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Functionalized 1,4-naphthoquinones have been employed as versatile synthons in organic synthesis, in addition to presenting a large array of biological activities. Herein, the applications of 2-amino-/ acetylamino-substituted 3-iodo-1,4-naphthoquinones in cross-coupling reactions are described to successfully afford sixteen novel 3-styryl-1,4-naphthoquinones (amino-stilbene-quinone hybrids) and four 3-alkynyl-1,4-naphthoquinone in overall good yields. Interestingly, the alkynylated derivatives could be obtained from ligand- and Pd-free CuI-mediated cross-coupling reactions, after extensive investigations to exclude Pd as a co-catalyst. Lastly, the desilanized terminal alkyne was subjected to click chemistry reactions to give two novel triazole-1,4-naphthoquinone hybrids.

Acute myeloid leukemia (AML) is a complex hematological disorder characterized by blockage of differentiation and high proliferation rates of myeloid progenitors. Anthracycline and cytarabine‑based therapy has remained the standard treatment for AML over the last four decades. Although this treatment strategy has increased survival rates, patients often develop resistance to these drugs. Despite efforts to understand the mechanisms underlying cytarabine resistance, there have been few advances in the field. The present study developed an in vitro AML cell line model resistant to cytarabine (HL‑60R), and identified chromosomal aberrations by karyotype evaluation and potential molecular mechanisms underlying chemoresistance. Cytarabine decreased cell viability, as determined by MTT assay, and induced cell death and cell cycle arrest in the parental HL‑60 cell line, as revealed by Annexin V/propidium iodide (PI) staining and PI DNA incorporation, respectively, whereas no change was observed in the HL‑60R cell line. In addition, the HL‑60R cell line exhibited a higher tumorigenic capacity in vivo compared with the parental cell line. Notably, no reduction in tumor volume was detected in mice treated with cytarabine and inoculated with HL‑60R cells. In addition, western blotting revealed that the protein expression levels of Bcl‑2, X‑linked inhibitor of apoptosis protein (XIAP) and c‑Myc were upregulated in HL‑60R cells compared with those in HL‑60 cells, along with predominant nuclear localization of the p50 and p65 subunits of NF‑κB in HL‑60R cells. Furthermore, the antitumor effect of LQB‑118 pterocarpanquinone was investigated; this compound induced apoptosis, a reduction in cell viability and a decrease in XIAP expression in cytarabine‑resistant cells. Taken together, these data indicated that acquired cytarabine resistance in AML was a multifactorial process, involving chromosomal aberrations, and differential expression of apoptosis and cell proliferation signaling pathways. Furthermore, LQB‑118 could be a potential alternative therapeutic approach to treat cytarabine‑resistant leukemia cells.

The preparation of two new Ru(II)/diphosphine complexes containing Lapachol (Lap) and Lawsone (Law): (1) [Ru(Lap)(dppm)2]PF6 and (2) [Ru(Law)(dppm)2]PF6, where dppm = bis(diphenylphosphino)methane, is reported here. The complexes were synthetized and fully characterized by elemental analyses, molar conductivity, UV–Vis, IR, 31P{1H}, 1H and 13C NMR, and the crystal structure of the complex (1) was determined by X-ray diffraction. Complexes (1) and (2) showed high in vitro cytotoxicity against four cancer cells (MDA-MB-231, MCF-7, A549 and DU-145), with IC50 values in the micromolar range (0.03 to 2.70 μM). Importantly, complexes (1) and (2) were more active than the cisplatin, the drug used as a reference in the cytotoxic assays. Moreover, complex (1) showed high selectivity to triple-negative breast cancer cells (MDA-MB-231). Studies of the mechanism of action in MDA-MB-231 cancer cells showed that complex (1) inhibits cell migration, colony formation, and induces cell cycle arrest and apoptosis by activation of the mitochondrial pathway through the loss of mitochondrial membrane potential (ΔΨm). Furthermore, complex (1) induces ROS (Reactive Oxygen Species) generation in MDA-MB-231 cells, which can cause DNA damage. Finally, complexes (1) and (2) interact with DNA by minor grooves and show a moderate interaction with BSA (Bovine Serum Albumin), with the involvement of hydrophobic interactions. Essentially, Ru(II)/diphosphine-naphthoquinone complexes have remarkable cytotoxic effects with high selectivity to triple-negative breast cancer (MDA-MB-231) and could be promising anticancer candidates for cancer treatment. Synopsis The naphthoquinones Lapachol and Lawsone can form new ruthenium compounds with promising anticancer properties.

Chronic myeloid leukemia (CML), a myeloproliferative disorder characterized by the BCR-ABL oncoprotein, presents its treatment based on tyrosine kinase inhibitors (TKIs), mainly imatinib. However, despite its clinical success, almost 30% of all CML patients demand alternative therapy. In this context, the development of drugs capable of overcoming TKIs resistance is imperative. LQB-118 is a compound with anti-tumour effect in two CML cell lines (K562, sensitive and K562-Lucena, resistant) whose mechanism of action is being elucidated. Here, we demonstrate that combined treatment of CML cell lines with imatinib and LQB-118 increased cell death and that microarray analysis of CML cells treated with LQB-118 presented several differentially expressed genes. Also, IGF-1R, AKT and mTOR protein levels are decreased after LQB-118 treatment and the compound alters the expression of all members of miR-29 family. CML cells silenced for IGF-1R were less sensitive to LQB-118 treatment than negative control and protein levels of IGF-1R and AKT were no longer altered after LQB-118 or imatinib treatment. Taken together, our results highlight IGF-1R/AKT/mTOR as a critical axis for LQB-118 activity and demonstrate that LQB-118 is effective in sensitizing CML cells to TKI, contributing to the development of a more efficient therapy.

Background: Despite the development of new therapies for leishmaniasis, among the 200 countries or territories reporting to the WHO, 87 were identified as endemic for Tegumentary Leishmaniasis and 75 as endemic for Visceral Leishmaniasis. The identification of antileishmanial drug candidates is essential to fill the drug discovery pipeline for leishmaniasis. In the hit molecule LQB-118 selected, the first generation of pterocarpanquinones was effective and safe against experimental visceral and cutaneous leishmaniasis via oral delivery. In this paper, we report the synthesis and antileishmanial activity of the second generation of pterocarpanoquinones. Methods: The second generation of pterocarpanquinones 2a-f was prepared through a palladium-catalyzed oxyarylation of dihydronaphtalen and chromens with iodolawsone, easily prepared by iodination of lawsone. The spectrum of antileishmanial activity was evaluated in promastigotes and intracellular amastigotes of L. amazonensis, L. braziliensis, and L. infantum. Toxicity was assessed in peritoneal macrophages and selective index calculated by CC50/IC50. Oxidative stress was measured by intracellular ROS levels and mitochondrial membrane potential in treated cells. Results: In this work, we answered two pertinent questions about the structure of the first-generation pterocarpanquinones: the configuration and positions of rings B (pyran) and C (furan) and the presence of oxygen in the B ring. When rings B and C are exchanged, we noted an improvement of the activity against promastigotes and amastigotes of L. amazonensis and promastigotes of L. infantum. As to the oxygen in ring B of the new generation, we observed that the oxygenated compound 2b is approximately twice as active against L. braziliensis promastigotes than its deoxy derivative 2a. Another modification that improved the activity was the addition of the methylenedioxy group. A variation in the susceptibility among species was evident in the clinically relevant form of the parasite, the intracellular amastigote. L. amazonensis was the species most susceptible to novel derivatives, whilst L. infantum was resistant to most of them. The pterocarpanoquinones (2b and 2c) that possess the oxygen atom in ring B showed induction of increased ROS production. Conclusions: The data presented indicate that the pterocarpanoquinones are promising compounds for the development of new leishmanicidal agents.

Styrenes were coupled with 3-iodolawsone in PEG-400 at 90 °C, leading stereoselectively to (E)-stilbene-quinone hybrids through Heck reactions. The best reaction conditions were found to be the use of NaOH (3 equiv) and 10 mol% of palladium acetate at 90 °C for 15 minutes. The chemical yields of the Heck reactions using styrenes with electron-withdrawing groups (65–98%) were greater than styrenes bearing electron-donating groups (7–32%) on the aromatic ring. In particular, the chemical yields of Heck reactions involving nitrostyrenes were the best ones observed.

The racemic pterocarpanquinone LQB-118 is active, in mice and hamsters, against tegumentary and visceral leishmaniasis. This compound also presents antiinflammatory and antineoplastic activity in mice. The low level of toxicity observed in these studies makes LQB-118 a promising drug candidate. In order to conduct further biological testing to investigate enantioselectivity in the above-mentioned activities, a multimilligram amount of each enantiomer of LQB-118 was produced. Furthermore, vibrational circular dichroism (VCD) and Density Functional Theory (DFT) calculations were used to determine unambiguously their absolute configurations. The comparison of experimental and calculated VCD data led to the assignment of (-)-LQB-118 as 7aR,12aR and, consequently, (+)-LQB-118 as 7aS12aS.

Electrochemical methods are considered useful tools for simulations of biological redox reactions. The activities of quinones depend on their bioreduction. Biologically active pterocarpanquinones LQB-149 (nitroderivative), 150 and 151 (bromo and chloroderivatives, respectively) were electrochemically investigated by cyclic voltammetry, differential pulse voltammetry, and in situ UV-Vis spectroelectrochemistry, in aprotic media (N,N-dimethylformamide (DMF) + tetra-N-butylammonium (TBAPF6)). The data obtained regarding their reduction mechanisms, positive reactivity with oxygen and analysis of the electrogenerated intermediates were useful in explaining their biological outcomes. The appearance of bands at 397 and 480 nm, for the halogenated compounds, suggests the generation of transient quinonemethides (QM), electrophilic intermediates related to their activity. As an additional proof for the intermediacy of QM, in the redox processes, chemical reduction of LQB-150, in the presence of hexanethiol was performed and led to a thioalkylated quinone. For the nitroderivative, a broad band appeared at 432 nm, corresponding to the generation of the nitroradical anion, giving rise to a dianion diradical, after reduction at the second wave potential. Computational data correlate well with electrochemical experiments. Homogeneous electron transfer to oxygen, yielding reactive oxygen species, the generation of electrophilic species and the radical reactivity, explain partially the mechanism of biological action.

Glioblastoma (GBM) is the most frequent malignant brain tumor. It represents the most aggressive astrocytoma with an overall survival of 14 months. Despite improvements in surgery techniques, radio‑ and chemotherapy, most patients present treatment resistance, recurrence and disease progression. Therefore, development of effective alternative therapies is essential to overcome treatment failure. The purpose of the study was to evaluate the antitumoral activity of the synthetic compound LQB‑118, in vitro. Monolayer and three‑dimensional (3D) cell culture systems of human‑derived GBM cell lines were used to evaluate the effect of LQB‑118 on cell viability, cell death and migration. LQB‑118 reduced cell viability as determined by MTT and trypan blue exclusion assays and promoted apoptosis in monolayer cell lines with an intrinsic temozolomide (TMZ)‑resistance profile. In 3D culture models, LQB‑118 reduced cell viability as evaluated by APH assay and inhibited cell migration while the TMZ resistance profile was maintained. Moreover, LQB‑118 reduced p38 and AKT expression and phosphorylation, whereas it reduced only the phosphorylated ERK1/2 form. LQB‑118 reduced p38 and NRF2 expression, an axis that is associated with TMZ resistance, revealing a mechanism to overcome resistance. LQB‑118 also demonstrated an additional effect when combined with ionizing radiation and cisplatin. In conclusion, the present data demonstrated that LQB‑118 maintained its effectiveness in a 3D cell conformation, which shares more similarities with the tumor mass. LQB‑118 is a promising agent for GBM treatment as monotherapy and associated with radiotherapy or cisplatin. Its effect is associated with inhibition of GBM‑related survival signaling pathways.

The electrochemistry of a redox-based bioactive pterocarpanquinone, designated as LQB-118, and its precursor chromenquinone (CQ) was investigated in protic and aprotic media with a focus on the reduction mechanism in both media, the reactivity with oxygen, and the interaction with biological targets, such as DNA. UV/Vis spectroelectrochemistry clarified the proposed mechanism. The appearance of bands at λ=331, 400, and 600 nm suggests the generation of transient quinonemethides (QM). Electrochemical experiments revealed homogeneous electron transfer to oxygen. LQB-118 itself interacts with calf-thymus DNA and ssDNA in solution. It, and its electrogenerated intermediates, have been shown to decrease the diagnostic oxidation peaks of guanosine and adenosine residues. These results, together with electrochemical evidence for the formation of QMs and the reductive addition of thiols, partly explain the reported cytotoxic and parasiticidal effects of this quinone. Overall, the electrochemical methods do well to predict the molecular mechanism of the biological activity of the present class of compounds. As an additional competitive advantage, electrochemistry allows reductive cleavage in situ, the characterization of the generated intermediate, the calculation of the number of transferred electrons, and positively mimics in vitro and in vivo experiments.

LQB 118, a hydride molecule, has been described as an antineoplastic and antiparasitic drug. Recently, LQB118 was also shown to display anti-inflammatory properties using an LPS-induced lung inflammation model. However, LQB 118 effects on the inflammatory response induced by zymosan has not been demonstrated. In this study, swiss mice were LQB 118 intraperitoneally (i.p.) treated and zymosan was used to induce peritoneal inflammation. Peritoneal fluid was collected and used for cell counting and proinflammatory cytokines quantification (IL-1β, IL-6, and TNF-α) by immunoenzymatic assay (ELISA). For in vitro studies, peritoneal macrophages zymosan-stimulated were used. Results demonstrated that LQB 118 treatment reduced polymorphonuclear cell migration and TNF-α, IL-1β, and IL-6 levels in the peritoneal cavity. In macrophages, LQB 118 treatment display no cytotoxic effect and is also able to reduce cytokines levels. To investigate LQB 118 putative mechanism of action, TLR2, CD69, and P-p38 MAPK expression were evaluated. LQB 118 treatment reduced CD69 expression and p38 phosphorylation induced by zymosan. Furthermore, LQB 118 was able to negatively modulate TLR2 expression in the presence of inflammatory stimulus. Thus, our study provide new evidences for the mechanisms related to the anti-inflammatory effect of LQB 118 in vivo and in vitro.

The syntheses, physico-chemical characterization and cytotoxicity toward three human cell lines (standard and resistant sarcoma cells, and fibroblast) of a new copper(II) complex [Cu(HBPA)(L1)Cl]·3H2O 2 are reported. Complex 2 was obtained through the reaction between the ligand stilbene-quinone (HL1) and Cu[HBPA]Cl2 1, where HBPA = 2-hydroxybenzyl-2pyridylmethylamine. The synthesis of HL1 was performed in high yield through Heck reaction on PEG-400. X-ray diffraction and solution studies (UV–Vis, EPR, ESI(+)−MS and ESI(+)−MS/MS) were performed for complex 2, in which the copper(II) center is coordinated to the quinone in its deprotonated form, to the ligand HBPA and to a chloro ligand. Similar reaction employing CuCl2·2H2O, instead of Cu[HBPA]Cl2 1 and HL1, has resulted in the obtainment of a furano-o-naphtoquinone (L2) with 99% selectivity, suggesting a new methodology to cyclize the ligand HL1. In order to obtain the analogous para-isomer (L3), and to evaluate the isomerism influence on cytotoxicity activity, a cyclization reaction of HL1 with NBS (N-bromosuccinimide) was also performed, which resulted in the obtainment of L2 (8%) and L3 (13%). X-ray diffraction studies were performed for L2 and complex 2, and the description of their structure elucidated. Results from MTT assay revealed that complex 2 is more active against sarcoma cell lines (MES-SA/Dx5 and MES-SA) than both the free ligand HL1 and complex 1, reducing cell viability to less than 50 μmol L−1. L2 was the most active in the series, presenting cytotoxicity against resistant MES-SA/Dx5 and its standard MES-SA cell line, respectively, three and ten times higher than the current drug doxorubicin.

The incidence of cancer grows annually worldwide and in Brazil it is the second cause of death. The search for anti-cancer drugs has then become urgent. It depends on the studies of natural and chemical synthesis products. The antitumor action of LQB-118, a pterocarpanquinone structurally related to lapachol, has been demonstrated to induce mechanisms linked to leukemia cell apoptosis. This work investigated some mechanisms of the in vitro antitumor action of LQB-118 on prostate cancer cells. LQB-118 reduced the expression of the c-Myc transcription factor, downregulated the cyclin D1 and cyclin B1 mRNA levels and upregulated the p21 cell cycle inhibitor. These effects resulted in cell cycle arrest in the S and G2/M phases and inhibition of tumor cell proliferation. LQB-118 also induced programmed cell death of the prostate cancer cells, as evidenced by internucleosomal DNA fragmentation and annexin-V positive cells. Except the cell cycle arrest in the S phase and enhanced c-Myc expression, all the mechanisms observed here for the in vitro antitumor action of LQB-118 were also found for Paclitaxel, a traditional antineoplastic drug. These findings suggest new molecular mechanisms for the LQB-118 in vitro antitumor action.

Objectives: The pterocarpanquinone LQB-118, previously demonstrated to be effective in vivo via oral delivery, was investigated for its mechanism in selective parasite killing. Methods: Oxidative stress in Leishmania amazonensis was analysed by evaluating reactive oxygen species (ROS) production (2′,7′-dichlorodihydrofluorescein diacetate) and the loss of mitochondrial membrane potential (DCm) using rhodamine, JC-1 and MitoCapture. Ultrastructural analysis was performed using transmission electron microscopy (TEM). DNA fragmentation was evaluated using terminal deoxyribonucleotidyl transferasemediated dUTP nick-end labelling (TUNEL). Results: Treatment with LQB-118 induced ROS production in the promastigotes of L. amazonensis in a concentration- dependent manner for the first 4 h and was sustained for 24 h. TEM analysis revealed several alterations typical of apoptosis. Promastigotes presented a reduction of DCm after 24 h of incubation with 2.5 mM (18.7%), 5 mM (63.7%) or 10 mM (70.7%) LQB-118. A sub-G0/G1 cell cycle phenotype was observed in 21%– 83% of the promastigotes incubated with 1.25–10 mM LQB-118. Concentration-dependent DNA fragmentation was observed in promastigotes treated with 2.5–10 mM LQB-118, and selective DNA fragmentation was observed in intracellular amastigotes after 72 h with 2.5 mM treatment. Conclusions: Our results suggest that LQB-118 selectively induces ROS-triggered and mitochondria-dependent apoptosis in this parasite.

Pterocarpanquinone (+/-)-LQB-118 presents antineoplastic and antiparasitic properties and also shows great inhibitory effect on TNF-α release in vitro. Here, its anti-inflammatory activity was evaluated in a lipopolysaccharide (LPS)-induced lung inflammation model in C57BL/6 mice. LPS inhalation induced a marked neutrophil infiltration to the lungs which was reduced by intraperitoneal treatment with (+/-)-LQB-118 in a similar manner to that of dexamethasone and even better than that of acetylsalicylic acid. Moreover, (+/-)-LQB-118 administration resulted in decrease of NF-κB activation and KC level in lungs, with a pronounced inhibitory effect on TNF-α release, measured in bronchoalveolar lavage fluid. Trying to understand the anti-inflammatory mechanism by which (+/-)-LQB-118 acts, we performed a molecular modeling analysis, including docking to estrogen receptors α and β. Results suggested that (+/-)-LQB-118 may bind to both receptors, with a similar orientation to 17-β-estradiol. Together, these results showed that (+/-)-LQB-118 exhibits an anti-inflammatory effect, most likely by inhibiting TNF-α release and NF-κB activation, which may be related to the estrogen receptor binding.

Countercurrent chromatography (CCC) was employed as a useful, fast and economic alternative to conventional chromatography techniques for the purification of a synthetic pterocarpanquinone, LQB-118. The separation was performed in a two-step CCC with the solvent system hexane-chloroform-methanol-water 2:1.5:5:2 in both steps. Traditional purification of these reaction products by silica gel column chromatography demanded a large amount of solvent and time, besides allowing the irreversible adsorption of the compound in the column. The use of 1H NMR for the calculation of KD of target compound is proposed as an alternative for HPLC measurements.

Toxoplasma gondii, the agent of Toxoplasmosis, is an obligate intracellular protozoan able to infect a wide range of vertebrate cells, including nonprofessional and professional phagocytes. Therefore, drugs must have intracellular activities in order to control this parasite. The most common therapy for Toxoplasmosis is the combination of sulfadiazine and pyrimethamine. This treatment is associated with adverse reactions, thus, the development of new drugs is necessary. In previous studies, naphthoquinone derivatives showed anti-cancer activity functioning as agents capable of acting on groups of DNA, preventing cancer cells duplication. These derivatives also display anti-parasitic activity against Plasmodium falciparum and Leishmania amazonensis. The derivative pterocarpanquinone tested in this work resulted from the molecular hybridization between pterocarpans and naphtoquinone that presents anti-tumoral and anti-parasitic activities of lapachol. The aim of this work was to determine if this derivative is able to change T. gondii growth within LLC-MK2 cells. The drug did not arrest host cell growth, but was able to decrease the infection index of T. gondii with an IC(50) of 2.5 μM. Scanning and transmission electron microscopy analysis showed morphological changes of parasites including membrane damage. The parasite that survived tended to encyst as seen by Dolichos biflorus lectin staining and Bag-1 expression. These results suggest that pterocarpanquinones are drugs potentially important for the killing and encystment of T. gondii.

Objectives This paper describes the antileishmanial properties of LQB-118, a new compound designed by molecular hybridization, orally active in Leishmania amazonensis-infected BALB/c mice. Methods In vitro antileishmanial activity was determined in L. amazonensis-infected macrophages. For in vivo studies, LQB-118 was administered intralesionally (15 μg/kg/day, five times a week), intraperitoneally (4.5 mg/kg/day, five times a week) or orally (4.5 mg/kg/day, five times a week) to L. amazonensis-infected BALB/c mice throughout experiments lasting 85 or 105 days. At the end of the experiments, serum levels of alanine aminotransferase, aspartate aminotransferase and creatinine were measured as toxicological parameters. Results LQB-118 was active against intracellular amastigotes of L. amazonensis [50% inhibitory concentration (IC(50)) 1.4 μM] and significantly less so against macrophages (IC(50) 18.5 μM). LQB-118 administered intralesionally, intraperitoneally or orally was found to control both lesion and parasite growth in L. amazonensis-infected BALB/c mice, without altering serological markers of toxicity. Conclusions These results demonstrate that the molecular hybridization of a naphthoquinone core to pterocarpan yielded a novel antileishmanial compound that was locally and orally active in an experimental cutaneous leishmaniasis model.

A new pterocarpanquinone ( 5a ) was synthesized through a palladium catalyzed oxyarylation reaction and was transformed, through electrophilic substitution reaction, into derivatives 5b – d . These compounds showed to be active against human leukemic cell lines and human lung cancer cell lines. Even multidrug resistant cells were sensitive to 5a , which presented low toxicity toward peripheral blood mononuclear cells (PBMC) cells and decreased the production of TNF-α by these cells. In the laboratory these pterocarpanquinones were reduced by sodium dithionite in the presence of thiophenol at physiological pH, as NAD(P)H quinone oxidoredutase-1 (NQO1) catalyzed two-electron reduction, and the resulting hydroquinone undergo structural rearrangements, leading to the formation of Michael acceptors, which were intercepted as adducts of thiophenol. These results suggest that these compounds could be activated by bioreduction.

Naturally occurring pterocarpans 1a , b , pterocarpan 1c , isoflavane 2 and ortho -quinone 3 were synthesized in the racemic form and their cytotoxic effect was evaluated on the human leukemia cell lines K562 (resistant to oxidative stress), Lucena-1 (MDR phenotype) and HL-60. Ortho -quinone 3 (IC 50 = 1.5 μM, 1.8 μM and 0.2 μM, respectively) and catechol pterocarpan 1a (IC 50 = 3.0 μM, 3.7 μM and 2.1 μM, respectively) were the most active compounds on these cells and were also evaluated on other human leukemia cell lines (Jurkat and Daudi). Ortho -quinone 3 was 2 to 10 times more potent than pterocarpan 1a , depending on the cell line considered, however, showed a greater toxicity for lymphocytes activated by PHA.

Cancer is a malignancy of worldwide prevalence, and although new therapeutic strategies are under investigation, patients still resort to reductive or palliative chemotherapy. Side effects are a great concern, since treatment can render patients susceptible to infections or secondary cancers. Thus, design of safer chemotherapeutic drugs must consider the risk of immunotoxicity. Pterocarpans are natural isoflavones that possess immunomodulatory and antineoplastic properties. Ubiquitous in nature, quinones are present in chemotherapeutic drugs such as doxorubicin and mitoxantrone. Our group has patented a hybrid molecule, the pterocarpanquinone LQB-118, and demonstrated its antineoplastic effect in vitro. In this report we describe its antineoplastic effect in vivo and assess its toxicity toward the immune system. Treated mice presented no changes in weight of primary and secondary organs of the immune system nor their cellular composition. Immunophenotyping showed that treatment increased CD4(+) thymocytes and proportionally reduced the CD4(+)CD8(+) subpopulation in the thymus. No significant changes were observed in T CD8(+) peripheral lymphocytes nor was the activation of fresh T cells affected after treatment. LQB-118 induced apoptosis in murine tumor cells in vitro, being synergistic with the autophagy promoter rapamycin. Furthermore, treatment significantly reduced ascites or solid Ehrlich and B16F10 melanoma growth in vivo, and ameliorated side effects such as cachexia. Based on its favorable preclinical profile and considering previous results obtained in vitro, this drug emerges as a promising candidate for further development.

Dihydronaphthalenes were oxyarylated with o-iodophenols, in PEG-400 at 140 or 170 °C, leading regio- and stereoselectively to 5-carbapterocarpans. By using Pd(OAc)2 (5–10 mol%) as precatalyst and Ag2CO3 (1.1 equiv) as base (conditions A), products were obtained in good to excellent chemical yields, in 5–30 minutes, irrespective of the pattern of substitution the starting materials. Alternatively, when p-hydroxyacetophenone oxime derived palladacycle (1 mol%) was used as precatalyst, and dicyclohexylamine (2 equiv) was used as base (silver-free, conditions B), the corresponding adducts were obtained in moderate to good yields, in 0.5 to 4 hours. Finally, the oxyarylation of dihydronaphthalenes­ and chromenquinone with o-iodophenols and 3-iodolawsone in PEG-400 under conditions A led regio- and stereoselectively to the formation of carbapterocarpanquinones and pterocarpanquinones in moderate yield. Financial support from Brazilian agencies CAPES-DGU (Project 200/09), CNPq, FAPERJ and UFRJ are acknowledged. Spanish MICINN (Projects PHB2008-0037-PC, CTQ2007-62771/BQU, CTQ2010-20387, Consolider INGENIO 2010 CSD2007-00006), FEDER, Generalitat Valenciana (Project PROMETEO/2009/038), and the University of Alicante are acknowledged.

Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Bioquímica de Tripanosomatídeos. Rio de Janeiro, RJ. Brasil. Universidade do Estado do Rio de Janeiro. Laboratório Imunol. Aplicada e Bioq. de Proteínas e Prod. Naturais. Rio de Janeiro, RJ, Brasil. Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Bioquímica de Tripanosomatídeos. Rio de Janeiro, RJ. Brasil. Universidade do Estado do Rio de Janeiro. Laboratório Imunol. Aplicada e Bioq. de Proteínas e Prod. Naturais. Rio de Janeiro, RJ, Brasil. Universidade do Estado do Rio de Janeiro. Departamento de Patologia e Laboratórios. Rio de Janeiro, RJ, Brasil. Universidade do Estado do Rio de Janeiro. Laboratório Imunol. Aplicada e Bioq. de Proteínas e Prod. Naturais. Rio de Janeiro, RJ, Brasil. Universidade Federal do Rio de Janeiro. Laboratório de Química. Macaé, RJ, Brasil. Universidade Federal do Rio de Janeiro. Instituto de Pesquisas de Produtos Naturais. Rio de Janeiro, RJ, Brasil. Universidade do Estado do Rio de Janeiro. Laboratório Imunol. Aplicada e Bioq. de Proteínas e Prod. Naturais. Rio de Janeiro, RJ, Brasil. Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Bioquímica de Tripanosomatídeos. Rio de Janeiro, RJ. Brasil. Visceral leishmaniasis (VL) is the most severe form of leishmaniasis and is the second major cause of death by parasites, after malaria. The arsenal of drugs against leishmaniasis is small, and each has a disadvantage in terms of toxicity, efficacy, price, or treatment regimen. Our group has focused on studying new drug candidates as alternatives to current treatments. The pterocarpanquinone LQB-118 was designed and synthesized based on molecular hybridization, and it exhibited antiprotozoal and anti-leukemic cell line activities. Our previous work demonstrated that LQB-118 was an effective treatment for experimental cutaneous leishmaniasis. In this study, we observed that treatment with 10 mg/kg of body weight/day LQB-118 orally inhibited the development of hepatosplenomegaly with a 99% reduction in parasite load. An in vivo toxicological analysis showed no change in the clinical, biochemical, or hematological parameters. Histologically, all of the analyzed organs were normal, with the exception of the liver, where focal points of necrosis with leukocytic infiltration were observed at treatment doses 5 times higher than the therapeutic dose; however, these changes were not accompanied by an increase in transaminases. Our findings indicate that LQB-118 is effective at treating different clinical forms of leishmaniasis and presents no relevant signs of toxicity at therapeutic doses; thus, this framework is demonstrated suitable for developing promising drug candidates for the oral treatment of leishmaniasis.

Coumestans 2a–i, bearing different patterns of substitution in A- and D-rings, were synthesized and evaluated as inhibitors of kidney Na+,K+-ATPase and ligands for the central benzodiazepine (BZP) receptor. The presence of a hydroxyl group in position 2 favours the effect on Na+,K+-ATPase but decreases the affinity for the BZP receptor, allowing the design of more selective molecules than the natural wedelolactone. On the other hand, the presence of a catechol in ring D is important for the effect on both molecular targets.

Toxoplasmosis is a widely disseminated disease caused by Toxoplasma gondii, an intracellular protozoan parasite. Standard treatment causes many side effects, such as depletion of bone marrow cells, skin rashes and gastrointestinal implications. Therefore, it is necessary to find chemotherapeutic alternatives for the treatment of this disease. It was shown that a naphthoquinone derivative compound is active against T. gondii, RH strain, with an IC50 around 2.5 μM. Here, three different naphthoquinone derivative compounds with activity against leukemia cells and breast carcinoma cell were tested against T. gondii (RH strain) infected LLC-MK2 cell line. All the compounds were able to inhibit parasite growth in vitro, but one of them showed an IC50 activity below 1 μM after 48 h of treatment. The compounds showed low toxicity to the host cell. In addition, these compounds were able to induce tachyzoite-bradyzoite conversion confirmed by morphological changes, Dolichus biflorus lectin cyst wall labeling and characterization of amylopectin granules in the parasites by electron microscopy analysis using the Thierry technique. Furthermore, the compounds induced alterations on the ultrastructure of the parasite. Taken together, our results point to the naphthoquinone derivative (LQB 151) as a potential compound for the development of new drugs for the treatment of toxoplasmosis.

We report the first synthesis of (±)-3,4-dihydroxy-8,9-methylenedioxypterocarpan, a natural isoflavonoid that shows antitumoral activity. The key step involved the Heck reaction between the 7,8-dibenzyloxychromen and the organomercurial derived from sesamol, followed by debenzylation. The Heck adduct was also employed in the synthesis of the corresponding coumestan derivative, using DDQ as oxidant agent.

Pterocarpanquinones (1a–e) and the aza-pterocarpanquinone (2) were synthesized through palladium catalyzed oxyarylation and azaarylation of conjugate olefins, and showed antineoplasic effect on leukemic cell lines (K562 and HL-60) as well as colon cancer (HCT-8), gliobastoma (SF-295) and melanoma (MDA-MB435) cell lines. Some derivatives were prepared (3–8) and evaluated, allowing establishing the structural requirements for the antineoplasic activity in each series. Compound 1a showed the best selectivity index in special for leukemic cells while 2 showed to be more bioselective for HCT-8, SF-295 and MDA-MB435 cells. Pterocarpanquinones 1a and 1c–e, as well as 8 were the most active on amastigote form of Leishmania amazonensis in culture. Compounds 1a, 1c and 8 showed the best selectivity index.

Despite the relevant therapeutic progresses obtained with imatinib, clinical resistance to this drug has emerged and reemerged after cytogenetic remission in a group of patients with chronic myeloid leukemia (CML). Therefore, novel treatment strategies are needed. In this study, we evaluated the anti-CML activity and mechanisms of action of LQB-118, a pterocarpanquinone structurally related to lapachol [2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone]. LQB-118 treatment resulted in an important reduction of cell viability in cell lines derived from CML, both the vincristine-sensitive K562 cell line, and the resistant K562-Lucena (a cell line overexpressing P-glycoprotein). In agreement with these results, the induction of caspase-3 activation by this compound indicated that a significant rate of apoptosis was taking place. In these cell lines, apoptosis induced by LQB-118 was accompanied by a reduction of P-glycoprotein, survivin, and XIAP expression. Moreover, this effect was not restricted to cell lines as LQB-118 produced significant apoptosis rate in cells from CML patients exhibiting multifactorial drug resistance phenotype such as P-glycoprotein, MRP1 and p53 overexpression. The data suggest that LQB-118 has a potent anti-CML activity that can overcome multifactorial drug resistance mechanisms, making this compound a promising new anti-CML agent.

The pentacyclic 1,4-naphthoquinones 1a-d were cytotoxic (IC(50) approximately 2-7 microM) to human leukemic cell lines K562 (oxidative stress-resistant), Lucena-1 (MDR phenotype) and Daudi. Fresh leukemic cells obtained from patients, some with the MDR phenotype, were also sensitive to these compounds. The pentacyclic 1,4-naphthoquinones 1a and 1c induced apoptotic cell death in cells from leukemic patients as determined by flow cytometry. Conversely, the cell lines were highly insensitive to lapachol (2) and alpha-lapachone (3). Mitomycin-C inhibited cell proliferation at concentrations as low as 0.5 microM. The low toxicity against lymphocytes activated by phytohemagglutinin shows that these compounds are selective for the cancer cells studied. Previous data suggest that these compounds (1a-d) can be bioactivated in situ by reduction followed by rearrangement leading to enones, which are powerful alkylating agents. In contrast, lapachol (2) and beta-lapachone (3), which cannot be bioactivated by reduction, showed little activity against the same cell lines.