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Disulfiram and dithiocarbamate analogues demonstrate promising antischistosomal effects
Abstract
Schistosomiasis is a neglected tropical disease with more than 200 million new infections per year. It is caused by parasites of the genus Schistosoma and can lead to death if left untreated. Currently, only two drugs are available to combat schistosomiasis: praziquantel and, to a limited extent, oxamniquine. However, the intensive use of these two drugs leads to an increased probability of the emergence of resistance. Thus, the search for new active substances and their targeted development are mandatory. In this study the substance class of “dithiocarbamates” and their potential as antischistosomal agents is highlighted. These compounds are derived from the basic structure of the human aldehyde dehydrogenase inhibitor disulfiram (tetraethylthiuram disulfide, DSF) and its metabolites. Our compounds revealed promising activity (in vitro) against adults of Schistosoma mansoni, such as the reduction of egg production, pairing stability, vitality, and motility. Moreover, tegument damage as well as gut dilatations or even the death of the parasite were observed. We performed detailed structure-activity relationship studies on both sides of the dithiocarbamate core leading to a library of approximately 300 derivatives (116 derivatives shown here). Starting with 100 μm we improved antischistosomal activity down to 25 μm by substitution of the single bonded sulfur atom for example with different benzyl moieties and integration of the two residues on the nitrogen atom into a cyclic structure like piperazine. Its derivatization at the 4-nitrogen with a sulfonyl group or an acyl group led to the most active derivatives of this study which were active at 10 μm. In light of this SAR study, we identified 17 derivatives that significantly reduced motility and induced several other phenotypes at 25 μm, and importantly five of them have antischistosomal activity also at 10 μm. These derivatives were found to be non-cytotoxic in two human cell lines at 100 μm. Therefore, dithiocarbamates seem to be interesting new candidates for further antischistosomal drug development.
... It inhibits human aldehyde dehydrogenases (ALDHs) [23] and thus leads to an accumulation of acetaldehyde and concomitant unpleasant symptoms like the flushing of skin, sweating, headache and nausea upon the ingestion of even small amounts of alcohol [24,25]. Disulfiram has been shown to be active in laboratory models against various parasites, such as the protozoans Giardia lamblia and Leishmania major [26,27], the nematode Trichuris muris [28], or the trematode Schistosoma mansoni [29][30][31]. However, disulfiram did not reach clinical treatment against any parasitosis. ...
... Previously, disulfiram metabolites were used as a basis for the development of dithiocarbamate derivatives showing promising effects with increased activity against S. mansoni and reduced mammalian cell toxicity [30]. In the present study, we used an established in vitro drug-screening cascade [32] in order to test disulfiram and dithiocarbamate derivatives on metacestode vesicles, isolated GL cells of E. multilocularis, and performed a limited structure-activity relationship (SAR) analysis of these dithiocarbamates. ...
... The synthesis of compounds was performed at the University of Marburg and by following the general routes published previously [30,33]. Structures, molecular weights, and activities against E. multilocularis metacestode vesicles are given in Table S1. ...
The metacestode stage of the fox tapeworm Echinococcus multilocularis causes the severe zoonotic disease alveolar echinococcosis. New treatment options are urgently needed. Disulfiram and dithiocarbamates were previously shown to exhibit activity against the trematode Schistosoma mansoni. As both parasites belong to the platyhelminths, here we investigated whether these compounds were also active against E. multilocularis metacestode vesicles in vitro. We used an in vitro drug-screening cascade for the identification of novel compounds against E. multilocularis metacestode vesicles with disulfiram and 51 dithiocarbamates. Five compounds showed activity against E. multilocularis metacestode vesicles after five days of drug incubation in a damage marker release assay. Structure–activity relationship analyses revealed that a S-2-hydroxy-5-nitro benzyl moiety was necessary for anti-echinococcal activity, as derivatives without this group had no effect on E. multilocularis metacestode vesicles. The five active compounds were further tested for potential cytotoxicity in mammalian cells. For two compounds with low toxicity (Schl-32.315 and Schl-33.652), IC50 values in metacestode vesicles and IC50 values in germinal layer cells were calculated. The compounds were not highly active on isolated GL cells with IC50 values of 27.0 ± 4.2 µM for Schl-32.315 and 24.7 ± 11.5 µM for Schl-33.652, respectively. Against metacestode vesicles, Schl-32.315 was not very active either with an IC50 value of 41.6 ± 3.2 µM, while Schl-33.652 showed a low IC50 of 4.3 ± 1 µM and should be further investigated in the future for its activity against alveolar echinococcosis.
... Large egg deposits by Schistosoma mansoni in the human body result in Katayama fever, glomerular disease, hepatosplenic disease, and periportal fibrosis, which progress into fatal conditions such as portal hypertension and ascites [11,12]. Praziquantel (Biltricide®) is the most recognized drug to treat Schistosomiasis at the moment [13,14], while Oxamniquine has been allowed to be used, though it is specific to some species [15]. The former is presently the most active against all species known so far but less effective against the worm's larval forms, causing recurrence and resistance [15][16][17]. ...
... Praziquantel (Biltricide®) is the most recognized drug to treat Schistosomiasis at the moment [13,14], while Oxamniquine has been allowed to be used, though it is specific to some species [15]. The former is presently the most active against all species known so far but less effective against the worm's larval forms, causing recurrence and resistance [15][16][17]. Hence, the hunt to develop new drugs with the potency to overcome the re-infection and resistance menace has become necessary. ...
The quest for a sound treatment on the vulnerable population suffering and dying as a result of the blood flukes, S. mansoni is on the increase because both Praziquantel and Oxamniquine widely used for the treatment of Schistosomiasis for over 51 years suffer resistance and recurrence. Here-in, chemo-informatics techniques such as QSAR modeling, pharmacokinetic, docking alongside MD simulation were harnessed in designing novel 7-keto- sempevirolsempevirol derivatives that are more competent against S. mansoni. Upon QSAR screening, compound 15, which appears to be in the model's acceptability space, emerges the best with a high predicted activity. 5 new analogues with improved activity against Schistosomiasis better than the standard drug PZQ were designed from compound 15 (template 15*) on an account of the descriptors significance from the model with robust and validated parameters. Also their pharmacokinetic profiles indicates that the designed compounds have the characteristics of a good drug. Furthermore, docking evaluation fulfilled ranges from −113.121 to −100.79 kcal/mol (moldock score), with compound U1 being the best (least moldock score of −113.121 compared to PZQ and 15* (template) having a moldock score value of (−87.21 and −83.37 kcal/mol). 100-ns MD Simulation on the U1-docked complex was run using Desmond 2019–4 package. The nature and steadiness of U1 compound within the enzyme active site was further confirmed by RMSD, RMSF, RoG and H-bond assessment. Hence, we recommend compound U1 targeting the SmCB1 enzyme (6YI7) for Schistosomiasis treatment and for further medicinal evaluation and utilization.
... Surprisingly, the intestinal tracts of schistosomes are severely damaged after artemether treatment [126]. Another anti-schistosome drug candidate, dithiocarbamates, was recently reported to be nontoxic to human cells in experiments [127]. According to research findings, dithiocarbamates can damage the tegument, cause intestinal dilatation, inhibit worm spawning, and reduce their pair stability and viability [127]. ...
... Another anti-schistosome drug candidate, dithiocarbamates, was recently reported to be nontoxic to human cells in experiments [127]. According to research findings, dithiocarbamates can damage the tegument, cause intestinal dilatation, inhibit worm spawning, and reduce their pair stability and viability [127]. Research on the schistosome vaccine is also a hot spot, and a systematic review has been made [9]. ...
Schistosomiasis, a severe parasitic disease, is primarily caused by Schistosoma mansoni, Schistosoma japonicum, or Schistosoma haematobium. Currently, praziquantel is the only recommended drug for human schistosome infection. However, the lack of efficacy of praziquantel against juvenile worms and concerns about the emergence of drug resistance are driving forces behind the research for an alternative medication. Schistosomes are obligatory parasites that survive on nutrients obtained from their host. The ability of nutrient uptake depends on their physiological structure. In short, the formation and maintenance of the structure and nutrient supply are mutually reinforcing and interdependent. In this review, we focus on the structural features of the tegument, esophagus, and intestine of schistosomes and their roles in nutrient acquisition. Moreover, we introduce the significance and modes of glucose, lipids, proteins, and amino acids intake in schistosomes. We linked the schistosome structure and nutrient supply, introduced the currently emerging targets, and analyzed the current bottlenecks in the research and development of drugs and vaccines, in the hope of providing new strategies for the prevention and control of schistosomiasis.
... Furthermore, DSF has come into focus as treatment alternative for cancer [43][44][45][46], obesity [47], and in the context of drug repurposing also for parasitic diseases such as giardiasis and amoebiasis [48][49][50]. In the accompanying article of Rennar et al. [51], the DSF-derived dithiocarbamates are discussed as potential antischistosomal agents. ...
... Besides negative effects on pairing stability, vitality (attachment capacity of couples and motility), and egg production, DSF caused severe morphological changes of the gonads and the tegument of adults as shown by CLSM and SEM. Similar harmful effects of DSF on the physiology of adult S. mansoni were also observed in the accompanying study of Rennar et al. [51], in which concentrations from 10 μM to 100 μM reduced egg production (≥10 μM), pairing stability (≥25 μM), and vitality/motility (≥25 μM) in vitro. In their study, however, Rennar et al. ...
Schistosomiasis is an infectious disease caused by blood flukes of the genus Schistosoma and affects approximately 200 million people worldwide. Since Praziquantel (PZQ) is the only drug for schistosomiasis, alternatives are needed. By a biochemical approach, we identified a tegumentally expressed aldehyde dehydrogenase (ALDH) of S. mansoni, SmALDH_312. Molecular analyses of adult parasites showed Smaldh_312 transcripts in both genders and different tissues. Physiological and cell-biological experiments exhibited detrimental effects of the drug disulfiram (DSF), a known ALDH inhibitor, on larval and adult schistosomes in vitro. DSF also reduced stem-cell proliferation and caused severe tegument damage in treated worms. In silico-modelling of SmALDH_312 and docking analyses predicted DSF binding, which we finally confirmed by enzyme assays with recombinant SmALDH_312. Furthermore, we identified compounds of the Medicine for Malaria Venture (MMV) pathogen box inhibiting SmALDH_312 activity. Our findings represent a promising starting point for further development towards new drugs for schistosomiasis.
... This mechanism involves the formation of the pores in the cell membrane, allowing proinflammatory cytokines to be released and ultimately causing cell rupture [65]. PM2.5 has a vital role in NLRP3 inflammasome and Caspase-1 activation [66], eventually leading to increased GSDMD cleavage, a critical step that results in pyroptosis [67]. Lian et al. reported pyroptosis being involved in PM2.5-induced liver dysfunction in mice [68]. ...
Fine particulate matter (PM2.5) pollution’s harmful effects on the environment and human health have gained global attention. After entering the liver via the bloodstream, these small particles could disrupt hepatic lipid metabolism and even cause liver damage, but the underlying mechanisms remain unclear. To investigate the impact of PM2.5 on the liver and metabolism, ApoE⁻/⁻ mice were used and then exposed to PM2.5 to establish a hyperlipidemic model. Our findings revealed the involvement of oxidative stress in this model, which was accompanied by elevated expression of inflammatory markers and enhanced GSDMD-mediated pyroptosis activation. Our results further show that PM2.5 exposure causes significant alterations in key metabolic hepatic proteins. Inhibiting pyroptosis with disulfiram (DSF) balances hepatic lipid-protein levels and decreases hepatic injury, suggesting its potential to protect the liver from PM2.5 exposure. N-acetyl-L-cysteine (NAC) treatment reversed PM2.5-induced oxidative stress, inhibiting pyroptosis and improving hepatocyte function, as demonstrated by the restored balance of hepatic proteins. Our investigation establishes a critical link between PM2.5 exposure and liver dysfunction through oxidative stress and pyroptosis pathways while demonstrating the therapeutic potential of DSF and NAC in protecting against PM2.5-induced metabolic disorders and hepatic injury. These insights provide a foundation for developing targeted interventions to address air pollution-related liver diseases, especially in vulnerable high-lipid populations.
... strains are concerning; 72 however, new therapeutic strategies are in development. 72,74,75 Conclusion Bacteria, fungal, TB, and schistosomiasis are uncommon causes of haemorrhagic cystitis burdened by high morbidity, especially if not promptly diagnosed. Due to the paucity of literature and the difficult-to-diagnose presentation, especially in Western countries, urologists are not well aware of which infectious disease agent may be the cause of haemorrhagic cystitis. ...
Purpose
Haemorrhagic cystitis may be due to different etiologies with infectious diseases representing an insidious cause to diagnose. The aim of this narrative review is to provide a comprehensive overview of less common but difficult-to-diagnose causes of infectious haemorrhagic cystitis of bacterial, mycobacterial, and parasitic origin, Moreover, we highlight possible diagnostic tools and currently available treatment options in order to give an updated tool for urologists to use in daily practice.
Patients and Methods
The search engine PubMed was used to select peer-reviewed articles published from 1/Jan/2010 to 31/Aug/2022.
Results
Bacteria, fungal, TB and schistosomiasis are uncommon causes of haemorrhagic cystitis burdened by high morbidity, especially if not promptly diagnosed.
Conclusion
Because haemorrhagic cystitis ranges in severity from mild dysuria associated with pelvic discomfort to severe life-threatening haemorrhage, punctual diagnosis, and immediate treatment are essential to avoid further complications.
... Diethyldithiocarbamate (DDC − ) is a metabolite of disulfiram, a drug used for the treatment of chronic alcoholism [16], that is being repurposed for the treatment of cancer (Clinicaltrials.gov Identifier: NCT04234022, NCT05210374) and infections caused by parasites [17][18][19], viruses [20], fungi [21][22][23] and bacteria [24][25][26][27]. The anticancer and antibacterial activity of DDC − is associated with the formation of complexes with metal ions, with copper ions (Cu 2+ ) being the most effective [25,[28][29][30]. ...
Surgical site infections (SSIs) are mainly caused by Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) biofilms. Biofilms are aggregates of bacteria embedded in a self-produced matrix that offers protection against antibiotics and promotes the spread of antibiotic-resistance in bacteria. Consequently, antibiotic treatment frequently fails, resulting in the need for alternative therapies. The present study describes the in vitro efficacy of the Cu(DDC)2 complex (2:1 M ratio of diethyldithiocarbamate (DDC-) and Cu2+) with additional Cu2+ against S. aureus and S. epidermidis biofilms in models mimicking SSIs and in vitro antibacterial activity of a liposomal Cu(DDC)2 + Cu2+ formulation. The in vitro activity on S. aureus and S. epidermidis biofilms grown on two hernia mesh materials and in a wound model was determined by colony forming unit (CFU) counting. Cu2+-liposomes and Cu(DDC)2-liposomes were prepared, and their antibacterial activity was assessed in vitro using the alamarBlue assay and CFU counting and in vivo using a Galleria mellonella infection model. The combination of 35 μM DDC- and 128 μM Cu2+ inhibited S. aureus and S. epidermidis biofilms on meshes and in a wound infection model. Cu(DDC)2-liposomes + free Cu2+ displayed similar antibiofilm activity to free Cu(DDC)2 + Cu2+, and significantly increased the survival of S. epidermidis-infected larvae. Whilst Cu(DDC)2 + Cu2+ showed substantial antibiofilm activity in vitro against clinically relevant biofilms, its application in mammalian in vivo models is limited by solubility. The liposomal Cu(DDC)2 + Cu2+ formulation showed antibiofilm activity in vitro and antibacterial activity and low toxicity in G. mellonella, making it a suitable water-soluble formulation for future application on infected wounds in animal trials.
... There is some in vitro evidence to suggest that disulfiram could be effective against the trematode genus Schistosoma. An early in vitro study found that disulfiram demonstrated antischistosomal activity at concentrations of 25-50 µM [102]. A subsequent study found that disulfiram and three of its metabolites (dithiocarbamic acid, dithiocarbamate S,S-dioxide, and thiocarbamate S-oxide) demonstrated antischistosomal activity, with disulfiram being more effective than its metabolites. ...
Background: Since disulfiram’s discovery in the 1940s and its FDA approval for alcohol use disorder, other indications have been investigated. This review describes potential clinical applications, associated risks, and challenges. Methods: For this narrative review, a PubMed search was conducted for articles addressing in vivo studies of disulfiram with an emphasis on drug repurposing for the treatment of human diseases. The key search terms were “disulfiram” and “Antabuse”. Animal studies and in vitro studies highlighting important mechanisms and safety issues were also included. Results: In total, 196 sources addressing our research focus spanning 1948–2022 were selected for inclusion. In addition to alcohol use disorder, emerging data support a potential role for disulfiram in the treatment of other addictions (e.g., cocaine), infections (e.g., bacteria such as Staphylococcus aureus and Borrelia burgdorferi, viruses, parasites), inflammatory conditions, neurological diseases, and cancers. The side effects range from minor to life-threatening, with lower doses conveying less risk. Caution in human use is needed due to the considerable inter-subject variability in disulfiram pharmacokinetics. Conclusions: While disulfiram has promise as a “repurposed” agent in human disease, its risk profile is of concern. Animal studies and well-controlled clinical trials are needed to assess its safety and efficacy for non-alcohol-related indications.
Glycyrrhetinic acid (GA) is a naturally occurring triterpene compound. The aim of this study was to employ the pharmacophore hybrid strategy to merge GA with various dithiocarbamates and obtain novel compounds with better antitumor activities. We present a two‐step synthetic protocol wherein the GA derivative underwent reaction with carbon disulfide and various secondary amines in a one‐pot manner under mild conditions, facilitating the preparation of a series of structurally novel GA‐dithiocarbamate derivatives. Bioassay screening revealed that the representative compound 3c demonstrated the capacity to reduce the mitochondrial membrane potential in Hep3B and Huh‐7 cells, induce nuclear apoptosis, inhibit invasion and migration, and prompt both early and late apoptosis. Furthermore, our research findings indicated that this apoptotic phenomenon may be associated with the expression of Bcl‐2, Bax, Bak, PARP, and cleaved‐PARP proteins. Utilizing network pharmacology for predicting core targets and signaling pathways of compound 3c for hepatocellular carcinoma (HCC) treatment involved employing molecular docking models to demonstrate high affinity between compound and target protein. In conjunction with Western blot analysis, compound 3c may impact HCC through the PI3K‐AKT‐mTOR pathway.
Introduction:
Schistosomiasis, one of the current Neglected Tropical Diseases (NTDs) affects over 230 million people globally, with nearly 700 million at risk in more than 74 countries. Praziquantel (PZQ) has served as the primary treatment for the past four decades; however, its effectiveness is limited as it solely eliminates adult worms. In regions where infections are frequent, PZQ exhibits only temporary efficacy and has restricted potential to disrupt the prolonged transmission of the disease.
Areas covered:
A comprehensive exploration using the PubMed database was conducted to review current pharmacotherapy approaches for schistosomiasis. This review also encompasses recent research findings related to potential novel therapeutics and the repurposing of existing drugs.
Expert opinion:
Current schistosoma treatment strategies, primarily relying on PZQ, face challenges like temporary effectiveness and limited impact on disease transmission. Drug repurposing, due to economic constraints, is decisive for NTDs. Despite PZQ's efficacy, its failure to prevent reinfection highlights the need for complementary strategies, especially in regions with persistent environmental foci. Integrating therapies against diverse schistosome stages boosts efficacy and impedes resistance. Uncovering novel agents is essential to address resistance concerns in tackling this neglected tropical disease. Integrated strategies present a comprehensive approach to navigate the complex challenges.
Herein, we report an operationally simple, environmentally benign and scalable approach towards the synthesis of S-benzyl/alkyl dithiocarbamates via a hydrogen borrowing reaction between alcohols and dithiocarbamate anions catalyzed using a hydroxyapatite-supported copper nano-catalyst. This strategy has a broad substrate scope and offers high yields of products using inexpensive and readily available alcohols as starting materials. The catalyst was prepared by easy and straightforward methods and analyzed by several analytical techniques, e.g., FESEM, HR-TEM, BET, XRD, EDS, and XPS, demonstrating the anchoring of Cu nanoparticles on hydroxyapatite in the zero oxidation state.
Schistosomiasis or bilharzia is caused by blood flukes of the genus Schistosoma and represents a considerable health and economic burden in tropical and subtropical regions. The treatment of this infectious disease relies on one single drug: praziquantel (PZQ). Therefore, new and potent antischistosomal compounds need to be developed. In our previous work, starting with the drug disulfiram, we developed dithiocarbamates with in vitro antischistosomal activities in the low micromolar range. Based on these results, we report in this study on the synthesis and biological testing of the structurally related dithiocarbazates against Schistosoma mansoni, one of the major species of schistosomes. In total, three series of dithiocarbazate derivatives were examined, and we found that the antischistosomal activity of N‐unbranched dithiocarbazates increased by further N‐substitution. Comparable tetra‐substituted dithiocarbazates were rarely described in the literature, thus a synthesis route was established. Due to the elaborate synthesis, the branched dithiocarbazates (containing an N‐aminopiperazine) were simplified, but the resulting branched dithiocarbamates (containing a 4‐aminopiperidine) were considerably less active. Taken together, dithiocarbazate‐containing compounds with an in vitro antischistosomal activity of 5 µM were obtained. Four different series of dithiocarbazates and dithiocarbamates demonstrated the antischistosomal potential of this type of compound. After the N‐aminopiperazine scaffold was identified as particularly promising, the in vitro antischistosomal activity could be increased to 5 µM by introducing a further substituent. The structurally related but synthetically more accessible 4‐aminopiperidines showed higher cell toxicity or lower antischistosomal activity.
The unique multilaminate appearance of the tegument surface of schistosomes was first described in 1973, in one of the earliest volumes of the International Journal for Parasitology. The present review, published almost 50 years later, traces the development of our knowledge of the tegument, starting with those earliest cytological advances, particularly the surface plasma membrane-membranocalyx complex, through an era of protein discovery to the modern age of protein characterization, aided by proteomics. More recently, analysis of single cell transcriptomes of schistosomes is providing insight into the organization of the cell bodies that support the surface syncytium. Our understanding of the tegument, notably the nature of the proteins present within the plasma membrane and membranocalyx, has provided insights into how the schistosomes interact with their hosts but many aspects of how the tegument functions remain unanswered. Among the unresolved aspects are those concerned with maintenance and renewal of the surface membrane complex, and whether surface proteins and membrane components are recycled. Current controversies arising from investigations about whether the tegument is a source of extracellular vesicles during parasitism, and if it is covered with glycolytic enzymes, are evaluated in the light of cytological and proteomic knowledge of the layer.
Background:
Schistosomiasis is endemic in 78 countries belonging to tropical and subtropical areas. However, autochthonous transmission of urogenital schistosomiasis was reported in Corsica (France) in 2013. We present evidence of autochthonous transmission of urogenital schistosomiasis in Almería (Spain) in 2003.
Methods:
Description of the outbreak in farmers and subsequent epidemiological studies aimed at searching for Bulinus snails and their genotypic characteristics.
Results:
The outbreak affected 4 farmers out of a group of 5 people who repeatedly bathed that summer in an irrigation pool in the area. Two of them presented macroscopic hematuria with bilharziomas, showing the presence of Schistosoma eggs in bladder biopsies. Two others were asymptomatic but the serology for schistosomiasis was positive. In 2015, the presence of the vector Bulinus truncatus was demonstrated in Almería in water collections of appropriate characteristics. DNA sequencing proving that local B. truncatus species were base-to-base identical to B. truncatus from Senegal.
Conclusions:
We present a new outbreak of autochthonous transmission of urogenital schistosomiasis in Europe. Although no new cases of autochthonous transmission have been reported, some other cases may have occurred at that time or later on and be unnoticed as many cases of schistosomiasis are asymptomatic or present mild and unspecific symptoms.
Schistosomiasis is a neglected tropical disease caused by blood flukes of the genus Schistosoma and causes severe morbidity in infected patients. In 2018, 290.8 million people required treatment, and 200,000 deaths are reported per year. Treatment of this disease depends on a single drug, praziquantel (PZQ). However, in the past few years, reduced sensitivity of the parasites toward PZQ has been reported. Therefore, there is an urgent need for new drugs against this disease. In the past few years, we have focused on a new substance class called biaryl alkyl carboxylic acid derivatives, which showed promising antischistosomal activity in vitro. Structure–activity relationship (SAR) studies of the carboxylic acid moiety led to three promising carboxylic amides (morpholine, thiomorpholine, and methyl sulfonyl piperazine) with an antischistosomal activity down to 10 µM (morpholine derivative) and no cytotoxicity up to 100 µM. Here, we show our continued work on this substance class. We investigated, in extended SAR studies, whether modification of the linker and the thiophene ring could improve the antischistosomal activity. We found that the exchange of the alkyl linker by a pentadienyl or benzyl linker was tolerated and led to similar antischistosomal effects, whereas the exchange of the thiophene ring was not tolerated. Our data suggest that the thiophene ring is important for the antischistosomal activity of this compound class. Biaryl alkyl carboxylic acid derivatives show antischistosomal activity in vitro. Extended structure–activity relationship studies were used to investigate the effects of modifications of the linker and the thiophene ring on the activity. It was found that replacement of the alkyl linker by more rigid structures is tolerated whereas replacement of the thiophene in the biaryl moiety leads to complete loss of the antischistosomal activity.
Human schistosomes combat the unique immune systems of two vastly different hosts during their indirect life cycles. In gastropod molluscs, they face a potent innate immune response composed of variable immune recognition molecules and highly phagocytic hemocytes. In humans, a wide variety of innate and adaptive immune processes exist in proximity to these parasites throughout their lifespan. To survive and thrive as the second most common parasitic disease in humans, schistosomes have evolved many techniques to avoid and combat these targeted host responses. Among these techniques are molecular mimicry of host antigens, the utilization of an immune resistant outer tegument, the secretion of several potent proteases, and targeted release of specific immunomodulatory factors affecting immune cell functions. This review seeks to describe these key immune evasion mechanisms, among others, which schistosomes use to survive in both of their hosts. After diving into foundational observational studies of the processes mediating the establishment of schistosome infections, more recent transcriptomic and proteomic studies revealing crucial components of the host/parasite molecular interface are discussed. In order to combat this debilitating and lethal disease, a comprehensive understanding of schistosome immune evasion strategies is necessary for the development of novel therapeutics and treatment plans, necessitating the discussion of the numerous ways in which these parasitic flatworms overcome the immune responses of both hosts.
Recently, the interest in the application of cell viability assays has been increasing in various fields. Cell viability assays may be broadly classified as (a) dye exclusion assays, (b) colorimetric assays, (c) fluorometric assays, (d) luminometric assays, and (e) flow cytometric assays. Dye exclusion assays include trypan blue, eosin, congo red, and erythrosine B stain assays, whereas 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetra-zolium bromide (MTT), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium, monosodium salt (WST-1), 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt (WST-8), lactate dehydrogenase (LDH), sulforhodamine B (SRB), neutral red uptake (NRU), and crystal violet stain (CVS) assays are among the colorimetric assays. Similarly, resazurin and 5-carboxyfluorescein diacetate acetoxymethyl ester (5-CFDA-AM) assays are based on fluorometric measurements, whereas luminometric assays comprise adenosine triphosphate and real-time viability assays. Major flow cytometric assays include membrane asymmetry, membrane permeability, and mitochondria assays. In this guideline, the mechanisms and the practice of assessment of the most common cell viability assays applied in research labs are discussed in detail. An ideal cell viability assay should be safe, rapid, reliable, efficient, and time-and cost-effective, and should not interfere with the test compound. Overall, it can be concluded that more than one cell viability assay should be applied in order to obtain reliable results.
The alcohol-abuse drug disulfiram has antitumor effects against diverse cancer types via inhibition of the ubiquitin-proteasome protein nuclear protein localization protein 4 (NPL4). However, the antitumor effects of NPL4 and disulfiram in clear cell renal cell carcinoma (ccRCC) are unclear. Here, we evaluated the therapeutic potential of targeting the ubiquitin-proteasome pathway using disulfiram and RNA interference and investigated the mechanisms underlying disulfiram in ccRCC. According to data from The Cancer Genome Atlas, NPL4 mRNA expression was significantly upregulated in clinical ccRCC samples compared with that in normal kidney samples, and patients with high NPL4 expression had poor overall survival compared with patients with low NPL4 expression. Disulfiram and NPL4 siRNA inhibited ccRCC cell proliferation in vitro, and disulfiram inhibited ccRCC tumor growth in a xenograft model. Synergistic antiproliferative effects were observed for combination treatment with disulfiram and sunitinib in vitro and in vivo. In RCC cells from mice treated with disulfiram and/or sunitinib, several genes associated with serine biosynthesis and aldose reductase were downregulated in cells treated with disulfiram or sunitinib alone and further downregulated in cells treated with both disulfiram and sunitinib. These findings provided insights into the mechanisms of disulfiram and suggested novel therapeutic strategies for RCC treatment.
Human schistosomiasis is a disease which globally affects over 229 million people. Three major species affecting humans are Schistosoma mansoni, S. haematobium and S. japonicum. Previous treatment of S. mansoni includes the use of oxamniquine (OXA), a prodrug that is enzymatically activated in S. mansoni but is ineffective against S. haematobium and S. japonicum. The OXA activating enzyme was identified and crystallized, as being a S. mansoni sulfotransferase (SmSULT). S. haematobium and S. japonicum possess homologs of SmSULT (ShSULT and SjSULT) begging the question; why does oxamniquine fail to kill S. haematobium and S. japonicum adult worms? Investigation of the molecular structures of the sulfotransferases indicates that structural differences, specifically in OXA contact residues, do not abrogate OXA binding in the active sites as previously hypothesized. Data presented argue that the ability of SULTs to sulfate and thus activate OXA and its derivatives is linked to the ability of OXA to fit in the binding pocket to allow the transfer of a sulfur group.
Background:
Neglected tropical diseases (NTDs) have long been overlooked in the global health agenda. They are intimately related to poverty, cause important local burdens of disease, but individually do not represent global priorities. Yet, NTDs were estimated to affect close to 2 billion people at the turn of the millennium, with a collective burden equivalent to HIV/AIDS, tuberculosis, or malaria. A global response was therefore warranted.
Main text:
The World Health Organization (WHO) conceived an innovative strategy in the early 2000s to combat NTDs as a group of diseases, based on a combination of five public health interventions. Access to essential NTD medicines has hugely improved thanks to strong public-private partnership involving the pharmaceutical sector. The combination of a WHO NTD roadmap with clear targets to be achieved by 2020 and game-changing partner commitments endorsed in the London Declaration on Neglected Tropical Diseases, have led to unprecedented progress in the implementation of large-scale preventive treatment, case management and care of NTDs. The coming decade will see as challenges the mainstreaming of these NTD interventions into Universal Health Coverage and the coordination with other sectors to get to the roots of poverty and scale up transmission-breaking interventions. Chinese expertise with the elimination of multiple NTDs, together with poverty reduction and intersectoral action piloted by municipalities and local governments, can serve as a model for the latter. The international community will also need to keep a specific focus on NTDs in order to further steer this global response, manage the scaling up and sustainment of NTD interventions globally, and develop novel products and implementation strategies for NTDs that are still lagging behind.
Conclusions:
The year 2020 will be crucial for the future of the global response to NTDs. Progress against the 2020 roadmap targets will be assessed, a new 2021-2030 NTD roadmap will be launched, and the London Declaration commitments will need to be renewed. It is hoped that during the coming decade the global response will be able to further build on today's successes, align with the new global health and development frameworks, but also keep focused attention on NTDs and mobilize enough resources to see the effort effectively through to 2030.
The anthelmintic drug praziquantel (PZQ) is used to treat schistosomiasis, a neglected tropical disease that affects over 200 million people worldwide. PZQ causes Ca2+ influx and spastic paralysis of adult worms and rapid vacuolization of the worm surface. However, the mechanism of action of PZQ remains unknown even after 40 years of clinical use. Here, we demonstrate that PZQ activates a schistosome transient receptor potential (TRP) channel, christened Sm.TRPMPZQ, present in parasitic schistosomes and other PZQ-sensitive parasites. Several properties of Sm.TRPMPZQ were consistent with known effects of PZQ on schistosomes, including (i) nanomolar sensitivity to PZQ; (ii) stereoselectivity toward (R)-PZQ; (iii) mediation of sustained Ca2+ signals in response to PZQ; and (iv) a pharmacological profile that mirrors the well-known effects of PZQ on muscle contraction and tegumental disruption. We anticipate that these findings will spur development of novel therapeutic interventions to manage schistosome infections, and broader interest in PZQ which is finally unmasked as a high affinity TRP channel ligand.
The parasitic disease schistosomiasis is the cause of more than 200 000 human deaths per year. Although the disease is treatable, there is one major shortcoming: praziquantel has been the only drug used to combat these parasites since 1977. The risk of the emergence of resistant schistosomes is known to be increasing, as a reduced sensitivity of these parasites toward praziquantel has been observed. We developed a new class of substances, which are derived from inhibitors of human aldose reductase, and which showed promising activity against Schistosoma mansoni couples in vitro. Further optimisation of the compounds led to an increase in anti‐schistosomal activity with observed phenotypes such as reduced egg production, vitality, and motility as well as tegumental damage and gut dilatation. Here, we performed structure–activity relationship studies on the carboxylic acid moiety of biarylalkyl carboxylic acids. Out of 82 carboxylic acid amides, we identified 10 compounds that are active against S. mansoni at 25 μm. The best five compounds showed an anti‐schistosomal activity up to 10 μm and induced severe phenotypes. Cytotoxicity tests in human cell lines showed that two derivatives had no cytotoxicity at 50 or 100 μm. These compounds are promising candidates for further optimisation toward the new anti‐schistosomal agents.
Due to rising costs and the difficulty to identify new targets, drug repurposing appears as a viable strategy for the development of new anti-cancer treatments. Although the interest of disulfiram (DSF), an anti-alcohol drug, to treat cancer was reported for many years, it is only very recently that one anticancer mechanism-of-action was highlighted. This would involve the inhibition of the p97 segregase adaptor NPL4, which is essential for the turnover of proteins involved in multiple regulatory and stress-response intracellular pathways. However, recently DSF was also reported as one of the first phosphoglycerate dehydrogenase (PHGDH) inhibitors, a tetrameric enzyme catalyzing the initial step of the serine synthetic pathway that is highly expressed in numerous cancer types. Here, we investigated the structure-activity relationships (SAR) of PHGDH inhibition by disulfiram analogues as well as the mechanism of action of DSF on PHGDH via enzymatic and cell-based evaluation, mass spectrometric and mutagenesis experiments.
Inosine 5′-monophosphate dehydrogenase (IMPDH) is an essential enzyme for the production of guanine nucleotides. Disruption of IMPDH activity has been explored as a therapeutic strategy for numerous purposes, such as for anticancer, immunosuppression, antiviral, and antimicrobial therapy. In the present study, we established a luciferase-based high-throughput screening system to identify IMPDH inhibitors from our chemical library of known bioactive small molecules. The screening of 1400 compounds resulted in the discovery of three irreversible inhibitors: disulfiram, bronopol, and ebselen. Each compound has a distinct chemical moiety that differs from other reported IMPDH inhibitors. Further evaluation revealed that these compounds are potent inhibitors of IMPDHs with kon values of 0.7 × 10⁴ to 9.3 × 10⁴ M⁻¹·s⁻¹. Both disulfiram and bronopol exerted similar degree of inhibition to protozoan and mammalian IMPDHs. Ebselen showed an intriguing difference in mode of inhibition for different IMPDHs, with reversible and irreversible inhibition to each Cryptosporidium parvum IMPDH and human IMPDH type II, respectively. In the preliminary efficacy experiment against cryptosporidiosis in severe combined immunodeficiency (SCID) mouse, a decrease in the number of oocyst shed was observed upon the oral administration of disulfiram and bronopol, providing an early clinical proof-of-concept for further utilization of these compounds as IMPDH inhibitors.
Schistosomiasis (bilharzia) is a neglected tropical disease caused by parasitic flatworms (blood flukes) of the genus Schistosoma, with considerable morbidity in parts of the Middle East, South America, Southeast Asia and, particularly, in sub-Saharan Africa. Infective larvae grow in an intermediate host (fresh-water snails) before penetrating the skin of the definitive human host. Mature adult worms reside in the mesenteric (Schistosoma mansoni and Schistosoma japonicum) or pelvic (Schistosoma haematobium) veins, where female worms lay eggs, which are secreted in stool or urine. Eggs trapped in the surrounding tissues and organs, such as the liver and bladder, cause inflammatory immune responses (including granulomas) that result in intestinal, hepato-splenic or urogenital disease. Diagnosis requires the detection of eggs in excreta or worm antigens in the serum, and sensitive, rapid, point-of-care tests for populations living in endemic areas are needed. The anti-schistosomal drug praziquantel is safe and efficacious against adult worms of all the six Schistosoma spp. infecting humans; however, it does not prevent reinfection and the emergence of drug resistance is a concern. Schistosomiasis elimination will require a multifaceted approach, including: treatment; snail control; information, education and communication; improved water, sanitation and hygiene; accurate diagnostics; and surveillance-response systems that are readily tailored to social-ecological settings.
Giardiasis, the infestation of the intestinal tract by Giardia lamblia, is one of the most prevalent parasitosis worldwide. Even though effective therapies exist for it, the problems associated with its use indicate that new therapeutic options are needed. It has been shown that disulfiram eradicates trophozoites in vitro and is effective in vivo in a murine model of giardiasis; disulfiram inactivation of carbamate kinase by chemical modification of an active site cysteine has been proposed as the drug mechanism of action. The triosephosphate isomerase from G. lamblia (GlTIM) has been proposed as a plausible target for the development of novel antigiardial pharmacotherapies, and chemical modification of its cysteine 222 (C222) by thiol-reactive compounds is evidenced to inactivate the enzyme. Since disulfiram is a cysteine modifying agent and GlTIM can be inactivated by modification of C222, in this work we tested the effect of disulfiram over the recombinant and trophozoite-endogenous GlTIM. The results show that disulfiram inactivates GlTIM by modification of its C222. The inactivation is species-specific since disulfiram does not affect the human homologue enzyme. Disulfiram inactivation induces only minor conformational changes in the enzyme, but substantially decreases its stability. Recombinant and endogenous GlTIM inactivates similarly, indicating that the recombinant protein resembles the natural enzyme. Disulfiram induces loss of trophozoites viability and inactivation of intracellular GlTIM at similar rates, suggesting that both processes may be related. It is plausible that the giardicidal effect of disulfiram involves the inactivation of more than a single enzyme, thus increasing its potential for repurposing it as an antigiardial drug.
The current approach of morbidity control of schistosomiasis, a helminth disease of poverty with considerable public health and socioeconomic impact, is based on preventive chemotherapy with praziquantel. There is a pressing need for new drugs against this disease whose control entirely depends on this single drug that has been widely used over the past 40 years. We argue that a broader anthelminthic approach supplementing praziquantel with new antischistosomals targeting different parasite development stages would not only increase efficacy but also reduce the risk for drug resistance. Repositioning drugs already approved for other diseases provides a shortcut to clinical trials, as it is expected that such drugs rapidly pass the regulatory authorities. The antischistosomal properties of antimalarial drugs (e.g., semisynthetic artemisinins, synthetic trioxolanes, trioxaquines and mefloquine) and of drugs being developed or registered for other purposes (e.g., moxidectin and miltefosin), administered alone or in combination with praziquantel, have been tested in the laboratory and clinical trials. Another avenue to follow is the continued search for new antischistosomal properties in plants. Here, we summarise recent progress made in schistosomiasis chemotherapy, placing particular emphasis on repositioning of existing drugs against schistosomiasis.
Electronic supplementary material
The online version of this article (doi:10.1186/s40249-017-0286-2) contains supplementary material, which is available to authorized users.
Schistosomes and other parasitic platyhelminths cause infectious diseases of worldwide significance for humans and animals. Despite their medical and economic importance, vaccines are not available and the number of drugs is alarmingly limited. For most platyhelminths including schistosomes, Praziquantel (PZQ) is the commonly used drug. With respect to its regular application in mass treatment programs, however, there is increasing concern about resistance development.
Previous studies demonstrated that inhibitors used to treat non-parasitic human diseases may be useful to be tested for their effects on parasites. To this end, we focused on biarylalkyl carboxylic acids (BACAs) as basis, which had been shown before to be interesting candidates in the context of finding alternative approaches to treat diabetes mellitus. We tested 32 chemically modified derivatives of these substances (biarylalkyl carboxylic acid derivatives (BACADs)) for their effects on adult Schistosoma mansoni in vitro. Treatment with 18 BACADs resulted in egg production-associated phenotypes and reduced pairing stability. In addition, 12 of these derivatives affected vitality and/or caused severe tegument damage, gut dilatation, or other forms of tissue disintegration which led to the death of worms. In most cases (10/12), one derivative caused more than one phenotype at a time. In vitro experiments in the presence of serum albumin (SA) and alpha-acidic glycoprotein (AGP) indicated a varying influence of these blood components on the effects of two selected derivatives. The variety of observed phenotypes suggested that different targets were hit. The results demonstrated that BACADs are interesting substances with respect to their anti-schistosomal effects.
Parasitic platyhelminths are responsible for serious infectious diseases, such as schistosomiasis, which affect humans as well as animals across vast regions of the world. The drug arsenal available for the treatment of these diseases is limited; for example, praziquantel is the only drug currently used to treat ≥240 million people each year infected with Schistosoma spp., and there is justified concern about the emergence of drug resistance. In this study, we screened biarylalkyl carboxylic acid derivatives for their antischistosomal activity against S. mansoni. These compounds showed significant influence on egg production, pairing stability, and vitality. Tegumental lesions or gut dilatation was also observed. Substitution of the terminal phenyl residue in the biaryl scaffold with a 3-hydroxy moiety and derivatization of the terminal carboxylic acid scaffold with carboxamides yielded compounds that displayed significant antischistosomal activity at concentrations as low as 10 μm with satisfying cytotoxicity values. The present study provides detailed insight into the structure-activity relationships of biarylalkyl carboxylic acid derivatives and thereby paves the way for a new drug-hit moiety for fighting schistosomiasis.
We present a case of acute schistosomiasis acquired in Corsica after bathing in the Cavu River during the summer of 2015. The diagnosis was made following epidemiological, laboratory and serological assessments. After a previous outbreak of urogenital schistosomiasis during the summer of 2013, when more than 120 infections were diagnosed, this further case indicates transmission was still effective in 2015, thus suggesting a permanent presence of schistosomiasis in Corsica. © 2016, European Centre for Disease Prevention and Control (ECDC). All rights reserved.
Die Schistosomiasis (Bilharziose) wird durch Trematoden der Gattung Schistosoma hervorgerufen und ist eine der weltweit bedeutendsten Infektionserkrankungen bei Mensch und Tier. Die adulten Parasiten leben als Pärchen in einem dauerhaften Paarungskontakt im Blutgefäßsystem ihres Wirbeltier-Endwirts. Diese „Dauerkopula“ ist Voraussetzung für die geschlechtliche Differenzierung des Weibchens bzw. dessen Reproduktionsorgane und damit für die Produktion von Eiern, welche abhängig von der Spezies größtenteils über den Darm (oder die Blase) in die Umwelt gelangen, um den parasitären Zyklus fortzusetzen.
18 novel dithiocarbamate derivatives were synthesized in order to investigate their inhibitory potency on acetylcholinesterase enzyme and antimicrobial activity. Structures of the synthesized compounds were elucidated by spectral data and elemental analyses. The synthesized compounds showed low enzyme inhibitory activity. However, they displayed good antimicrobial activity profile. Antibacterial activity of compounds 4a, 4e, and 4p (MIC = 25 μg/mL) was equal to that of chloramphenicol against Klebsiella pneumoniae (ATCC 700603) and Escherichia coli (ATCC 35218). Most of the compounds exhibited notable antifungal activity against Candida albicans (ATCC 10231), Candida glabrata (ATCC 90030), Candida krusei (ATCC 6258), and Candida parapsilosis (ATCC 7330). Moreover, compound 4a, which carries piperidin-1-yl substituent and dimethylthiocarbamoyl side chain as variable group, showed twofold better anticandidal effect against all Candida species than reference drug ketoconazole.
Prophylactic prevention is considered as the most promising strategy to tackle
STI/HIV. Twenty-five dithiocarbamate-thiourea hybrids (14-38) were synthesized as woman
controlled topical vaginal microbicides to counter Trichomonas vaginalis and sperm along with
RT inhibition potential. The four promising compounds (18, 26, 28 and 33) were tested for safety
through cytotoxic assay against human cervical cell line (HeLa) and compatibility with vaginal
flora, Lactobacillus. Docking study of most promising vaginal microbicide (33) revealed that it
docked in a position and orientation similar to known reverse transcriptase inhibitor Nevirapine.
The preliminary in vivo pharmacokinetics of compound 33 was performed in NZ-rabbits to
evaluate systemic toxicity in comparison to Nonoxynol-9.
Schistosomiasis is a neglected tropical disease caused by blood-dwelling flukes of the genus Schistosoma. While the disease may affect as many as 249 million people, treatment largely relies on a single drug, praziquantel. The near exclusive use of this drug for such a prevalent disease has led to concerns regarding the potential for drug resistance to arise and the effect this would have on affected populations. In this study, we use an in vitro assay of drug sensitivity to test the effect of praziquantel on miracidia hatched from eggs obtained from fecal samples of Kenyan adult car washers and sand harvesters as well as school children. Whereas in a previous study we found the car washers and sand harvesters to harbor Schistosoma mansoni with reduced praziquantel sensitivity, we found no evidence for the presence of such strains in any of the groups tested here. Using miracidia derived from seven car washers to infect snails, we used the shed cercariae to establish a strain of S. mansoni with significantly reduced praziquantel sensitivity in mice. This was achieved within 5 generations by administering increasing doses of praziquantel to the infected mice until the parasites could withstand a normally lethal dose. This result indicates that while the threat of praziquantel resistance may have diminished in the Kenyan populations tested here, there is a strong likelihood it could return if sufficient praziquantel pressure is applied.
Schistosomiasis is a chronic enteropathogenic disease caused by blood flukes of the genus Schistosoma. The disease afflicts approximately 240 million individuals globally, causing approximately 70 million disability-adjusted life years lost. Chronic infections with morbidity and mortality occur as a result of granuloma formation in the intestine, liver, or in the case of Schistosoma haematobium, the bladder. Various methods are utilized to diagnose and evaluate liver fibrosis due to schistosomiasis. Liver biopsy is still considered the gold standard, but it is invasive. Diagnostic imaging has proven to be an invaluable method in assessing hepatic morbidity in the hospital setting, but has practical limitations in the field. The potential of non-invasive biological markers, serum antibodies, cytokines, and circulating host microRNAs to diagnose hepatic fibrosis is presently undergoing evaluation. This review provides an update on the recent advances made with respect to gastrointestinal disease associated with chronic schistosomiasis.
Carbamate kinase from Giardia lamblia is an essential enzyme for the survival of the organism. The enzyme catalyzes the final step in the arginine dihydrolase
pathway converting ADP and carbamoyl phosphate to ATP and carbamate. We previously reported that disulfiram, a drug used to
treat chronic alcoholism, inhibits G. lamblia CK and kills G. lamblia trophozoites in vitro at submicromolar IC50 values. Here, we examine the structural basis for G. lamblia CK inhibition of disulfiram and its analog, thiram, their activities against both metronidazole-susceptible and metronidazole-resistant
G. lamblia isolates, and their efficacy in a mouse model of giardiasis. The crystal structure of G. lamblia CK soaked with disulfiram revealed that the compound thiocarbamoylated Cys-242, a residue located at the edge of the active
site. The modified Cys-242 prevents a conformational transition of a loop adjacent to the ADP/ATP binding site, which is required
for the stacking of Tyr-245 side chain against the adenine moiety, an interaction seen in the structure of G. lamblia CK in complex with AMP-PNP. Mass spectrometry coupled with trypsin digestion confirmed the selective covalent thiocarbamoylation
of Cys-242 in solution. The Giardia viability studies in the metronidazole-resistant strain and the G. lamblia CK irreversible inactivation mechanism show that the thiuram compounds can circumvent the resistance mechanism that renders
metronidazole ineffectiveness in drug resistance cases of giardiasis. Together, the studies suggest that G. lamblia CK is an attractive drug target for development of novel antigiardial therapies and that disulfiram, an FDA-approved drug,
is a promising candidate for drug repurposing.
A family of detoxifying enzymes called aldehyde dehydrogenases (ALDHs) has been a subject of recent interest, as its role in detoxifying aldehydes that accumulate through metabolism and to which we are exposed from the environment has been elucidated. Although the human genome has 19 ALDH genes, one ALDH emerges as a particularly important enzyme in a variety of human pathologies. This ALDH, ALDH2, is located in the mitochondrial matrix with much known about its role in ethanol metabolism. Less known is a new body of research to be discussed in this review, suggesting that ALDH2 dysfunction may contribute to a variety of human diseases including cardiovascular diseases, diabetes, neurodegenerative diseases, stroke, and cancer. Recent studies suggest that ALDH2 dysfunction is also associated with Fanconi anemia, pain, osteoporosis, and the process of aging. Furthermore, an ALDH2 inactivating mutation (termed ALDH2*2) is the most common single point mutation in humans, and epidemiological studies suggest a correlation between this inactivating mutation and increased propensity for common human pathologies. These data together with studies in animal models and the use of new pharmacological tools that activate ALDH2 depict a new picture related to ALDH2 as a critical health-promoting enzyme.
Oxamniquine resistance evolved in the human blood fluke (Schistosoma mansoni) in Brazil in the 1970s. We crossed parental parasites differing ~500-fold in drug response, determined drug sensitivity
and marker segregation in clonally derived second-generation progeny, and identified a single quantitative trait locus (logarithm
of odds = 31) on chromosome 6. A sulfotransferase was identified as the causative gene by using RNA interference knockdown
and biochemical complementation assays, and we subsequently demonstrated independent origins of loss-of-function mutations
in field-derived and laboratory-selected resistant parasites. These results demonstrate the utility of linkage mapping in
a human helminth parasite, while crystallographic analyses of protein-drug interactions illuminate the mode of drug action
and provide a framework for rational design of oxamniquine derivatives that kill both S. mansoni and S. haematobium, the two species responsible for >99% of schistosomiasis cases worldwide.
Dithiocarbamates and their complexes with transition metals have been used as common pesticides, vulcanizing or analytical agents for decades. These compounds are one of the most reported inhibitors of nuclear factor-kappa B (NF-kappa B) signaling cascade. Recently, it has been found that dithiocarbamates are very potent inhibitors of proteasome. NF-kappa B plays a central role in the immune system and is described as major actor in many of human cancers mainly because of its protective effects against apoptosis. Molecular mechanisms involved in regulation and function of NF-kappa B pathway have been elucidated recently. In particular, pivotal zinc containing proteins that alter NF-kappa B signal transduction were recognized, Additionally, proteasome system was found to be a key player in NF-kappa B pathway and is an attractive target for anticancer drug development Collectively, the capability of dithiocarbamates to inhibit NF-kappa B and proteasome makes these compounds promising anticancer agents. This review focuses on the biological activity of dithiocarbamate coordination compounds with regard to their possible molecular targets in NF-kappa B signaling and proteasome (JAMM domain proteins). Future research should aim to find the most suitable dithiocarbamate coordination compounds for treatment of cancer and other diseases.
The WST-1 assay is an efficient test for cell viability measurement and the standard incubation time is 2h. In order to test if one-time addition of WST-1 reagent can reflect the relative cell viability trend of the testing agents at different time points, the effects of 2h standard incubation time and long term incubation time (2h+24h, 2h+48h) of WST-1 were compared in the rat airway smooth muscle cells (ASM cells) after adding of the testing protein MRP-14. Our study demonstrated that the effect of different dosages of the protein after 2h WST-1 incubation on ASM cells showed a tendency of inhibition and achieved the maximal inhibition effect at 72h. The relative cell viability trend of the 2h+24h group was the same to that of the 2h WST-1 incubation, which means that 24h prolonged incubation time of WST-1 reagent could still reflect the relative cell viability trend. In conclusion, the study suggested that the WST-1 is a proper candidate reagent for continuous monitation of cell viability.
Glioblastomas (GBM) are associated with high rates of relapse. These brain tumors are often resistant to chemotherapies like temozolomide (TMZ) and there are very few treatment options available to patients. We recently reported that polo-like kinase-1 (PLK1) is associated with the proliferative subtype of GBM; which has the worst prognosis. In this study, we addressed the potential of repurposing disulfiram (DSF), a drug widely used to control alcoholism for the past six decades. DSF has good safety profiles and penetrates the blood-brain barrier. Here we report that DSF inhibited the growth of TMZ resistant GBM cells, (IC90=100 nM), but did not affect normal human astrocytes. At similar DSF concentrations, self-renewal was blocked by ~100% using neurosphere growth assays. Likewise the drug completely inhibited the self-renewal of the BT74 and GBM4 primary cell lines. Additionally, DSF suppressed growth and self-renewal of primary cells from two GBM tumors. These cells were resistant to TMZ, had unmethylated MGMT, and expressed high levels of PLK1. Consistent with its role in suppressing GBM growth, DSF inhibited the expression of PLK1 in GBM cells. Likewise, PLK1 inhibition with siRNA, or small molecules (BI-2536 or BI-6727) blocked growth of TMZ resistant cells. Our studies suggest that DSF has the potential to be repurposed for treatment of refractory GBM.
Aldehyde dehydrogenases (ALDHs) belong to a superfamily of enzymes that play a key role in the metabolism of aldehydes of both endogenous and exogenous derivation. The human ALDH superfamily comprises 19 isozymes that possess important physiological and toxicological functions. The ALDH1A subfamily plays a pivotal role in embryogenesis and development by mediating retinoic acid signaling. ALDH2, as a key enzyme that oxidizes acetaldehyde, is crucial for alcohol metabolism. ALDH1A1 and ALDH3A1 are lens and corneal crystallins, which are essential elements of the cellular defense mechanism against ultraviolet radiation-induced damage in ocular tissues. Many ALDH isozymes are important in oxidizing reactive aldehydes derived from lipid peroxidation and thereby help maintain cellular homeostasis. Increased expression and activity of ALDH isozymes have been reported in various human cancers and are associated with cancer relapse. As a direct consequence of their significant physiological and toxicological roles, inhibitors of the ALDH enzymes have been developed to treat human diseases. This review summarizes known ALDH inhibitors, their mechanisms of action, isozyme selectivity, potency, and clinical uses. The purpose of this review is to 1) establish the current status of pharmacological inhibition of the ALDHs, 2) provide a rationale for the continued development of ALDH isozyme-selective inhibitors, and 3) identify the challenges and potential therapeutic rewards associated with the creation of such agents.
Praziquantel (PZQ) is an essential medicine for treating parasitic flatworm infections such as schistosomiasis, which afflicts over 250 million people. However, PZQ is not universally effective, lacking activity against liver flukes of the Fasciola genus. The reason for this insensitivity is unclear, as the mechanism of PZQ action is unknown. Here, we use ligand- and target-based methods to demonstrate that PZQ activates a transient receptor potential melastatin ion channel (TRPMPZQ) in schistosomes by engaging a hydrophobic ligand binding pocket within the voltage sensor–like domain of the channel to cause calcium entry and worm paralysis. PZQ activates TRPMPZQ homologs in other PZQ-sensitive flukes, but not Fasciola hepatica. However, a single amino acid change in the F. hepatica TRPMPZQ binding pocket, to mimic schistosome TRPMPZQ, confers PZQ sensitivity. After decades of clinical use, the molecular basis of PZQ action at a druggable TRP channel is resolved.
The nitro group is considered to be a versatile and unique functional group in medicinal chemistry. Despite a long history of use in therapeutics, the nitro group has toxicity issues and is often categorized as a structural alert or a toxicophore, and evidence related to drugs containing nitro groups is rather contradictory. In general, drugs containing nitro groups have been extensively associated with mutagenicity and genotoxicity. In this context, efforts towards the structure-mutagenicity or structure-genotoxicity relationships have been undertaken. The current perspective covers various aspects of agents that contain nitro groups, their bioreductive activation mechanisms, and their toxicities, and approaches to combat their toxicity issues. In addition, recent advances in the field of anticancer, antitubercular and antiparasitic agents containing nitro groups, along with a patent survey on hypoxia-activated prodrugs containing nitro groups, are also covered.
Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in southern China in late 2002 and caused a global outbreak with a fatality rate around 10% in 2003. Ten years later, a second highly pathogenic human CoV, MERS-CoV, emerged in the Middle East and has spread to other countries in Europe, North Africa, North America and Asia. As of November 2017, MERS-CoV had infected at least 2102 people with a fatality rate of about 35% globally, and hence there is an urgent need to identify antiviral drugs that are active against MERS-CoV. Here we show that a clinically available alcohol-aversive drug, disulfiram, can inhibit the papain-like proteases (PLpros) of MERS-CoV and SARS-CoV. Our findings suggest that disulfiram acts as an allosteric inhibitor of MERS-CoV PLpro but as a competitive (or mixed) inhibitor of SARS-CoV PLpro. The phenomenon of slow-binding inhibition and the irrecoverability of enzyme activity after removing unbound disulfiram indicate covalent inactivation of SARS-CoV PLpro by disulfiram, while synergistic inhibition of MERS-CoV PLpro by disulfiram and 6-thioguanine or mycophenolic acid implies the potential for combination treatments using these three clinically available drugs.
Purpose of review:
Preventive chemotherapy is advocated for the global control and elimination of schistosomiasis. Despite the well known short-term benefits of treating patients for schistosomiasis, the impact of mass drug administration (MDA) campaigns to control the disease in the long term remains unresolved.
Recent findings:
Many studies have advocated the success of MDA programs in order to attract donor funds for elimination efforts but such successes are often short-lived given the drug does not alter the life cycle of the organism or prevent reinfection. Within a matter of months to years after halting treatment, the prevalence, intensity of infection and morbidity of disease return to baseline levels. Other mitigating factors contribute to the failings of MDA campaigns namely: poverty, poor drug coverage, poor drug compliance, and, in the case of Asiatic schistosomiasis, zoonotic transmission. Genetic and innate and acquired immunologic mechanisms complicate the epidemiologic picture of schistosomiasis globally, and may contribute indirectly to MDA shortcomings. The possibility of drug resistance is an ever present concern because of the sole reliance on one drug, praziquantel.
Summary:
Preventive chemotherapy is advocated for the global control and elimination of schistosomiasis. The short-term benefits of MDA campaigns are well documented but the long-term benefits are questionable.
Background:
Schistosomiasis is a snail-borne parasitic disease endemic in several tropical and subtropical countries. However, in the summer of 2013, an unexpected outbreak of urogenital schistosomiasis occurred in Corsica, with more than 120 local people or tourists infected. We used a multidisciplinary approach to investigate the epidemiology of urogenital schistosomiasis in Corsica, aiming to elucidate the origin of the outbreak.
Methods:
We did parasitological and malacological surveys at nine potential sites of infection. With the snails found, we carried out snail-parasite compatibility experiments by exposing snails to schistosome larvae recovered from the urine of a locally infected Corsican patient. Genetic analysis of both mitochondrial (cox1) and nuclear (internal transcribed spacer) DNA data from the Schistosoma eggs or miracidia recovered from the infected patients was conducted to elucidate the epidemiology of this outbreak.
Findings:
We identified two main infection foci along the Cavu River, with many Bulinus truncatus snails found in both locations. Of the 3544 snails recovered across all sites, none were naturally infected, but laboratory-based experimental infections confirmed their compatibility with the schistosomes isolated from patients. Molecular characterisation of 73 eggs or miracidia isolated from 12 patients showed infection with Schistosoma haematobium, S haematobium-Schistosoma bovis hybrids, and S bovis. Further sequence data analysis also showed that the Corsican schistosomes were closely related to those from Senegal in west Africa.
Interpretation:
The freshwater swimming pools of the Cavu River harbour many B truncatus snails, which are capable of transmitting S haematobium-group schistosomes. Our molecular data suggest that the parasites were imported into Corsica by individuals infected in west Africa, specifically Senegal. Hybridisation between S haematobium and the cattle schistosome S bovis had a putative role in this outbreak, showing how easily and rapidly urogenital schistosomiasis can be introduced and spread into novel areas where Bulinus snails are endemic, and how hybridisation could increase the colonisation potential of schistosomes. Furthermore our results show the potential risk of schistosomiasis outbreaks in other European areas, warranting close monitoring and surveillance of all potential transmission foci.
Funding:
WHO, ANSES, RICET, and the Ministry of Health and Consumption.
In viral proteins, labile Zn-sites, where Zn2+ is crucial for maintaining the native protein structure but the Zn-bound cysteines are reactive, are promising drug targets. Here, we aim to (i) identify labile Zn-sites in viral proteins using guidelines established from our previous work and (ii) assess if clinically safe Zn-ejecting agents could eject Zn2+ from the predicted target site and thus inhibit viral replication. As proof-of-concept, we identified a labile Zn-site in the hepatitis C virus (HCV) NS5A protein and showed that the anti-alcoholism drug, disulfiram, could inhibit HCV replication to a similar extent as the clinically used antiviral agent, ribavirin. The discovery of a novel viral target and a new role for disulfiram in inhibiting HCV replication will enhance the therapeutic armamentarium against HCV. The strategy presented can also be applied to identify labile sites in other bacterial or viral proteins that can be targeted by disulfiram or other clinically safe Zn-ejectors.
A SERIES of coumarin derivatives carrying different biologically active side chains and heterocyclic substituents were synthesized from 8-acetyl-4-methyl-7-hydroxycoumarin. Among these side chains are alkylamino, semicarbazono- and N4-substituted thiosemicarba-zonoethyl, 1-hydrazonoethyl and substituted 1-hydroximinoethyl groups, while heterocyclic substituents were drived fom pyran, oxadiazole, thiadiazole and thiazolidinone rings. Also, some derivatives of pyrano[2,3-h]chromen-9-carbaldehyde were synthesized. Some of these new products were studied for their chemoprophylactic effect in Schistosoma mansoni infected mice.
A SERIES of coumarin derivatives bearing heterocyclic substituents was synthesized. Bromination of the key compound 8-acetyl-7-hydroxy-4-methylcoumarin (I) under varied conditions gave the brominated derivatives II, III and IV. Conversions of III by several cyclo-condensations gave the corresponding thiazole V, quinoxaline VI, quinoxalinone VIII and furanone IX derivatives. Also, methylation and cyclocondensation of the methylene-active acetyl groups of II with several aldehydes gave the corresponding pyridone various amines gave the corresponding amino side chains. Some of these newly synthesized products were studied for their chemoprophylatic effect on Schistosoma mansoni infected mice. Compound Xc a showed moderate effect.
A new tetrazolium compound, sodium salt of 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate (1a), which produces a highly water-soluble formazan dye, due to the presence of two sulfonate groups, was synthesized and its potential utility evaluated in assays of NADH and cell proliferation. The compound proved to have a similar sensitivity to 2, 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) in the assay of NADH and was also useful as an indicator of cell viability, with less cytotoxicity than XTT, in the proliferation assay using P388 cell lines.
Neglected tropical diseases (NTDs) have become recognised as important health problems facing at least a billion people in the low-income countries and the poorest communities in middle-income countries. WHO plays a leading role in developing strategies to address these diseases, pharmaceutical companies provide drug donations to treat or control the NTDs and many partners from different constituencies have become increasingly committed to their control or elimination. This review looks to the post-2015 agenda and emphasises that despite the progress made over recent years, if the targets established are to be achieved, then not only will additional financial resources be required to up-scale treatments and increase access, but increased applied and operational research will be necessary to address problems and human capacity in NTD skills will need to be strengthened. Continuing advocacy for the relevance of control or elimination of NTDs must be placed in the context of universal health coverage and access to donated essential medicines for the poor as a right. The evidence that investment in NTD interventions are cost-effective and impact not only on health, but also to enhance socio-economic development, must be refined and promulgated. The global burden of disease attributable to NTDs requires reassessment to appropriately define the true burden, while the potential for unexpected events, political, climatic, environmental as well as biological, have the potential to reduce future progress towards the agreed post-2015 targets. NTD progress towards the WHO Roadmap targets and the fulfilment of the World Health Assembly Resolution 66.12 of 2013 demand continued commitment from all partner constituencies when challenges emerge.
Abstract The present study reported the synthesis of tetrahydrocarbazoles hybridized with dithioate derivatives. Three series were synthesized namely alkyl dithiocarbonates (4a-d), heterocyclic dithiocarbamates (6a-g) and dialkyl dithiocarbamate (7). The synthesized compounds were tested in vitro on human breast adenocarcinoma cell line (MCF7) and the human colon tumor cell line (HCT116). Most of the synthesized compounds exploited potent antitumor activity, especially compound 6f [4-chlorophenylpiperazine derivative], which showed cytotoxic activity against MCF7 superior to doxorubicin with IC50 value of 7.24 nM/mL.
Human schistosomiasis-or bilharzia-is a parasitic disease caused by trematode flukes of the genus Schistosoma. By conservative estimates, at least 230 million people worldwide are infected with Schistosoma spp. Adult schistosome worms colonise human blood vessels for years, successfully evading the immune system while excreting hundreds to thousands of eggs daily, which must either leave the body in excreta or become trapped in nearby tissues. Trapped eggs induce a distinct immune-mediated granulomatous response that causes local and systemic pathological effects ranging from anaemia, growth stunting, impaired cognition, and decreased physical fitness, to organ-specific effects such as severe hepatosplenism, periportal fibrosis with portal hypertension, and urogenital inflammation and scarring. At present, preventive public health measures in endemic regions consist of treatment once every 1 or 2 years with the isoquinolinone drug, praziquantel, to suppress morbidity. In some locations, elimination of transmission is now the goal; however, more sensitive diagnostics are needed in both the field and clinics, and integrated environmental and health-care management will be needed to ensure elimination.
The one-pot three-component reaction of primary and secondary amines, carbon disulfide and β-nitrostyrene derivatives in neat condition at room temperature afforded functionalized dithiocarbamate derivatives in good to high yields. High bond-forming efficiency and easy work-up are advantages of this reaction. In vitro antimicrobial activities of synthesized compounds were studied against four Gram-positive bacteria, four Gram-negative bacteria and four fungi. The screening for the antimicrobial activity was performed by twofold serial dilution technique. Notably, some synthesized compounds displayed comparable or even better antibacterial and antifungal activities against some tested strains than the reference drugs ampicillin, streptomycin and amphotericin B, respectively.
Graphical abstract
A series of novel dithiocarbamates 4a-j have been synthesized via three-component reaction and compared pharmacologically concerning their antimicrobial and antibacterial activities as well as antifungal activity
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After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200 000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies.
Syntheses of trans-isomers of ketoconazole, and the corresponding des-acetyl, 1-methyl-, 1-formyl and 1-methanesulfonyl analogs were investigated. These isomers, along with the corresponding cis-diastereomers were characterized by their carbon-13 nmr spectra.
Results from infected patients, not cured by multiple doses of praziquantel (PZQ), have been reported from different geographic locations, suggesting that resistance to the drug may be present. This has been coupled with several in vivo (e.g., studies on mice infected with 'resistant isolates') and in vitro tests (e.g., direct application and measurement of the effects of the drug on schistosomes maintained in culture) demonstrating a significant reduction in the drug's efficacy. Despite little field evidence that schistosomes are becoming less sensitive to the drug, 100% cure after PZQ is rarely achieved; meanwhile, the percentage of cure rates in endemic areas could be an overestimate if one accounts for the sensitivity of most egg counting methods coupled with the limited faecal sampling. To be proactive, the efficacy of PZQ has to be monitored on a systematic basis not only for cure, but also for the reduction of egg excretion complemented with periodical assessment for the susceptibility to the drug on local strains. Investigation of field isolates with confirmed diminished sensitivity to the drug will help in determining the frequency, epidemiology, genetic and physiologic basis for the observed resistance. Monitoring for changes in drug responsiveness in high transmission areas, where treatment failure as a result of immature or resistant parasites can not be differentiated, should be initiated. New chemotherapeutic alternatives and strategies in addition to a simple rapid, inexpensive test to detect resistance should be encouraged.
A series of novel dithiocarbamates with benzimidazole and chalcone scaffold have been designed synthesised and evaluated for their antimitotic activity. Compounds 4c and 9d display the most promising antimitotic activity with IC(50) of 1.66 μM and 1.52 μM respectively.
The mechanisms by which adult male Schistosoma mansoni transport amino acids have been investigated using radioactive amino acids during 2-min incubation times. The transport constants (Kt) for mediated uptake of glycine, proline, methionine, arginine, glutamate, and tryptophan were calculated to be 0.60-1.05, 1.67-1.98, 2.0, 0.10-0.35, 0.30-0.50, and 0.5-1.0 mM, respectively. Maximal velocities (Vmax) were 5.5–7.5, 25, 6.4, 1.5-2.0, 2.5, and 3.0–6.0 μmoles absorbed/g worm protein/2 min, respectively. Cysteine is taken up solely by diffusion. Proline uptake is unique in that no significant diffusion component was found. The other amino acids studied were absorbed by diffusion as well as by specific transport systems. In the 2-min incubation periods employed glycine, proline, glutamate, and methionine were not significantly metabolized indicating that the uptake studies using these substrates reflect transport. Metabolism of the other amino acids used in these studies was not examined. The specificity of the transport systems was studied by testing the inhibitory effects of various amino acids on the uptake of each of the amino acids studied. The results suggest the presence of at least five transport systems. There is a highly specific transport locus for proline, and one for acidic amino acids. There are probably at least two transport systems, each of broad and overlapping specificity, for most of the neutral amino acids. Basic amino acids also appear to be taken up by complex transport systems, at least one of which overlaps with the neutral sites. The results are discussed with respect to the nutrition of the parasite and the host-parasite relationship.