Antileishmanial activity of terpenylquinones on Leishmania infantum and their effects on Leishmania topoisomerase IB

A review on potential therapeutic targets for the treatment of leishmaniasis

Leishmania, a protozoan parasite, is responsible for the occurrence of leishmaniasis, a disease that is prevalent in tropical regions. Visceral Leishmaniasis (VL), also known as kala-azar in Asian countries, is one of the most significant forms of VL, along with Cutaneous Leishmaniasis (CL) and Mucocutaneous Leishmaniasis (ML). Management of this condition typically entails the use of chemotherapy as the sole therapeutic option. The current treatments for leishmaniasis present several drawbacks, including a multitude of side effects, prolonged treatment duration, disparate efficacy across different regions, and the emergence of resistance. To address this urgent need, it is imperative to identify alternative treatments that are both safer and more effective. The identification of appropriate pharmacological targets in conjunction with biological pathways constitutes the initial stage of drug discovery. In this review, we have addressed the key metabolic pathways that represent potential pharmacological targets as well as prominent treatment options for leishmaniasis.

One-pot synthesis of polyhydroquinoline-1,2,3-triazole hybrids in deep eutectic solvent as anti-leishmanial agents and molecular modeling studies

The novel hybrids with 1,2,3-triazole and polyhydroquinoline scaffolds were successfully synthesized by multicomponent reaction of propargyloxybenzaldehyde, 1,3-cyclohexadione, ethylacetoacetate and ammonium acetate followed through click reaction in the presence of deep eutectic solvent ChCl/ZnCl2 as an efficient catalyst. Their anti-leishmanial activity was evaluated against amastigote and promastigote forms of L. tropica, L. major, and two different species of L. infantum. Furthermore, to determine the cytotoxicity of the hybrids, they were evaluated against the murine macrophage cell line J774.A1. Based on the results, three hybrids showed the highest antileishmanial activity. However, they revealed low cytotoxicity. Hybrid 6j was the most potent compound against both the forms of all leishmanial types, with IC50 = 13.5 and 11.9 µg/mL for L. major, 37.5 and 25 µg/mL for L. tropica, 17.5 and 20 µg/mL for L. infantum (MCAN/IR//96/LON49) and 35.5 and 30 µg/mL for L. infantum (MCAN/ES/98/LIM-877), respectively. Finally, molecular docking and molecular dynamics simulations were also performed to identify possible mechanism antileishmanial activity.Communicated by Ramaswamy H. Sarma.

Compounds with potentialities as novel chemotherapeutic agents in leishmaniasis at preclinical level

Leishmaniasis are neglected infectious diseases caused by kinetoplastid protozoan parasites from the genus Leishmania. These sicknesses are present mainly in tropical regions and almost 1 million new cases are reported each year. The absence of vaccines, as well as the high cost, toxicity or resistance to the current drugs determines the necessity of new treatments against these pathologies. In this review, several compounds with potentialities as new antileishmanial drugs are presented. The discussion is restricted to the preclinical level and molecules are organized according to their chemical nature, source and molecular targets. In this manner, we present antimicrobial peptides, flavonoids, withanolides, 8-aminoquinolines, compounds from Leish-Box, pyrazolopyrimidines, and inhibitors of tubulin polymerization/depolymerization, topoisomerase IB, proteases, pteridine reductase, N-myristoyltransferase, as well as enzymes involved in polyamine metabolism, response against oxidative stress, signaling pathways, and sterol biosynthesis. This work is a contribution to the general knowledge of these compounds as antileishmanial agents.

New synthetic molecules incorporated into polymeric micelles used for treatment against visceral leishmaniasis

Treatment against visceral leishmaniasis (VL) presents problems, mainly related to drug toxicity, high cost and/or by emergence of resistant strains. In the present study, two vanillin synthetic derivatives, 3 s [4-(2-hydroxy-3-(4-octyl-1H-1,2,3-triazol-1-yl)propoxy)-3-methoxybenzaldehyde] and 3 t [4-(3-(4-decyl-1H-1,2,3-triazol-1-yl)-2-hydroxypropoxy)-3-methoxybenzaldehyde], were evaluated as therapeutic candidates in a murine model against Leishmania infantum infection. Molecules were used pure (3 s and 3 t) or incorporated into Poloxamer 407-based micelles (3 s/M and 3 t/M) in the infected animals, which also received amphotericin B (AmpB) or Ambisome® as control. Results showed that 3 s/M and 3 t/M compositions induced a Th1-type immune response in treated animals, with higher levels of IFN-γ, IL-2, TNF-α, IL-12, nitrite, and IgG2a antibodies. Animals presented also low toxicity and significant reductions in the parasite load in their spleens, livers, bone marrows and draining lymph nodes, as compared as control groups mice, with the evaluations performed one and 30 days after the application of the therapeutics. In conclusion, preliminary data suggest that 3 s/M and 3 t/M could be considered for future studies as therapeutic agents against VL.

Antiprotozoal activity of natural products from Nigerien plants used in folk medicine

In the course of the screening of plants from Niger for antiprotozoal activity, the methanol extract of Cassia sieberiana, and the dichloromethane extracts of Ziziphus mauritiana and Sesamun alatum were found to be active against protozoan parasites, namely Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and/or Plasmodium falciparum. Myricitrin (1), quercitrin (2) and 1-palmitoyl-lysolecithin (3) were isolated from C. sieberiana. From Z. mauritiana, the three triterpene derivatives 13, 15, and 16 are described here for the first time. Their chemical structures were determined by 1D and 2D NMR experiments, UV, IR and HRESIMS data. The absolute configurations were assigned via comparison of the experimental and calculated ECD spectra. In addition, eight known cyclopeptide alkaloids (4, 5, 7-12), and five known triterpenoids (6, 14, 17-19) were isolated. The antiprotozoal activity of the isolated compounds, as well as of eleven quinone derivatives (20-30) previously isolated from S. alatum was determined in vitro. The cytotoxicity in L6 rat myoblast cells was also evaluated. Compound 18 showed the highest antiplasmodial activity (IC₅₀ = 0.2 µm) and compound 24 inhibited T. b. rhodesiense with an IC₅₀ value of 0.007 µM. However, it also displayed significant cytotoxicity in L6 cells (IC₅₀ = 0.4 µm).

Natural-Product-Inspired Microwave-Assisted Synthesis of Novel Spirooxindoles as Antileishmanial Agents: Synthesis, Stereochemical Assignment, Bioevaluation, SAR, and Molecular Docking Studies

Leishmaniasis is a neglected tropical disease, and there is an emerging need for the development of effective drugs to treat it. To identify novel compounds with antileishmanial properties, a novel series of functionalized spiro[indoline-3,2'-pyrrolidin]-2-one/spiro[indoline-3,3'-pyrrolizin]-2-one 23a-f, 24a-f, and 25a-g were prepared from natural-product-inspired pharmaceutically privileged bioactive sub-structures, i.e., isatins 20a-h, various substituted chalcones 21a-f, and 22a-c amino acids, via 1,3-dipolar cycloaddition reactions in MeOH at 80 °C using a microwave-assisted approach. Compared to traditional methods, microwave-assisted synthesis produces higher yields and better quality, and it takes less time. We report here the in vitro antileishmanial activity against Leishmania donovani and SAR studies. The analogues 24a, 24e, 24f, and 25d were found to be the most active compounds of the series and showed IC₅₀ values of 2.43 µM, 0.96 µM, 1.62 µM, and 3.55 µM, respectively, compared to the standard reference drug Amphotericin B (IC₅₀ = 0.060 µM). All compounds were assessed for Leishmania DNA topoisomerase type IB inhibition activity using the standard drug Camptothecin, and 24a, 24e, 24f, and 25d showed potential results. In order to further validate the experimental results and gain a deeper understanding of the binding manner of such compounds, molecular docking studies were also performed. The stereochemistry of the novel functionalized spirooxindole derivatives was confirmed by single-crystal X-ray crystallography studies.

Demystifying the potential of inhibitors targeting DNA topoisomerases in unicellular protozoan parasites

DNA topoisomerases are a group of enzymes omnipresent in all organisms. They maintain the DNA topology during replication, repair, recombination, and transcription. However, the structure of topoisomerase in protozoan parasites differs significantly from that of human topoisomerases; thus, this enzyme acts as a crucial target in drug development against parasitic diseases. Although the therapeutic potential of drugs targeting the parasitic topoisomerase is well known, to manage the shortcomings of currently available therapeutics and the emergence of drug resistance, the discovery of novel antiparasitic molecules is an urgent need. In this review, we describe various investigational and repurposed topoisomerase inhibitors developed against protozoan parasites over the past few years. Teaser: Fatal parasitic diseases are an increasing cause for concern; here, we provide a compilation of different inhibitors targeting DNA topoisomerases, enzymes that are essential for, and unique to, protozoan parasites; therefore, inhibitors are efficient and have few adverse effects.

Capparis spinosa inhibits Leishmania major growth through nitric oxide production in vitro and arginase inhibition in silico

Cutaneous leishmaniasis is an infectious disease, considered as a major public health problem in different regions of the world. The current treatments are limited due to their toxicity and treatment failures, which have increased the search for new substances of natural origin to control this infection. Capparis spinosa is an important medicinal plant, rich in biochemical compounds with a broad range of activities including antimicrobial effects. Nevertheless, more investigations are still needed to determine its effect on Leishmania parasites. This study aimed to evaluate the effect of C. spinosa' extracts on Leishmania major promastigotes and amastigotes growth as well as on L-arginine metabolic pathways, especially the production of leishmanicidal molecules such as nitric oxide. Our results showed that C. spinosa' methanolic and aqueous extracts contained polyphenols and flavonoids at different concentrations. The methanolic extract of C. spinosa, compared to the aqueous extract, showed significantly higher amounts of total polyphenols (21.23 ± 1.08) mg GAE/g of dw (P < 0.05), as well as a higher antioxidant activity evaluated respectively by Reducing Power and DPPH (EC₅₀: 0.31 ± 0.02 and 7.69 ± 1.28) mg/ml. Both extracts significantly inhibited L. major promastigotes and intra-macrophagic amastigotes growth in vitro in a dose-dependent manner (P < 0.001) and induced NO production not only in Leishmania-infected macrophages but also in uninfected macrophages, without showing any cytotoxicity in vitro. Furthermore, in silico docking studies showed that C. spinosa compounds identified by RP-HPLC exhibited inhibitory activity against the arginase enzyme. The leishmanicidal effect of C. spinosa may be due to its phenolic content and its mechanism of action may be mediated by an increase in NO production and by the inhibition of arginase enzyme in silico. These findings support the hypothesis that C. spinosa might be a valuable source of new biomolecules for leishmaniasis treatment.

Design, synthesis and evaluation of novel β-carboline ester analogues as potential anti-leishmanial agents

Leishmaniasis is one of today's most neglected diseases. The emergence of new anti-leishmanial therapies emphasizes several study groups funded by the World Health Organization. The present investigation will focus on the research to determine a few new potential derivatives of β-carboline ester derivatives against leishmaniasis. The in-silico predicted ADMET properties of most of the titled compounds are in an acceptable range and having drug like properties. Among all the tested analogs, compound ES-3 (EC₅₀ 3.36 μM; SI > 29.80) showed comparable and equipotent anti-leishmanial activity as that of standard drug miltefosine (EC₅₀ 4.80 μM; SI > 20.80) against amastigote forms of the tested L. infantum strain. Two compounds ES-6 and ES-10 exhibited significant activity with EC₅₀ 10.16, 13.56 μM; SI > 4.90, 7.37, respectively. In-silico based molecular docking and dynamics study of the significantly active analog also performed to study the putative binding mode, interaction pattern at the active site of the target leishmanial trypanothione reductase enzyme as well as stability of the target-ligand complex. The changes in the conformation of molecules during MD (frame wise trajectory analysis) provided new insights for the development of novel potent molecules. These findings will further give insight that will help modify the compound ES-3 for better potency and the design of novel inhibitors for leishmaniasis.Communicated by Ramaswamy H. Sarma.

DNA Topoisomerases in the Unicellular Protozoan Parasites: Unwinding the Mystery

DNA topoisomerases are a group of enzymes present ubiquitously in all organisms from unicellular protozoan parasites to humans. These enzymes control the topological problems caused by DNA double helix in the cell during nucleic acid metabolism. Certain types of topoisomerases present in unicellular parasites are quite different from human topoisomerases (hTop) concerning structure, expression, and function. Many protozoan parasites causing fatal diseases have DNA topoisomerases, which play vital roles in their survival. Given the fact that the structures of the protozoan parasite topoisomerases are different from humans, DNA topoisomerase acts as an essential target for potent drug development for parasitic diseases. Moreover, various studies revealed the therapeutic potential of these drugs targeting the parasitic topoisomerases. Therefore, the characterization of parasitic topoisomerases is pivotal for the development of future potential drug targets. Considering the importance of this ubiquitous enzyme as a potential drug target, we describe in detail all the reported protozoan topoisomerases in an organized manner including Leishmania, Trypanosoma, Plasmodium, Giardia, Entamoeba, Babesia, Theileria, Crithidia, Cryptosporidium, Toxoplasma, etc. This review highlights the unique attributes associated with the structure and function of different types of DNA topoisomerases from the unicellular protozoan parasites. So, it would be beneficial for researchers to obtain awareness about the currently characterized topoisomerases and the ones that need better characterization, understand the structure-function relationship of parasitic topoisomerases, to develop the potent anti-parasitic drugs, and also provides a future platform for therapeutic development.

In vitro nematocidal activity of Punica granatum L. against gastrointestinal helminths in goats

The objective of this study was to evaluate the in vitro ovicidal activity, phytochemistry, and toxicity of a saline extract obtained from peel of Punica granatum L fruits. The ovicidal activity was evaluated by the hatching inhibition of eggs recovered from fecal samples of naturally infected goats; the phytochemical analysis was carried out using the fruit peel; and the toxicity was tested on Artemia salina, using saline extract. The results showed that the ovicidal effect of the tested extract was 99% (25 mg mL^-1), 99% (12.5 mg mL^-1), 98% (6.25 mg mL^-1), and 95% (3.12 mg mL^-1), higher than that of the control drug, thiabendazole (83%). The phytochemical analysis showed presence of phenols, anthraquinones, and condensed and hydrolysable tannins in the fruit extract. The toxicity test of the extract of P. granatum showed an LC50 of 6.19 mg mL^-1, which indicates a safe use for a concentration of 3.12 mg mL^-1, since it was the tested concentration that was below the reliable LC50. The saline extract from peels of P. granatum has ovicidal activity, important secondary metabolites, and absence of toxicity at the lowest concentration tested. However, in vivo tests in experimental models are recommended before performing experiments in ruminants.

Flau-A, a naphthoquinone derivative, is a promising therapeutic candidate against visceral leishmaniasis: A preliminary study

Visceral leishmaniasis (VL) is a neglected tropical disease found in tropical and subtropical regions in the world. The therapeutics used for the treatment against disease presents problems, mainly related to drug toxicity, route of administration, high cost and/or by emergence of resistant strains. In this context, the search for alternative antileishmanial candidates is desirable. Recently, a naphthoquinone derivative namely 2-(2,3,4-tri-O-acetyl-6-deoxy-β-L-galactopyranosyloxy)-1,4-naphthoquinone or Flau-A showed an effective in vitro biological action against Leishmania infantum. In the present study, the efficacy of this naphthoquinone derivative was evaluated in an in vivo infection model. BALB/c mice (n = 12 per group) were infected and later received saline or were treated with empty micelles (B/Mic), free Flau-A or it incorporated in Poloxamer 407-based micelles (Flau-A/Mic). The products were administered subcutaneously in the infected animals, which were then euthanized one (n = 6 per group) and 15 (n = 6 per group) days post-therapy, when immunological and parasitological evaluations were performed. Results showed that animals treated with Flau-A or Flau-A/Mic produced significantly higher levels of antileishmanial IFN-γ, IL-12, TNF-α, GM-CSF, nitrite and IgG2a isotype antibody, when compared to data found in the control (saline and B/Mic) groups; which showed significantly higher levels of parasite-specific IL-4, IL-10 and IgG1 antibody. In addition, animals receiving free Flau-A or Flau-A/Mic presented also significant reductions in the parasite load in their spleens, livers, bone marrows and draining lymph nodes, when compared to the controls. A low hepatic and renal toxicity was also found. Overall, Flau-A/Mic showed better immunological and parasitological results, when compared to the use of free molecule. In conclusion, preliminary data suggest that this composition could be considered in future studies as promising therapeutic candidate against VL.

In vitro anti-Leishmania activity and molecular docking of spiro-acridine compounds as potential multitarget agents against Leishmania infantum

Leishmaniasis is an infectious disease with several limitations regarding treatment schemes. This work reports the anti-Leishmania activity of spiroacridine compounds against the promastigote (IC₅₀ = 1.1 to 6.0 µg / mL) and amastigote forms of the best compounds (EC₅₀ = 4.9 and 0.9 µg / mL) inLeishmania (L.) infantumand proposes an in-silico study with possible selective therapeutic targets for L. infantum. The substituted dimethyl-amine compound (AMTAC 11) showed the best leishmanicidal activity in vitro, and was found to interact with TryRandLdTopoI. comparisons with standard inhibitors were performed, and its main interactions were elucidated. Based on the biological assessment and the structure-activity relationship study, the spiroacridine compounds appear to be promisinganti-leishmaniachemotherapeutic agents to be explored.

Naphthoquinones and Derivatives for Chemotherapy: Perspectives and Limitations of their Anti-trypanosomatids Activities

Chagas disease, Sleeping sickness and Leishmaniasis, caused by trypanosomatids Trypanosoma cruzi, Trypanosoma brucei and Leishmania spp., respectively, are considered neglected tropical diseases, and they especially affect impoverished populations in the developing world. The available chemotherapies are very limited, and a search for alternatives is still necessary. In folk medicine, natural naphthoquinones have been employed for the treatment of a great variety of illnesses, including parasitic infections. This review is focused on the anti-trypanosomatid activity and mechanistic analysis of naphthoquinones and derivatives. Among all the series of derivatives tested in vitro, naphthoquinone-derived 1,2,3-triazoles were very active on T. cruzi infective forms in blood bank conditions, as well as in amastigotes of Leishmania spp. naphthoquinones containing a CF₃ on a phenyl amine ring inhibited T. brucei proliferation in the nanomolar range, and naphthopterocarpanquinones stood out for their activity on a range of Leishmania species. Some of these compounds showed a promising selectivity index (SI) (30 to 1900), supporting further analysis in animal models. Indeed, high toxicity to the host and inactivation by blood components are crucial obstacles to be overcome to use naphthoquinones and/or their derivatives for chemotherapy. Multidisciplinary initiatives embracing medicinal chemistry, bioinformatics, biochemistry, and molecular and cellular biology need to be encouraged to allow the optimization of these compounds. Large scale automated tests are pivotal for the efficiency of the screening step, and subsequent evaluation of both the mechanism of action in vitro and pharmacokinetics in vivo is essential for the development of a novel, specific and safe derivative, minimizing adverse effects.

New Antineoplastic Naphthohydroquinones Attached to Labdane and Rearranged Diterpene Skeletons

Terpenylquinones are mixed biogenesis primary or secondary metabolites widespread in Nature with many biological activities, including the antineoplastic cytotoxicity, that have inspired this work. Here, we present a cytotoxic structure-activity relationship of several diterpenylhydroquinone (DTHQ) derivatives, obtained from the natural labdane diterpenoid myrceocommunic acid used as starting material. Different structural modifications, that changed the functionality and stereochemistry of the decalin, have been implemented on the bicyclic core through epoxidation, ozonolysis or decarboxylation, and through induction of biomimetic breaks and rearrangements of the diterpene skeleton. All the isomers generated were completely characterized by spectroscopic procedures. The resulting compounds have been tested in vitro on cultured cancer cells, showing their relevant antineoplastic cytotoxicity, with GI₅₀ values in the μM and sub-μM range. The rearranged compound 8 showed the best cytotoxic results, with GI₅₀ at the submicromolar range, retaining the cytotoxicity level of the parent compounds. In this report, the versatility of the labdane skeleton for chemical transformation and the interest to continue using structural modifications to obtain new bioactive compounds are demonstrated.

Antileishmanial activity of cordiaquinone E towards Leishmania (Leishmania) amazonensis

Leishmaniasis is caused by several protozoan species of Leishmania, and being endemically present in 98 countries around the world, it is also a severe public-health problem. The available antileishmanial drugs are toxic and yet present risks of recurrent infection. Efforts to find new, effective, and safe oral agents for the treatment of leishmaniasis are continuing throughout the world. This work aimed to evaluate the antileishmania activity of cordiaquinone E (CORe), isolated from the roots of Cordia polycephala (Lam.) I. M. Johnston. Cytotoxicity, and possible mechanisms of action against promastigote and amastigote forms of Leishmania amazonensis were examined. CORe was effective in inhibiting promastigote (IC₅₀ 4.5 ± 0.3 µM) and axenic amastigote (IC₅₀ 2.89 ± 0.11 µM) growth in concentrations found non-toxic for the host cell (CC₅₀ 246.81 ± 14.5 µM). Our results revealed that CORe presents direct activity against the parasite, inducing cell death by apoptosis. CORe present greater activity against intracellular amastigotes (EC₅₀ 1.92 ± 0.2 µM), yet with much higher selectivity indexes than the reference drugs, being respectively more benign towards RAW 264.7 macrophages than meglumine antimoniate and amphotericin B, (respectively by 4.68 and 42.84 fold). The antiamastigote activity was associated with increased TNF-α, IL-12, NO, and ROS levels, as well as decreased IL-10 levels. These results encourage the progression of studies on this compound for the development of new leishmanicidal agents.

A Novel Cytotoxic Conjugate Derived from the Natural Product Podophyllotoxin as a Direct-Target Protein Dual Inhibitor

Natural products are the ideal basis for the design of novel efficient molecular entities. Podophyllotoxin, a naturally occurring cyclolignan, is an example of natural product which displays a high versatility from a biological activity point of view. Based on its unique chemical structure, different derivatives have been synthesized presenting the original antitumoral properties associated with the compound, i.e., the tubulin polymerization inhibition and arising anti-topoisomerase II activity from structural modifications on the cyclolignan skeleton. In this report, we present a novel conjugate or hybrid which chemically combines both biological activities in one single molecule. Chemical design has been planned based in our lead compound, podophyllic aldehyde, as an inhibitor of tubulin polymerization, and in etoposide, an approved antitumoral drug targeting topoisomerase II. The cytotoxicity and selectivity of the novel synthetized hybrid has been evaluated in several cell lines of different solid tumors. In addition, these dual functional effects of the novel compound have been also evaluated by molecular docking approaches.

Immunogenicity and Protective Effect of a Virus-Like Particle Containing the SAG1 Antigen of Toxoplasma gondii as a Potential Vaccine Candidate for Toxoplasmosis

This study was carried out to evaluate the vaccination effect of a virus-like particle (VLP) including the surface antigen 1 (SAG1) of Toxoplasma gondii as a potential vaccine for toxoplasmosis. The SAG1 virus-like particles (SAG1-VLPs) were expressed by Sf9 cells, and their expression was confirmed through cloning, RT-PCR analysis, and western blot method. The immunogenicity and vaccine efficacy of SAG1-VLPs were assessed by the antibody response, cytokine analysis, neutralization activity, splenocyte assay, and survival rates through a mouse model. In particular, IgG, IgG1, IgG2a, and IgA were markedly increased after immunization, and the survival rates of T. gondii were strongly inhibited by the immunized sera. Furthermore, the immunization of SAG1-VLPs effectively decreased the production of specific cytokines, such as IL-1β, IL-6, TNF-α, and IFN-γ, after parasite infection. In particular, the immunized group showed strong activity and viability compared with the non-immunized infection group, and their survival rate was 75%. These results demonstrate that SAG1-VLP not only has the immunogenicity to block T. gondii infection by effectively inducing the generation of specific antibodies against T. gondii, but is also an effective antigen delivery system for preventing toxoplasmosis. This study indicates that SAG1-VLP can be effectively utilized as a promising vaccine candidate for preventing or inhibiting T. gondii infection.

Investigating the Antiparasitic Potential of the Marine Sesquiterpene Avarone, Its Reduced form Avarol, and the Novel Semisynthetic Thiazinoquinone Analogue Thiazoavarone

The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The semisynthetic compound, as well as the natural metabolites avarone and avarol, were pharmacologically investigated in order to assess their antiparasitic properties against sexual and asexual stages of Plasmodium falciparum, larval and adult developmental stages of Schistosomamansoni (eggs included), and also against promastigotes and amastigotes of Leishmania infantum and Leishmania tropica. Furthermore, in depth computational studies including density functional theory (DFT) calculations were performed. A toxic semiquinone radical species which can be produced starting both from quinone- and hydroquinone-based compounds could mediate the anti-parasitic effects of the tested compounds.