Inhibition of Tyrosinase by 4H-Chromene Analogues: Synthesis, Kinetic Studies and Computational Analysis

Inhibition of mushroom tyrosinase was observed with synthetic dihydropyrano[3,2-b]chromenediones. Among them, DHPC04 displayed the most potent tyrosinase inhibitory activity with a Ki value of 4μM, comparable to the reference standard inhibitor kojic acid. A kinetic study suggested that these synthetic heterocyclic compounds behave as competitive inhibitors for the L-DOPA binding site of the enzyme. Furthermore, molecular modeling provided important insight into the mechanism of binding interactions with the tyrosinase copper active site

Cytochemical and functional characterization of blood and inflammatory cells from the lizard Ameiva ameiva

Conselho Nacional de Desenvolvimento Científico e Tecnológico (MCT-CNPq), Fundação de Coordenação de Pessoal de Nível Superior (CAPES), Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Fundação Estadual do Norte Fluminense (FENORTE), Financiadora de Estudos e Projetos (FINEP), Programa Nacional de Cooperação Acadêmica (PROCAD) and Programa de Núcleos de Excelência (PRONEX)Universidade Estadual do Pará. Departamento de Fisiologia. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Belém, PA, Brasil.Universidade Federal do Pará. Centro de Ciências Biológicas. Laboratório de Parasitologia. Belém, PA, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Laboratório de Ultraestrutura Celular Hertha Meyer. Rio de Janeiro, RJ, Brasil.Universidade Estadual do Norte Fluminense. Centro de Biociências e Biotecnologia. Laboratório de Biologia Celular e Tecidual. Campos de Goytacazes, RJ, Brasil.The fine structure and differential cell count of blood and coelomic exudate leukocytes were studied with the aim to identify granulocytes from Ameiva ameiva, a lizard distributed in the tropical regions of the Americas. Blood leukocytes were separated with a Percoll cushion and coelomic exudate cells were obtained 24 h after intracoelomic thioglycollate injection. In the blood, erythrocytes, monocytes, thrombocytes, lymphocytes, plasma cells and four types of granulocytes were identified based on their morphology and cytochemistry. Types I and III granulocytes had round intracytoplasmic granules with the same basic morphology; however, type III granulocyte had a bilobued nucleus and higher amounts of heterochromatin suggesting an advance stage of maturation. Type II granulocytes had fusiformic granules and more mitochondria. Type IV granulocytes were classified as the basophil mammalian counterpart based on their morphology and relative number. Macrophages and granulocytes type III were found in the normal coelomic cavity. However, after the thioglycollate injection the number of type III granulocyte increased. Granulocytes found in the coelomic cavity were related to type III blood granulocyte based on the morphology and cytochemical localization of alkaline phosphatase and basic proteins in their intracytoplasmic granules. Differential blood leukocyte counts showed a predominance of type III granulocyte followed by lymphocyte, type I granulocyte, type II granulocyte, monocyte and type IV granulocyte. Taken together, these results indicate that types I and III granulocytes correspond to the mammalian neutrophils/heterophils and type II to the eosinophil granulocytes

Ultrastructural study of the gametocytes and merogonic stages of fallisia audaciosa (Haemosporina: Garniidae) that infect neutrophils of the lizard Plica umbra (Reptilia: Iguanidae)

Universidade Federal do Pará. Centro de Ciências Biológicas. Departamento de Patologia. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Universidade Estadual do Norte Fluminense. Centro de Biociências e Biotecnologia. Laboratório de Biologia Celular e Tecidual. Campos de Goytacazes, RJ, Brasil.Universidade Federal do Rio de Janeiro. Instituto de Biofísica Carlos Chagas Filho. Laboratório de Ultraestrutura Celular Hertha Meyer. Rio de Janeiro, RJ, Brasil.Little is known regarding the ultrastructure of the genus Fallisia (Apicomplexa: Haemosporina: Garniidae). This report describes the fine structure of some developmental stages of Fallisia audaciosa that infect neutrophils in the peripheral blood of the Amazonian lizard Plica umbra (Reptilia: Iguanidae). The parasites lie within a parasitophorous vacuole and exhibit the basic structures of members of the Apicomplexa, such as the pellicle and the cytostome. Invaginations of the inner membrane complex were seen in the gametocytes and may be concerned with nutrition. The meronts were irregularly shaped before division, a feature unusual among members of the Apicomplexa. The unusual presence of a parasitic protozoan within neutrophils, in some way interfering with or modulating the microbicidal activity of such cells, is discussed

Physalis angulata induces in vitro differentiation of murine bone marrow cells into macrophages

Universidade Federal do Pará. Instituto de Ciências Biológicas. Laboratório de Parasitologia. Laboratório de Biologia Estrutural. Belém, PA, Brazil / Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Belém, PA, Brasil.Universidade Federal do Pará. Instituto de Ciências Biológicas. Laboratório de Parasitologia. Laboratório de Biologia Estrutural. Belém, PA, Brazil / Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Universidade Federal do Pará. Instituto de Ciências Biológicas. Laboratório de Parasitologia. Laboratório de Biologia Estrutural. Belém, PA, Brazil / Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Universidade Federal do Pará. Instituto de Ciências Biológicas. Laboratório de Neuroquímica Molecular e Celular. Belém, PA, Brazil.Universidade Federal do Pará. Instituto de Ciências Biológicas. Laboratório de Parasitologia. Laboratório de Biologia Estrutural. Belém, PA, Brazil / Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Background: The bone marrow is a hematopoietic tissue that, in the presence of cytokines and growth factors, generates all of the circulating blood cells. These cells are important for protecting the organism against pathogens and for establishing an effective immune response. Previous studies have shown immunomodulatory effects of different products isolated from plant extracts. This study aimed to evaluate the immunomodulatory properties of aqueous Physalis angulata (AEPa) extract on the differentiation of bone marrow cells. Results: Increased cellular area, higher spreading ability and several cytoplasmatic projections were observed in the treated cells, using optical microscopy, suggesting cell differentiation. Furthermore, AEPa did not promote the proliferation of lymphocytes and polymorphonuclear leukocytes, however promotes increased the number of macrophages in the culture. The ultrastructural analysis by Transmission Electron Microscopy of treated cells showed spreading ability, high number of cytoplasmatic projections and increase of autophagic vacuoles. Moreover, a high level of LC3b expression by treated cells was detected by flow cytometry, suggesting an autophagic process. Cell surface expression of F4/80 and CD11b also indicated that AEPa may stimulate differentiation of bone marrow cells mainly into macrophages. In addition, AEPa did not differentiate cells into dendritic cells, as assessed by CD11c analysis. Furthermore, no cytotoxic effects were observed in the cells treated with AEPa. Conclusion: Results demonstrate that AEPa promotes the differentiation of bone marrow cells, particularly into macrophages and may hold promise as an immunomodulating agent

Constitutive nitric oxide synthase-like enzyme in two species involved in cutaneous and mucocutaneous leishmaniasis

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) Finance code 001, PROPESP-UFPA and Instituto Nacional de Biologia Estrutural e Bioimagem-INBEB [CNPq – Grant number 465395/2014 ].Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Leishmaniose Prof. Dr. Ralph Lainson. Ananindeua, PA, Brasil / Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil.Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil.Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil.Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil / National Institute of Science and Technology in Structural Biology and Bioimaging. Rio de Janeiro, RJ, Brazil.Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil / National Institute of Science and Technology in Structural Biology and Bioimaging. Rio de Janeiro, RJ, Brazil.National Institute of Science and Technology in Structural Biology and Bioimaging. Rio de Janeiro, RJ, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Ananindeua, PA, Brasil.Federal University of Para. Institute of Biological Sciences. Laboratory of Structural Biology. Belém, PA, Brazil / National Institute of Science and Technology in Structural Biology and Bioimaging. Rio de Janeiro, RJ, Brazil.Leishmania is an obligate intracellular parasite that primarily inhabits macrophages. The destruction of the parasite in the host cell is a fundamental mechanism for infection control. In addition, inhibition of the leishmanicidal activity of macrophages seems to be related to the ability of some species to inhibit the production of nitric oxide (NO) by depleting arginine. Some species of Leishmania have the ability to produce NO from a constitutive nitric oxide synthase-like enzyme (cNOS-like). However, the localization of cNOS-like in Leishmania has not been described before. As such, this study was designed to locate cNOS-like enzyme and NO production in promastigotes of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis. NO production was initially quantified by flow cytometry, which indicated a significant difference in NO production between L. (L.) amazonensis (GMFC = 92.17 +/− 4.6) and L. (V.) braziliensis (GMFC = 18.89 +/− 2.29) (P < 0.05). Analysis of cNOS expression by immunoblotting showed more expression in L. (L.) amazonensis versus L. (V.) braziliensis. Subsequently, cNOS-like immunolabeling was observed in promastigotes in regions near vesicles, the flagellar pocket and mitochondria, and small clusters of particles appeared to be fusing with vesicles suggestive of glycosomes, peroxisome-like-organelles that compartmentalize the glycolytic pathway in trypanosomatid parasites. In addition, confocal microscopy analysis demonstrated colocalization of cNOS-like and GAPDH, a specific marker for glycosomes. Thus, L. (L.) amazonensis produces greater amounts of NO than L. (V.) braziliensis, and both species present the cNOS-like enzyme inside glycosomes

Inhibition of Melanization by Kojic Acid Promotes Cell Wall Disruption of the Human Pathogenic Fungus Fonsecaea sp.

Chromoblastomycosis (CBM) is a chronic human subcutaneous mycosis caused by various aetiologic agents. CBM does not have an established treatment but may be managed using antifungal agents, surgical removal of the lesions, or cryotherapy. Kojic acid (KA), a known tyrosinase inhibitor with a variety of biological actions, including fungistatic action against the fungus Cryptococcus neoformans, mediated by inhibiting melanin production, seems to be an alternative to improve the treatment of CBM. The aim of the present study was to analyze the action of KA against the pathogenic fungus Fonsecaea sp., an aetiological agent of CBM. The fungal culture was incubated with KA, and the amount of melanin was assessed, followed by cytochemical detection. Subsequently, the samples were analyzed by light microscopy, transmission and scanning electron microscopy. Culture analysis revealed that 100 g/mL KA significantly decreased the melanization of the fungus and the exocytosis of melanin into the culture supernatant. Additionally, KA induced less growth of biofilm formation and intense disruption of the cell wall, and decreased the number of melanin-containing vesicles in the culture supernatant. Finally, KA inhibited fungal filamentation in culture and the subsequent phagocytosis process. Thus, KA may be a promising substance to help in the treatment of CBM

Leishmanicidal Activity of (+)-Phyllanthidine and the Phytochemical Profile of Margaritaria nobilis (Phyllanthaceae)

The effects of the Securinega alkaloid (+)-phyllanthidine on Leishmania (L.) amazonensis and the first chemical investigation of Margaritaria nobilis L.f. (Phyllanthaceae) are described. Treating the parasites with this alkaloid caused a dose-dependent reduction in promastigote growth of 67.68% (IC50 82.37 μg/mL or 353 µM) and in amastigote growth of 83.96% (IC50 49.11 μg/mL or 210 µM), together with ultrastructural alterations in the promastigotes. No cytotoxic effect was detected in mammalian cells (CC50 1727.48 µg/mL or CC50 5268 µM). Classical chromatographic techniques and spectral methods led to the isolation and identification of betulinic acid, kaempferol, corilagin, gallic acid and its methyl ester, besides (+)-phyllanthidine from M. nobilis leaves and stems. Margaritaria nobilis is another source of the small group of Securinega alkaloids, together with other Phyllanthaceae (Euphorbiaceae s.l.) species. The low toxicity to macrophages and the effects against promastigotes and amastigotes are suggestive that (+)-phyllanthidine could be a promising antileishmanial agent for treating cutaneous leishmaniasis

A Novel Function for Kojic Acid, a Secondary Metabolite from <i>Aspergillus</i> Fungi, as Antileishmanial Agent

<div><p>Kojic acid (KA) is a fungal metabolite used as a topical treatment skin-whitening cosmetic agent for melasma in humans; however its potential as an anti-leishmanial agent is unknown. Chemotherapy is one of the most effective treatments for Leishmaniasis. However, the drugs available are expensive, invasive, require long-term treatment and have severe side effects. Thus, the development of new effective leishmanicidal agents is a necessity. In this study we investigated the anti-leishmanial effect of KA on <i>L. amazonensis</i>, following <i>in vitro</i> and <i>in vivo</i> infections. KA (50 μg/mL) was found to decrease the growth by 62% (IC₅₀ 34 μg/mL) and 79% (IC₅₀ 27.84 μg/mL) of promastigotes and amastigotes <i>in vitro</i>, respectively. Ultrastructural analysis of KA-treated amastigotes showed the presence of vesicles bodies into the flagellar pocket, and an intense intracellular vacuolization and swelling of the mitochondrion. During the <i>in vitro</i> interaction of parasites and the host cell, KA reverses the superoxide anions (O₂^-) inhibitory mechanism promoted by parasite. In addition, 4 weeks after KA-topical formulation treatment of infected animals, a healing process was observed with a high production of collagen fibers and a decrease in parasite burden. Thus, these results demonstrated the great potential of KA as an anti-leishmanial compound.</p></div

Ultrastructural effects of KA on intracellular amastigotes of <i>Leishmania (L.) amazonensis</i>.

<p>(<b>A</b>) General view of untreated infected macrophages showing a typical morphology. Note parasites (<b>stars</b>) within the parasitophorous vacuoles. (<b>B</b>) General view of infected macrophages treated for 1 h and cultivated for 24 h, showing large parasitophorous vacuole. Note reduced number of amastigotes, parasite and flagellar fragments (<b>arrowheads</b>). (<b>C</b>) Infected and treated macrophages presented vacuoles with damaged parasites (<b>stars</b>) or without amastigote forms. (<b>D</b>) Higher magnification of (<b>C</b>); parasites inside PV with alterations in the flagellar membrane (<b>thin arrows</b>) and vesicles inside the flagellar pocket (<b>asterisks</b>). (<b>E</b>) Intracellular amastigotes with membrane profiles in the flagellar pocket (<b>thin arrows</b>) and in the parasite cytoplasm (<b>arrows</b>); intense formation of lipid-like bodies (<b>asterisks</b>) in the cytoplasm of amastigotes forms. (<b>F</b>) Intracellular parasites presented concentric membrane (<b>arrow</b>), kinetoplast swelling (<b>arrow heads</b>) and lipid-like bodies (<b>asterisks</b>). <i>N</i>, nucleus; <i>FP</i>, flagellar pocket; <i>K</i>, kinetoplast; <i>F</i>, flagellum; <i>M</i>, mitochondria; <i>PV</i> parasitophorous vacuole. Bars: (<b>A–C</b>) 5 μm; (<b>D–F</b>) 2 μm.</p