Development of new steroid-based hydrazide and (thio)semicarbazone compounds with anticancer properties.

Most breast and prostate cancers are caused by abnormal production or action of steroidal hormones. Hormonal drugs based on steroid scaffolds represent a significant class of chemotherapeutics that are routinely used in chemotherapy. In this study, the synthesis of new 17a-homo lactone and 17α-(pyridine-2-ylmethyl) androstane derivatives with hydrazide and semicarbazone motifs is presented. All compounds were screened for their effect on cell viability against a panel of five cancer cell lines and one healthy cell line. Two compounds showed significant cytotoxicity against cancer cells, with low toxicity against healthy cells. The relative binding affinities of compounds for the ligand-binding domains of estrogen receptor α, estrogen receptor ß, androgen receptor and glucocorticoid receptor were tested using a fluorescence screen in yeast. Potential for inhibition of aldo-keto reductase 1C3 and 1C4 activity was measured in vitro. Experimental results are analyzed in the context of molecular docking simulations. Our results could help guide design of steroid compounds with improved anticancer properties against androgen- and estrogen-dependent cancers.

Sublethal effect and detoxifying metabolism of metaflumizone and indoxacarb on the fall armyworm, Spodoptera frugiperda.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae), is a highly polyphagous invasive pest that damages various crops. Pesticide control is the most common and effective strategy to control FAW. In this study, we evaluated the toxicity of metaflumizone and indoxacarb against third-instar FAW larvae using the insecticide-incorporated artificial diet method under laboratory conditions. Both metaflumizone and indoxacarb exhibited substantial toxicity against FAW, with LC50 values of 2.43 and 14.66 mg/L at 72 h, respectively. The sublethal effects of metaflumizone and indoxacarb on parental and F1 generation FAW were investigated by exposing third-instar larvae to LC10 and LC30 concentrations of these insecticides. Sublethal exposure to these two insecticides significantly shortened adult longevity, extended pupal developmental times and led to reduced pupal weight, pupation rates, and adult fecundity in the treated parental generation and F1 generation at LC10 or LC30 concentrations, in comparison to the control group. The larval developmental times were shortened in the parental generation but prolonged in the F1 generation, after being treated with sublethal concentrations of metaflumizone. Furthermore, larvae exposed to LC10 or LC30 concentrations of indoxacarb exhibited elevated activity levels of cytochrome P450 monooxygenase and glutathione S-transferase, which coincides with the observed synergistic effect of piperonyl butoxide and diethyl maleate. In conclusion, the high toxicity and negative impact of metaflumizone and indoxacarb on FAW provided significant implications for the rational utilization of insecticides against this pest.

New ruthenium(II) complexes with cyclic thio- and semicarbazone: evaluation of cytotoxicity and effects on cell migration and apoptosis of lung cancer cells.

We describe the synthesis, physicochemical characterization, and in vitro antitumor assays of four novel analogous ruthenium(II) complexes with general formula cis-[RuII(N-L)(P-P)2]PF6, where P-P = bis(diphenylphosphine)methane (dppm, in complexes 1 and 2) or bis(diphenylphosphine)ethane (dppe, in complexes 3 and 4) and N-L = 5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione (Btsc, in complexes 1 and 3) or 5,6-diphenyltriazine-3-one (Bsc, in complexes 2 and 4). The data were consistent with cis arrangement of the biphosphine ligands. For the Btsc and Bsc ligands, the data pointed to monoanionic bidentate coordination to ruthenium(II) through N,S and N,O, respectively. Single-crystal X-ray diffraction showed that complex 1 crystallized in the monoclinic system, space group P21/c. Determination of the cytotoxicity profiles of complexes 1-4 gave SI values ranging from 1.19 to 3.50 against the human lung adenocarcinoma cell line A549 and the non-tumor lung cell line MRC-5. Although the molecular docking studies suggested that the interaction between DNA and complex 4 was energetically favorable, the experimental results showed that they interacted weakly. Overall, our results demonstrated that these novel ruthenium(II) complexes have interesting in vitro antitumor potential and this study may contribute to further studies in medicinal inorganic chemistry.

Synthesis, antimicrobial, antibiofilm and computational studies of isatin-semicarbazone tethered 1,2,3-triazoles.

In present era, heterocyclic compounds containing two or three nitrogen atoms play a vital role in drug discovery. In this context, a new class of isatin-semicarbazone tethered 1,2,3-triazole hybrids was synthesized via Cu(I)-mediated azide alkyne cycloaddition reaction. Structural characteristics of the newly derived compounds were identified by various spectral techniques like FTIR, 1H NMR, 13C NMR, HRMS and single crystal X-ray crystallography. Synthesized derivatives were also screened for in vitro antimicrobial and antibiofilm activity against different microbial species. Triazole hybrid 7e showed significant efficacy towards E. coli having MIC of 0.0063 µmol/mL, whereas 6a, 6b, 7a, 7c, 7e, and 7f showed highest percentage of biofilm inhibition against P. aeruginosa. Bioassay results suggested that these triazole hybrids could act as biomaterial for antimicrobial and antibiofilm applications and may constitute a new promising class of antimicrobial and antibiofilm agents. These results were further supported by in silico docking, DFT calculations and ADME studies.

Selenosemicarbazone Metal Complexes as Potential Metal-based Drugs.

The discovery of the anticancer activity of cisplatin has marked the emergence of modern Inorganic Medicinal Chemistry. This field of research is concerned with the application of inorganic compounds to therapy or diagnosis of disease. In particular, metal coordination of bioactive ligands has gained recognition in drug design. The interaction between transition metal ions and the organic drugs could enhance their diagnostic and therapeutic potentials by improving the stability and/or bioavailability or by achieving a metal-drug synergism through a dual or multiple mechanisms of action. The isosteric replacement of sulfur by selenium in thiosemicarbazones leads to selenosemicarbazones. This class of compounds exhibits numerous biological activities like antitumor, antimicrobial, antiviral, etc. and, in most cases, they were more pronounced in comparison to the sulfur analogues. On the other hand, while the effect of transition metal complexation on the biological activity of thiosemicarbazones has been widely studied, the pharmacological activity of the corresponding metal-selenosemicarbazone compounds has been less explored. In this work, the most relevant results related to the selenosemicarbazone metal complexes as potential metal-based drugs have been reviewed.

The coordination modes of (thio)semicarbazone copper(II) complexes strongly modulate the solution chemical properties and mechanism of anticancer activity.

Thiosemicarbazones are promising candidates for anticancer therapy and their mechanism of action is often linked to their metal chelating ability. In this study, five (thio)semicarbazones with different donor sets (NNS, NNO, ONS, ONO) were selected and their behaviour in aqueous solution, the stability of their copper(II) complexes in addition to their cytotoxicity, DNA-binding, DNA cleavage ability and inhibition of topoisomerase IIα were investigated and compared. We aimed to reveal relationships between the structural variations, the significantly different physico-chemical properties, solution speciation and biological activity. The cytotoxicity of the ligands did not show correlation with the solubility, lipophilicity and permeability; and the decreased activity of the oxygen donor containing compounds was explained by their stronger preference towards chelation of iron(III) over iron(II). Meanwhile, among the copper complexes the most lipophilic species with the highest stability and membrane permeability exhibited the highest cytotoxicity. The studied copper(II) complexes interact with DNA, and reaction with glutathione led to heavy DNA cleavage in the case of the highly stable complexes which could be reduced in a reversible reaction with moderate rate. All the tested copper complexes inhibited topoisomerase IIα, however, this property of the complexes with low stability is most probably linked to the liberated free copper(II).

Thio- and selenosemicarbazones as antiprotozoal agents against Trypanosoma cruzi and Trichomonas vaginalis.

Herein, we report the preparation of a panel of Schiff bases analogues as antiprotozoal agents by modification of the stereoelectronic effects of the substituents on N-1 and N-4 and the nature of the chalcogen atom (S, Se). These compounds were evaluated towards Trypanosoma cruzi and Trichomonas vaginalis. Thiosemicarbazide 31 showed the best trypanocidal profile (epimastigotes), similar to benznidazole (BZ): IC50 (31)=28.72 µM (CL-B5 strain) and 33.65 µM (Y strain), IC50 (BZ)=25.31 µM (CL-B5) and 22.73 µM (Y); it lacked toxicity over mammalian cells (CC50 > 256 µM). Thiosemicarbazones 49, 51 and 63 showed remarkable trichomonacidal effects (IC50 =16.39, 14.84 and 14.89 µM) and no unspecific cytotoxicity towards Vero cells (CC50 ≥ 275 µM). Selenoisosters 74 and 75 presented a slightly enhanced activity (IC50=11.10 and 11.02 µM, respectively). Hydrogenosome membrane potential and structural changes were analysed to get more insight into the trichomonacidal mechanism.

Carbazole-based semicarbazones and hydrazones as multifunctional anti-Alzheimer agents.

With the aim to combat a multi-faceted neurodegenerative Alzheimer's disease (AD), a series of carbazole-based semicarbazide and hydrazide derivatives were designed, synthesized and assessed for their cholinesterase (ChE) inhibitory, antioxidant and biometal chelating activity. Among them, (E)-2-((9-ethyl-9H-carbazol-3-yl)methylene)-N-(pyridin-2-yl)hydrazinecarbothioamide (62) and (E)-2-((9-ethyl-9H-carbazol-3-yl)methylene)-N-(5-chloropyridin-2-yl)hydrazinecarbothioamide (63) emerged as the premier candidates with good ChE inhibitory activities (IC50 values of 1.37 µM and 1.18 µM for hAChE, IC50 values of 2.69 µM and 3.31 µM for EqBuChE, respectively). All the test compounds displayed excellent antioxidant activity (reduction percentage of DPPH values for compounds (62) and (63) were 85.67% and 84.49%, respectively at 100 µM concentration). Compounds (62) and (63) conferred specific copper ion chelating property in metal chelation study. Molecular docking studies of compounds (62) and (63) indicate strong interactions within the active sites of both the ChE enzymes. Besides that, these compounds also exhibited significant in silico drug-like pharmacokinetic properties. Thus, taken together, they can serve as a starting point in the designing of multifunctional ligands in pursuit of potential anti-AD agents that might further prevent the progression of ADs.Communicated by Ramaswamy H. Sarma.

Azobenzene-Semicarbazone Enables Optical Control of Insect Sodium Channels and Behavior.

Photopharmacology uses molecular photoswitches to establish control over the action of bioactive molecules. The application of photopharmacology in the research of invertebrate sodium channels has not been investigated. Here we report several photochromic ligands of metaflumizone. One ligand, termed ABM04, underwent reversible trans-cis isomerization under ultraviolet or blue light irradiation. cis-ABM04 had excellent larvicidal activity against mosquito larvae with an LC50 value of 4.39 µM and showed insecticidal activity against Mythimna separata with an LC50 value of 7.19 µM. However, trans-ABM04 was not found to have biological activity. ABM04 (10 µM) can induce depolarization of dorsal unpaired median neurons and enable the real-time photoregulation of mosquito larval behavior. The precise regulation of invertebrate sodium channels is realized for the first time, which provides a new strategy for the basic and accurate research of invertebrate sodium channels.

Design and Synthesis of Novel Betulin Derivatives Containing Thio-/Semicarbazone Moieties as Apoptotic Inducers through Mitochindria-Related Pathways.

Two new series of betulin derivatives with semicarbazone (7a-g) or thiosemicarbazone (8a-g) groups at the C-28 position were synthesized. All compounds were evaluated for their in vitro cytotoxicities in human hepatocellular carcinoma cells (HepG2), human breast carcinoma cells (MCF-7), human lung carcinoma cells (A549), human colorectal cells (HCT-116) and normal human gastric epithelial cells (GES-1). Among these compounds, 8f displayed the most potent cytotoxicity with an IC50 value of 5.86 ± 0.61 µM against MCF-7 cells. Furthermore, the preliminary mechanism studies in MCF-7 cells showed that compound 8f could trigger the intracellular mitochondrial-mediated apoptosis pathway by losing MMP level, which was related with the upregulation of Bax, P53 and cytochrome c expression; the downregulation of Bcl-2 expression; activation of the expression levels of caspase-3, caspase-9, cleaved caspase-3 and cleaved caspase-9; and an increase in the amounts of intracellular reactive oxygen species. These results indicated that compound 8f may be used as a valuable skeleton structure for developing novel antitumor agents.

Semicarbazones, thiosemicarbazone, thiazole and oxazole analogues as monoamine oxidase inhibitors: Synthesis, characterization, biological evaluation, molecular docking, and kinetic studies.

A series of semicarbazone, thiosemicarbazone, thiazole, and oxazole derivatives were designed, synthesized, and examined for monoamine oxidase inhibition using two isoforms, i.e., MAO-A and MAO-B. Among all the analogues, 3c and 3j possessed substantial activity against MAO-A with IC50 values of 5.619 ± 1.04 µM and 0.5781 ± 0.1674 µM, respectively. Whereas 3d and 3j were active against monoamine oxidase B with the IC50 values of 9.952 ± 1.831 µM and 3.5 ± 0.7 µM, respectively. Other derivatives active against MAO-B were 3c and 3g with the IC50 values of 17.67 ± 5.6 µM and 37.18 ± 2.485 µM. Moreover, molecular docking studies were achieved for the most potent compound (3j) contrary to human MAO-A and MAO-B. Kinetic studies were also performed for the most potent analogue to evaluate its mode of interaction with MAO-A and MAO-B.

Complex formation of an estrone-salicylaldehyde semicarbazone hybrid with copper(II) and gallium(III): Solution equilibria and biological activity.

The solution chemical properties such as proton dissociation, complex formation with copper(II) and gallium(III) ions in addition to antibacterial and antitumor activity of a novel tridentate salicyaldehyde semicarbazone-estrone hybrid (estrone-SC) and a related bicyclic compound (thn-SC) were investigated. The crystal structure of complex [Cu(thn-SCH-1)Cl] was studied by single crystal X-ray diffraction method. Estrone-SC and thn-SC form mono-ligand complexes with Cu(II) characterized by relatively high stability, however, they are much less stable than their thiosemicarbazone analogues. The neutral Cu(II) complexes with (O-,N,O-)(H2O) coordination mode predominate at physiological pH. Estrone-SC and thn-SC are more efficient Ga(III) binders in comparison with thiosemicarbazones, although the complexes also suffer dissociation at pH 7.4. The Cu(II) complex of estrone-SC displayed significant cytotoxicity in A549, SW480 and CH1/PA cancer cells, and moderate apoptosis induction and ROS formation. The semicarbazone compounds did not exhibit antibacterial effect; unlike the related Cu(II)-thiosemicarbazone complexes represented by the fairly low MIC values (3-50 µM) obtained on the Gram-positive Staphylococcus aureus and Enterococcus faecalis bacteria.

Design, synthesis and insecticidal activity of novel semicarbazones and thiosemicarbazones derived from chalcone.

Thirty semicarbazone and thiosemicarbazone derivatives (2a-w and 4a-g) from chalcones containing furan and thiophene ring were designed and synthesized. They were characterized by IR, 1H NMR, 13C NMR and HRMS. The crystal structure of compound 2r was characterized by single crystal X-ray diffraction. It crystallizes in the monoclinic system with space group P21/c. The insecticidal activity of the synthesized compounds was screened against Leucania separata and Pieris rapae using beta-cypermethrin as the comparative standard. The results displayed that most of them had remarkable insecticidal activity. Among them, compounds 2e-g showed better activity than beta-cypermethrin against L. separata and P. rapae. Compound 2p also possessed a better activity than beta-cypermethrin against P. rapae. The insecticidal activities of these compounds have been reported for the first time.

Design, synthesis, and biological activity of novel semicarbazones as potent Ryanodine receptor1 inhibitors of Alzheimer's disease.

Ryanodine receptors (RyRs) are important ligand-gated Ca2+ channels; their excessive activation leads to Ca2+ leakage in the sarcoplasmic reticulum that may cause neurological diseases. In this study, three series of novel potent RyR1 inhibitors based on dantrolene and bearing semicarbazone and imidazolyl moieties were designed and synthesized, and their biological activity was evaluated. Using a single-cell calcium imaging method, the calcium overload inhibitory activities of 26 target compounds were tested in the R614C cell line, using dantrolene as a positive control. The preliminary investigation showed that compound 12a suppressed Ca2+ release as evidenced by store overload-induced Ca2+release (SOICR) (31.5 ± 0.1%, 77.2 ± 0.1%, 93.7 ± 0.2%) at 0.1 µM, 3 µM and 10 µM, respectively. Docking simulation results showed that compound 12a could bind at the active site of the RyR1 protein. The Morris water-maze test showed that compound 12a significantly improved the cognitive behavior of AD-model mice. Further studies on the structural optimization of this series of derivatives are currently underway in our laboratory.

Synthesis, cytotoxicity, and in vivo antitumor activity study of parthenolide semicarbazones and thiosemicarbazones.

Parthenolide is an important sesquiterpene lactone with potent anticancer activities. In order to further improve its biological activity, a series of parthenolide semicarbazone or thiosemicarbazone derivatives was synthesized and evaluated for their anticancer activity. Derivatives were tested in vitro against 5 human tumor cell lines, and many of these showed higher cytotoxicity than parthenolide. Five compounds were further studied for their antitumor activity in mice. The in vivo result indicated that compound 4d showed both promising antitumor activity against mice colon tumor and small side effects on immune systems. The cell apoptosis and cell cycle distribution of compound 4d were also studied. Molecular docking studies revealed multiple interactions between 4d and NF-κB. Our findings demonstrate the potential of semicarbazones as a promising type of compounds with anticancer activity.

Novel Steroidal 5α,8α-Endoperoxide Derivatives with Semicarbazone/Thiosemicarbazone Side-chain as Apoptotic Inducers through an Intrinsic Apoptosis Pathway: Design, Synthesis and Biological Studies.

A series of novel steroidal 5α,8α-endoperoxide derivatives bearing semicarbazone (7a-g) or thiosemicarbazone (7h-k) side chain were designed, synthesized and evaluated for their cytotoxicities in four human cancer cell lines (HepG2, HCT-116, MCF-7, and A549) using the MTT assay in vitro. The results showed that compound 7j exhibited significant cytotoxic activity against HepG2 cells (IC50 = 3.52 µM), being more potent than ergosterol peroxide. Further cellular mechanism studies in HepG2 cells indicated that compound 7j triggered the mitochondrial-mediated apoptosis by decreasing mitochondrial membrane potential (MMP), which was associated with up-regulation of Bax, down-regulation of Bcl-2, activation levels of the caspase cascade, and formation of reactive oxygen species (ROS). The above findings indicated that compound 7j may be used as a promising skeleton for antitumor agents with improved efficacy.

Synthesis and Biological Evaluation of Novel (thio)semicarbazone-Based Benzimidazoles as Antiviral Agents against Human Respiratory Viruses.

Respiratory RNA viruses are responsible for recurrent acute respiratory illnesses that still represent a major medical need. Previously we developed a large variety of benzimidazole derivatives able to inhibit these viruses. Herein, two series of (thio)semicarbazone- and hydrazone-based benzimidazoles have been explored, by derivatizing 5-acetyl benzimidazoles previously reported by us, thereby evaluating the influence of the modification on the antiviral activity. Compounds 6, 8, 16 and 17, bearing the 5-(thio)semicarbazone and 5-hydrazone functionalities in combination with the 2-benzyl ring on the benzimidazole core structure, acted as dual inhibitors of influenza A virus and human coronavirus. For respiratory syncytial virus (RSV), activity is limited to the 5-thiosemicarbazone (25) and 5-hydrazone (22) compounds carrying the 2-[(benzotriazol-1/2-yl)methyl]benzimidazole scaffold. These molecules proved to be the most effective antiviral agents, able to reach the potency profile of the licensed drug ribavirin. The molecular docking analysis explained the SAR of these compounds around their binding mode to the target RSV F protein, revealing the key contacts for further assessment. The herein-investigated benzimidazole-based derivatives may represent valuable hit compounds, deserving subsequent structural improvements towards more efficient antiviral agents for the treatment of pathologies caused by these human respiratory viruses.

Design, Synthesis and Biological Evaluation of Novel 4-phenoxypyridine Derivatives Containing Semicarbazones Moiety as Potential c-Met Kinase Inhibitors.

BACKGROUND: The Hepatocyte Growth Factor Receptor (HGFR) c-Met is over-expressed and/or mutated in various human tumor types. Dysregulation of c-Met/HGF signaling pathway affects cell proliferation, survival and motility, leading to tumor growth, angiogenesis, and metastasis. Therefore, c-Met has become an attractive target for cancer therapy. OBJECTIVE: This study is aimed to evaluate a new series of 4-phenoxypyridine derivatives containing semicarbazones moiety for its cytotoxicity. METHODS: A series of novel 4-phenoxypyridines containing semicarbazone moieties were synthesized and evaluated for their in vitro cytotoxic activities against MKN45 and A549 cancer cell lines and some selected compounds were further examined for their inhibitory activity against c-Met kinase. In order to evaluate the mechanism of cytotoxic activity of compound 24, cell cycle analysis, Annexin V/PI staining assay, AO/EB assay, wound-healing assay and docking analysis with c-Met were performed. RESULTS: The results indicated that most of the compounds showed moderate to good antitumor activity. The compound 28 showed well cytotoxic activity against MKN45 and A549 cell lines with IC50 values of 0.25µM and 0.67µM, respectively. Compound 24 showed good activity on c-Met and its IC50 value was 0.093µM. CONCLUSION: Their preliminary Structure-Activity Relationships (SARs) studies indicated that electronwithdrawing groups on the terminal phenyl rings are beneficial for improving the antitumor activity. Treatments of MKN45 cells with compound 24 resulted in cell cycle arrest in G2/M phase and induced apoptosis in a dose-dependent manner. In addition, AO/EB assays indicated 24 induced dose-dependent apoptosis of A549 and MKN45 cells. Wound-healing assay results indicated that compound 24 strongly inhibited A549 cell motility.

Synthesis and preliminary screening for the biological activity of some steroidal Δ4-unsaturated semicarbazone derivatives.

Eleven new steroidal mono- and bis(semicarbazones) 2a-e, 4d and 3a-e have been prepared starting from various 3-oxo-α,ß-unsaturated steroids. Mono-semicarbazones 2a-e were further subjected to ethyl chloroacetate in boiling absolute ethanol but, instead of expected intramolecular cyclocondensation reaction products, the new carbazate esters 5a-e were obtained. The structures of all synthesized compounds and identification of each E/Z isomer were deduced by elemental analysis, HRMS, NMR, and IR spectroscopy. Preliminary screening for the cytotoxic activity in vitro of the new compounds has been conducted against three cancer cell lines, K562, Jurkat and HeLa cells. HeLa cells were the most sensitive while K562 cells were the least sensitive to the cytotoxic action of the novel steroid derivatives. Compounds 2e, 3c and 5e were found to have the best but still moderate cytotoxic effects. All tested compounds showed very weak antimicrobial activities. These results demonstrate that the replacement of thioxo group with carbonyl group in steroidal hydrazone derivatives resulted in decrease in their biological activity.

Semicarbazone derivatives as promising therapeutic alternatives in leishmaniasis.

In the present study, we investigated the in vitro and in vivo leishmanicidal activity of synthetic compounds, containing a semicarbazone scaffold as a peptide mimetic framework. The leishmanicidal effect against amastigotes of Leishmania amazonensis was also evaluated at concentration of 100 µM-0.01 nM. The derivatives 2e, 2f, 2g and 1g, beyond the standards miltefosine and pentamidine, significantly diminished the number of L. amazonensis amastigotes in macrophages. These derivatives were also active against amastigotes of L. braziliensis. As 2g presented potent leishmanicidal activity against the amastigotes of L. amazonensis in macrophages, we also investigated the in vivo leishmanicidal activity of this compound against L. amazonensis. Approximately 105L. amazonensis promastigotes were subcutaneously inoculated into the dermis of the right ear of BALB/c mice, which were subsequently treated with 2g (p.o. or i.p.), miltefosine (p.o.) or glucantime (i.p.) at 30 µmol/kg/day x 28 days. Thus, a similar reduction in the lesion size was observed after the administration of 2g through oral (63.7 ±â€¯10.1%) and intraperitoneal (61.8 ±â€¯3.7%) routes. A larger effect was observed after treatment with miltefosine (97.7 ±â€¯0.4%), and glucantime did not exhibit activity at the dose administered. With respect to the ear parasite load, 2g diminished the number of parasites by p.o. (30.5 ±â€¯5.1%) and i.p. (33.3 ±â€¯4.3%) administration. In addition, 2g induced in vitro apoptosis, autophagy and cell cycle alterations on L. amazonensis promastigotes. In summary, the derivative 2g might represent a lead candidate for antileishmanial drugs, as this compound displayed pronounced leishmanicidal activity.