RESUMO
As part of our continuous studies involving the prospection of natural products from Brazilian flora aiming at the discovery of prototypes for the development of new antiparasitic drugs, the present study describes the isolation of two natural acetylene acetogenins, (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11'-yn-19'-enyl)butanolide (1) and (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11'-ynyl)butanolide (2), from the seeds of Porcelia macrocarpa (Warm.) R.E. Fries (Annonaceae). Using an ex-vivo assay, compound 1 showed an IC50 value of 29.9 µM against the intracellular amastigote forms of Leishmania (L.) infantum, whereas compound 2 was inactive. These results suggested that the terminal double bond plays an important role in the activity. This effect was also observed for the semisynthetic acetylated (1a and 2a) and eliminated (1b and 2b) derivatives, since only compounds containing a double bond at C-19 displayed activity, resulting in IC50 values of 43.3 µM (1a) and 23.1 µM (1b). In order to evaluate the effect of the triple bond in the antileishmanial potential, the mixture of compounds 1 + 2 was subjected to catalytic hydrogenation to afford a compound 3 containing a saturated side chain. The antiparasitic assays performed with compound 3, acetylated (3a), and eliminated (3b) derivatives confirmed the lack of activity. Furthermore, an in-silico study using the SwissADME online platform was performed to bioactive compounds 1, 1a, and 1b in order to investigate their physicochemical parameters, pharmacokinetics, and drug-likeness. Despite the reduced effect against amastigote forms of the parasite to the purified compounds, different mixtures of compounds 1 + 2, 1a + 2a, and 1b + 2b were prepared and exhibited IC50 values ranging from 7.9 to 38.4 µM, with no toxicity for NCTC mammalian cells (CC50 > 200 µM). Selectivity indexes to these mixtures ranged from >5.2 to >25.3. The obtained results indicate that seeds of Porcelia macrocarpa are a promising source of interesting prototypes for further modifications aiming at the discovery of new antileishmanial drugs.
Assuntos
Acetogeninas/farmacologia , Acetileno/farmacologia , Annonaceae/química , Antiprotozoários/farmacologia , Leishmania/efeitos dos fármacos , Acetogeninas/química , Acetileno/análogos & derivados , Antiprotozoários/química , Humanos , Leishmaniose/tratamento farmacológico , Sementes/químicaRESUMO
BACKGROUND: The search for novel metallic chemical compounds with toxicogenic effects has been of great importance for more efficient cancer treatment. OBJECTIVE: The study evaluated the cytotoxic, genotoxic and mutagenic activity of organoteluran RF07 in the S-180 cell line. METHODS: The bioassays used were cell viability with 3-(4,5-dimethyl-2-thiazole)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) test, evaluation of apoptosis and necrosis using fluorescence and flow cytometry, cytokinesisblock micronucleus test and comet assay. The compound was tested at 1; 2.5 and 5µM. RESULTS: The results showed the cytotoxicity of RF07 at concentrations of 2.5, 5, 10 and 20µM when compared to the negative control. For genotoxicity tests, RF07 showed effects in all concentrations assessed by increased index and frequencies of damage and mutagenic alterations. The compound was also cytotoxic due to the significant decrease in the nuclear division index, with significant values of apoptosis and necrosis. The results of fluorescence and flow cytometry showed apoptosis as the main type of cell death caused by RF07 at 5µM, which is thought to avoid an aggressive immune response of the organism. CONCLUSION: In addition to cytotoxic and genotoxic effects, RF07 creates good perspectives for future antitumor formulations.
Assuntos
Antineoplásicos/química , Dano ao DNA/efeitos dos fármacos , Compostos Organometálicos/química , Sarcoma 180/tratamento farmacológico , Compostos de Espiro/química , Animais , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Camundongos , Testes de Mutagenicidade , Mutagênicos/metabolismo , Necrose/tratamento farmacológico , Compostos Organometálicos/farmacologia , Transdução de Sinais , Compostos de Espiro/farmacologiaRESUMO
Tellurium compounds have been described as potential leishmanicides, bearing promising leishmanicidal and antimalarial effects. Therefore, the present study investigated the pharmacological potential of the organotellurane compound RF07 through preADMET parameters, such as absorption, distribution, metabolism and excretion. After studying the pharmacokinetic properties of RF07, studies were carried out on dogs naturally infected with visceral leishmaniasis after the administration of RF07, in order to assess pathophysiological parameters. Thus, dogs were divided into 4 groups with administration of daily intraperitoneal injections for 3 weeks (containing RF07 or placebo). During the trial, hematological parameters, renal and hepatic toxicity were evaluated. Serum urea, creatinine, alkaline phosphatase, transaminases (GOT and GPT), as well as hemogram results, were evaluated before the first administration and during the second and third weeks after the start of the treatment. In dogs with VL, RF07 improved liver damage, regulated GPT levels and significantly decreased leukocyte count, promoting its regularization. These phenomena occurred at the end of the third week of treatment. The administration of RF07 promoted a significant decrease in the average levels of GOT and GPT after the third week of treatment and did not significantly alter the hematological parameters. The application of RF07 in the treatment of visceral leishmaniasis suggests that it is an alternative to the disease, since the reversal of clinical signs in dogs with VL requires the use of 0.6â¯mg/kg.
Assuntos
Antiprotozoários , Leishmaniose Visceral , Compostos Organometálicos , Compostos de Espiro , Telúrio , Alanina Transaminase/sangue , Fosfatase Alcalina/sangue , Animais , Antiprotozoários/farmacocinética , Antiprotozoários/farmacologia , Antiprotozoários/uso terapêutico , Aspartato Aminotransferases/sangue , Contagem de Células Sanguíneas , Peso Corporal/efeitos dos fármacos , Creatinina/sangue , Cães , Absorção Intestinal , Rim/efeitos dos fármacos , Rim/patologia , Leishmaniose Visceral/sangue , Leishmaniose Visceral/tratamento farmacológico , Leishmaniose Visceral/patologia , Leishmaniose Visceral/veterinária , Fígado/efeitos dos fármacos , Fígado/patologia , Masculino , Modelos Biológicos , Compostos Organometálicos/farmacocinética , Compostos Organometálicos/farmacologia , Compostos Organometálicos/uso terapêutico , Compostos de Espiro/farmacocinética , Compostos de Espiro/farmacologia , Compostos de Espiro/uso terapêutico , Telúrio/farmacocinética , Telúrio/farmacologia , Telúrio/uso terapêutico , Ureia/sangueRESUMO
Thimet oligopeptidase (TOP, EC 3.4.24.15) and neurolysin (NEL, EC 3.4.24.16) are closely related zinc-dependent metalo-oligopeptidases, which take part in the metabolism of oligopeptides (from 5 to 17 amino acid residues) inside and outside cells. Both peptidases are ubiquitously distributed in tissues. TOP is one of the main intracellular peptide-processing enzymes being important for the antigen selection in the MHC Class I presentation route, while NEL function has been more associated with the extracellular degradation of neurotensin. Despite efforts being made to develop specific inhibitors for these peptidases, the most used are: CPP-Ala-Ala-Tyr-PABA, described by Orlowski et al. in 1988, and CPP-Ala-Aib-Tyr-PABA (JA-2) that is an analog more resistant to proteolysis, which development was made by Shrimpton et al. in 2000. In the present work, we describe other analogs of these compounds but, with better discriminatory capacity to inhibit specifically NEL or TOP. The modifications introduced in these new analogs were based on a key difference existent in the extended binding sites of NEL and TOP: the negatively charged Glu469 residue of TOP corresponds to the positively charged Arg470 residue of NEL. These residues are in position to interact with the residue at the P1' and/or P2' of their substrates (mimicked by the Ala-Ala/P1'-P2' residues of the CPP-Ala-Ala-Tyr-PABA). Therefore, exploring this single difference, the following compounds were synthesized: CPP-Asp-Ala-Tyr-PABA, CPP-Arg-Ala-Tyr-PABA, CPP-Ala-Asp-Tyr-PABA, CPP-Ala-Arg-Tyr-PABA. Confirming the predictions, the replacement of each non-charged residue of the internal portion Ala-Ala by a charged residue Asp or Arg resulted in compounds with higher selectivity for NEL or TOP, especially due to the electrostatic attraction or repulsion by the NEL Arg470 or TOP Glu469 residue. The CPP-Asp-Ala-Tyr-PABA and CPP-Ala-Asp-Tyr-PABA presented higher affinities for NEL, and, the CFP-Ala-Arg-Tyr-PABA showed higher affinity for TOP.
Assuntos
Metaloendopeptidases/metabolismo , Oligopeptídeos/farmacologia , Cinética , Metaloendopeptidases/antagonistas & inibidores , Mutação/genética , Oligopeptídeos/síntese química , Oligopeptídeos/química , Especificidade por Substrato/efeitos dos fármacosRESUMO
Hypervalent tellurium compounds have a particular reactivity towards thiol compounds which are related to their biological properties. In this work, this property was assembled to tellurium-functionalized surfaces. These compounds were used as linkers in the immobilization process of thiolated biomolecules (such as DNA) on microcantilever surfaces. The telluride derivatives acted as reversible binding agents due to their redox properties, providing the regeneration of microcantilever surfaces and allowing their reuse for further biomolecules immobilizations, recycling the functional surface. Initially, we started from the synthesis of 4-((3-((4-methoxyphenyl) tellanyl) phenyl) amino)-4-oxobutanoic acid, a new compound, which was immobilized on a silicon surface. In nanomechanical systems, the detection involved a hybridization study of thiolated DNA sequences. Fluorescence microscopy technique was used to confirm the immobilization and removal of the telluride-DNA system and provided revealing results about the potentiality of applying redox properties to chalcogen derivatives at surfaces.
Assuntos
Técnicas Biossensoriais , DNA/química , Silício/química , Telúrio/química , Sequência de Bases/genética , Nanoestruturas/química , Hibridização de Ácido Nucleico , Compostos de Sulfidrila/química , Propriedades de SuperfícieRESUMO
Microtubules are important drug targets in tumor cells, owing to their role in supporting and determining the cell shape, organelle movement and cell division. The complementarity-determining regions (CDRs) of immunoglobulins have been reported to be a source of anti-tumor peptide sequences, independently of the original antibody specificity for a given antigen. We found that, the anti-Lewis B mAb light-chain CDR1 synthetic peptide Rb44, interacted with microtubules and induced depolymerization, with subsequent degradation of actin filaments, leading to depolarization of mitochondrial membrane-potential, increase of ROS, cell cycle arrest at G2/M, cleavage of caspase-9, caspase-3 and PARP, upregulation of Bax and downregulation of Bcl-2, altogether resulting in intrinsic apoptosis of melanoma cells. The in vitro inhibition of angiogenesis was also an Rb44 effect. Peritumoral injection of Rb44L1 delayed growth of subcutaneously grafted melanoma cells in a syngeneic mouse model. L1-CDRs from immunoglobulins and their interactions with tubulin-dimers were explored to interpret effects on microtubule stability. The opening motion of tubulin monomers allowed for efficient L1-CDR docking, impairment of dimer formation and microtubule dissociation. We conclude that Rb44 VL-CDR1 is a novel peptide that acts on melanoma microtubule network causing cell apoptosis in vitro and melanoma growth inhibition in vivo.
RESUMO
BACKGROUND: From a previous screening of Brazilian biodiversity for antiprotozoal activity, the hexane extract from leaves of Nectandra leucantha (Nees & Mart.) (Lauraceae) demonstrated activity against Trypanosoma cruzi. Chromatographic separation of this extract afforded bioactive dehydrodieugenol (1). Furthermore, methylated derivative 2 (dehydrodieugenol dimethyl ether) was prepared and also tested against T. cruzi. PURPOSE: To examine the therapeutical potential of compounds 1 and 2 against T. cruzi as well as to elucidate the mechanism of action of bioactive compound 1 against T. cruzi. METHODS/STUDY DESIGN: Crude hexane extract from leaves was subjected to chromatographic steps to afford bioactive compound 1. In order to analyze the effect of additional methyl group in the antiparasitic activity of 1, derivative 2 was prepared (both are no pan-assay interference compounds - PAINS). These compounds were evaluated in vitro against T. cruzi (trypomastigote and amastigote forms) and analyzed for the potential effect in host cells through the production of nitric oxide and reactive oxygen species. Finally, the plasma membrane effect of the most potent compound 1 was investigated in T. cruzi trypomastigotes. RESULTS: Compounds 1 and 2 displayed activity against amastigotes of T. cruzi. Although both compounds promoted activity against intracellular amastigotes, the production of nitric oxide and reactive oxygen species of host cells were unaltered, suggesting an antiparasitic activity other than host cell activation. Considering 1 the most effective compound against T. cruzi, the interference in the plasma membrane of the trypomastigotes was investigated using the fluorescent probe SYTOX® Green. After a short-term incubation, the fluidity and integrity of the plasma membrane was completely altered, suggesting it as a primary target for compound 1 in T. cruzi. CONCLUSION: Compounds 1 and 2 selectively eliminated the intracellular parasites without host cell activation and could be important scaffolds for the search of new hit compounds.
Assuntos
Antiprotozoários/uso terapêutico , Doença de Chagas/tratamento farmacológico , Eugenol/uso terapêutico , Lauraceae/química , Extratos Vegetais/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Animais , Antiprotozoários/farmacologia , Brasil , Fitoterapia , Extratos Vegetais/farmacologia , Folhas de Planta/químicaRESUMO
Hypervalent tellurium compounds (telluranes) are promising therapeutical agents with negligible toxicities for some diseases in animal models. The C-Te bond of organotellurium compounds is commonly considered unstable, disfavoring their applicability in biological studies. In this study, the stability of a set of telluranes composed of an inorganic derivative and noncharged and charged organic derivatives was monitored in aqueous media with 1H, 13C, and 125Te NMR spectroscopy and high-resolution mass spectrometry. Organic telluranes were found to be remarkably resistant and stable to hydrolysis, whereas the inorganic tellurane AS101 is totally converted to the hydrolysis product, trichlorooxytellurate, [TeOCl 3 ]-, which was also observed in the hydrolysis of TeCl 4 . The noteworthy stability of organotelluranes in aqueous media makes them prone to further structure-activity relationship studies and to be considered for broad biological investigations.
RESUMO
The present work aims at investigating the mechanism of action of the Rb9 peptide, which contains the VHCDR 3 sequence of anti-sodium-dependent phosphate transport protein 2B (NaPi2B) monoclonal antibody RebMab200 and displayed antitumor properties. Short peptides corresponding to the hypervariable complementarity-determining regions (CDRs) of immunoglobulins have been associated with antimicrobial, antiviral, immunomodulatory and antitumor activities regardless of the specificity of the antibody. We have shown that the CDR derived peptide Rb9 induced substrate hyperadherence, inhibition of cell migration and matrix invasion in melanoma and other tumor cell lines. Rb9 also inhibited metastasis of murine melanoma in a syngeneic mouse model. We found that Rb9 binds to and interferes with Hsp90 chaperone activity causing attenuation of FAK-Src signaling and downregulation of active Rac1 in B16F10-Nex2 melanoma cells. The peptide also bound to an adhesion G-protein coupled receptor, triggering a concentration-dependent synthesis of cAMP and activation of PKA and VASP signaling as well as IP-3 dependent Ca2+ release. Hsp90 is highly expressed on the cell surface of melanoma cells, and synthetic agents that target Hsp90 are promising cancer therapeutic drugs. Based on their remarkable antitumor effects, the CDR-H3-derived peptides from RebMab200, and particularly the highly soluble and stable Rb9, are novel candidates to be further studied as potential antitumor drugs, selectively acting on cancer cell motility and invasion.
Assuntos
Regiões Determinantes de Complementaridade/genética , Proteínas de Choque Térmico HSP90/genética , Melanoma Experimental/tratamento farmacológico , Peptídeos/genética , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Adesão Celular/genética , Adesão Celular/imunologia , Movimento Celular/genética , Regiões Determinantes de Complementaridade/imunologia , Proteínas de Choque Térmico HSP90/imunologia , Região Variável de Imunoglobulina/genética , Região Variável de Imunoglobulina/imunologia , Melanoma Experimental/genética , Melanoma Experimental/imunologia , Camundongos , Invasividade Neoplásica/genética , Neuropeptídeos/genética , Peptídeos/administração & dosagem , Peptídeos/imunologia , Receptores Acoplados a Proteínas G/genética , Proteínas Cotransportadoras de Sódio-Fosfato Tipo IIb/genética , Proteínas Cotransportadoras de Sódio-Fosfato Tipo IIb/imunologia , Proteínas rac1 de Ligação ao GTP/genéticaRESUMO
Hypervalent organotellurium compounds (organotelluranes) have shown several promising applications, including their use as potent and selective cysteine protease inhibitors and antiprotozoal agents. Here, we report the antimalarial activities of three organotellurane derivatives (RF05, RF07 and RF19) in two Plasmodium falciparum strains (CQS 3D7 and CQR W2), which demonstrated significant decreases in parasitemia in vitro. The inhibition of intracellular P. falciparum proteases by RF05, RF07 and RF19 was determined and the IC50 values were 3.7±1.0µM, 1.1±0.2µM and 0.2±0.01µM, respectively. Using an assay performed in the presence of the ER Ca(2+)-ATPase inhibitor we showed that the main enzymatic targets were cysteine proteases stimulated by calcium (calpains). None of the compounds tested caused haemolysis or a significant decrease in endothelial cell viability in the concentration range used for the inhibition assay. Taken together, the results suggest promising compounds for the development of antimalarial drugs.
Assuntos
Antimaláricos/farmacologia , Calpaína/antagonistas & inibidores , Inibidores de Cisteína Proteinase/farmacologia , Compostos Organometálicos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Telúrio/farmacologia , Antimaláricos/toxicidade , Cálcio/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Inibidores de Cisteína Proteinase/toxicidade , Descoberta de Drogas , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/parasitologia , Humanos , Concentração Inibidora 50 , Malária Falciparum/tratamento farmacológico , Compostos Organometálicos/toxicidade , Telúrio/toxicidadeRESUMO
The kinetic resolution of racemates and desymmetrization are the most common approaches to the preparation of enantiomerically enriched compounds. These procedures allow the access of high valuable, chiral building blocks for many purposes in academic or industrial R&D endeavors. Nevertheless, the scope of stereochemistry recognition in biotransformations usually occurs at the site of the transformation or when it is close to it (not more than 3 bonds). However, there are a growing number of enzymatic transformations which surpass the limits of stereorecognition of remote chiral (or prochiral) centers. In this account, we would like to present some aspects of biocatalyzed remote resolutions and remote desymmetrizations to call attention for these challenging transformations.
Assuntos
Biocatálise , Bioquímica , Estereoisomerismo , Hidrolases , CinéticaRESUMO
In the intraerythrocytic trophozoite stages of Plasmodium falciparum, the calcium-dependent cysteine protease calpain (Pf-calpain) has an important role in the parasite calcium modulation and cell development. We established specific conditions to follow by confocal microscopy and spectrofluorimetry measurements the intracellular activity of Pf-calpain in live cells. The catalytic activity was measured using the fluorogenic Z-Phe-Arg-MCA (where Z is carbobenzoxy and MCA is 4-methylcoumaryl-7-amide). The calmodulin inhibitor calmidazolium and the sarcoplasmic reticulum calcium ATPase inhibitor thapsigargin were used for modifications in the cytosolic calcium concentrations that persisted in the absence of extracellular calcium. The observed calcium-dependent peptidase activity was greatly inhibited by specific cysteine protease inhibitor E-64 and by the selective calpain inhibitor ALLN (N-acetyl-l-leucyl-l-leucyl-l-norleucinal). Taken together, we observed that intracellular Pf-calpain can be selectively detected and is the main calcium-dependent protease in the intraerythrocytic stages of the parasite. The method described here can be helpful in cell metabolism studies and antimalarial drug screening.
Assuntos
Calpaína/metabolismo , Plasmodium chabaudi/enzimologia , Plasmodium falciparum/enzimologia , Proteínas de Protozoários/metabolismo , Animais , Cálcio/metabolismo , Calpaína/análise , Calpaína/antagonistas & inibidores , Inibidores de Cisteína Proteinase/farmacologia , Leupeptinas/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Confocal , Proteínas de Protozoários/análise , Proteínas de Protozoários/antagonistas & inibidores , Espectrometria de FluorescênciaRESUMO
Tellurium compounds have shown several biological properties and recently the leishmanicidal effect of one organotellurane was demonstrated. These findings led us to test the effect of the organotellurium compound RF07 on Leishmania (Leishmania) chagasi, the agent of visceral leishmaniasis in Latin America. In vitro assays were performed in L. (L.) chagasi-infected bone marrow derived macrophages treated with different concentrations of RF07. In in vivo experiments Golden hamsters were infected with L. (L.) chagasi and injected intraperitoneally with RF07 whereas control animals received either Glucantime or PBS. The effect of RF07 on cathepsin B activity of L. (L.) chagasi amastigotes was assayed spectrofluorometrically using fluorogenic substrates. The main findings were: 1) RF07 showed significant leishmanicidal activity against intracellular parasites at submicromolar concentrations (IC50 of 529.7±26.5 nM), and the drug displayed 10-fold less toxicity to macrophages (CC50 of 5,426±272.8 nM); 2) kinetics assays showed an increasing leishmanicidal action of RF07 at longer periods of treatment; 3) one month after intraperitoneal injection of RF07 L. (L.) chagasi-infected hamsters showed a reduction of 99.6% of parasite burden when compared to controls that received PBS; 4) RF07 inhibited the cathepsin B activity of L. (L.) chagasi amastigotes. The present results demonstrated that the tellurium compound RF07 is able to destroy L. (L.) chagasi in vitro and in vivo at concentrations that are non toxic to the host. We believe these findings support further study of the potential of RF07 as a possible alternative for the chemotherapy of visceral leishmaniasis.
Assuntos
Antiprotozoários/farmacologia , Leishmania/efeitos dos fármacos , Compostos Organometálicos/farmacologia , Compostos de Espiro/farmacologia , Animais , Catepsina B/metabolismo , Cricetinae , Feminino , Leishmania/metabolismo , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Compostos Organometálicos/química , Compostos Organometálicos/toxicidade , Testes de Sensibilidade Parasitária , Proteólise/efeitos dos fármacos , Compostos de Espiro/química , Compostos de Espiro/toxicidade , Testes de ToxicidadeRESUMO
BACKGROUND: Antitumor cyclopalladated complexes with low toxicity to laboratory animals have shown leishmanicidal effect. These findings stimulated us to test the leishmanicidal property of one palladacycle compound called DPPE 1.2 on Leishmania (Leishmania) amazonensis, an agent of simple and diffuse forms of cutaneous leishmaniasis in the Amazon region, Brazil. METHODOLOGY/PRINCIPAL FINDINGS: Promastigotes of L. (L.) amazonensis and infected bone marrow-derived macrophages were treated with different concentrations of DPPE 1.2. In in vivo assays foot lesions of L. (L.) amazonensis-infected BALB/c mice were injected subcutaneously with DPPE 1.2 and control animals received either Glucantime or PBS. The effect of DPPE 1.2 on cathepsin B activity of L. (L.) amazonensis amastigotes was assayed spectrofluorometrically by use of fluorogenic substrates. The main findings were: 1) axenic L. (L.) amazonensis promastigotes were destroyed by nanomolar concentrations of DPPE 1.2 (IC50 = 2.13 nM); 2) intracellular parasites were killed by DPPE 1.2 (IC50 = 128.35 nM), and the drug displayed 10-fold less toxicity to macrophages (CC50 = 1,267 nM); 3) one month after intralesional injection of DPPE 1.2 infected BALB/c mice showed a significant decrease of foot lesion size and a reduction of 97% of parasite burdens when compared to controls that received PBS; 4) DPPE 1.2 inhibited the cysteine protease activity of L. (L.) amazonensis amastigotes and more significantly the cathepsin B activity. CONCLUSIONS/SIGNIFICANCE: The present results demonstrated that DPPE 1.2 can destroy L. (L.) amazonensis in vitro and in vivo at concentrations that are non toxic to the host. We believe these findings support the potential use of DPPE 1.2 as an alternative choice for the chemotherapy of leishmaniasis.
Assuntos
Antiprotozoários/administração & dosagem , Antiprotozoários/farmacologia , Leishmania mexicana/efeitos dos fármacos , Leishmania mexicana/isolamento & purificação , Leishmaniose Cutânea/tratamento farmacológico , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/farmacologia , Animais , Brasil , Cricetinae , Modelos Animais de Doenças , Feminino , Fluorometria/métodos , Humanos , Injeções Subcutâneas , Leishmaniose Cutânea/parasitologia , Leishmaniose Cutânea/patologia , Macrófagos/efeitos dos fármacos , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Parasitária , Resultado do TratamentoRESUMO
Leishmaniasis and Chagas' are parasitic protozoan diseases that affect the poorest population in the world, causing a high mortality and morbidity. As a result of highly toxic and long-term treatments, novel, safe and more efficacious drugs are essential. In this work, the CH(2)Cl(2) phase from MeOH extract from the leaves of Baccharis retusa DC. (Asteraceae) was fractioned to afford two flavonoids: naringenin (1) and sakuranetin (2). These compounds were in vitro tested against Leishmania spp. promastigotes and amastigotes and Trypanosoma cruzi trypomastigotes and amastigotes. Compound 2 presented activity against Leishmania (L.) amazonensis, Leishmania (V.) braziliensis, Leishmania (L.) major, and Leishmania (L.) chagasi with IC(50) values in the range between 43 and 52 µg/mL and against T. cruzi trypomastigotes (IC(50)=20.17 µg/mL). Despite of the chemical similarity, compound 1 did not show antiparasitic activity. Additionally, compound 2 was subjected to a methylation procedure to give sakuranetin-4'-methyl ether (3), which resulted in an inactive compound against both Leishmania spp. and T. cruzi. The obtained results indicated that the presence of one hydroxyl group at C-4' associated to one methoxyl group at C-7 is important to the antiparasitic activity. Further drug design studies aiming derivatives could be a promising tool for the development of new therapeutic agents for Leishmaniasis and Chagas' disease.
Assuntos
Antiprotozoários/farmacologia , Baccharis/química , Flavanonas/farmacologia , Leishmania/efeitos dos fármacos , Extratos Vegetais/farmacologia , Trypanosoma/efeitos dos fármacos , Animais , Antiprotozoários/química , Antiprotozoários/isolamento & purificação , Bioensaio , Cricetinae , Flavanonas/química , Flavanonas/isolamento & purificação , Flavonoides/química , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Concentração Inibidora 50 , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/parasitologia , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Relação Estrutura-AtividadeRESUMO
Bioactivity-guided fractionation of n-hexane phase from MeOH extract of the seeds of Cassia fistula L. (Leguminosae) yielded two bioactive substances against Cladosporium cladosporioides and C. sphaerospermum. After spectroscopic analysis, these compounds were characterised as the known benzyl 2-hydroxy-3,6-dimethoxybenzoate and its dimer dibenzyl 2,2'-dihydroxy-3,6,3â³,6â³-tetramethoxy-biphenyl-1,1'-dicarboxylate, which showed a new structural arrangement.
Assuntos
Antifúngicos/análise , Cassia/química , Ésteres/análise , Conformação Molecular , Sementes/química , Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Brasil , Fracionamento Químico , Cromatografia Líquida de Alta Pressão , Cladosporium/efeitos dos fármacos , Dimerização , Ésteres/isolamento & purificação , Ésteres/farmacologia , Hexanos , Hidroxibenzoatos/análise , Metanol , Estrutura Molecular , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The infections by protozoans of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which cause renal and cardiac toxicity. As part of a search for new drugs against leishmaniasis, we evaluated the in vitro Leishmania protease inhibition activity of extracts (hexanic, ethyl-acetate, and ethanolic) and fukugetin, a bioflavonoid purified from the ethyl-acetate extract of the pericarp of the fruit of Garcinia brasiliensis, a tree native to Brazilian forests. The isolated compound was characterized by using spectral analyses with nuclear magnetic resonance, mass spectroscopy, ultraviolet, and infrared techniques. The ethyl-acetate extract and the compound fukugetin showed significant activity as inhibitors of Leishmania's proteases, with mean (±SD) IC(50) (50% inhibition concentration of protease activity) values of 15.0±1.3 µg/mL and 3.2±0.5 µM/mL, respectively, characterizing a bioguided assay. In addition, this isolated compound showed no activity against promastigote and amastigote forms of L. (L.) amazonensis and mammalian cells. These results suggest that fukugetin is a potent protease inhibitor of L. (L.) amazonensis and does not cause toxicity in mammalian or Leishmania cells in vitro. This study provides new perspectives on the development of novel drugs that have leishmanicidal activity obtained from natural products and that target the parasite's proteases.
Assuntos
Antiprotozoários/farmacologia , Garcinia/química , Leishmania/efeitos dos fármacos , Leishmania/enzimologia , Extratos Vegetais/farmacologia , Inibidores de Proteases/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Animais , Brasil , Frutas/química , Humanos , Concentração Inibidora 50 , Leishmaniose/parasitologia , Peptídeo Hidrolases/metabolismo , Proteínas de Protozoários/metabolismo , RatosRESUMO
The 3C proteinase, essential for human poliovirus (PV) replication, has unique characteristics as its three-dimensional structure resembles chymotrypsin, but its catalytic nucleophile is a cysteine SH group rather than the OH group of serine. Here, we describe the use of tellurium compounds as inhibitors of PV3C proteinase. A rapid, stoichiometric and covalent inactivation of PV3C was observed with both a chloro-telluroxetane and a bis-vinylic organotellurane. These compounds also inhibit human cathepsins B, L, S, and K with second order rate constants higher than those obtained for PV3C. Chloro-telluroxetane inhibits replication of PV in human embryonic rhabdomyosarcoma cells in the low micromolar range and below the toxic level for the host cells. Bis-vinylic organotellurane is more effective as antiviral agent but reduces the cell viability by 20% at 10 µm, a concentration almost completely inhibiting virus growth. This is the first description of inhibition of viral 3C proteinase with antiviral property by this class of compounds.
Assuntos
Inibidores Enzimáticos/farmacologia , Compostos Organometálicos/farmacologia , Poliovirus/enzimologia , Telúrio/química , Proteínas Virais/antagonistas & inibidores , Proteases Virais 3C , Cisteína Endopeptidases/metabolismo , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Estrutura Molecular , Compostos Organometálicos/química , Relação Estrutura-Atividade , Proteínas Virais/metabolismoRESUMO
A new series of organotelluranes were synthesized and investigated, and the structure-activity relationships in cysteine proteases inhibition were determined. It was possible to identify the relevance of structural components linked to the reactivity of these compounds as inhibitors. For example, dibromo-organotelluranes showed to be more reactive than dichloro-organotelluranes towards cysteine cathepsins V and S. Besides, no remarkable enantio-selectivity was verified. In general the achiral organotelluranes were more reactive than the chiral congeners against cysteine cathepsins V and S. A reactivity order for organochalcogenanes and cysteine cathepsins was proposed after the comparison of the inhibitory potencies of organotelluranes with the related organoselenanes.
Assuntos
Catepsinas/antagonistas & inibidores , Inibidores de Proteases/química , Telúrio/química , Catepsinas/metabolismo , Calcogênios/síntese química , Calcogênios/química , Calcogênios/farmacologia , Cisteína Endopeptidases/metabolismo , Humanos , Cinética , Inibidores de Proteases/síntese química , Inibidores de Proteases/farmacologia , Relação Estrutura-AtividadeRESUMO
In this minireview, the more recent findings about the effects of peculiar reactive thiol drugs on mitochondria are presented. These include the following compounds: metallo meso-tetrakis porphyrins, palladacycles, telluranes and phenothiazines. Metallo meso-tetrakis porphyrins can exhibit both beneficial and deleterious effects on mitochodria that are modulated by the central metal, cell location, and availability of axial ligands. Therefore, these compounds have the versatility to be used for cell and mitochondria protection and death. The antioxidant activity of manganese porphyrins is related to a glutathione peroxidase-like activity. By attacking exclusively the membrane protein thiol groups without glutathione depletion, palladacycles are able to induce mitochondrial permeability transition (MPT) and cytochrome c release in the absence of oxidative stress. In hepatoma cells, the mitochondrial action of palladacycles was able to induce apoptotic death. As opposed to palladacycles, telluranes and phenothiazines are able to conjugate the capacity to promote the MPT in a dose-dependent manner in association with efficient antioxidant activity toward lipids. These studies demonstrated that the action of drugs on mitochondrial bioenergetics can be modulated by peculiar reactivity with thiol groups. Therefore, they contribute to studies of toxicity as well as the design of new drugs.