RESUMO
In this work extensive misconceptions of university students' -from nutrition area- about the metabolism of carbohydrates (CHM) in the human organism have been documented. The results lead to consider their difficulties concerning the learning of a complex set of imbricated biochemical models involved. Pursuant to these considerations, three physiological models are proposed as conceptual axes around which CHM in the human organism could be taught, in order to avoid fragmentation in students' knowledge and to give simple physiological contexts where to integrate those biochemical models. These contexts are: (a) a physiological model of the carbon cycle, (b) a physiological model of blood glucose uptake and homeostasis, and (c) a physiological model of the availability of small metabolites.
Assuntos
Metabolismo dos Carboidratos , Estudantes , Humanos , Aprendizagem , Carboidratos , EnsinoRESUMO
Nowadays there is a concern to improve the quality of education by including an interdisciplinary approach of concepts and their integration in the curriculum of scientific disciplines. The development of microbial fuel cells as a potential alternative for production of renewable energies gives undergraduate students the challenge of integrating interdisciplinary concepts in a hot topic of global interest as alternative energies. We present a laboratory experiment that has been part of a third-year undergraduate course in biology where students gained experience in assembling microbial fuel cells and the understanding of how they work. In this process, the students could integrate biological, biochemical, and electric concepts. In addition, the acquisition of manual skills and experimental design decisions are important for the development of future professionals.
Assuntos
Fontes de Energia Bioelétrica , Humanos , Avaliação Educacional , Currículo , Estudantes , Estudos InterdisciplinaresRESUMO
BACKGROUND: We have previously shown that some synthetic hydroxylated stigmastanes derived from plant sterols inhibit in vitro HSV-1 replication in ocular cell lines and decrease cytokine production in stimulated macrophages, suggesting that these steroids might combine antiviral and immunomodulating properties. In this paper we report the synthesis of some analogs fluorinated at C-6 in order to study the effect of this modification on bioactivity. METHODS: The following methods were used: organic synthesis of fluorinated analogs, cytotoxicity determination with MTT assays, cytokine production quantification with ELISAs, glucocorticoid activity determination by displacement assays, immunofluorescence and transcriptional activity assays, studies of the activation of signaling pathways by Western blot, antiviral activity evaluation through virus yield reduction assays. RESULTS: We report the chemical synthesis of new fluorinated stigmastanes and show that this family of steroidal compounds exerts its immunomodulating activity by inhibiting ERK and Akt signaling pathways, but do not act as glucocorticoids. We also demonstrate that fluorination enhances the antiviral activity. CONCLUSIONS: Fluorination on C-6 did not enhance the anti-inflammatory effect, however, an increase in the in vitro antiviral activity was observed. Thus, our results suggest that it is possible to introduce chemical modifications on the parent steroids in order to selectively modulate one of the effects. GENERAL SIGNIFICANCE: This family of steroids could allow the development of an alternative treatment for ocular immunopathologies triggered by HSV-1, without the undesirable side effects of the currently used drugs.
Assuntos
Antivirais/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , Herpesvirus Humano 1/efeitos dos fármacos , Fatores Imunológicos/farmacologia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Receptores de Glucocorticoides/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sitosteroides/farmacologia , Estigmasterol/farmacologia , Animais , Chlorocebus aethiops , Citocinas/biossíntese , Células HEK293 , Humanos , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Células VeroRESUMO
Recent studies have shown that low concentrations of brassinolide induce a rapid generation of nitric oxide in mesophyll cells of maize leaves, which can be easily detected by fluorimetric methods. In this work we describe a series of natural and synthetic brassinosteroids that are able to trigger in vitro NO production in tomato cells that exhibits dose-response behavior. We propose that this effect can be used to develop a new rapid and very sensitive bioassay for brassinosteroid activity that offers several advantages when compared to the current methodologies.
Assuntos
Bioensaio/métodos , Brassinosteroides/análise , Fluorometria/métodos , Óxido Nítrico/metabolismo , Células Vegetais/metabolismo , Folhas de Planta/metabolismo , Esteroides Heterocíclicos/análise , Zea mays/metabolismo , Folhas de Planta/citologia , Zea mays/citologiaRESUMO
In the present study the in vitro antiviral activity of dehydroepiandrosterone (DHEA) and 17 synthetic derivatives against herpes simplex type 1 (HSV-1) was determined. DHEA, epiandrosterone (EA), two synthetic DHEA analogs and three synthetic EA analogs showed a selective inhibitory effect on HSV in vitro multiplication. DHEA and E2, a synthetic derivative of EA, were not found to be virucidal to cell-free HSV-1 and did not impair virus adsorption or penetration. We determined that treatment with both compounds decreased viral protein synthesis. Moreover, inhibitory effect of DHEA and E2 on extracellular viral titer was stronger than the inhibition found on total viral infectivity, suggesting that the antiherpetic activity of these compounds may also be in part due to an inhibition in virus formation and release. Since DHEA is a known Raf/MEK/ERK signaling pathway activator, we studied the role of this pathway on HSV-1 infection. ERK1/2 phosphorylation was stimulated in HSV-1 infected cultures. UO126, a Raf/MEK/ERK signaling pathway inhibitor, impaired viral multiplication, while anisomycin, an activator of this pathway, enhanced it. Treatment with DHEA 6 h before infection enhanced HSV-1 multiplication. On the contrary, pre-treatment with E2, which does not modulate Raf/MEK/ERK signaling pathway, did not produce an increase of viral replication. Taking together these results, the antiviral activity of DHEA seems to occur via a mechanism independent of its ability to modulate ERK phosphorylation.
Assuntos
Antivirais/química , Antivirais/farmacologia , Desidroepiandrosterona/análogos & derivados , Desidroepiandrosterona/farmacologia , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 1/fisiologia , Replicação Viral/efeitos dos fármacos , Animais , Chlorocebus aethiops , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Células Vero , Carga Viral , Proteínas Virais/antagonistas & inibidoresRESUMO
In this paper we report the synthesis of four ring-A difluorinated analogs of brassinosteroids. The bioactivity of these new compounds was evaluated using the rice lamina inclination test. The results show that one of these analogs elicits a bioactivity comparable to that of 28-homocastasterone, a highly active natural brassinosteroid. This finding suggests that both hydroxyls at C-2 and C-3 in active brassinosteroids are involved as hydrogen bond acceptors in their interactions with the cellular receptor.
Assuntos
Esteroides/química , Esteroides/síntese química , Brassinosteroides , Colestanóis/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Esteroides Heterocíclicos/química , Relação Estrutura-AtividadeRESUMO
BACKGROUND: Dehydroepiandrosterone (DHEA) exhibits a wide range of biological functions including antiviral activity. In this work, we present in vitro anti-adenovirus (AdV) activity of seven DHEA and twelve epiandrosterone (EA) analogues. METHODS: The cytotoxic effect of the compounds was determined by the MTT assay and the antiviral activity by a virus yield inhibition assay. The mode of antiviral activity was examined using time-of-addition experiments, adsorption and internalization assays and Western blot analysis. RESULTS: EA, DHEA, and two synthetic derivatives inhibit virus replication with selectivity indices ranging between 42 and 83. Virus adsorption and internalization are not the target of the inhibitory action; meanwhile, AdV protein synthesis was diminished in the presence of DHEA. CONCLUSIONS: DHEA and some synthetic derivatives present antiviral activity similar to cidofovir, which was used as reference drug. These steroidal compounds adversely affect virus protein synthesis and viral mature particle formation.
Assuntos
Adenoviridae/efeitos dos fármacos , Androsterona/farmacologia , Antivirais/farmacologia , Desidroepiandrosterona/farmacologia , Androsterona/análogos & derivados , Animais , Antivirais/química , Western Blotting , Chlorocebus aethiops , Cidofovir , Citosina/análogos & derivados , Citosina/farmacologia , Desidroepiandrosterona/análogos & derivados , Humanos , Camundongos , Organofosfonatos/farmacologia , Células Vero , Proteínas Virais/biossíntese , Replicação Viral/efeitos dos fármacosRESUMO
In this paper we report the synthesis of four fluorinated analogues of brassinosteroids in which fluorine was introduced stereoselectively at C-2. The bioactivity of these new compounds was evaluated using the rice lamina inclination test. The results show that two of these analogues elicit high bioactivity, suggesting the involvement of hydrogen bond interactions between the active brassinosteroids and their cellular receptor.
Assuntos
Colestanóis/síntese química , Colestanóis/farmacologia , Halogenação/efeitos dos fármacos , Esteroides Heterocíclicos/síntese química , Esteroides Heterocíclicos/farmacologia , Bioensaio , Brassinosteroides , Colestanóis/química , Oryza/efeitos dos fármacos , Esteroides Heterocíclicos/químicaRESUMO
In this work the antiviral activity of 20 dehydroepiandrosterone (DHEA) analogs with different substituents at positions C-3, C-15, C-16 and C-17 were evaluated against vesicular stomatitis virus (VSV) in Vero cell cultures. The selectivity indexes (SI) obtained with DHEA and epiandrosterone (EA) were 50 and 72.6, respectively. The work showed that the compounds 21-norpregna-5,17(20)-dien-3beta,16alpha-diyl-diacetate, 17,17-ethylendioxyandrostan-5,15-dien-3beta-ol and 3beta-hydroxypregn-17(20)-en-16-one had higher SI values than ribavirin, which was used as a reference drug. The antiviral mode of action of DHEA was also investigated against VSV replication in Vero cells, and time of addition experiments showed that DHEA mainly affected a late event in the virus growth cycle. Analysis of RNA and protein synthesis indicated that DHEA adversely affected positive strand RNA synthesis and viral mature particle formation.
Assuntos
Antivirais/farmacologia , Desidroepiandrosterona/análogos & derivados , Desidroepiandrosterona/farmacologia , Estomatite Vesicular/tratamento farmacológico , Vesiculovirus/efeitos dos fármacos , Animais , Chlorocebus aethiops , Técnica Indireta de Fluorescência para Anticorpo , RNA Viral/química , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Vero , Estomatite Vesicular/virologia , Vesiculovirus/genética , Vesiculovirus/crescimento & desenvolvimento , Replicação Viral/efeitos dos fármacosRESUMO
Stromal keratitis resulting from ocular infection with Herpes simplex virus type 1 (HSV-1) is a common cause of blindness. This report investigates the antiviral and anti-inflammatory properties of two new synthetic stigmastane analogs in the experimental model of HSV-1-induced ocular disease in mice. (22S,23S)-22,23-dihydroxystigmast-4-en-3-one (1) and (22S,23S)-22,23-dihydroxystigmasta-1,4-dien-3-one (2) exhibited anti-HSV-1 activity in vitro and ameliorated the signs of murine herpetic stromal keratitis (HSK), although none of the compounds showed antiviral activity in vivo. We discuss that the improvement of HSK could be due to an immunomodulatory effect of both compounds.