Search Results (204)

The present work reports the bioguided isolation of constituents from the ethanol extract of Holarrhena floribunda stem bark, their identification by UHPLC-ESI-QTOF-MS/MS identification, and the in silico prediction of the pharmacokinetic and toxicity parameters. The crude extract, along with its n-hexane and alkaloid-rich fractions, displayed moderate to good antiplasmodial activity in vitro against chloroquine-sensitive (3D7) and multidrug-resistant (Dd2) strains of Plasmodium falciparum, with IC₅₀ values ranging from 6.54 to 43.54 µg/mL. Seventeen steroidal alkaloids (1–17) were identified in the most active fraction using UHPLC-ESI-QTOF-MS/MS, based on their fragmentation patterns and analysis with the Structural Similarity Network Annotation Platform for Mass Spectrometry (SNAP-MS). Furthermore, bioguided isolation of the ethanol extract yielded twenty-one compounds (3, 5, 10, 14–16, 18–31), whose structures were elucidated by spectroscopic methods. Among them, compounds 5, 14, and 27 showed the highest potency against the two strains of P. falciparum, with IC₅₀ values between 25.97 and 55.78 µM. In addition, the in silico prediction of pharmacokinetic parameters and drug-likeness using the SwissADME web tool indicated that most of the evaluated compounds (1, 3–5, and 14–16) complied with Lipinski’s rule of five. Full article

Pachysandra terminalis (P. terminalis), a plant belonging to the Buxaceae family, is known as a great source of aminosteroid alkaloids. In a previous communication, we reported on the isolation of a variety of aminosteroids from P. terminalis, which presented interesting activity against the protozoan pathogens, Trypanosoma brucei rhodesiense and Plasmodium falciparum. In the present study, variations in the alkaloid profile of P. terminalis related to seasonal changes as well as differences between plant organs (leaves and twigs) and between plant populations were investigated to prioritize candidates for targeted isolation in further studies. For this purpose, sample material of P. terminalis was collected from the two nearby populations in monthly intervals over one year. The ethanolic (75%) extracts were analyzed using UHPLC/+ESI-QqTOF-MS/MS, and the resulting data converted to variables encoding the intensity of MS signals in particular m/z and retention time (t_R) intervals over the chromatographic runs. The very large and complex data matrix of these <t_R:m/z> variables was evaluated using multivariate data analysis, especially principal component analysis (PCA) and volcano plot analysis of t-test data. The results of these analyses, for the first time, allowed a holistic analysis of variation in the alkaloid profiles in P. terminalis organs over the vegetation period. The evaluation of the PCA scores and loadings plots of principal components 1 through 3, as well as of volcano plots, highlighted 25 different compounds, mostly identified as aminosteroid alkaloids, that were most relevant for the differences between leaves and twigs and between the two populations and mainly determined the changes in their chemical profiles over the vegetation period. Full article

Understanding Plasmodium falciparum population genetic diversity is crucial to assess the impact of malaria control interventions. This study investigated P. falciparum genetic diversity using merozoite surface protein 1 (msp1), msp2 and glutamate-rich protein (glurp) in Korhogo district, Northern Côte d’Ivoire. DNA was extracted from dried blood spots (DBSs) collected in the health district of Korhogo between 2019 and 2020. The msp1, msp2, and glurp genes were amplified by polymerase chain reaction (PCR), and amplicon sizes were determined by capillary electrophoresis. Out of 179 samples randomly selected and genotyped, 82% were successfully amplified for msp1, 85% for msp2, and 75% for glurp. For msp1, the K1 allelic family had 20 genotypes, MAD20 had 23, and RO33 had only one genotype. For msp2, there were 59 and 33 genotypes for 3D7 and FC27, respectively, and for glurp, 45 genotypes were detected. The parasite population was highly diverse with an expected heterozygosity (H_E) of ≥0.9 for all 3 markers. Our study showed high genetic diversity of msp1, msp2, and glurp in P. falciparum isolates from Korhogo district, Northern Côte d’Ivoire. These data could provide baseline information on P. falciparum genetic diversity for further epidemiological studies, needed to assess interventions implemented in this area. Full article

The study of various microorganisms isolated from an Indian Ocean sponge, Scopalina hapalia ML-263, led to the selection of a promising Actinobacteria strain, Micromonospora sp. SH-82. Genomic analysis identified this strain as a new species, revealing the presence of 23 biosynthetic gene clusters (BGCs), some of which are associated with the synthesis of specialized metabolites such as polyketides deriving from polyketide synthases (PKSs). The strain was cultivated under favorable conditions for the production of bioactive molecules, resulting in the isolation and identification of seven microbial metabolites. Three of them are potentially novel, two erythronolides and one erythromycin, all characterized by a rare C10–C11 double bond. Some of these compounds also display atypical conformations, forming hemiacetals or spiroacetals. Their identification was achieved through detailed chemical analyses (NMR and ESI⁺-HRMS). A molecular networking approach was employed to assess the presence of potentially novel molecules in the microbial crude extract, supported by the identification of isolated molecules. Four molecules (1, 2, 3 and 5) were evaluated for their cytotoxic activities against cancer cell lines (HCT-116 and MDA-MB-231) and the immortalized retinal pigment epithelial RPE1 cells. No activity was observed in the latter, suggesting a lack of toxicity toward healthy cells. Moreover, megalomicin C1 (3), one of the isolated compounds, showed interesting antiplasmodial activity against Plasmodium falciparum 3D7, with an IC₅₀ of 6.37 ± 2.99 µM. Full article

In Brazil, Plasmodium infections in non-human primates (NHPs) have been associated with P. simium and P. brasilianum, which are morphologically and genetically similar to the human-infecting species P. vivax and P. malariae, respectively. Surveillance and monitoring of wild NHPs are crucial for understanding the distribution of these parasites and assessing the risk of zoonotic transmission. This study aimed to detect the presence of Plasmodium spp. genetic material in Platyrrhini primates from 47 municipalities in the states of Bahia and Minas Gerais. The animals were captured using Tomahawk-type live traps baited with fruit or immobilized with tranquilizer darts. Free-ranging individuals were chemically restrained via inhalation anesthesia using VetBag^® or intramuscular anesthesia injection. Blood samples were collected from the femoral vein. A total of 298 blood and tissue samples were collected from 10 primate species across five genera: Alouatta caraya (25), Alouatta guariba clamitans (1), Callicebus melanochir (1), Callithrix geoffroyi (28), Callithrix jacchus (4), Callithrix kuhlii (31), Callithrix penicillata (175), Callithrix spp. hybrids (15), Leontopithecus chrysomelas (16), Sapajus robustus (1), and Sapajus xanthosthernos (1). Molecular diagnosis was performed using a nested PCR targeting the 18S small subunit ribosomal RNA (18S SSU rRNA) gene, followed by sequencing. Of the 298 samples analyzed, only one (0.3%) from Bahia tested positive for Plasmodium brasilianum/P. malariae. This represents the first detection of this parasite in a free-living C. geoffroyi in Brazil. These findings highlight the importance of continued surveillance of Plasmodium infections in NHPs to identify regions at risk for zoonotic transmission. Full article

Background: Experimental models using Plasmodium berghei ANKA (PbA)-infected mice have been essential for uncovering cerebral malaria (CM) pathogenesis. However, variability in experimental CM (ECM) incidence, onset, and mortality introduce challenges when analyses rely solely on infection day, which may reflect different disease stages among animals. Methods: We applied machine learning to predict ECM risk and onset in a cohort of 153 C57BL/6, 164 CBA, and 53 Swiss Webster mice. First, we fitted a logistic regression model to estimate the risk of ECM at any day using parasitemia data from day 1 to day 4. Next, we developed and trained a Random Forest Regressor model to predict the exact day of symptom onset. Results: A total of 64.5% of the cohort developed ECM, with onset ranging between 5 and 11 days. Early increases in parasitemia were strong predictors for the development of ECM, with an increase in parasitemia equal to or greater than 0.05 between day 1 and day 3 predicting the development of ECM with 97% sensitivity. The Random Forest model predicted the day of ECM onset with high precision (mean absolute error: 0.43, R²: 0.64). Conclusion: Parasitemia dynamics can effectively identify mice at high risk of ECM, enabling more accurate modeling of early pathological processes and improving the consistency of experimental analyses. Full article

Microsporidia MB (MB), a promising biological control agent, suppresses Plasmodium falciparum transmission in Anopheles mosquitoes. This study examined the spatial distribution of MB infection in natural populations of An. gambiae s.l. mosquitoes collected in Nigeria and Niger Republic, and its association with insecticide susceptibility in the mosquitoes. Microsporidia MB has wide geographic distribution across Nigeria and Niger Republic. The overall prevalence of MB in F₀ mosquitoes was 12.25% (95% CI: 7.76–16.75%); 25 mosquitoes out of 204 were positive. Geographic variation was observed, with a higher prevalence (5/15 mosquitoes) in Ebonyi State (33.33%, CI: 9.48–57.19%, Fisher’s exact test, p = 0.008). Infection rates were higher in An. coluzzii mosquitoes (21/133 mosquitoes), estimated at 15.79% (CI: 9.59–21.99%) compared to An. gambiae s.s. mosquitoes (4/71), with approximately 5.63% (CI: 0.27–11.00%, χ² = 4.44; df = 1, p = 0.035). Resistant mosquitoes had a significantly higher prevalence of MB infection than susceptible mosquitos at 28.57% (CI: 16.74–40.40%) with an odds ratio of 3.33 (CI: 1.23–9.03, p = 0.017). These findings suggests that MB can be exploited as an alternative for vector control in Nigeria and Niger, but its possible association with pyrethroid resistance suggests that it should be taken into account as a potential confounder when designing insecticide resistance management strategies. Full article

Background: Drug therapy remains the principal management strategy for malaria but is increasingly challenged by the emergence of drug-resistant malaria parasites. The need for new antimalarial drugs is urgent, yet drug discovery and development are hindered by high costs, long durations, and safety concerns that prevent approval. The current study aimed to determine antiplasmodial activities of approved drugs in combination with artemether (ART) and lumefantrine (LU). Methods: Using the SYBR Green I assay test, this study investigated the efficacy of epirubicin (EPI) and pelitinib (PEL) combined with ART and LU at fixed drug–drug ratios (4:1, 3:1, 1:1, 1:2, 1:3 and 1:4) and volume/volume. These combinations, as well as single drug treatments, were tested against cultured strains of Plasmodium falciparum (W2, DD2, D6, 3D7 and F32-ART) and fresh and cultured clinical isolates. The fifty percent inhibition concentration (IC₅₀) and a mean sum of fifty percent fractional inhibition concentration (FIC₅₀) were determined. Results: Synergism was observed when EPI was combined with both ART and LU across all fixed ratios with a mean of mean FIC₅₀ values of <0.6. The combination of LU and EPI against the 3D7 strain demonstrated the highest efficacy with a synergism FIC₅₀ value of 0.18. Most combinations of PEL with ART and LU showed antagonism (FIC₅₀ > 1) when tested against strains of P. falciparum and clinical isolates. Conclusions: This study underscores the utility of alternative drug discovery and development strategies to bypass cost, time, and safety barriers, thereby enriching the antimalarial drug pipeline and accelerating the transition from lab to market. Full article

Background: Malaria remains a significant global health burden, particularly in sub-Saharan Africa, accounting for high rates of illness and death. The growing resistance to frontline antimalarial therapies underscores the urgent need for novel drug targets and therapeutics. Bromodomain-containing proteins, which regulate gene expression through chromatin remodeling, have gained attention as potential targets. Plasmodium falciparum bromodomain protein 1 (PfBDP1), a 55 kDa nuclear protein, plays a key role in recognizing acetylated lysine residues and facilitating transcription during parasite development. Methods: This study investigated ex vivo PfBDP1 gene mutations and identified potential small molecule inhibitors using computational approaches. Malaria-positive blood samples were collected. Genomic DNA was extracted, assessed for quality, and amplified using PfBDP1-specific primers. DNA sequencing and alignment were performed to determine single-nucleotide polymorphism (SNP). Structural modeling used the PfBDP1 crystal structure (PDB ID: 7M97), and active site identification was conducted using CASTp 3.0. Virtual screening and pharmacophore modeling were performed using Pharmit and AutoDock Vina, followed by ADME/toxicity evaluations with SwissADME, OSIRIS, and Discovery Studio. GROMACS was used for 100 ns molecular dynamics simulations. Results: The malaria prevalence rate stood at 12.24%, and the sample size was 165. Sequencing results revealed conserved PfBDP1 gene sequences compared to the 3D7 reference strain. Virtual screening identified nine lead compounds with binding affinities ranging from −9.8 to −10.7 kcal/mol. Of these, CHEMBL2216838 had a binding affinity of −9.9 kcal/mol, with post-screening predictions of favorable drug-likeness (8.60), a high drug score (0.78), superior pharmacokinetics, and a low toxicity profile compared to chloroquine. Molecular dynamics simulations confirmed its stable interaction within the PfBDP1 active site. Conclusions: Overall, this study makes a significant contribution to the ongoing search for novel antimalarial drug targets by providing both molecular and computational evidence for PfBDP1 as a promising therapeutic target. The prediction of CHEMBL2216838 as a lead compound with favorable binding affinity, drug-likeness, and safety profile, surpassing those of existing drugs like chloroquine, sets the stage for preclinical validation and further structure-based drug design efforts. These findings are supported by prior experimental evidence showing significant parasite inhibition and gene suppression capability of predicted hits. Full article

It is becoming evident that the therapeutic effect of reawakening the immune response is to limit tumor cell growth and expansion. The use of immune checkpoint inhibitors, like blocking antibodies against programmed cell death receptor (PD) 1 and/or cytotoxic T lymphocyte antigen (CTLA) 4 alone or in combination with other drugs, has led to unexpected positive results in some tumors but not all. Several other molecules inhibiting lymphocyte antitumor effector subsets have been discovered in the last 30 years. Herein, we focus on the leukocyte-associated immunoglobulin (Ig)-like receptor 1 (LAIR1/CD305). LAIR1 represents a typical immunoregulatory molecule expressed on almost all leukocytes, unlike other regulatory receptors expressed on discrete leukocyte subsets. It bears two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the intracytoplasmic protein domain involved in the downregulation of signals mediated by activating receptors. LAIR1 binds to several ligands, such as collagen I and III, complement component 1Q, surfactant protein D, adiponectin, and repetitive interspersed families of polypeptides expressed by erythrocytes infected with Plasmodium malariae. This would suggest LAIR1 involvement in several cell-to-cell interactions and possibly in metabolic regulation. The presence of both cellular and soluble forms of LAIR would indicate a fine regulation of the immunoregulatory activity, as happens for the soluble/exosome-associated forms of PD1 and CTLA4 molecules. As a consequence, LAIR1 appears to play a role in some autoimmune diseases and the immune response against tumor cells. The finding of LAIR1 expression on hematological malignancies, but also on some solid tumors, could open a rationale for the targeting of this molecule to treat neoplasia, either alone or in combination with other therapeutic options. Full article

Coinfection with parasites and viruses can exacerbate disease transmission, outcomes and therapy. This study searched the Web of Science, PubMed, Scopus and JSTOR databases for publications on the prevalence of parasitic coinfection in people living with viruses from 1 January 2005 to 30 April 2022, and 356 studies were included and systematically reviewed. A meta-analysis was performed to assess the global prevalence of and factors potentially associated with parasitic infection (helminths and protozoa) in virus-infected people, and the infection burden was estimated. A variety of parasites (29 families, 39 genera, and 63 species) and viruses (8 kinds) were identified. The prevalence of parasitic coinfection in (all) virus-infected people was estimated to be 21.34% (95% CI 17.58–25.10, 5593 of 29,190 participants) and 34.13% (95% CI 31.32–36.94, 21,243/76,072 participants) for helminths and protozoa, respectively. Specially, in human immunodeficiency virus (HIV)-infected people, the global prevalence was 19.96% (95% CI 16.18–23.74) for helminths and 34.18% (95% CI 31.33–37.03) for protozoa, respectively. The global prevalence of protozoa was 41.79% (95% CI 15.88–67.69) in hepatitis B virus (HBV)-infected people and 17.75% (95% CI 3.54–31.95) in DENV-infected people, respectively. The global burden of parasitic infections in HIV-infected people was 7,664,640 for helminths and 13,125,120 for protozoa, respectively, and that in HBV- and dengue virus (DENV)-infected people was 137,019,428 and 629,952, respectively. The prevalence of parasitic coinfection at the family, genus, and species levels in virus- or HIV-infected people were comprehensively estimated and further analyzed by subgroups. Among the most commonly identified parasites, the five helminth genera with the highest prevalence in HIV-infected people were Schistosoma (12.46%, 95% CI 5.82–19.10), Ascaris (7.82%, 95% CI 6.15–9.49), Strongyloides (5.43%, 95% CI 4.11–6.74), Trichuris (4·82%, 95% CI 2.48–7.17) and Ancylostoma (2.79%, 95% CI 1.32–4.27), whereas the top five protozoan genera were Toxoplasma (48.85%, 95% CI 42.01–55.69), Plasmodium (34.96%, 95% CI 28.11–41.82), Cryptosporidium (14.27%, 95% CI 11.49–17.06), Entamoeba (12.33%, 95% CI 10.09–14.57) and Blastocystis (10.61%, 95% CI 6.26–14.97). The prevalence of parasitic coinfection in virus-infected people was associated with income level. The findings provide valuable global epidemiological information for informing normative guidance, improving surveillance, and developing public healthcare strategies. Full article

Malaria remains a major public health threat in Cameroon, with an estimated 3 million new cases of Plasmodium spp. infections reported each year. The aim of this study was to assess the occurrence of Plasmodium infections in Cameroon in a group of symptomatic and asymptomatic individuals, residents of the town of Mbalmayo, located in the Central Region of Cameroon. Screening was conducted in December 2024 at the Mbalayo District Hospital. This study involved a total of 93 people aged between 1 and 70 years old, who voluntarily agreed to have their blood samples taken and tested for malaria. As part of this study, the demographic variables of the participants were taken, malaria rapid diagnostic tests (mRDTs) were performed, and blood samples were applied to the Whatman FTA cards for further real-time PCR diagnostics. The occurrence of Plasmodium infections in the residents of Mbalmayo differed depending on the diagnostic method used (30.1% with mRDT vs. 60.2% when RT-PCR assays were performed). A total of 55 malaria cases were found to be caused by P. falciparum, while one case was found to be caused by P. vivax. Nearly half of the study participants exhibited no signs or symptoms of malaria, whereas 35.7% reported fever, 17.9% respiratory symptoms, and 10.7% gastrointestinal symptoms. The prevalence of malaria remains high in populations inhabiting the Central Region in Cameroon. P. falciparum is the dominant species in the region. A considerable proportion of infected individuals are asymptomatic, which supports the finding that asymptomatic carriers play a critical role in disease transmission. The differences between the results depending on the diagnostic method used (mRDT vs. RT-PCR) suggest that there is a need to use a combination of different methods for the identification of malaria, especially in cases of low parasitemia. Full article

In response to vaccination and/or infectious agents, the liver produces acute-phase proteins (APPs) driven by IL-6, which circulate in blood plasma as components of the humoral innate defense. This study investigates the liver of mice for possible effects of protective vaccination against primary blood-stage infections of Plasmodium chabaudi malaria on the expression of genes encoding APPs and IL-6 family members. Female Balb/c mice were vaccinated with a non-infectious vaccine prior to challenge with 10⁶ P. chabaudi-infected erythrocytes, resulting in about 80% survival of otherwise lethal infections. Gene expression microarrays were used to determine the relative transcript levels of genes in the livers of vaccinated and unvaccinated mice on days 0, 1, 4, 8, and 11 p.i. (post infectionem). Vaccination induced significant (p-value < 0.05) differences in the expression of malaria-responsive genes toward the end of crisis on day 11 p.i., when mice recovered from infections. These genes include Saa4, Apcs, Cp, and Crp, encoding APPs described to inhibitorily interact with parasitic blood stages; the genes F2, F7, F8, F9, F10, and F13b, and Plg, Plat, and Serpina5, encoding proteins balancing coagulation vs. fibrinolysis dysregulated by malaria, respectively; the genes Hc, C8a, C8b, C8g, and C9, encoding components of lytic complement membrane attack complex (MAC); and Cfh, Cfi, and C4bp, encoding complement-regulatory proteins. Vaccination accelerated, albeit differently, the malaria-induced activation of all three complement pathways, evidenced as higher transcript levels of C1qa, C1qb, C1qc, Fcna, Cfp, C3, Cfh, C8a, and C9 on day 4 p.i., C1ra, C1s, and C2 on day 1 p.i., and Serping1, encoding the multifunctional protease inhibitor C1INH, on day 0 p.i. Protective vaccination may also accelerate downregulation of the malaria-promoting lethality of IL-6 trans-signaling, which may contribute to an overall accelerated recovery of mice from otherwise lethal blood-stage malaria. Full article

In order to detail the antiplasmodial effects of quinones (Q) and nitroaromatic compounds (ArNO₂), we investigated their reduction mechanism by Plasmodium falciparum flavoenzyme type II NADH:ubiquinone oxidoreductase (PfNDH2). The reactivity of Q and ArNO₂ (n = 29) follows a common trend and exhibits a parabolic dependence on their single-electron reduction potential ($E_7^1$), albeit with significantly scattered data. The reactivity of quinones with similar $E_7^1$ values increases with their lipophilicity. Quinones are reduced by PfNDH2 in a two-electron way, but ArNO₂ are reduced in a single-electron way. The inhibition studies using NAD⁺ and ADP-ribose showed that quinones oxidize the complexes of reduced enzyme with NADH and NAD⁺. This suggests that, as in the case of other NDH2s, quinones and the nicotinamide ring of NAD(H) bind at separate sites. A scheme of PfNDH2 catalysis is proposed, consistent with both the observed ‘ping-pong’ mechanism and the presence of two substrate binding sites. Molecular docking showed that Q and ArNO₂ bind in a similar manner and that lipophilic quinones have a higher affinity for the binding site. One may expect that PfNDH2 can be partially responsible for the previously observed enhanced antiplasmodial activity of aziridinylbenzoquinones caused by their two-electron reduction, as well as for the redox cycling and oxidative stress-type action of ArNO₂. Full article

Background/Objectives: Many tropical diseases such as malaria, Chagas, human African Trypanosomiasis, and Lymphatic filariasis coexist in endemic countries, affecting more than 1 billion people worldwide, and are recognised as major global vector-borne diseases. Tackling this disease requires an accurate diagnosis that is sensitive, specific, and rapid. This study aimed to describe and validate a new highly sensitive and specific multiple-analysis system that can effectively detect numerous etiological agents in a single test. Methods: A total of 230 human blood samples were assessed retrospectively for parasite characterisation, as well as 58 stool samples from non-human primates. Primers and probes were designed in the small subunit ribosomal RNA gene, except for Plasmodium spp., for which the novel target was Cytochrome Oxidase Subunit 1. Results: The analytical specificity of the presented method was 100%, with no unspecific amplifications or cross-reactions with other blood parasitic diseases. The detection limit obtained was between 0.6 and 3.01 parasites/µL for Plasmodium species, 1.8 parasites/mL for Trypanosomatidae, and 2 microfilariae/mL in the case of Filariae. The sensitivity, specificity, predictive values, and kappa coefficient reached almost 100%, except for Filariae, whose sensitivity dropped to 93.9% and whose negative predicted value dropped to 89.5%. The operational features described a turnaround and a hands-on time shorter than the compared methods with a lower cost per essay. Conclusions: This work presents a cost-effective and highly sensitive multiplexed tool (RT-PCR-bp) capable of performing simultaneous detection for blood parasitic diseases using specific fluorescence probes, enabling the diagnosis of low parasite loads and coinfections. Full article