Search Results (150)

Background/Objectives: Leishmaniasis is a zoonotic and anthropozoonotic disease with significant public health impact worldwide and is classified as a neglected tropical disease. The search for new affordable treatments, particularly oral and/or topical ones that are easy to administer and have fewer side effects, remains a priority for the scientific community in this field of research. In previous investigations, 3-alkoxy-1-benzyl-5-nitroindazole derivatives showed remarkable in vitro results against Leishmania species, and predictions of absorption, distribution, metabolism, excretion, and toxicity properties, as well as pharmacological scores, of the compounds classified as active were superior to those of amphotericin B, indicating their potential as candidates for in vivo studies. Therefore, the aim of the present study was to evaluate the in vivo antileishmanial activity of the indazole derivatives NV6 and NV16. Methods: The compounds were administered intralesionally at concentrations of 10 and 5 mg/kg in a BALB/c mouse model of cutaneous leishmaniasis caused by Leishmania amazonensis. To evaluate the efficacy of the compounds, indicators such as lesion size, ulcer area, lesion weight, and parasitic load were determined. Amphotericin B was used as a positive control. Results: The compound NV6 showed leishmanicidal activity comparable to that observed with amphotericin B, with a significant reduction in lesion development and parasite load, while NV16 caused a reduction in ulcer area. Conclusions: These results provide strong evidence for the antileishmanial activity of NV6 and support future studies to improve its pharmacokinetic profile, as well as the investigation of combination therapies with other chemotherapeutic agents currently in use. Full article

Background/Objectives: Currently there are very few effective oral antileishmanial treatments. In this study we evaluated a new bis(pyridine-2-carboxamidine) antileishmanial drug (JNII40_base) and its hydrochloride salt (JNII40_HCl). Methods: The characterization studies performed allowed us to determine the crystallinity, hydration water, and presence of hydrogen bonds in these drugs. Different dissolution methods were employed to predict intestinal absorption. A high-performance liquid chromatography–mass spectrophotometry (HPLC-MS/MS) method was developed for the determination of JNII40 in plasma. Results: Pharmacokinetic studies in rats of JNII40_base at 100 and 20 mg/kg, and JNII40_HCl at 20 mg/kg, showed a non-linear pharmacokinetic at high doses. An innovative biorelevant medium of phosphate buffer pH 6.8 with polysorbate 80 at 0.6% (w/v) showed high concentration values for JNII40_base at 30 min, which predicts good intestinal absorption. These results were consistent with the bioavailability data, which exhibited a significant (p < 0.05) increase in maximum plasma concentration (C_max) and a slight delay in time to maximum (T_max) compared to JNII40_HCl. Furthermore, the sustained release of JNII40_base in this biorelevant media was related to high plasma concentration values at 24 h (C_24h) observed in bioavailability studies. These plasma concentrations of JNII40_base were above the half-maximal inhibitory concentration (IC₅₀) against promastigote and amastigote forms of Leishmania donovani, which is indicative of effectiveness and should reduce the occurrence of drug resistance during treatments. Conclusions: The bioavailability and pharmacokinetic data support the consideration of this drug for further in vivo studies as an oral antileishmanial treatment. Full article

Sarcomphalus joazeiro (Mart.) is a promising candidate for the formulation of new therapies against parasitic infections. This study aimed to quantify the content of phenolic compounds and evaluate the antioxidant, antileishmanial, and cytotoxic potential of ethanolic extracts of the leaves (EELSJ) and bark (EEBSJ) of S. joazeiro. Quantification of phenolic acids (caffeic acid, p-coumaric acid, ferulic acid, cinnamic acid) and flavonoids (naringenin, pinocembrin, and apigenin) was performed by high-performance liquid chromatography with a diode array detector (HPLC-DAD). The extracts were subjected to antioxidant assays, including Fe³⁺ reduction, Fe²⁺ chelation, and inhibition of oxidative degradation of deoxyribose (2-DR). The antileishmanial activity was evaluated against promastigote forms of Leishmania amazonensis, while cytotoxicity was assessed in J774.G8 macrophages. Among the biological effects evaluated, EELSJ showed potent hydroxyl radical (•OH) scavenging activity, with IC₅₀ < 10 µg/mL, which potentially correlates with its phenolic acid and flavonoid content (0.7066 mg/g). In comparison, EEBSJ showed a lower phenolic content (0.197 mg/g) and demonstrated Fe²⁺ chelating activity (IC₅₀ = 14.96 ± 0.0477 µg/mL). EELSJ also exhibited antileishmanial activity against L. amazonensis (IC₅₀ = 246.20 µg/mL), with low cytotoxicity (CC₅₀ = 343.3 µg/mL; SI = 1.39), whereas EEBSJ showed minimal antileishmanial effect and marked cytotoxicity toward J774.G8 macrophages (CC₅₀ = 5.866 µg/mL). The leaves of S. joazeiro stand out as the most promising plant organ for future investigations. Future studies should focus on investigating their action mechanisms in more detail. Full article

Benzimidazole derivatives are well known for their anthelmintic activity. Investigating the potential efficacy of new derivatives of this class against various parasites is essential to identify novel drug candidates. For this purpose, an in-house molecular database was screened, and four benzimidazole-based molecules were chosen to evaluate antiprotozoal activity. The compounds (K1–K4) had been previously synthesized through a four-step procedure. The potential in vitro cytotoxic properties of the compounds were assessed against the Leishmania (L.) major strain and L929 mouse fibroblast cells. The tests indicated that K1 (3-Cl phenyl) demonstrated an antileishmanial effect (IC₅₀ = 0.6787 µg/mL) and cytotoxicity at elevated concentrations (CC₅₀ = 250 µg/mL) in healthy cells. These findings were comparable to those of AmpB. The antileishmanial activity values were determined as follows: K2; 8.89 µg/mL, K3; 45.11 µg/mL, K4; and 69.19 µg/mL. The CC₅₀ values were determined as follows: K2, 63 µg/mL; K3; 0.56 µg/mL; and K4, 292 µg/mL. Molecular docking and dynamic simulations were conducted to elucidate the potential mechanisms of action of the test substances. In silico investigations indicated interactions between the compounds and the active site of pteridine reductase 1 (PTR1), which is a biosynthetic enzyme essential for parasite proliferation. N-alkyl benzimidazole-based compounds exhibit potential inhibitory activity against L. (L.) major promastigotes. Therefore, these findings suggest that in vivo evaluation is warranted, and structural modifications may lead to the identification of more effective antileishmanial agents. Full article

The serendipitous discovery of antiparasitic drugs, such as quinine and artemisinin, of plant origin reveals that searching new chemical pharmacophores from medicinal plants is valuable. The present study sought to explore the antiplasmodial, antileishmanial, and antitrypanosomal activities of Lippia adoensis extracts. Crude extracts of L. adoensis leaves and twigs, which were obtained by extraction using 70% ethanol in water, were assayed for antiplasmodial activity against P. falciparum 3D7 and Dd2 through the SYBR green I-based fluorescence assay; and for antileishmanial, antitrypanosomal, and cytotoxic effects on Leishmania donovani, Trypanosoma brucei brucei, and Vero cells, respectively, using resazurin colorimetric assays. In vitro phytochemical analysis of L. adoensis extracts was performed using standard methods. Moreover, liquid chromatography–mass spectrometry (LC-MS) feature-based detection and molecular networking flow on Global Natural Product Social (GNPS) were also used for the phytochemical screening of L. adoensis extracts. Crude extracts from L. adoensis inhibited the growth of P. falciparum (3D7 and Dd2) (IC₅₀s; (3D7): 10.00 and 97.46 μg/mL; (Dd2): 29.48 and 26.96 μg/mL), L. donovani (IC₅₀s: 22.87–10.52 μg/mL), and T. brucei brucei (IC₅₀s: 2.30–55.06 μg/mL). The extracts were found to be non-cytotoxic to Vero cells, thus yielding median cytotoxic concentrations (CC₅₀s) above 100 μg/mL. In vitro phytochemical analysis of the crude extracts revealed the presence of alkaloids, terpenoids, phenolic compounds, and carbohydrates. The LC-MS tandem molecular networking flow predicted that the extracts contained valsafungin A and bacillamidin in the first cluster, and fatty acids, ketone, and aldehyde derivatives in the second cluster. Overall, the present study demonstrated the antiparasitic effects of L. adoensis extracts, thus justifying the use of this plant in the traditional treatment of fever and malaria conditions. Nevertheless, detailed metabolomic studies and antiparasitic mechanisms of action of the extracts are expected to unveil the potential antiparasitic hit compounds. Full article

Caffeic acid phenethyl ester (CAPE) is a polyphenol produced by many plants and is found in red and green propolis. Here, we evaluated the antileishmanial activity of this natural product against Leishmania amazonensis. CAPE exhibited IC₅₀ values of 8.07 µM (95% CI, 6.79–9.62 µM) and 13.51 µM (95% CI, 10.71–17.16 µM) against L. amazonensis promastigotes and intracellular amastigotes, respectively. Additionally, CAPE inhibited L. amazonensis arginase in a non-competitive manner with a K_i value of 1.51 ± 0.04 µM. These results highlight the potential of CAPE as a promising lead compound for developing new therapies against leishmaniasis. Full article

Quinolones represent one of the largest classes of synthetic antibiotics used in both human and veterinary medicine. Since the discovery of nalidixic acid, a substantial body of research has been carried out on quinolones, resulting in the synthesis of several quinolone derivatives with exceptional pharmacology. In addition to their antibacterial action, quinolones have a broad spectrum of diverse biological activities. In this regard, the present review examines the literature of recent years describing synthesis protocols, reactivity and biological properties, with particular emphasis on the antibacterial, antimalarial, antitrypanosomal, antileishmanial, antiviral and anticancer activities of this famous class of molecules. Finally, this review highlights the potential of quinolones as preferred pharmacophores in medicinal chemistry. The aim is to highlight the innovative aspects of the rational design of new therapeutic agents with this structural motif, in the face of emerging antibiotic resistance and the urgent need for new active molecules. Full article

Background/Objectives: Cutaneous leishmaniasis (CL) is a vector-borne neglected disease that can cause permanent deformities. Current chemotherapy based on injections with toxic drugs or oral miltefosine poses many drawbacks, urging the need for new oral therapies. Here, we proposed to increase the bioavailability of NAT22, an intralesionally but not orally active antileishmanial chalcone, through nanocrystallization to promote its oral use in CL. Methods/Results: NAT22 nanocrystals were produced using a solvent-free green process of dry and wet milling that reduced NAT22 crystal sizes by around 1500-fold to 257 nm (nanoNAT22). Such reduction in size increased water solubility by 15-fold to 4.3 µg/mL and ensured stability in the absence of stabilizers for at least one month. Of note, nanoNAT22 in aqueous medium was more selective for parasites (SI = 35.2) than NAT22 in 1% DMSO (SI = 7.6). Leishmania amazonensis-infected mice treated with oral nanoNAT22 had lesion sizes and parasite loads similar to those achieved with intralesional Glucantime^®, and significantly smaller than NAT22. Conclusions: Together, these results indicate that nanocrystallization is an effective process to render NAT22 chalcone also orally active against CL. 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

The treatment of leishmaniasis has limitations due to drug toxicity and the increasing resistance of the parasite. In this study, we analyze the role of oxidative stress in the pathogenesis and treatment of leishmaniasis, as well as in new therapeutic alternatives of natural origin. The evasion mechanisms against the host immune response involve surface molecules present in the parasite, which modulate oxidative stress to ensure its survival. Drug treatment requires strict monitoring to minimize adverse reactions and ensure patient safety, as mechanisms such as lipid peroxidation, mitochondrial dysfunction, and depletion of antioxidant defenses are associated with drug toxicity. Plant-derived products with antileishmanial activity impact the parasite’s redox balance, inducing apoptosis and reducing its parasitic load. Most studies are still in preliminary stages, making in vivo assays and clinical studies essential, along with the development of accessible formulations. Oxidative stress is involved in the pathogenesis of leishmaniasis, as Leishmania manipulates the host’s redox balance to survive. It also contributes to drug toxicity, as antimonials and amphotericin B increase reactive oxygen species, causing cellular damage. Several plant-derived compounds have demonstrated antileishmanial activity by modulating oxidative stress and promoting parasite apoptosis. Examples include alkaloids from Aspidosperma nitidum, lignans from Virola surinamensis, flavonoids from Geissospermum vellosii, and triterpenoids such as β-sitosterol. Although these compounds show promising selectivity, most studies remain in preliminary stages, requiring in vivo assays and clinical studies to confirm efficacy and safety, as well as the development of affordable formulations. Full article

Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. An estimated 700,000 to 1 million new cases occur annually. Current therapies are limited by high toxicity, cost, prolonged treatment period, and rising resistance in endemic regions. The Asteraceae family has emerged as a promising source of bioactive compounds with proven leishmanicidal activity. In this study, the assessment of the antileishmanial activity of Helianthus tuberosus and Vernonanthura squamulosa extracts, the isolation of the sesquiterpene lactones heliangin and glaucolide A, respectively, and the evaluation of the activity of the compounds were conducted. Dichloromethane extracts of H. tuberosus and V. squamulosa were active on Leishmania amazonensis promastigotes, inhibiting the replication of the parasites in 97.2 ± 3.1% and 89.1 ± 1.1%, respectively, at 100 μg/mL. Heliangin was active against promastigotes of L. amazonensis (IC₅₀ = 9.3 μM) and intracellular amastigotes (IC₅₀ = 0.8 μM), while glaucolide A exhibited moderate activity against promastigotes (IC₅₀ = 46.7 μM) and did not show activity against intracellular amastigotes. Based on these results, heliangin was further evaluated in an animal model of cutaneous leishmaniasis using BALB/c mice infected with L. amazonensis. Heliangin (8 mg/Kg), when administered in combination with Glucantime, significantly reduced lesion progression and parasite load compared to the vehicle-treated group (p < 0.001). These findings show that heliangin is a potential candidate for leishmaniasis treatment, especially in combination with therapeutic drugs. Full article

Background/Objectives: Leishmaniasis is one of the 20 Neglected Tropical Diseases according to the WHO, affecting approximately 12 million people in four continents, generating serious public health problems. The lack of therapeutic options, associated with toxicity and the emergence of resistance to the few available drugs, makes it urgent to develop new drug options. In this context, the aims of this work are to expand the knowledge about the pharmacophore group responsible for the antileishmanial potential of 2-aminothiophene derivatives. Thus, new compounds were synthesized containing chemical modifications at the C-3, C-4, and C-5 positions of the 2-aminothiophene ring, in addition to the S-Se bioisosterism. Methods: Dozens of 2-AT and 2-aminoselenophen (2-AS) derivatives were sequentially synthesized through applications of the Gewald reaction and were then evaluated in vitro for their activities against L. amazonensis and for cytotoxicity against macrophages. Results: Several series of compounds were synthesized, and it was possible to identify some substitution patterns favorable to the activity generating compounds with IC₅₀ values below 10 µM, such as the non-essentiality of the presence of a carbonitrile group at C-3; the importance of the presence and size of cycloalkyl/piperidinyl chains at C-4 and C-5 in modulating the activity; and the increase in activity without affecting the safety of the S/Se bioisosteric substitution. Conclusions: Taken together, these findings reaffirm the great potential of 2-aminothiophenes to generate antileishmanial drug candidates and offers contributions to the drug design of compounds with an even more promising profile for the problem of leishmaniasis. Full article

Leishmaniasis is a neglected tropical disease caused by a protozoan of the genus Leishmania, which has visceral and cutaneous forms. The symptoms of leishmaniasis include high fever and weakness, and the cutaneous infection also causes lesions under the skin. The drugs used to treat leishmaniasis have become less effective due to the resistance mechanisms of the protozoa. In addition, the current compounds have low selectivity for the pathogen, leading to various side effects, which results in lower adherence to treatment. Various strategies were developed to solve this problem. The bioconjugation between natural compounds with antimicrobial activity and cell-penetrating peptides could alleviate the resistance and toxicity of current treatments. This work aims to conjugate the cell penetration peptide TAT to the guanidine GVL1. The GVL1-TAT bioconjugate exhibited leishmanicidal activity against Leishmania amazonensis and Leishmania infantum with a high selectivity index. In addition, the bioconjugate was more active against the intracellular enzyme CPP than the individual compounds. This target is very important for the viability and virulence of the parasite within the host cell. Docking studies confirmed the higher interaction of the conjugate with CPP and suggested that other proteins, such as trypanothione reductase, could be targeted. Thus, the data indicated that guanidines conjugated with cell-penetrating peptides could be a good approach for developing antileishmanial molecules. Full article

Background/Objectives: New drugs are required for the treatment of liver cancers and protozoal parasite infections. Analogs of the known anticancer active and antileishmanial 2′,4′,6′-trimethoxychalcone SU086 were prepared and investigated. Methods: The chalcones were prepared according to the Claisen–Schmidt condensation protocol and analyzed. They were tested for activity against two liver cancer cell lines (HepG2 and HuH-7) and protozoal parasites (Toxoplasma gondii and Leishmania major). Unspecific toxicity and expression of Hsp90 and Hsp70 upon treatment were analyzed in liver cancer cells. Results: A new chalcone, 2′,4′,6′-trimethoxy-3-pentafluorosulfanylchalcone (246TMP-3SF5), with a pentafluorosulfanyl (SF₅) substituent showed pronounced activities against liver cancer cells and T. gondii parasites which were superior to the activities of the parent chalcone SU086 in these models. In contrast, SU086 and its anthracene analog 2′,4′,6′-trimethoxy-9-anthracenylchalcone (246TMP-Anth) were most active against L. major promastigotes. The new SF₅-substituted chalcone behaved like the known Hsp90 inhibitor 17-AAG and upregulated Hsp70 expression in liver cancer cells. Conclusions: The SF₅-substituted SU086 analog has potential to become a new drug for the therapy of hepatoma and toxoplasmosis. Full article

Background: Vector-borne diseases, such as leishmaniasis and arboviral infections, represent a great challenge to human health with limited therapeutic options. In addition, sexually transmitted infections, such as herpes, affect billions of people worldwide and the emergence of new strains resistant to common antivirals, such as acyclovir (ACV), poses a serious threat to humans. In this context, coumarins have proved to be a valuable source of new derivatives with promising biological activities to fight these diseases. Methodology: 3-aryl and/or 4-(N-aryl)aminocoumarins were synthesized, and their drug-like profile was evaluated using silico tools. Their biological activity against Leishmania amazonensis promastigotes was evaluated using the MTT assay, while their antiviral activity against replication of Chikungunya, Mayaro, Zika, and type 1 Herpes simplex virus (HSV-1) in Vero cells was analyzed using plaque reduction assays. Results: The in silico studies pointed to satisfactory pharmacokinetic and toxicological properties as drug candidates. Hence, their antileishmanial activity was evaluated. None of the compounds exhibited significant activity and compound 2b showed the highest activity (IC₅₀ = 47.10 µM). We further evaluated their cytotoxicity and antiviral activity. Compound 2e showed good activity against ACV-sensitive and -resistant HSV-1 strains with EC₅₀ values of 48.68 µM and 66.26 µM, respectively (selectivity index values of 12.5 and 9.2). Mechanism of action studies indicated that this compound acts at late steps of HSV-1 replication, such as virus egress. Conclusions: Compound 2e possesses a different mechanism of action compared to ACV and presents a promising alternative for the treatment of HSV-1 infections. Full article