibitors, along with its interaction with hemoglobin's heme group, potentially synergizing against the parasite's gut. In this context, we report the synthesis of 22 hybrid analogs combining hydrazones and quinolines, evaluated against S. mansoni. Five of these hybrids demonstrated schistosomicidal activity in vitro, with GPQF-8Q10 being the most effective, causing worm mortality within 24 h at a concentration of 25 µM. GPQF-8Q8 proved to be the most promising in vivo, significantly reducing egg presence in feces (by 52.8%) and immature eggs in intestines (by 45.8%). These compounds exhibited low cytotoxicity in Vero cells and an in in vivo animal model (Caenorhabditis elegans), indicating a favorable selectivity index. This suggests their potential for the development of new schistosomiasis therapies. Further studies are needed to uncover specific target mechanisms, but these findings offer a promising starting point.

7-Chloroquinolinehydrazones as First-in-Class Anticancer Experimental Drugs in the NCI-60 Screen among Different Investigated Series of Aryl, Quinoline, Pyridine, Benzothiazole and Imidazolehydrazones

In the context of a continuously increasing global cancer risk, the search for new effective and affordable anticancer drugs remains a constant demand. This study describes chemical experimental drugs able to destroy cancer cells by arresting their growth. New hydrazones with quinoline, pyridine, benzothiazole and imidazole moieties have been synthesized and evaluated for their cytotoxic potential against 60 cancer cell lines. 7-Chloroquinolinehydrazones were the most active in the current study and exhibited good cytotoxic activity with submicromolar GI₅₀ values on a large panel of cell lines from nine tumor types (leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, ovarian cancer, renal cancer, prostate cancer and breast cancer). This study provided consistent structure-activity relationships in this series of experimental antitumor compounds.

Some Scaffolds as Anti-leishmanial Agents: An Review

Leishmaniasis is a parasitic infectious neglected tropical disease transmitted to humans by the parasites of Leishmania species. Mainly three types of leishmaniasis cases such as visceral (VL), cutaneous (CL) and mucocutaneous leishmaniasis are usually observed. In many western countries, almost 700,000 to 1million peoples are suffering from leishmaniasis and it is estimated that around 26000 to 65000 deaths occurs annually. For its treatment few drugs are available however none of them are ideal to treat leishmaniasis due to long treatment, discomfort mode of administration, risk of high level toxicity, high resistance against etc. Hence so many patients are unable to take complete treatment due to the high drug resistance. The present review will focus on antileishmanial activity of reported derivatives of betacarboline, chalcone, azole, quinoline, quinazoline, benzimidazole, benzadiazapine, thiaazoles, semicarbazone and hydontoin analogues. We believe that this present study will helpful to researcher to design new antileishmanial agents.

In vitro and in vivo antiplasmodial activity of novel quinoline derivative compounds by molecular hybridization

Chloroquine (CQ) has been the main treatment for malaria in regions where there are no resistant strains. Molecular hybridization techniques have been used as a tool in the search for new drugs and was implemented in the present study in an attempt to produce compound candidates to treat malarial infections by CQ-resistant strains. Two groups of molecules were produced from the 4-aminoquinoline ring in conjugation to hydrazones (HQ) and imines (IQ). Physicochemical and pharmacokinetic properties were found to be favorable when analyzed in silico and cytotoxicity and antiplasmodial activity were assayed in vitro and in vivo showing low cytotoxicity and selectiveness to the parasites. Candidates IQ5 and IQ6 showed important values of parasite growth inhibition in vivo on the 5th day after infection (IQ5 15 mg/kg = 72.64% and IQ6 15 mg/kg = 71.15% and 25 mg/kg = 93.7%). IQ6 also showed interaction with ferriprotoporphyrin IX similarly to CQ. The process of applying condensation reactions to yield imines is promising and capable of producing molecules with antiplasmodial activity.

Antischistosomal properties of aurone derivatives against juvenile and adult worms of Schistosoma mansoni

Schistosomiasis is a neglected disease caused by helminth flatworms of the genus Schistosoma, affecting over 240 million people in more than 70 countries. The treatment relies on a single drug, praziquantel, making urgent the discovery of new compounds. Aurones are a natural type of flavonoids that display interesting pharmacological activities, particularly as chemotherapeutic agents against parasites. In pursuit of treatment alternatives, the present work conducted an in vitro and in vivo antischistosomal investigation with aurone derivatives against Schistosoma mansoni. After preparation of aurone derivatives and their in vitro evaluation on adult schistosomes, the three most active aurones were evaluated in cytotoxicity and haemolytic assays, as well as in confocal laser-scanning microscope studies, showing tegumental damage in parasites in a concentration-dependent manner with no haemolytic or cytotoxic potential toward mammalian cells. In a mouse model of schistosomiasis, at a single oral dose of 400 mg/kg, the selected aurones showed worm burden reductions of 35% to 65.0% and egg reductions of 25% to 70.0%. The most active thiophenyl aurone derivative 18, unlike PZQ, had efficacy in mice harboring juvenile S. mansoni, also showing significant inhibition of oviposition by parasites, giving support for the antiparasitic potential of aurones as lead compounds for novel antischistosomal drugs.

Antileishmanial compounds from Connarus suberosus: Metabolomics, isolation and mechanism of action

Leishmaniasis is a disease impacting public health worldwide due to its high incidence, morbidity and mortality. Available treatments are costly, lengthy and toxic, not to mention the problem of parasite resistance. The development of alternative treatments is warranted and natural products demonstrate promising activity. This study investigated the activity of Connarus suberosus extracts and compounds against Leishmania species. Several C. suberosus extracts were tested against L. amazonensis promastigotes. Active and inactive extracts were analyzed by UHPLC-MS and data evaluated using a metabolomics platform, revealing an unknown neoflavonoid (connarin, 3), isolated together with the pterocarpans: hemileiocarpin (1) and leiocarpin (2). The aforementioned compounds (1-3), together with the benzoquinones: rapanone (4), embelin (5) and suberonone (6) previously isolated by our group from the same species, were tested against: (i) L. amazonensis and L. infantum promastigotes, and (ii) L. amazonensis intracellular amastigotes, with the most active compound (3) also tested against L. infantum amastigotes. Cytotoxicity against murine peritoneal macrophages was also investigated. Compounds 2 and 3 presented an IC50 33.8 μM and 11.4 μM for L. amazonensis promastigotes; and 44.3 μM and 13.3 μM for L. infantum promastigotes, respectively. For L. amazonensis amastigotes, the IC50 of 2 was 20.4 μM with a selectivity index (SI) of 5.7, while the IC50 of 3 was 2.9 μM with an SI of 6.3. For L. infantum amastigotes, the IC50 of 3 was 7.7 μM. Compounds 2 and 3 presented activity comparable with the miltefosine positive control, with compound 3 found to be 2-4 times more active than the positive control, depending on the Leishmania species and form. The extracts and isolated compounds showed moderate toxicity against macrophages. Compounds 2 and 3 altered the mitochondrial membrane potential (ΔΨm) and neutral lipid body accumulation, while 2 also impacted plasma membrane permeabilization, culminating in cellular disorder and parasite death. Transmission electron microscopy of L. amazonensis promastigotes treated with compound 3 confirmed the presence of lipid bodies. Leiocarpin (2) and connarin (3) demonstrated antileishmanial activity. This study provides knowledge of natural products with antileishmanial activity, paving the way for prototype development to fight this neglected tropical disease.

Ethanolic extract of Croton blanchetianus Ball induces mitochondrial defects in Leishmania amazonensis promastigotes

Leishmaniasis is a neglected disease caused by Leishmania. Chemotherapy remains the mainstay for leishmaniasis control; however, available drugs fail to provide a parasitological cure, and are associated with high toxicity. Natural products are promising leads for the development of novel chemotherapeutics against leishmaniasis. This work investigated the leishmanicidal properties of ethanolic extract of Croton blanchetianus (EECb) on Leishmania infantum and Leishmania amazonensis, and found that EECb, rich in terpenic compounds, was active against promastigote and amastigote forms of both Leishmania species. Leishmania infantum promastigotes and amastigotes presented IC50 values of 208.6 and 8.8 μg/mL, respectively, whereas Leishmania amazonensis promastigotes and amastigotes presented IC50 values of 73.6 and 3.1 μg/mL, respectively. Promastigotes exposed to EECb (100 µg/mL) had their body cellular volume reduced and altered to a round shape, and the flagellum was duplicated, suggesting that EECb may interfere with the process of cytokinesis, which could be the cause of the decline in the parasite multiplication rate. Regarding possible EECb targets, a marked depolarization of the mitochondrial membrane potential was observed. No cytotoxic effects of EECb were observed in murine macrophages at concentrations below 60 µg/mL, and the CC50 obtained was 83.8 µg/mL. Thus, the present results indicated that EECb had effective and selective effects against Leishmania infantum and Leishmania amazonensis, and that these effects appeared to be mediated by mitochondrial dysfunction.

Parasitological and immunological evaluation of a novel chemotherapeutic agent against visceral leishmaniasis

AIMS

Treatment for visceral leishmaniasis (VL) is hampered by the toxicity and/or high cost of drugs, as well as by emergence of parasite resistance. Therefore, there is an urgent need for new antileishmanial agents.

METHODS AND RESULTS

In this study, the antileishmanial activity of a diprenylated flavonoid called 5,7,3,4'-tetrahydroxy-6,8-diprenylisoflavone (CMt) was tested against Leishmania infantum and L amazonensis species. Results showed that CMt presented selectivity index (SI) of 70.0 and 165.0 against L infantum and L amazonensis promastigotes, respectively, and of 181.9 and 397.8 against respective axenic amastigotes. Amphotericin B (AmpB) showed lower SI values of 9.1 and 11.1 against L infantum and L amazonensis promastigotes, respectively, and of 12.5 and 14.3 against amastigotes, respectively. CMt was effective in the treatment of infected macrophages and caused alterations in the parasite mitochondria. L infantum-infected mice treated with miltefosine, CMt alone or incorporated in polymeric micelles (CMt/Mic) presented significant reductions in the parasite load in distinct organs, when compared to the control groups. An antileishmanial Th1-type cellular and humoral immune response were developed one and 15 days after treatment, with CMt/Mic-treated mice presenting a better protective response.

CONCLUSION

Our data suggest that CMt/Mic could be evaluated as a chemotherapeutic agent against VL.

In Vitro Schistosomicidal Activity of the Alkaloid-Rich Fraction from Ruta graveolens L. (Rutaceae) and Its Characterization by UPLC-QTOF-MS

Schistosomiasis is a neglected tropical disease that affects million people worldwide, mostly in developing countries. Ruta graveolens (Rutaceae) is a plant used in folk medicine to treat several diseases, including parasitic infections. In this study, we reported the in vitro schistosomicidal activity of the R. graveolens extract (Rg) and its active fraction (Rg-FAE). Also, the characterization of Rg-FAE by UPLC-ESI-QTOF-MS analysis and its in vitro antileishmanial activity against Leishmania braziliensis were also performed. In vitro schistosomicidal assays were assessed against adult worms of S. mansoni, while cell viability against peritoneal macrophages was measured by MTT assay. Rg (100 μg/mL) exhibited noticeable schistosomicidal activity, causing 100% mortality and decreasing motor activity of all adult male and female schistosomes, but with low activity against L. braziliensis. After chromatographic fractionation of Rg, fraction Rg-FAE was obtained, showing high activity against adult schistosomes. UPLC-ESI-QTOF-MS analysis of Rg-FAE revealed the presence of eleven alkaloids and one furanocoumarin. No significant antileishmanial activity was found for Rg, while Rg-FAE exhibited activity against L. braziliensis promastigotes. We demonstrated, for the first time, that the R. graveolens extract (Rg) and its alkaloid-rich fraction (Rg-FAE) are active against adult worms of S. mansoni, with no significant cytotoxicity on macrophages. Our findings open the route to further antiparasitic studies with the active fraction of R. graveolens and its identified compounds, especially alkaloids.

The alkylaminoalkanethiosulfuric acids exhibit in-vitro antileishmanial activity against Leishmania (Viannia) braziliensis: a new perspective for use of these schistosomicidal agents

The alkylaminoalkanethiosulfuric acids (AAATs) are amphipathic compounds effective against experimental schistosomiasis, of low toxicity, elevated bioavailability after a single oral dose and prompt tissue absorption.

OBJECTIVES

To explore the in-vitro antileishmanial potential of AAATs using five compounds of this series against Leishmania (Viannia) braziliensis.

METHODS

Their effects on promastigotes and axenic amastigotes, and cytotoxicity to macrophages were tested by the MTT method, and on Leishmania-infected macrophages by Giemsa stain. Effects on the mitochondrial membrane potential of promastigotes and axenic amastigotes and DNA of intracellular amastigotes were tested using JC-1 and TUNEL assays, respectively.

KEY FINDINGS

The 2-(isopropylamino)-1-octanethiosulfuric acid (I) and 2-(sec-butylamino)-1-octanethiosulfuric acid (II) exhibit activity against both promastigotes and intracellular amastigotes (IC₅₀ 25-35 µm), being more toxic to intracellular parasites than to the host cell. Compound I induced a loss of viability of axenic amastigotes, significantly reduced (30%) the mitochondrial membrane potential of both promastigotes and axenic amastigotes and promoted selective DNA fragmentation of the nucleus and kinetoplast of intracellular amastigotes.

CONCLUSIONS

In this previously unpublished study of trypanosomatids, it is shown that AAATs could also exhibit selective antileishmanial activity, a new possibility to be investigated in oral treatment of leishmaniasis.

A chloroquinoline derivate presents effective in vitro and in vivo antileishmanial activity against Leishmania species that cause tegumentary and visceral leishmaniasis

The identification of new therapeutics to treat leishmaniasis is desirable, since available drugs are toxic and present high cost and/or poor availability. Therefore, the discovery of safer, more effective and selective pharmaceutical options is of utmost importance. Efforts towards the development of new candidates based on molecule analogs with known biological functions have been an interesting and cost-effective strategy. In this context, quinoline derivatives have proven to be effective biological activities against distinct diseases. In the present study, a new chloroquinoline derivate, AM1009, was in vitro tested against two Leishmania species that cause leishmaniasis. The present study analyzed the necessary inhibitory concentration to preclude 50% of the Leishmania promastigotes and axenic amastigotes (EC₅₀ value), as well as the inhibitory concentrations to preclude 50% of the murine macrophages and human red blood cells (CC₅₀ and RBC₅₀ values, respectively). In addition, the treatment of infected macrophages and the inhibition of infection using pre-treated parasites were also investigated, as was the mechanism of action of the molecule in L. amazonensis. To investigate the in vivo therapeutic effect, BALB/c mice were infected with L. amazonensis and later treated with AM1009. Parasitological and immunological parameters were also evaluated. Clioquinol, a known antileishmanial quinoline derivate, and amphotericin B (AmpB), were used as molecule and drug controls, respectively. Results in both in vitro and in vivo experiments showed a better and more selective action of AM1009 to kill the in vitro parasites, as well as in treating infected mice, when compared to results obtained using clioquinol or AmpB. AM1009-treated animals presented significantly lower average lesion diameter and parasite burden in the infected tissue and organs evaluated in this study, as well as a more polarized antileishmanial Th1 immune response and low renal and hepatic toxicity. This result suggests that AM1009 should be considered a possible therapeutic target to be evaluated in future studies for treatment against leishmaniasis.

In Vitro and in Vivo Antischistosomal Activities of Chalcones

In this study, we evaluated the in vitro and in vivo schistosomicidal activities of chalcones against Schistosoma mansoni worms. In vitro assays revealed that chalcones 1 and 3 were the most active compounds, without affecting significantly mammalian cells. Confocal laser scanning microscopy and scanning electron microscopy studies revealed reduction on the numbers of tubercles and morphological alterations in the tegument of S. mansoni worms after in vitro incubation with chalcones 1 and 3. In a mouse model of schistosomiasis, the oral treatment (400 mg/kg) with chalcone 1 or 3 significantly caused a total worm burden reduction in mice. Chalcone 1 showed significant inhibition of the S. mansoni ATP diphosphohydrolase activity, which was corroborated by molecular docking studies. The results suggested that chalcones could be explored as lead compounds with antischistosomal properties.

Synthesis, Biological Activity, and Mechanism of Action of 2-Pyrazyl and Pyridylhydrazone Derivatives, New Classes of Antileishmanial Agents

In this work, we report the antileishmanial activity of 23 compounds based on 2-pyrazyl and 2-pyridylhydrazone derivatives. The compounds were tested against the promastigotes of Leishmania amazonensis and L. braziliensis, murine macrophages, and intracellular L. amazonensis amastigotes. The most potent antileishmanial compound was selected for investigation into its mechanism of action. Among the evaluated compounds, five derivatives [(E)-3-((2-(pyridin-2-yl)hydrazono)methyl)benzene-1,2-diol (2 b), (E)-4-((2-(pyridin-2-yl)hydrazono)methyl)benzene-1,3-diol (2 c), (E)-4-nitro-2-((2-(pyrazin-2-yl)hydrazono)methyl)phenol (2 s), (E)-2-(2-(pyridin-2-ylmethylene)hydrazinyl)pyrazine (2 u), and (E)-2-(2-((5-nitrofuran-2-yl)methylene)hydrazinyl)pyrazine (2 v)] exhibited significant activity against L. amazonensis amastigote forms, with IC₅₀ values below 20 μm. The majority of the compounds did not show any toxic effect on murine macrophages. Preliminary studies on the mode of action of members of this hydrazine-derived series indicate that the accumulation of reactive oxygen species (ROS) and disruption of parasite mitochondrial function are important for the pharmacological effect on L. amazonensis promastigotes.

Emerging therapeutic targets for treatment of leishmaniasis

INTRODUCTION

Parasitic diseases that pose a threat to human life include leishmaniasis - caused by protozoan parasite Leishmania species. Existing drugs have limitations due to deleterious side effects like teratogenicity, high cost and drug resistance. This calls for the need to have an insight into therapeutic aspects of disease. Areas covered: We have identified different drug targets via. molecular, imuunological, metabolic as well as by system biology approaches. We bring these promising drug targets into light so that they can be explored to their maximum. In an effort to bridge the gaps between existing knowledge and prospects of drug discovery, we have compiled interesting studies on drug targets, thereby paving the way for establishment of better therapeutic aspects. Expert opinion: Advancements in technology shed light on many unexplored pathways. Further probing of well established pathways led to the discovery of new drug targets. This review is a comprehensive report on current and emerging drug targets, with emphasis on several metabolic targets, organellar biochemistry, salvage pathways, epigenetics, kinome and more. Identification of new targets can contribute significantly towards strengthening the pipeline for disease elimination.