Search Results (100)

Background: Nanoemulsions are colloidal drug delivery systems consisting of an oil phase dispersed in water and stabilized by surfactants, producing droplets in the nanometer range. By virtue of their small droplet size and large interfacial area, they enhance drug dissolution, intestinal absorption, and site-specific delivery while offering controlled, prolonged release and a reduced risk of systemic side effects. Artemether (ART), an antimalarial agent, suffers from poor aqueous solubility and limited oral bioavailability, which restricts its therapeutic efficacy. Objective: The present study aimed to develop and optimize an Artemether-loaded nanoemulsion to improve the drug’s dissolution rate and oral bioavailability. Methods: The nanoemulsion was formulated using a combination of Sunflower oil and Vippa oil as the oil phase, with Tween 80 and Span 80 as the surfactant system, and was prepared by an ultrasonication technique. A three-factor, three-level Box–Behnken Design (BBD) was employed to systematically optimize the formulation composition and processing parameters. The formulations were evaluated for droplet size, polydispersity index (PDI), zeta potential, drug content, entrapment efficiency, pH, viscosity, refractive index, electrical conductivity, and cumulative in vitro drug release. Results: The optimized nanoemulsion exhibited a droplet size of 139.6 ± 1.3 nm, a PDI of 0.256 ± 0.03 indicating a narrow and uniform size distribution, and a zeta potential of −30.08 ± 1.1 mV reflecting good physical stability. The formulation demonstrated a high entrapment efficiency of 95.42 ± 1.18%, confirming efficient drug loading within the lipid core. Additional physicochemical evaluation revealed a pH of 6.4 ± 0.2, a low viscosity of 2.84 ± 0.15 cP, a refractive index of 1.338 ± 0.002, and a conductivity of 215 ± 12 µS/cm, collectively confirming the formation of a physiologically compatible, isotropic oil-in-water nanoemulsion. The formulation achieved 97.90 ± 0.97% cumulative in vitro drug release over a 12 h period, demonstrating a sustained release profile. Conclusions: The optimized Artemether-loaded nanoemulsion, developed using a Box–Behnken Design, significantly enhanced the drug’s dissolution and exhibited favorable physicochemical characteristics, high entrapment efficiency, and controlled release behavior. These findings suggest that nanoemulsion is a promising carrier system warranting further in vivo evaluation to confirm its potential for improving the oral bioavailability of Artemether. Full article

Background/Objectives: The emergence of drug-resistant Plasmodium falciparum highlights the need for new antiplasmodial compounds with distinct mechanisms of action. Microbial secondary metabolites, particularly from Streptomyces species, remain important sources of bioactive molecules. This study aimed to evaluate antiplasmodial metabolites associated with a Mongolian Streptomyces isolate. Methods: Streptomyces sp. strain D10 was isolated from Mongolian soil samples and extracted with ethyl acetate. Bioassay-guided fractionation was performed, followed by LC–HRMS analysis and GNPS-based spectral dereplication. Antiplasmodial activity was evaluated against P. falciparum 3D7, K1, and Dd2 strains using a SYBR Green I assay. Cytotoxicity was assessed in HSF cells. Stage-specific susceptibility assays were conducted using synchronized 3D7 parasites. Comparative docking analyses against β-hematin and the chloroquine resistance transporter (PfCRT), together with target prediction and molecular docking analyses, were performed to explore potential mechanisms. In vivo efficacy was evaluated using a Plasmodium yoelii 17XNL mouse model. Results: Fractionation yielded an active fraction (C2), and LC–HRMS and GNPS-based dereplication suggested a bile acid-like metabolite, with ursodeoxycholic acid (UDCA) returned as a putative spectral library candidate associated with fraction C2. Fraction C2 and UDCA showed comparable antiplasmodial activity against P. falciparum 3D7 (IC₅₀ = 6.55 ± 3.00 and 4.68 ± 0. 65 µg/mL, respectively) without detectable cytotoxicity up to 200 µg/mL. Activity was retained against multidrug-resistant K1 and Dd2 strains. Stage-specific assays demonstrated inhibitory activity across ring, trophozoite, and schizont stages without significant stage-dependent differences. Comparative docking analyses suggested interaction profiles distinct from chloroquine in β-hematin and PfCRT models. Additional docking analyses identified PfGluPho, PfMAPK, and PfPFT-β as potential targets. In vivo, UDCA reduced parasitemia in a dose-dependent manner without significant toxicity. Conclusions: UDCA exhibited moderate antiplasmodial activity across in vitro, in silico, and in vivo evaluations with a favorable selectivity profile, supporting further investigation of bile acid-like metabolites as potential antimalarial scaffolds. Full article

Background: Malaria parasites import essential nutrients from plasma into their host erythrocytes through the plasmodial surface anion channel (PSAC), a conserved ion and nutrient channel on the infected cell surface. A parasite-encoded ternary complex consisting of CLAG3, RhopH2, and RhopH3 determines PSAC activity, but the precise contributions of each member to formation of the nutrient uptake pore remains uncertain. Methods: Here, we devised a two-step CRIPSR transfection strategy to examine an amphipathic CLAG3 helix, termed α-helix 44 (α-H44), as a candidate pore-lining domain. Results: A CLAG3 truncation protein without α-H44 phenocopies a CLAG3 knockout line, suggesting a critical role of α-H44 in formation of the nutrient channel; CLAG3 restoration using a recodonized α-H44 restores PSAC activity fully. A saturation mutagenesis library that splits the helix into four sequential segments was devised and implemented. Two engineered mutants exhibit distinct PSAC phenotypes; their cultures failed to expand in a modified medium that approximates in vivo nutrient availability. Conclusions: These studies support a α-H44 role in channel permeation and block by a strain-specific inhibitor. Our strategy will enable saturation mutagenesis to determine how PSAC achieves its unique ion and nutrient selectivity and should help guide drug discovery against this antimalarial target. Full article

Tetrahydroprotoberberine alkaloids (THPBs) are bioactive natural products bearing stereogenic centers that frequently exhibit enantiomer-specific pharmacological effects. Xylopinine (XPN), a representative THPB, shows cytotoxic, antimicrobial, and antimalarial activity in vitro, and displays pronounced stereoselectivity in vivo, with the naturally occurring (S)-enantiomer emphasizing the need for reliable enantioselective analysis. In this study, we present the synthesis of racemic XPN from norlaudanosine, and its first comprehensive cyclodextrin-assisted capillary electrophoresis screening dedicated to the enantioseparation of XPN. Sulfated- and sulfobutyl-ether-β-cyclodextrin (S-β-CyD, SBE-β-CyD) provided efficient resolution (R_s > 3), while heptakis-(6-deoxy-6-(2-carboxyethyl)thio)-β-CyD (subetadex, SBX) yielded outstanding separation (R_s > 9). The enantiomer migration order was consistently R,S, except when using SBE-β-CyD, which showed the inverse sequence. Chiral HPLC using a Chiralpak AD column in polar organic mode with methanol modified with 0.1% diethylamine as mobile phase enabled the semi-preparative isolation of XPN enantiomers, with the (S)-enantiomer exceeding 95% purity. The absolute configuration was confirmed by circular dichroism spectroscopy. ¹H NMR titration and 2D rotating-frame nuclear Overhauser effect correlation spectroscopy (ROESY) consistently revealed multi-site recognition of XPN by SBX, supporting the inclusion of both aromatic rings (A and D). Full article

The use of metal-based complexes is currently taking centre stage in the field of nanomedicine for the treatment and control of various ailments. Rhenium(I) tricarbonyl complexes have frequently been evaluated in vitro for their anticancer activities, and a few have advanced to in vivo and clinical trials, owing to the distinct application characteristics of these complexes. Their inception in drug development is key. This study explores a detailed chronological overview of the medical applications of Re(I) tricarbonyl complexes over the past six years (2019–2024), focusing on their applications and clinical tests in the control and management of various ailments. An in-depth examination of their activities in anticancer treatments, Chagas disease, antifungal infections, antimalarial, and microbial infections was conducted, comparing the complexes to various standard antibiotics, conventional antimalarial drugs, antifungals, and standard anticancer agents. 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

Plasmodium malariae is a neglected human malaria parasite despite its global distribution and propensity for persistent, sub-microscopic infections, which are associated with a mild but significant disease burden. Artemisinin-based therapies appear to be efficacious, but the susceptibility profiles of field isolates are largely unknown. We performed ex vivo assays with isolates collected from asymptomatic volunteers in Gabon. The mean concentrations required to inhibit 50% of growth (IC50) with chloroquine (n = 21), artesunate (n = 20), atovaquone (n = 21), and lumefantrine (n = 14) were 7.2 nM, 2.7 nM, 3.1 nM, and 7.4 nM, respectively. Our study provides novel data on the ex vivo susceptibility of P. malariae to several key antimalarials, including the first dataset for atovaquone. Full article

Background: Malaria significantly impacts the health of populations living in poverty and vulnerable conditions. Resistance to current antimalarial drugs remains a major challenge and highlights the urgent need for novel, effective, and safer therapies. Violacein, a purple pigment, has demonstrated potent antiplasmodial activity, making it a promising antimalarial candidate. However, to date, no in vitro metabolism studies of violacein have been published. In this study, the metabolic stability of violacein was evaluated using human (HLMs), mouse (MLMs), and rat (RLMs) liver microsomes and the metabolites generated by HLMs and RLMs were assessed. Methods: Liquid chromatography quadrupole mass spectrometry (LC-MS/MS) was used to investigate the metabolic stability of violacein, while liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was used to identify the metabolites. In silico analyses were used to support in vitro metabolite identification by providing insights into potential metabolic pathways and predicting metabolite structures, thereby enhancing the accuracy and efficiency of the identification process. Results: The half-life (t_1/2) for violacein in RLMs, MLMs, and HLMs was 36, 81, and 216 min, respectively. The in vitro intrinsic clearance (CL_{int, in vitro}) values were 38.4, 17.0, and 6.4 µL/min/mg for RLMs, MLMs, and HLMs, respectively, while the in vivo intrinsic clearance (CL_{int, in vivo}) was 93.7, 67.0, and 6.6 mL/min/kg, respectively. A slow elimination profile was observed in HLMs followed by MLMs, with rapid elimination in RLMs, indicating greater stability of violacein in HLMs and MLMs when compared with RLMs. Four violacein metabolites were identified in HLMs and RLMs, two of which were formed by phase I metabolism, one by phase II metabolism, and one by phase I + II metabolism. Conclusions: This study provides the first published analysis of the metabolic stability of violacein. Full article

Background: Chloroquine (CQ) has been extensively validated for its safety as an antimalarial drug. The treatment regimen combining CQ with 5-fluorouracil (5-FU) has demonstrated promising antitumor effects in both in vitro and animal models. However, the clinical application of this combination therapy still faces numerous challenges, primarily due to the unelucidated mechanistic underpinnings. Methods: We validated the synergistic effect of CQ in antitumor therapy using 5-fluorouracil and N-acetylcysteine. Subsequently, we employed lysosomal pH probes and inhibitors (5-BDBD and bafilomycin A1) to verify the mechanism of CQ in synergistic antitumor therapy. Finally, the therapeutic efficacy and underlying mechanisms of CQ were further confirmed through in vivo experiments. Results: Here, we found that CQ can inhibit the ATP-induced activation of mammalian target of rapamycin (mTOR), enhancing the inhibition of 5-FU on the proliferation and survival of tumors. Mechanistically, CQ affects the lysosomal pH value, leading to the inhibition of P2X4 receptor activity. The ATP-P2X4-mTOR axis is consequently disrupted, resulting in the weakened activation of mTOR. Conclusions: Our findings suggest that CQ may inhibit ATP-induced mTOR activation by suppressing P2X4 receptor signaling, thereby altering the apoptosis resistance of tumors. The combination of CQ and 5-FU represents a promising therapeutic strategy, particularly for mTOR-hyperactivated malignancies refractory to conventional chemotherapy. These findings not only advance our understanding of the mechanisms underlying CQ-based combination therapy but also highlight the therapeutic potential of pharmacologically targeting mTOR and its alternative pathways in combination chemotherapy regimens. Full article

New chemical entities are constantly being investigated towards antimalarial drug discovery, and they require animal models for toxicity and efficacy testing. Murine models show physiological similarities to humans and are therefore indispensable in the search for novel antimalarial drugs. They provide a preclinical basis (following in vitro assessments of newly identified lead compounds) for further assessment in the drug development pipeline. Specific mouse strains, non-humanized and humanized, have successfully been infected with rodent Plasmodium species and the human Plasmodium species, respectively. Infected mice provide a platform for the assessment of treatment options being sought. In vivo pharmacokinetic evaluations are necessary when determining the fate of potential antimalarials in addition to the efficacy assessment of these chemical entities. This review describes the role of murine models in the drug development pipeline. It also explains some in vivo pharmacokinetic, safety, and efficacy parameters necessary for making appropriate choices of lead compounds in antimalarial drug discovery. Despite the advantages of murine models in antimalarial drug discovery, certain limitations are also highlighted. Full article

Background: Malaria remains a global health crisis, with the World Health Organization (WHO) reporting 241 million cases and 627,000 deaths worldwide in 2020, predominantly affecting Sub-Saharan Africa. The region accounted for 95% of cases and 96% of deaths, reflecting the immense challenges in malaria prevention and treatment. Plasmodium falciparum Schizont Egress Antigen-1 (PfSEA-1) is crucial in facilitating immune evasion and promoting the sequestration of infected red blood cells (RBCs), contributing to severe malaria symptoms, including cerebral malaria, and necessitates the urgent identification of novel or repurposed drugs targeting PfSEA1. Methods: The protein structure of PfSEA-1 (UniProt ID: A0A143ZXM2) was modelled in three dimensions, prepared, and subjected to a 50 ns molecular dynamics (MD) simulation to achieve a stable structure. The equilibrated structure was minimised for molecular docking against the DrugBank compound library. Docking analysis identified potential inhibitors, including Alparabinos, Dihycid, Ambenzyne, Amiflupipquamine, Ametchomine, and Chlobenethyzenol, with docking scores ranging from −8.107 to −4.481 kcal/mol. Advanced analyses such as interaction fingerprints, density functional theory (DFT), and pharmacokinetics evaluations were conducted. Finally, a 100 ns MD simulation in the NPT ensemble was performed to assess the stability of protein–ligand complexes, with binding free energy and total energy calculations derived from the simulation trajectories. Results and Discussion: The identified compounds exhibited satisfactory pharmacokinetic profiles and binding interactions with PfSEA-1. The MD simulations demonstrated overall stability, with minor fluctuations in some instances. Key intermolecular interactions were observed, supporting the binding stability of the identified compounds. Binding free energy calculations confirmed favourable interactions, underscoring their potential as therapeutic agents against Plasmodium falciparum. While the in silico results are promising, experimental validation is essential to confirm their efficacy and safety for clinical use. Conclusion: These findings highlight PfSEA-1 as a promising antimalarial target and identify potential inhibitors with strong binding affinities and favourable pharmacokinetics. While the computational results are encouraging, further in vitro and in vivo validation is necessary to confirm their therapeutic potential and facilitate future drug development. Full article

Tapirira guianensis is a tropical plant found in South America and is widely used by indigenous communities owing to its medicinal properties. Its seeds are rich in phenolic compounds that are known for their anti-inflammatory, antioxidant, and antimicrobial properties. Despite its traditional use, there are limited scientific data on the biological activities of its seed extracts, especially in the context of antimalarial and cytoprotective effects. In this study, we investigated the chemical composition, antioxidant potential, cytotoxic effects, and antimalarial properties of hydroethanolic, ethanolic, and aqueous seed extracts. A 1:1 (v/v) water/ethanol combination efficiently extracted bioactive compounds and delivered the highest phenolic compound content. Furthermore, the hydroethanolic extracts exhibited significant biological activities, including an ability to reduce cancer-cell viability, protect against damage caused by reactive oxygen species (ROS), and decrease chromosomal aberrations, while exhibiting high efficacy against both chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum strains. Hence, the use of T. guianensis seed extract as a natural source of bioactive compounds with cytoprotective, antiproliferative, antioxidant, and antimalarial properties is innovative and highlights the need for additional in vivo studies to better elucidate its mechanisms of action and safety. Full article

Background/Objectives: Cutibacterium acnes (C. acnes), a bacterium residing in hair follicles, triggers acne by inducing monocyte-mediated inflammatory cytokine production. Gedunin, a limonoid derived from Azadirachta indica (commonly known as neem), is renowned for its antifungal, antimalarial, anticancer, anti-inflammatory, and neuroprotective effects. However, its role in mitigating C. acnes-induced skin inflammation remains unexplored. This study investigates the anti-inflammatory effects of gedunin on C. acnes-induced skin inflammation and elucidates the underlying mechanisms. Methods: The anti-inflammatory activity of gedunin was assessed using RAW 264.7 mouse macrophage cells and mouse bone-marrow-derived macrophages (BMDMs). Key inflammatory mediators, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and interleukin-6 (IL-6), were evaluated. Mechanistic studies focused on the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, along with the NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome. An in vivo acne model was employed to examine gedunin’s therapeutic efficacy. Results: Gedunin significantly reduced the expression of IL-1β, TNF-α, iNOS, COX-2, and IL-6 in RAW 264.7 cells. It inhibited NF-κB activation without affecting the MAPK pathways, including JNK/SAPK, ERK, and p38 MAPK. Gedunin also suppressed the activation of the NLRP3 inflammasome in BMDMs. In the mouse acne model, gedunin effectively alleviated C. acnes-induced inflammation, primarily by targeting NF-κB signaling. Conclusions: Gedunin demonstrates potential as a therapeutic agent for acne treatment by targeting key inflammatory pathways, particularly NF-κB signaling. This study highlights gedunin’s promise as an alternative approach to managing C. acnes-induced skin inflammation. Full article

Background/Objectives: Preclinical studies have shown that the anti-malarial drug hydroxychloroquine (HCQ) improves the anti-cancer effects of various therapeutic agents by impairing autophagy. These findings are difficult to translate in vivo as reaching an effective HCQ concentration at the tumor site for extended times is challenging. Previously, we found that free HCQ in combination with gefitinib (Iressa^®, ZD1839) significantly reduced tumor volume in immunocompromised mice bearing gefitinib-resistant JIMT-1 breast cancer xenografts. Here, we sought to evaluate whether a liposomal formulation of HCQ could effectively modulate autophagy in vivo and augment treatment outcomes in the same tumor model. Methods: We developed two liposomal formulations of HCQ: a pH-loaded formulation and a formulation based on copper complexation. The pharmacokinetics of each formulation was evaluated in CD1 mice following intravenous administration. An efficacy study was performed in immunocompromised mice bearing established JIMT-1tumors. Autophagy markers in tumor tissue harvested after four weeks of treatment were assessed by Western blot. Results: The liposomal formulations engendered ~850-fold increases in total drug exposure over time relative to the free drug. Both liposomal and free HCQ in combination with gefitinib provided comparable therapeutic benefits (p > 0.05). An analysis of JIMT-1 tumor tissue indicated that the liposomal HCQ and gefitinib combination augmented the inhibition of autophagy in vivo compared to the free HCQ and gefitinib combination as demonstrated by increased LC3-II and p62/SQSTM1 (p62) protein levels. Conclusions: The results suggest that liposomal HCQ has a greater potential to modulate autophagy in vivo compared to free HCQ; however, this did not translate to better therapeutic effects when used in combination with gefitinib to treat a gefitinib-resistant tumor model. Full article

Agunmu (ground herbal medicine) is a form of West African traditional medicine consisting of a cocktail of herbs. The goal of this study is to evaluate a formulation of Agunmu made from M. indica, A. repens, E. chlorantha, A. boonei, and B. ferruginea, sold in the open market and commonly used for the treatment of malaria by the locals, for its antimalarial effects and to determine the active principles that may contribute to the antimalarial effect. The ethanolic extract obtained from this formulation (Ag-Iba) was analyzed, using TLC, LC-MS, and Tandem-MS techniques, to determine its phytochemical properties. The extract was tested in vitro against representative bacteria strains, cancer and normal human cell lines, and susceptible (D6) and resistant (W2) Plasmodium falciparum. In subsequent in vivo experiments, graded doses of the extract were used to treat mice infected with chloroquine-susceptible (NK-65) and chloroquine-resistant (ANKA) strains of Plasmodium berghei. Bacteria growth was monitored with a disc diffusion assay, cancer cell viability was determined with MTS assay, and percentage parasitemia and parasite clearance were determined by microscopy. Bound heme content, host mitochondria permeability transition (mPT) pore opening, F₀F₁-ATPase, and lipid peroxidation were determined via spectrophotometry. Indices of oxidative stress, anti-oxidant activities, toxicity, cell death, and inflammatory responses were obtained using biochemical and ELISA techniques. The histology of the liver and spleen was performed using the standard method. We elucidated the structures of the critical active principles in the extract to be flavonoids: kaempferol, quercetin, myricetin, and their glycosides with little or no detectable levels of the toxic Aristolochic acids that are found in Aristolochia repens, one of the components of the formulation. The extract also showed anti-plasmodial activity in in vitro and in vivo models. Furthermore, the extract dose-dependently decreased mitochondrial dysfunction, cell death, and inflammatory and oxidative damage but increased antioxidant potentials. Presumably, the active principles in the extract work as a combinatorial therapy to elicit potent antimalarial activity. Overall, our study unraveled the active components from a commercial herbal formulation that could be reformulated for antimalarial therapy. Full article