Search Results (57)

Cryptosporidium is a waterborne gastrointestinal parasite that causes diarrheal disease worldwide. Currently, there are no effective therapeutics to treat cryptosporidiosis. Since natural products are a known source of anti-parasitic compounds, we screened a library of extracts and pure compounds isolated from bacteria and fungi collected from subterranean environments for anti-Cryptosporidium activity. Seven norditerpene lactones isolated from the fungus Oidiodendron truncatum collected from the Soudan Iron mine in Minnesota showed potent activity and were further tested to identify the most active compounds. The availability of a diverse suite of natural structural analogs with varying activities allowed us to determine some structure–activity relationships for both anti-parasitic activity and cytotoxicity. The two most potent compounds, oidiolactones A and B, had EC₅₀s against C. parvum of 530 and 240 nM, respectively, without cytotoxicity to host cells. Both compounds also inhibited the related parasite Toxoplasma gondii. Oidiolactone A was active against asexual, but not sexual, stages of C. parvum, and killed parasites within 8 h of treatment. This compound reduced C. parvum infection by 70% in IFNγ−/− mice, with no signs of toxicity. The high potency, low cytotoxicity, and in vivo activity combined with high production and synthetic accessibility make these oidiolactones attractive scaffolds for the development of new anti-Cryptosporidium therapeutics. Full article

Toxoplasma gondii, an obligate intracellular protozoan parasite infecting nucleated cells of warm-blooded vertebrates, causes severe complications in immunocompromised hosts. Current therapies remain limited by suboptimal efficacy and toxicity, necessitating novel anti-toxoplasmic agents. Piceatannol (PIC), a natural stilbenoid, demonstrates multifaceted bioactivity including antimicrobial and anti-parasitic effects, suggesting therapeutic potential against T. gondii. Our previous study revealed PIC’s potent anti-parasitic activity, selectively inhibiting T. gondii proliferation and altering parasite morphology without host cytotoxicity. In this study, mechanistic analyses indicated that PIC disrupts mitochondrial integrity in tachyzoites, reducing mitochondrial membrane potential and ATP production while elevating ROS levels. Transcriptomic profiling identified significant suppression of oxidative phosphorylation-related genes, consistent with mitochondrial dysfunction. These findings establish PIC as a promising candidate targeting T. gondii through the mechanism of mitochondrial impairment. Full article

Background/Objectives: Toxoplasmosis is a zoonotic disease caused by Toxoplasma gondii. The parasite infection in humans continues to rise due to an increasing seroprevalence rate in domestic and wild warm-blooded animals that serve as a major reservoir of the parasite. There are fewer drugs available for the treatment of toxoplasmosis. However, these drugs are limited in efficacy against tachyzoites and bradyzoites. Also, there are clinical side effects and geographical barriers to their use, especially in immunocompromised patients, children, and pregnant women. Tannins, a class of natural products, are known to have antimicrobial properties. However, little is known about the effects of Corilagin (CG) and Punicalagin (PU), which are classified as tannins, on T. gondii growth and their possible mechanism of action in vitro. We hypothesize that CG and PU could inhibit T. gondii growth in vitro and cause mitochondria membrane disruption via oxidative stress. Methods: Here, we investigated the anti-T. gondii activity of the two named tannins using a fluorescent-based reporter assay. Results: The 50% effective concentrations (EC_50s) values for CG and PU that inhibited T. gondii parasites growth in vitro were determined to be 3.09 and 19.33 µM, respectively. Pyrimethamine (PY) was used as a standard control which gave an EC₅₀ value of 0.25 µM. Interestingly, CG and PU were observed to cause high reactive oxygen species (ROS) and mitochondrial superoxide (MitoSOX) production in tachyzoites. This resulted in a strong mitochondria membrane potential (MMP) disruption in T. gondii tachyzoites. Conclusions: Therefore, the possible mechanism(s) of action of CG and PU against T. gondii is associated with the disruption of the mitochondria redox biology. Thus, the high ROS and MitoSOX produced as a result of these compounds created high oxidative stress, leading to mitochondrial dysfunction. Full article

Background/Objectives: New drugs are urgently needed for the treatment of neglected tropical diseases including leishmaniasis and eumycetoma, as well as globally occurring parasitic diseases such as toxoplasmosis. Fragrances, both natural and synthetic, were shown to be a rich source for the development of new anti-infectives and warrant deeper investigations. Exemplarily, we synthetically optimized the fragrance 4-(4,8-dimethyl-3,7-nonadienyl)-pyridine, a.k.a. Maritima, a pyridine derivative with marine odor. Methods: A new cationic N-cetyl-modified derivative of Maritima (dubbed Cetyl-Maritima), obtained by alkylation of Maritima, was tested for its activity against Madurella mycetomatis (M. mycetomatis) fungi, as well as against Toxoplasma gondii (T. gondii) and Leishmania major (L. major) protozoal parasites. Results: Cetyl-Maritima was found to be more strongly antifungal than the parent Maritima and a known antibiotic cetylpyridinium salt. Cetyl-Maritima also showed a similar activity against T. gondii parasites and, most notably, exhibited sub-micromolar activity against L. major amastigotes. Conclusions: The considerable antileishmanial activity of Cetyl-Maritima might lead to the development of a new potent and cost-effective drug candidate for the therapy of leishmaniasis and other infectious diseases caused by kinetoplastid parasites. Full article

Background/Objectives: Acridine, an aromatic heterocyclic compound, serves as a basis for the synthesis of potent bioactive derivatives, displaying a broad spectrum of biological activity, such as antibacterial, antitumor, and antiparasitic activity. With the ability to undergo various types of electrophilic substitutions, introducing different side chains could lead to compounds being active towards various and potentially multiple biotargets. Toxoplasma gondii, a ubiquitous protozoan parasite with worldwide distribution, poses a major health threat, particularly in immunocompromised patients and fetuses. Current treatment options for toxoplasmosis are scarce, with notable limitations, especially regarding side myelotoxicity and inactivity towards T. gondii cysts, causing a need for novel drug candidates. The aim of this study was to evaluate selected N-(9-acrydinil) amino acid derivatives as potential anti-T. gondii agents. Methods: Synthesis of new derivatives was performed using a two-step method, with the initial mixing of 9-chloroacridine with methanol and sodium alkoxide solution and subsequent adding of appropriate amino acids. Cytotoxicity of the tested compounds was evaluated on the Vero cell line using a MTT assay, while their anti-T. gondii activity was investigated using T. gondii RH strain tachyzoites. Results: CC₅₀ values of the derivatives ranged from 41.72 to 154.10 µM. Anti-T. gondii activity, displayed as a reduction in the number of viable tachyzoites compared to the untreated control, ranged from 0 to 33.3%. One of the derivatives displayed activity comparable to the standard treatment option while retaining acceptable cytotoxicity. Esterification, presence of aromatic substituents and the length of the amino acid side chain were identified as key factors that affect both toxicity and activity of these derivatives. Conclusions: Promising results obtained throughout this study provide guidelines for further structural modifications of N-(9-acrydinil) amino acid derivatives in order to synthesize drug candidates competitive to standard treatment options for toxoplasmosis. Full article

Pleopeltis crassinervata has demonstrated antimicrobial effects, including anti-Toxoplasma activity, which has been attributed to the presence of compounds such as terpenes and fatty acid methyl esters. In this study, the effects of P. crassinervata hexane subfraction one (Hsf1) on the Toxoplasma gondii tachyzoite ultrastructure were evaluated using TEM and SEM, and lytic cycle processes such as adhesion, invasion, and proliferation were evaluated using phase-contrast microscopy. Additionally, the antioxidant capacity of the subfraction and its main compounds (phytol and hexadecenoic acid methyl ester) were determined as well as their effects on parasite viability. Hsf1 exhibited a dose-dependent inhibitory effect on the lytic process at a concentration of 47.2 µg/mL. Among the eighteen compounds identified in this subfraction, six were evaluated, of which two (phytol and hexadecanoic acid methyl ester) significantly reduced the viability of T. gondii to 0.11% and 16.6%, respectively, at a concentration of 100 µg/mL. Additionally, Hsf1 demonstrated an antioxidant capacity of 30% as assessed using the ORAC method. The two active compounds also exhibited antioxidant properties, with antioxidant capacities of 13.33% and 33% for hexadecanoic acid methyl ester and phytol, respectively, at concentrations up to 15.4 mg/mL. Hsf1 showed membrane damage and conoid extrusion in T. gondii tachyzoites, suggesting direct interference with the lytic cycle of the parasite. These findings underscore the therapeutic potential of Hsf1 as a promising tool for controlling infections caused by T. gondii, thereby providing an alternative in the search for new antiparasitic agents. However, further research is required to determine the in vivo pharmacological effects and properties of these compounds with potential anti-Toxoplasma activity. Full article

Toxoplasma gondii is a globally widespread pathogen of significant veterinary and medical importance, causing abortion or congenital disease in humans and other warm-blooded animals. Nevertheless, the current treatment options are restricted and sometimes result in toxic side effects. Hence, it is essential to discover drugs that demonstrate potent anti-Toxoplasma activity. Herein, we found that vorinostat, a pan-HDAC inhibitor, exhibited an IC₅₀ value of 260.1 nM against the T. gondii RH strain and a selectivity index (SI) > 800 with respect to HFF cells. Vorinostat disrupted the entire lytic cycle of T. gondii in vitro. Proteome analysis indicated that vorinostat remarkably perturbed the protein expression of T. gondii, and proteins involved in “DNA replication” and “membrane” were significantly dysregulated. Furthermore, we found that vorinostat significantly enhanced ROS production and induced parasite apoptosis. Importantly, vorinostat could prolong survival in a murine model. Our findings reveal that vorinostat is effective against T. gondii both in vitro and in vivo, suggesting its potential as a therapeutic option for human toxoplasmosis. Full article

Signal-dependent transport into and out of the nucleus mediated by members of the importin (IMP) superfamily is crucial for eukaryotic function, with inhibitors targeting IMPα being of key interest as anti-infectious agents, including against the apicomplexan Plasmodium species and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. We recently showed that the FDA-approved macrocyclic lactone ivermectin, as well as several other different small molecule inhibitors, can specifically bind to and inhibit P. falciparum and T. gondii IMPα functions, as well as limit parasite growth. Here we focus on the FDA-approved antiparasitic moxidectin, a structural analogue of ivermectin, for its IMPα-targeting and anti-apicomplexan properties for the first time. We use circular dichroism and intrinsic tryptophan fluorescence measurements to show that moxidectin can bind directly to apicomplexan IMPαs, thereby inhibiting their key binding functions at low μM concentrations, as well as possessing anti-parasitic activity against P. falciparum in culture. The results imply a class effect in terms of IMPα’s ability to be targeted by macrocyclic lactone compounds. Importantly, in the face of rising global emergence of resistance to approved anti-parasitic agents, the findings highlight the potential of moxidectin and possibly other macrocyclic lactone compounds as antimalarial agents. Full article

Toxoplasma gondii is a protozoan, and the etiologic agent of toxoplasmosis, a disease that causes high mortality in immunocompromised individuals and newborns. Despite the medical importance of toxoplasmosis, few drugs, which are associated with side effects and parasite resistance, are available for its treatment. Here, we show a screening of molecules present in COVID-Box to discover new hits with anti-T. gondii activity. COVID-Box contains 160 molecules with known or predicted activity against SARS-CoV-2. Our analysis selected 23 COVID-Box molecules that can inhibit the tachyzoite forms of the RH strain of T. gondii in vitro by more than 70% at 1 µM after seven days of treatment. The inhibitory curves showed that most of these molecules inhibited the proliferation of tachyzoites with IC₅₀ values below 0.80 µM; Cycloheximide and (-)-anisomycin were the most active drugs, with IC₅₀ values of 0.02 μM. Cell viability assays showed that the compounds are not toxic at active concentrations, and most are highly selective for parasites. Overall, all 23 compounds were selective, and for two of them (apilimod and midostaurin), this is the first report of activity against T. gondii. To better understand the effect of the drugs, we analyzed the effect of nine of them on the ultrastructure of T. gondii using transmission electron microscopy. After treatment with the selected drugs, the main changes observed in parasite morphology were the arrestment of cell division and organelle alterations. Full article

We recently identified that the cerebral mRNA expression of inducible costimulator (ICOS) and its ligand, ICOSL, both significantly increase during the elimination of Toxoplasma gondii cysts from the brains of infected mice by the perforin-mediated cytotoxic activity of CD8⁺ T cells. In the present study, we examined the role of ICOS in activating the effector activity of CD8⁺ T cells in response to the presence of cysts in infected mice. Following the adoptive transfer of splenic CD8⁺ T cells from chronically infected ICOS-deficient (ICOS^−/−) and wild-type (WT) mice to infected SCID mice, fewer CD8⁺ T cells were detected in the brains of the recipients of ICOS^−/− CD8⁺ T cells than the recipients of WT CD8⁺ T cells. Interestingly, even with the lower migration rate of the ICOS^−/− CD8⁺ T cells, those T cells eliminated T. gondii cysts more efficiently than WT CD8⁺ T cells did in the brains of the recipient mice. Consistently, the ICOS^−/− CD8⁺ T cells secreted greater amounts of granzyme B in response to T. gondii antigens in vitro than WT CD8⁺ T cells did. We identified that CD8⁺ T cells of infected ICOS^−/− mice express significantly greater levels of CD28 on their surface than CD8⁺ T cells of infected WT mice, and the relative expression of CD28 mRNA to CD8β mRNA levels in the brains of the recipients of those CD8⁺ T cells were strongly correlated with their relative expression levels of mRNA for T-bet transcription factors and perforin. Furthermore, blocking CD28 signaling using a combination of anti-CD80 and anti-CD86 antibodies eliminated the increased cytotoxic activity of the ICOS^−/− CD8⁺ T cells in vitro. The present study uncovered notable compensatory interactions between ICOS and CD28, which protected the cytotoxic effector activity of CD8⁺ T cells against microbial infection in a murine model of chronic infection with T. gondii. Full article

Toxoplasma gondii forms tissue cysts in neurons and astrocytes in the brain to establish chronic infection, and astrocytes express the CXCL10 chemokine in chronically infected mice. Since chemokines mediate the migration of T cells to attack their targets, and since CXCL10 plays key roles in T cell-mediated control of the proliferation of tachyzoites (the acute stage form) of T. gondii during the acute stage of infection, we examined whether CXCL10 is involved in recruiting anti-cyst CD8⁺ cytotoxic T cells to eliminate the cysts in their brains. We employed adoptive transfer of CD8⁺ immune T cells to infected, T cell-deficient SCID and RAG1^−/− mice in combination with blocking CXCL10 activity by neutralizing antibody or a deletion of this chemokine gene. The treatment of chronically infected (infected and treated with sulfadiazine) SCID mice with the anti-CXCL10 antibody did not inhibit the recruitment of the transferred CD8⁺ T cells into their brains and the removal of cerebral T. gondii cysts by the T cells. In addition, the neutralization of CXCL10 did not reduce the cerebral expression of mRNA for the mediators (perforin and granzyme B [GzmB]) of the cytotoxic activity of CD8⁺ T cells in the SCID mice. Consistently, the adoptive transfer of CD8⁺ immune T cells to chronically infected RAG1^−/−CXCL10^−/− mice did not show any defects in recruiting the CD8⁺ T cells into their brains and eliminating the cysts when compared to infected RAG1^−/− mice. The former rather displayed enhanced cyst removal with increased cerebral expression of GzmB mRNA. These results indicate that the absence of CXCL10 activity does not ablate the capability of CD8⁺ cytotoxic T cells to migrate into the brain and eliminate T. gondii cysts from the brains of chronically infected mice. These results also suggest that the immune system utilizes distinct chemokines to control T. gondii depending on the two different life cycle stages, tachyzoite and cyst, of this protozoan parasite. Full article

Toxoplasmosis, a zoonotic infection caused by Toxoplasma gondii (T. gondii), poses a significant risk to human health and public safety. Despite the availability of clinical treatments, none effectively mitigate the intestinal barrier damage, which is the primary defense against T. gondii invasion. This study introduced aldehyde groups into the indole scaffold of a peptide-like structure to investigate the protective effects of these indole aldehyde derivatives on the intestinal barrier in mice with acute T. gondii infection. This approach leveraged the propensity of peptides and aldehyde groups to form hydrogen bonds. We synthesized a range of indole derivatives using the Vilsmeier–Haack reaction and evaluated their intestinal barrier protective effects both in vitro and in vivo. Our findings revealed that indole derivatives A1 (1-Formyl-1H-indole-3-acetonitrile), A3 (Indole-3-carboxaldehyde), A5 (2-Chloro-1H-indole-3-carboxaldehyde), A8 (1-Methyl-indole-3-carboxaldehyde), and A9 (1-Methyl-2-phenyl-1H-indole-3-carboxaldehyde) demonstrated a higher selectivity index compared to the positive control, spiramycin. These derivatives enhanced gastrointestinal motility, increased glutathione (GSH) levels in the small intestine, and reduced malondialdehyde (MDA) and nitric oxide (NO) levels in the small intestine tissue and diamine oxidase (DAO) and NO levels in the serum of infected mice. Notably, A3 exhibited comparable anti-T. gondii tachyzoites activity in the peritoneal cavity. Molecular docking studies indicated that the aldehyde group on the indole scaffold not only formed a hydrogen bond with NTPase-II but also interacted with TgCDPK1 through hydrogen bonding. Among the derivatives, A3 showed promising intestinal barrier protective effects in mice with acute T. gondii infection. This research suggests that indole derivatives could serve as a potential therapeutic strategy for intestinal diseases induced by T. gondii, offering a novel direction for treating intestinal barrier damage and providing valuable insights for the chemical modification of drugs targeting T. gondii. Furthermore, it contributes to the advancement of therapeutic approaches for toxoplasmosis. Full article

Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii that is highly prevalent worldwide. Although the infection is asymptomatic in immunocompetent individuals, it severely affects immunocompromised individuals, causing conditions such as encephalitis, myocarditis, or pneumonitis. The limited therapeutic efficacy of drugs currently used to treat toxoplasmosis has prompted the search for new therapeutic alternatives. The aim of this study was to determine the anti-Toxoplasma activity of extracts obtained from two species of the genus Tabebuia. Twenty-six extracts, 12 obtained from Tabebuia chrysantha and 14 from Tabebuia rosea, were evaluated by a colorimetric technique using the RH strain of T. gondii that expresses β-galactosidase. Additionally, the activity of the promising extracts and their active compounds was evaluated by flow cytometry. β-amyrin was isolated from the chloroform extract obtained from the leaves of T. rosea and displayed important anti-Toxoplasma activity. The results show that natural products are an important source of new molecules with considerable biological and/or pharmacological activity. Full article

Toxoplasmosis is a globally prevalent zoonotic disease with significant clinical implications, including neurotoxoplasmosis, a leading cause of cerebral lesions in AIDS patients. The current pharmacological treatments for toxoplasmosis face clinical limitations, necessitating the urgent development of new therapeutics. Natural sources have yielded diverse bioactive compounds, serving as the foundation for clinically used derivatives. The exploration of marine bacteria-derived natural products has led to marinoquinolines, which feature a pyrroloquinoline core and demonstrate in vitro and in vivo anti-Plasmodium activity. This study investigates the in vitro anti-Toxoplasma gondii potential of six marinoquinoline derivatives. Additionally, it conducts absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions, and evaluates the in vivo efficacy of one selected compound. The compounds displayed half-maximal effective concentration (EC₅₀) values between 1.31 and 3.78 µM and half-maximal cytotoxic concentration (CC₅₀) values ranging from 4.16 to 30.51 µM, resulting in selectivity indices (SI) from 3.18 to 20.85. MQ-1 exhibiting the highest in vitro SI, significantly reduced tachyzoite numbers in the peritoneum of RH-infected Swiss mice when it was orally administered at 12.5 mg/kg/day for eight consecutive days. Also, MQ-1 significantly reduced the cerebral parasite burden in chronically ME49 infected C57BL/6 mice when it was orally administered at 25 mg/kg/day for 10 consecutive days. These findings underscore the promising anti-T. gondii activity of marinoquinolines and their potential as novel therapeutic agents against this disease. Full article

Toxoplasmosis is a disease that causes high mortality in immunocompromised individuals, such as AIDS patients, and sequelae in congenitally infected newborns. Despite its great medical importance, there are few treatments available and these are associated with adverse events and resistance. In this work, after screening the drugs present in the Medicines for Malaria Venture Pandemic Box, we found new hits with anti-Toxoplasma gondii activity. Through our analysis, we selected twenty-three drugs or drug-like compounds that inhibited the proliferation of T. gondii tachyzoites in vitro by more than 50% at a concentration of 1 µM after seven days of treatment. Nineteen of these compounds have never been reported active before against T. gondii. Inhibitory curves showed that most of these drugs were able to inhibit parasite replication with IC₅₀ values on the nanomolar scale. To better understand the unprecedented effect of seven compounds against T. gondii tachyzoites, an ultrastructural analysis was carried out using transmission electron microscopy. Treatment with 0.25 µM verdinexor, 3 nM MMV1580844, and 0.25 µM MMV019724 induced extensive vacuolization, complete ultrastructural disorganization, and lytic effects in the parasite, respectively, and all of them showed alterations in the division process. Treatment with 1 µM Eberconazole, 0.5 µM MMV1593541, 1 µM MMV642550, 1 µM RWJ-67657, and 1 µM URMC-099-C also caused extensive vacuolization in the parasite. The activity of these drugs against intracellular tachyzoites supports the idea that the drugs selected in the Pandemic Box could be potential future drugs for the treatment of acute toxoplasmosis. Full article