Search Results (185)

Primary amoebic meningoencephalitis (PAM) is a rapidly progressive and fulminant disease that affects the central nervous system caused by the free-living amoeba Naegleria fowleri. The adhesion to extracellular matrix (ECM) proteins is considered as one of the key steps in the success of the infection and could represent an interesting target to be explored in the prevention and treatment of the disease. In this work, the effect of two sesquiterpenes with proven anti-Naegleria activity on the adhesion of the parasite was evaluated using an in vitro ECM-based model, compared with the reference drugs amphotericin B and staurosporine. Both laurinterol and (+)-elatol inhibited the adhesion of the N. fowleri trophozoites to the main proteins of the ECM when treating them at different concentrations and exposure times. This work not only reinforces the therapeutic potential of laurinterol and (+)-elatol against N. fowleri infection but also introduces the application of ECM-based adhesion assays as a novel and valuable tool for screening candidate compounds that disrupt host–pathogen interactions critical to PAM pathogenesis. Full article

The sustainable production of plant bioactive compounds is increasingly important as natural habitats decline. This study investigates whether in vitro cell cultures of Eryngium planum, Lychnis flos-cuculi, and Kickxia elatine can serve as alternative sources of biologically active biomass with antimicrobial and anti-Acanthamoeba properties. Callus cultures were established under optimized and controlled conditions, and metabolomic profiling was completed using UPLC-HRMS/MS. In silico analysis, using a molecular docking approach, was applied to understand the interaction between target compounds and Acanthamoeba profilin and identify possible targets for antimicrobial properties. Untargeted metabolomic analysis confirmed the presence of valuable compounds in the callus cultures of the studied species. Biological activity was assessed through anti-Acanthamoeba and antimicrobial assays. Lychnis flos-cuculi and Kickxia elatine callus extracts showed significant inhibitory effects on Acanthamoeba trophozoites, with 87.5% and 80.1% inhibition at 10 mg/mL, respectively. In contrast, E. planum extract stimulated amoebic growth. The anti-Acanthamoeba activity correlated with the presence of ferulic acid and p-coumaric acid in L. flos-cuculi extract, and acteoside in K. elatine extract. Antibacterial testing revealed moderate activity of E. planum and K. elatine extracts against Staphylococcus spp., while Gram-negative bacteria and fungi were largely resistant. These findings highlight the potential of in vitro cultures—particularly those from L. flos-cuculi and K. elatine—as promising, sustainable sources of anti-Acanthamoeba and antimicrobial agents, warranting further investigation into their pharmacologically active constituents. Full article

Balantioides coli is the only ciliate currently described as an intestinal parasite of humans, although it can also infect other animals, particularly pigs. Its in vitro cultivation remains challenging, and no axenic culture system is currently available. Cultures are initiated by adding small amounts of feces containing cysts or trophozoites to the culture medium. Implantation success is lower when starting from cysts, and the mechanisms and early events of excystation remain poorly understood. In this study, we describe the sequence of events involved in excystation and identify factors potentially important for culture establishment. Cysts were obtained from orangutan feces and genetically confirmed as B. coli. Only viable cysts, determined by trypan blue or methylene blue exclusion, were used. After artificial digestion with pepsin and trypsin, cysts were incubated at 28 °C for up to 72 h in DMEM supplemented with L-glutamine, yeast extract, fetal bovine serum, and starch granules. Excystation began with a fissure in the cyst wall, allowing for bacterial entry. This appeared to stimulate the trophozoites, the increased motility of which progressively weakened and ruptured the wall, allowing for their emergence. Wall rupture and bacterial entry were critical for activation., whereas starch type had no apparent influence. Excystation occurred within the first hours; otherwise, cysts degenerated. Full article

Malaria is a parasitic infectious disease that is endemic in many tropical countries. Even though several effective antimalarial agents have been implemented, treatment failure still occurs, and malaria continues to cause neurological complications and death, particularly in severe or drug-resistant cases. Hence, novel therapeutic agents with distinct mechanisms of action, as well as alternative chemical compounds that can overcome resistance, are still needed to improve malaria therapy. This study aimed to investigate the antimalarial activities of Brucea javanica, a tropical plant extracts against Plasmodium falciparum, the major species associated with severe malaria. In this study, malaria parasites were treated with plant extracts using single and co-incubation methods, along with artesunate and chloroquine, and their inhibitory effect on parasite development was determined by microscopy. The results show that all tested doses of the extracts that effectively inhibited malaria parasites did not cause hemolysis of red blood cells (RBCs). The root extract (RE) and fruit extract (FE) inhibited parasite growth at IC₅₀ values of 0.41 ± 1.14 µg/mL and 0.26 ± 1.15 µg/mL, respectively. These plant extracts significantly interrupted malaria development at the ring stage, as presented by a reduction in the conversion rate to trophozoites and schizonts. The defective parasites treated with plant extracts were characterized by nuclear clumping, leading to pyknotic cell death. Moreover, RE and FW extracts elicited an additive effect with artesunate and chloroquine, significantly reducing IC₉₀ levels for the inhibition of parasite development. In conclusion, B. javanica extracts inhibited the asexual blood-stage development of malaria parasites. They distinctively show the additive effects of ATS and CRQ, elucidating their potential for further studies on novel formulas of antimalarial drug regimens. Full article

Acanthamoeba is a free-living amoeba widely distributed in nature, responsible for clinical cases of encephalitis and keratitis in humans. Due to the increase in the number of cases in recent years, understanding the damage mechanisms employed by the amoeba is very important for the clinical management of the disease, development of diagnostic tools and identification of therapeutic targets. To date, most experimental studies to determine the virulence factors and pathogenesis of Acanthamoeba have employed genotype T4 as an infection model, resulting in minimal information regarding other genotypes. In this work, we explored the direct and indirect effect of A. lenticulata genotype T5 trophozoites and their excretion/secretion products over a Vero cell monolayer. Using confocal and real-time microscopy, we witnessed a significant direct mechanical action of the trophozoites on the cells during the adhesion stage. Additionally, we observed the formation of digitiform phagocytic structures through which the nuclear material of the target cell appears to be specifically sucked by the amoeba without the involvement of any lytic mechanism. Moreover, an increase in lysosomal activity in the cytoplasm of trophozoites of Acanthamoeba, and the effect of the excretion/secretion products on the actin filaments of the target cells were observed during the first 2–3 h post-infection. Full article

The synthesis of a series of six chloro[N-alkyl-N-cinnamyl-benzimidazol-2-yliden]silver(I) complexes was successfully achieved, wherein allyl (3a), methoxymethyl (3b), benzyl (3c), 3-fluorobenzyl (3d), 4-fluorobenzyl (3e) and 4-methyl-benzyl (3f) substituents were grafted on the benzimidazole ring. The isolated silver N-heterocyclic carbene (NHC) complexes were identified by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. Conclusive evidence for the structures of complexes 3c and 3d was provided by single-crystal X-ray crystallography. The in vitro inhibitory activity of the six Ag-NHC complexes was tested against trophozoites and cysts of the pathogenic Acanthamoeba castellanii strain and the efficacy sequence is as follows: 3d > 3c > 3f > 3a > 3b > 3e. At a concentration of 100 µM in complexes 3c, 3d and 3f and after 72 h of incubation, 5.3, 3.2 and 6.3% A. castellanii trophozoite viabilities were observed, respectively. The utilization of elevated silver(I) drug concentrations, 1000 µM, resulted in the near-total eradication of pathogenic protozoa. Full article

The increasing resistance of Trichomonas vaginalis to the only approved chemical family of drugs for treatment, the 5-nitroimidazoles, has prompted the exploration of new therapeutic agents against this prevalent non-viral sexually transmitted infection. Natural products have emerged as a significant source of novel treatments for trichomoniasis. The aim of this study was to evaluate the anti-T. vaginalis activity of citral (3,7-dimethyl-2,6-octadienal), the main constituent of the essential oil of Cymbopogon species, commonly known as lemongrass. Our findings indicate that citral exhibits a minimum inhibitory concentration (MIC) of 100 μM, effectively inhibiting the growth of T. vaginalis trophozoites within 12 h of exposure, and a 50% inhibitory concentration (IC₅₀) of approximately 40 μM after 24 h. Furthermore, the evaluation of nitric oxide (NO) levels suggests that citral possesses antioxidant properties. Molecular docking studies reveal a weak interaction with three parasite proteins: thioredoxin reductase (TvTrxR), purine nucleoside phosphorylase (TvPNP), and methionine gamma lyase (TvMGL). The present study highlights the potential of citral as a candidate for the development of no-nitroimidazole drugs, offering new avenues for trichomoniasis treatment and underscoring the importance of further investigation into citral’s mechanism of action. Full article

Giardiasis is a common intestinal infection caused by Giardia lamblia. The standard treatment for this parasitic infection involves the administration of nitroimidazoles, albendazoles, and nitrothiazoles. However, in recent years, Giardia lamblia strains resistant to these treatments have been reported. Additionally, the current therapies exhibit considerable side effects, highlighting the need for new compounds that specifically target this parasite. The aim of this study was to evaluate nitrothiazole analogs and assess their impact on the metabolic, redox, and structural gene expression of this parasite. First, the compounds CNZ-7, CNZ-8, FLP-2, FLP-6, and FLP-8 were tested at concentrations ranging from 0 to 50 µM to determine their IC₅₀ in G. lamblia cultures. Subsequently, gene expression changes and structural cell damage in trophozoites were analyzed following incubation with the IC₅₀ of each compound. The giardicidal activity of the compounds was also evaluated in a nitazoxanide-resistant strain. The results showed that FLP-2, FLP-6, and FLP-8 exhibited a stronger effect on trophozoite viability compared to nitazoxanide (NTZ) and metronidazole (MTZ). Both compounds induced an increase in the expression of phosphofructokinase (PFK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK), pyruvate phosphate dikinase (PPDK), and pyruvate:ferredoxin oxidoreductase (PFOR). Additionally, FLP-2 caused ultrastructural alterations in trophozoites. Furthermore, FLP-2, FLP-6, and FLP-8 demonstrated efficacy against drug-resistant strains. These findings suggest that FLP-2, FLP-6, and FLP-8 are promising candidates for the treatment of giardiasis, as they effectively reduce parasite viability, modify gene expression, and exhibit activity against drug-resistant G. lamblia strains. Full article

Tritrichomonas foetus is a sexually transmitted protozoan that causes early embryonic death in cattle. A challenge in trichomonosis research is that in vivo studies of treatments, diagnostic strategies, and vaccines are severely hampered by the logistical challenge and cost of maintaining adult bulls. Since natural infections are diagnosed in postpubescent animals, the paradigm is that only mature breeding bulls can be infected. In this study, we hypothesized that prepubescent bull calves could be artificially infected with T. foetus trophozoites for the purpose of conducting research trials. Initial attempts to directly infect bull calves with two different parasite isolates resulted in the sporadic and transient detection of parasite DNA but not culturable trophozoites. In vitro and in vivo studies suggested that urine directly inhibited trophozoites, likely by osmotic damage and mechanical flushing action. Studies utilizing a perineal urethrostomy to remove urine flow from the prepuce resulted in the ability to colonize the prepuce, with live organisms being cultured for as long as 15 days post-inoculation. Future studies optimizing this technique have the potential to accelerate the pace of bovine trichomonosis research and may have applications in the study of human trichomoniasis. Full article

Amebiasis is a globally prevalent infection that can lead to fatal outcomes if not adequately treated. Conventional treatment with imidazoles often fails due to side effects and resistance, emphasizing the need for alternative therapies. The probiotic Escherichia coli Nissle 1917 (EcN) has shown potential in combating intestinal pathogens. This study aimed to evaluate the amebicidal activity of EcN in vitro and its effect on the production of reactive oxygen species (ROS). Trophozoites of Entamoeba histolytica (2.5 × 10⁴ cells/mL) were cultured in 96-well plates and exposed to varying concentrations of EcN (10²–10⁹ cells/mL). Plates were incubated at 36 °C for 6, 12, and 18 h, after which trophozoite viability was assessed. Intracellular ROS production, including superoxide and hydrogen peroxide, was measured using fluorescent probes. The highest efficacy was observed after 18 h at a CFU concentration of 10⁹ cells/mL. Increased ROS production at all probiotic concentrations suggested a role in EcN’s amebicidal mechanism. Morphological changes in trophozoites, such as rounding, vacuolization, and size reduction, were noted after EcN exposure, indicating growth inhibition. These findings suggest EcN induces structural and morphological changes in E. histolytica, inhibiting its growth in vitro. The findings suggest the potential efficacy of EcN; however, definitive confirmation requires data from human clinical trials. Full article

Infections from the protozoa Entamoeba histolytica (E. histolytica), Giardia lamblia (G. lamblia), and Trichomonas vaginalis (T. vaginalis) pose a public health issue, with albendazole and mebendazole serving as the second-line medications for treating these parasitic infections. However, the low aqueous solubility of these compounds has led to the exploration of new strategies to enhance their solubility, with the formation of salts being a commonly employed strategy. The sulfonates A1, A2, and A3 of albendazole, along with M1, M2, and M3 of mebendazole, were synthesized. The antiparasitic activity in vitro was assessed against the trophozoites of E. histolytica, G. lamblia, and T. vaginalis. The salts A2, A3, M2, and M3 demonstrated a greater antiparasitic effect (IC₅₀ 37.95–125.53 µM) compared to the positive controls albendazole and mebendazole. The salts A1, A3, M2, and M3 do not exhibit cytotoxic effects at concentrations of 500 µM on the Vero cell line. Taken together, these findings indicate that the formation of these new solid saline phases enhances the antiparasitic effects in vitro, which is crucial in the current search for improved, safe, and effective antiparasitic agents. Full article

Microbial keratitis, a vision-threatening infection commonly linked to contact lens use, poses a significant challenge, particularly when caused by Acanthamoeba species. Acanthamoeba keratitis (AK) is difficult to treat due to the organism’s ability to form resilient cysts, necessitating prolonged and complex therapeutic interventions. This study evaluated novel amidopropyl dimethylamines (APDs) and amidopropyl quaternary trimethylammoniums (APTs) for their antimicrobial efficacy against Acanthamoeba castellanii and Acanthamoeba polyphaga cysts. Minimum effective concentrations were determined, and time–kill assays assessed microbial inactivation over 24 h. The results indicated that certain APTs, particularly elaidamidopropyl trimethylammonium (EAPT) and oleamidopropyl trimethylammonium (OAPT), demonstrated superior cysticidal activity compared to the commercially used MAPD, achieving greater log reductions within 24 h (p < 0.0001) at a concentration of 25 µM. The enhanced efficacy of these compounds is potentially attributed to their unsaturated alkyl chains and positive charge, improving antimicrobial activity through the greater disruption of the Acanthamoeba cell membrane. These findings highlight the potential of APTs as alternative agents for incorporation into multipurpose lens disinfectants and AK treatment, offering improved disinfection efficacy. Further investigation is justified to optimise formulations for clinical and commercial applications. Full article

The free-living amoeba Acanthamoeba castellanii is a unicellular eukaryote distributed in a wide range of soil or aquatic environments, either natural or human-made, such as rivers, lakes, drinking water, or swimming pools. Besides its capacity to transport potential pathogens, such as bacteria or viruses, Acanthamoeba spp. can have intrinsic pathogenic properties by causing severe infections at the ocular and cerebral level, named granulomatous amoebic encephalitis and amoebic keratitis, respectively. During its life cycle, A. castellanii alternates between a vegetative and mobile form, named the trophozoite, and a resistant, latent, and non-mobile form, named the cyst. The cyst wall of Acanthamoeba is double-layered, with an inner endocyst and an outer ectocyst, and is mainly composed of cellulose and proteins. The resistance of cysts to many environmental stresses and disinfection treatments has been assigned to the presence of cellulose. The current review aims to present the importance of this glycopolymer in Acanthamoeba cysts and to further report the pathways involved in encystment and excystment. Full article

Colpodella species are predatory biflagellates phylogenetically related to pathogenic Apicomplexans. Following the attachment of Colpodella sp. to its prey, cytoplasmic contents of the prey are aspirated into a posterior food vacuole during myzocytosis. Trophozoites also endocytose nutrients as demonstrated by the uptake of 40 and 100 nm nanoparticles in Colpodella sp. ATCC 50594. This nutrient uptake is actin-mediated. However, the markers of myzocytosis and endocytosis are unknown. Furthermore, the relationship between Colpodella sp. ATCC 50594 and Colpodella sp. identified in arthropods, humans, and animals are unknown. In this study, we investigated the conservation of the coronin and Kelch 13 genes in Colpodella sp. ATCC 50594 using polymerase chain reaction (PCR). Kelch 13 distribution in Colpodella sp. ATCC 50594 was investigated using anti-Kelch 13 antibodies by immunofluorescence. Both genes were amplified from Colpodella sp. ATCC 50594. We amplified DNA encoding 18S rRNA with similarity to 18S rRNA amplified using piroplasm primers from the Italian Colpodella sp. identified in cattle and ticks. The detection of the coronin and Kelch 13 genes in Colpodella sp. provides, for the first time, markers for actin binding and endocytosis in Colpodella species that can be investigated further to gain important insights into the mechanisms of nutrient uptake in Colpodella sp. Full article