Search

Infectious diseases such as tuberculosis and leishmaniasis are leading causes of human death. One of the major factors contributing to the poor control of these diseases is primarily the reduced effectiveness of the existing chemotherapies as result of the increasing rise of multidrug-resistant strains of their causative agents. This leads to the imperative need to develop new and effective drugs. In search for such agents, a series of hydroquinone-triazole hybrids was investigated. The design, synthesis, and biological activities against the human virulent H37Rv strain of Mycobacterium tuberculosis (Mtb) and Leishmaniasis major (L. major), causative pathogen of human cutaneous leishmaniasis, are herein reported. The hybrids were synthesized following a two-step process Michael addition and Click chemistry. They were found to be noncytotoxic toward human kidney embryonic cells but expressed poor cellular antileishmanial and antimycobacterial activities. Hybrid 14, 2‐{4‐[(phenylsulfanyl)methyl]‐1H‐1,2,3‐triazol‐1‐yl}benzene‐1,4‐diol, was the most active among synthesized molecules, with MIC90 16 and IC50 23 µM against Mtb and L. major parasite, respectively, but had a poor safety profile, being as toxic to mammalian cells as to mycobacteria and parasites. Thus, compound 14 did not stand as potential anti-infective hit for further investigation. Future endeavor will focus on the investigation of more rigid and flexible hybrids of both scaffolds in order to assess the impact a spacer might have on their biological activity.

The increasing prevalence of multidrug-resistant strains of Mycobacterium tuberculosis (Mtb), the pathogen of human tuberculosis (TB), serves as a strong incentive for the discovery and development of new agents for the treatment of this plight. In search for such drugs, we investigated a series of benzyltriazole derivatives. We herein report the design, synthesis and biological activity of disubstituted benzyltriazoles against the human virulent H37Rv strain of Mtb as well as the toxicity on human embryonic kidney (HEK-293) cells. The derivative 21 featuring trifluoromethyl substituent in para position on the phenyl ring and n-butyl chain in position 4 on the triazole ring was the most active with MIC90 and MIC99 values of 1.73 and 3.2 µM, respectively, in the albumin-free medium. It also displays high selectivity towards bacteria growth inhibition (SI > 58), thus stands as a better hit for further investigation, including lead optimization, DMPK parameters determination and assessment of its activity in animal models.

Currently available drugs being used to treat leishmaniasis have several shortcomings, including high toxicity, drug administration that requires hospitalization, and the emergence of parasite resistance against clinically used drugs. As a result, there is a dire need for the development of new antileishmanial drugs that are safe, affordable, and efficient. In this study, two new series of synthesized quinazolinone derivatives were investigated as potential future antileishmanial agents, by assessing their activities against the Leishmania (L.) donovani and L. major species. The cytotoxicity profiles of these derivatives were assessed in vitro on Vero cells. The compounds were found to be safer and without any toxic activities against mammalian cells, compared to the reference drug, halofuginone, a clinical derivative of febrifugine. However, they had demonstrated poor antileishmanial growth inhibition efficacies. The two compounds that had been found the most active were the mono quinazolinone 2d and the bisquinazolinone 5b with growth inhibitory efficacies of 35% and 29% for the L. major and L. donovani 9515 promastigotes, respectively. These outcomes had suggested structural redesign, inter alia the inclusion of polar groups on the quinazolinone ring, to potentially generate novel quinazolinone derivatives, endowed with effective antileishmanial potential.

A series of fourteen methoxy substituted 2-benzoyl-1-benzofuran derivatives were synthesised and their affinities determined for adenosine A1 and A2A receptors via radioligand binding assays to establish the structure activity relationships pertinent for A1 and A2A affinity. Compound 3j (6,7-dimethoxybenzofuran-2-yl)(3-methoxyphenyl)methanone exhibited A1 affinity (A1Ki (rat) = 6.880 µM) as well as A2A affinity (A2AKi (rat) = 0.5161 µM). Compounds 3a–b & 3i–k exhibited selective affinity towards A1 with Ki values below 10 µM. The results indicate that C6,7-diOCH3 substitution on ring A in combination with meta (C3′)–OCH3 substitution on ring B is beneficial for A1 and A2A affinity and activity. Compounds 3a–b & 3j–k showed low cytotoxicity. Upon in vitro and in silico evaluation, compound 3j may be considered lead-like (i.e. a molecular entity suitable for optimization) and, thus, of value in the design of novel, potent and selective adenosine A1 and A2A receptor antagonists.

Leishmaniasis is a neglected tropical disease affecting thousands worldwide, especially in developing countries where it co-exists with malaria. Only a handful of drugs are clinically available to treat the disease, but significant limitations threaten their very use. New, safe and effective drugs, including those against malaria-leishmaniasis co-infections, are thus imperative. We assessed the in vitro anti-infective potential of previously synthesized, potent antimalarial artemisinin derivatives. Analogue esters featuring 1,1'-biphenyl and thiophenyl moieties were as much as 30-fold more potent than clinical artemisinins against L. donovani parasites, qualifying them as antipromastigote hits for further investigation in the search for malaria-leishmaniasis co-infection therapies.

Molecular hybridization is an increasingly important strategy in rational drug design and development. A series of novel quinazolinone-triazole hybrids have been synthesized and their antileishmanial activity investigated. Derivatives (E)-3-(prop-2-yn-1-yl)-2-styrylquinazolin-4(3H)-one, and (E)-3-{[1-(4-bromobenzyl)-1H-1,2,3-triazol4-yl]methyl}-2-styrylquinazolin-4(3H)-one were observed to moderately inhibit the growth of promastigotes. An overall lack of significant antileishmanial activity may be attributable to the poor aqueous solubility of the derivatives. Future research endeavors will focus on potential remediation by investigating the anchoring of hydrophilic moieties to the quinazolinone scaffold.

The emergence of drug-resistant tuberculosis (DR-TB) as well as the requirement for long, expensive and toxic drug regimens impede efforts to control and eliminate TB. Therefore, there’s a need for effective and affordable anti-mycobacterial agents which can shorten the duration of therapy and are active against Mycobacterium tuberculosis (Mtb) in both active and latent phases. Nitrofurantoin (NFT) is a hypoxic agent with activity against a myriad of anaerobic pathogens and, like the first-line TB drug, rifampicin (RIF), kills non-replicating bacilli. However, the poor ability of NFT to cross host cell membranes and penetrate tissue means that it does not reach therapeutic concentrations. To improve TB efficacy of NFT, a series of NFT analogues was synthesized and evaluated in vitro for anti-mycobacterial activity against the laboratory strain, Mtb H37Rv, and for potential cytotoxicity using human embryonic kidney (HEK-293) and Chinese hamster ovarian (CHO) cells. The NFT analogues showed good safety profiles, enhanced anti-mycobacterial potency, improved lipophilicity, as well as reduced protein binding affinity. Analogue 9 which contains an eight carbon aliphatic chain was the most active, equipotent to isoniazid (INH), a major front-line agent, with MIC90 = 0.5 μM, 30-fold more potency than the parent drug, nitrofurantoin (MIC90 = 15 μM), and 100-fold more selective towards mycobacteria. Therefore, 9 was identified as a validated hit for further investigation in the urgent search for new, safe and affordable TB drugs.

Tuberculosis is the deadliest infectious disease affecting humankind with a death toll of approximately 1.7 million people in 2016. The increasing prevalence of multidrug-resistant strains of the causative pathogen, Mycobacterium tuberculosis (Mtb) which results in reduced effectiveness of the current therapies, underscores the urgent need for the development of new antitubercular drugs. In the search for such drugs, we investigated two series of ciprofloxacin (CPX) derivatives (analogues and hybrids). We herein report the design, synthesis, and biological activity of these series against the human virulent Mtb H37Rv strain in vitro. The small propionyl analogue 11 (MIC90 1.6 μM; SI > 61) and the large cholesteryl hybrid 32 (MIC90 2.0 μM; SI > 6) were the most active derivatives, comparable to CPX (MIC90 1.8 μM). However, the slightly less active but non-cytotoxic para-fluorobenzyl hybrid 28 (MIC90 3.7 μM; SI 27) was more selective toward bacteria than 32. Thus, the CPX derivatives 11 and 28 were identified as preferred antitubercular hits for further investigation including distribution, metabolism and pharmacokinetic parameters determination and in vivo activity assessment in animal models.

The true importance of cell-free DNA in human biology, together with the potential scale of its clinical utility, is tarnished by a lack of understanding of its composition and origin. In investigating the cell-free DNA present in the growth medium of cultured 143B cells, we previously demonstrated that the majority of cell-free DNA is neither a product of apoptosis nor necrosis. In the present study, we investigated the composition and origin of this cell-free DNA population using next-generation sequencing. We found that the cell-free DNA comprises mainly of repetitive DNA, including α-satellite DNA, mini satellites, and transposons that are currently active or exhibit the capacity to become reactivated. A significant portion of these cell-free DNA fragments originates from specific chromosomes, especially chromosomes 1 and 9. In healthy adult somatic cells, the centromeric and pericentromeric regions of these chromosomes are normally densely methylated. However, in many cancer types, these regions are preferentially hypomethylated. This can lead to double-stranded DNA breaks or it can directly impair the formation of proper kinetochore structures. This type of chromosomal instability is a precursor to the formation of nuclear anomalies, including lagging chromosomes and anaphase bridges. DNA fragments derived from these structures can recruit their own nuclear envelope and form secondary nuclear structures known as micronuclei, which can localize to the nuclear periphery and bud out from the membrane. We postulate that the majority of cell-free DNA present in the growth medium of cultured 143B cells originates from these micronuclei.

5-nitrofurans (NFs) have been in clinical use for over 60 years. These affordable drugs are used for the treatment of a broad spectrum of diseases ranging from urinary tract infections to cancer. The anti-pathogenic effect of clinical NFs occurs following a step-wise process involving activation by azoreduction, followed by nitroreduction catalysed by azoreductases and nitroreductases (NTRs), respectively. Azoreduction yields stable metabolites that have the ability to covalently bind to cellular proteins. Nitroreduction, on the other hand, occurs by type I or II reduction of the nitro group in the presence of parasitic NADPH-cytochrome P450 reductases. Type I NTRs catalyse, under anaerobic conditions, the reduction of NFs to produce anti-pathogenic hydroxylamine. Under aerobic conditions, nitroreduction catalysed by type II NTRs produces reactive oxygen and nitrogen species (ROS/RNS), causing oxidative stress to pathogens and ultimate death. This multi-activity nature of NFs thus allows the repurposing of these drugs from agricultural chemicals and basic antibiotics to efficient therapies against human life-threatening diseases. Cases of NF resistance in pathogens are also limited likely due to this multi-activity, as well as effectivity under both aerobic and anaerobic conditions. However, multi-activity of these drugs can also infer toxicity. Molecular derivatisation is an effective strategy to improve efficacy, lower toxicity, diversify activity and address pathogen resistance associated with the use of these drugs.

Background Investigating the biological functions of cell-free DNA (cfDNA) is limited by the interference of vast numbers of putative sources and causes of DNA release into circulation. Utilization of three-dimensional (3D) spheroid cell cultures, models with characteristics closer to the in vivo state, may be of significant benefit for cfDNA research. Methods CfDNA was isolated from the growth medium of C3A spheroid cultures in rotating bioreactors during both normal growth and treatment with acetaminophen. Spheroid growth was monitored via planimetry, lactate dehydrogenase activity and glucose consumption and was related to isolated cfDNA characteristics. Results Changes in spheroid growth and stability were effectively mirrored by cfDNA characteristics. CfDNA characteristics correlated with that of previous two-dimensional (2D) cell culture and human plasma research. Conclusions 3D spheroid cultures can serve as effective, simplified in vivo-simulating “closed-circuit” models since putative sources of cfDNA are limited to only the targeted cells. In addition, cfDNA can also serve as an alternative or auxiliary marker for tracking spheroid growth, development and culture stability. Biological significance 3D cell cultures can be used to translate “closed-circuit” in vitro model research into data that is relevant for in vivo studies and clinical applications. In turn, the utilization of cfDNA during 3D culture research can optimize sample collection without affecting the stability of the growth environment. Combining 3D culture and cfDNA research could, therefore, optimize both research fields.

Non-invasive screening that utilizes cell-free DNA (cfDNA) offers remarkable potential as a method for the early detection of genetic disorders and a wide variety of cancers. Unfortunately, one of the most prominent elements delaying the translation of cfDNA analyses to clinical practice is the lack of knowledge regarding its origin and composition. The elucidation of the origin of cfDNA is complicated by the apparently arbitrary variability of quantitative and qualitative characteristics of cfDNA in the blood of healthy as well as diseased individuals. These factors may contribute to false positive/negative results when applied to clinical pathology. Although many have acknowledged that this is a major problem, few have addressed it. We believe that many of the current difficulties encountered in in vivo cfDNA studies can be partially circumvented by in vitro models. The results obtained in this study indicate that the release of cfDNA from 143B cells is not a consequence of apoptosis, necrosis or a product of DNA replication, but primarily the result of actively released DNA, perhaps in association with a protein complex. Moreover, this study demonstrates the potential of in vitro cell culture models to obtain useful information about the phenomenon of cfDNA.

The most prominent factor that delays the translation of cell-free DNA (cfDNA) analyses to clinical practice is the lack of knowledge regarding its origin and composition. The elucidation of the former is complicated by the seemingly random fluctuation of quantitative and qualitative characteristics of cfDNA in the blood of healthy and diseased individuals. Besides methodological discrepancies, this could be ascribed to a web of cellular responses to various environmental cues and stressors. Since all cells release cfDNA, it follows that the cfDNA in the blood of cancer patients is not only representative of tumor derived DNA, but also of DNA released by healthy cells under different conditions. Additionally, cfDNA released by malignant cells is not necessarily just aberrant, but likely includes non-mutated chromosomal DNA fragments. This may cause false positive/negative results. Although many have acknowledged that this is a major problem, few have addressed it. We propose that many of the current stumbling blocks encountered in in vivo cfDNA studies can be partially circumvented by in vitro models. Accordingly, the purpose of this work was to evaluate the release of cfDNA from cultured cells and to gauge its potential use for elucidating the nature of cfDNA. Results suggest that the occurrence of cfDNA is not a consequence of apoptosis or necrosis, but primarily a result of actively secreted DNA, perhaps in association with a protein complex. This study demonstrates the potential of in vitro cell culture models to obtain useful information about the phenomenon of cfDNA.