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1.
Artigo em Inglês | MEDLINE | ID: mdl-24229178

RESUMO

The structure of colloids with competing interactions which are confined in a harmonic external trap potential is analyzed numerically by energy minimization in two spatial dimensions. A wealth of different cluster structures is found to be stable including clusters with a fringed outer rim (reminiscent to an ornamental border), clusters perforated with voids, as well as clusters with a crystalline core and a disordered rim. All cluster structures occur in a two-dimensional parameter space. The structural ordering can therefore be efficiently tuned by changing few parameters only providing access to a controlled fabrication of colloidal clusters.

2.
Phys Rev E Stat Nonlin Soft Matter Phys ; 86(5 Pt 1): 051402, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23214779

RESUMO

Using Langevin dynamics simulations we investigate the self-assembly of colloidal particles in two dimensions interacting via an isotropic potential, which comprises both a hard-core repulsion and an additional softened square-well potential of controllable width α. In dilute concentrations, the particles assemble in small clusters with a well-defined crystalline order. For small values of α the particles form triangular lattices. As α is increased, more particles can be captured by the potential well giving rise to different crystalline symmetries and the structural phase transitions between them. The main structures observed are triangular, square, and a mixture of square and triangular cells forming an Archimedean tiling. In the concentrated regime the particles form a single percolated cluster with essentially the same orderings at the same ranges of α values as observed in the dilute regime, thus showing that cluster boundary effects have a minor influence on the cluster crystal symmetry. By using energy analysis and geometry arguments we discuss how the different observed structures minimize the system energy at different values of α.


Assuntos
Coloides/química , Transferência de Energia , Modelos Químicos , Modelos Moleculares , Reologia/métodos , Simulação por Computador , Transição de Fase
3.
Auton Autacoid Pharmacol ; 28(4): 103-8, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18771479

RESUMO

1. The ruthenium complexes are important tools in inorganic chemistry. Different biological properties are found in the presence of distinct coordinate ligands, which offer a variety of potential clinical and pharmacological uses. 2. The aim of this work was to evaluate the antinociceptive and behavioural effects of the ruthenium complex, trans-[RuCl(2)(i-dinic)(4)]Cl, in mice. 3. The potential analgesic activity was tested using the formalin and hot plate tests and the behavioural effect was evaluated using the rotarod and spontaneous locomotor tests. The complex was administered at concentrations of 1.3, 4.5 and 18.0 mumol kg(-1) i.p. Morphine (6.0 mg kg(-1), i.p.) and diclofenac sodium (20.0 mg kg(-1), i.p.) were used as reference drugs. 4. The compound had no sedative activity on motor ataxia in the behavioural and analgesic tests. No significant effect was observed in the first phase of the formalin test, however, an effect was observed in the second phase. 5. The complex studied was probably more powerful than the reference drugs as an antinociceptive agent, as this mechanism also involved the nitric oxide (NO) pathway. From this perspective, further experimental studies will be useful to understand the effect of these compounds on NO and the relationship between prostaglandin and NO biosynthesis.


Assuntos
Analgésicos/farmacologia , Comportamento Animal/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Compostos de Rutênio/farmacologia , Analgésicos/síntese química , Animais , Diclofenaco/administração & dosagem , Diclofenaco/farmacologia , Relação Dose-Resposta a Droga , Injeções Intraperitoneais , Masculino , Camundongos , Camundongos Endogâmicos , Estrutura Molecular , Morfina/administração & dosagem , Morfina/farmacologia , Relaxamento Muscular/efeitos dos fármacos , Entorpecentes/farmacologia , Ácidos Nicotínicos/química , Compostos Organometálicos/síntese química , Compostos Organometálicos/farmacologia , Medição da Dor/métodos , Tempo de Reação/efeitos dos fármacos , Compostos de Rutênio/síntese química , Compostos de Rutênio/química
4.
Phytother Res ; 21(8): 771-6, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17486685

RESUMO

Ilex paraguariensis St Hilaire (Aquifoliaceae) is a plant widely cultivated in South America and with various reputed medicinal properties that can be attributed to phenolic constituents of the leaves: caffeine, theophylline and theobromine, besides the flavonoids, quercetin and rutin. This study examined the antiparkinsonian activity of the hydroalcohol extract of Ilex paraguariensis in models of protection against cerebral injury induced by MPTP and reversal of the catatonia induced by reserpine in mice. The hydroalcohol extract prevented MPTP-induced hypolocomotion at doses of 250 and 500 mg/kg at the all time points observed and also prevented the reserpine-induced catalepsy at the same doses. The extract potentiated the effect of apomorphine in preventing catatonia, suggesting a non-dopaminergic activity, probably through antagonism of adenosine. In biochemical studies the hydroalcohol extract caused a significant decrease in the NO levels, exhibited a DPPH-scavenging ability and was effective in preventing the oxidation of deoxyribose. The results obtained suggest that the hydroalcohol extract of Ilex paraguariensis may have an antiparkinsonian profile in animal models, probably through its antioxidant activity and antagonist action on adenosine A(2A) receptors.


Assuntos
Ilex paraguariensis/química , Transtornos Parkinsonianos/tratamento farmacológico , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Animais , Modelos Animais de Doenças , Radical Hidroxila , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico , Extratos Vegetais/administração & dosagem , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Reserpina/toxicidade
5.
Evid Based Complement Alternat Med ; 3(1): 39-48, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16550222

RESUMO

Indole compounds, related to the metabolism of tryptophan, constitute an extensive family, and are found in bacteria, plants and animals. Indolic compounds possess significant and complex physiological roles, and especially indole alkaloids have historically constituted a class of major importance in the development of new plant derived drugs. The indole alkaloid alstonine has been identified as the major component of a plant-based remedy, used in Nigeria to treat mental illnesses by traditional psychiatrists. Although it is certainly difficult to compare the very concept of mental disorders in different cultures, the traditional use of alstonine is remarkably compatible with its profile in experimental animals. Even though alstonine in mice models shows a psychopharmacological profile closer to the newer atypical antipsychotic agents, it also shows important differences and what seems to be an exclusive mechanism of action, not entirely clarified at this point. Considering the seemingly unique mode of action of alstonine and that its traditional use can be viewed as indicative of bioavailability and safety, this review focuses on the effects of alstonine in the central nervous system, particularly on its unique profile as an antipsychotic agent. We suggest that a thorough understanding of traditional medical concepts of health and disease in general and traditional medical practices in particular, can lead to true innovation in paradigms of drug action and development. Overall, the study of this unique indole alkaloid may be considered as another example of the richness of medicinal plants and traditional medical systems in the discovery of new prototypic drugs.

6.
Pharmacol Biochem Behav ; 77(3): 481-9, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15006458

RESUMO

Anxiolytic properties may be a crucial feature of newer antipsychotics associated with the improvement of negative symptoms in schizophrenic patients. The indole alkaloid alstonine acts as an atypical antipsychotic in behavioral models, but differs in its dopamine and serotonin binding profile. The purpose of this study was to verify if alstonine possesses anxiolytic properties in mice. The hole-board and light/dark models were used; moreover, the participation of D(1), 5-HT(2), NMDA and gamma-aminobutyric acid (GABA) receptors was likewise investigated. Alstonine clearly behaves as anxiolytic in both hole-board and light/dark situations. Pretreatment with the 5-HT(2A/2C) serotonin receptor antagonist ritanserin reverted the effects of alstonine in both the hole-board and light/dark models, suggesting the involvement of these receptors in the alstonine mechanism of action. The involvement of glutamate NMDA receptors should also be considered, given that alstonine partially reversed the increase in locomotion induced by MK-801 in the hole board, as well as MK-801-induced hyperlocomotion in motor activity apparatus.


Assuntos
Alcaloides/farmacologia , Ansiolíticos/farmacologia , Antipsicóticos/farmacologia , Alcaloides de Triptamina e Secologanina/farmacologia , Alcaloides/uso terapêutico , Animais , Ansiolíticos/uso terapêutico , Antipsicóticos/uso terapêutico , Ansiedade/tratamento farmacológico , Ansiedade/psicologia , Escuridão/efeitos adversos , Relação Dose-Resposta a Droga , Iluminação/métodos , Locomoção/efeitos dos fármacos , Locomoção/fisiologia , Masculino , Camundongos , Alcaloides de Triptamina e Secologanina/uso terapêutico
7.
An Acad Bras Cienc ; 71(2): 189-201, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10412490

RESUMO

Although recently developed drugs have brought significant improvement, the treatment of psychotic disorders still presents serious drawbacks. Since inherent complexity and lack of satisfactory understanding of the underlying pathophysiology impose limits for rational drug design, resourceful approaches in the search for antipsychotics are pertinent. This paper reports pharmacological properties of alstonine, a heteroyohimbine type alkaloid, which exhibited an antipsychotic-like profile, inhibiting amphetamine-induced lethality, apomorphine-induced stereotypy and potentiating barbiturate-induced sleeping time. Atypical features of alstonine were the prevention of haloperidol-induced catalepsy and lack of direct interaction with D1, D2 and 5-HT2A receptors, classically linked to antipsychotic mechanism of action.


Assuntos
Antipsicóticos/farmacologia , Plantas Medicinais , Alcaloides de Triptamina e Secologanina/farmacologia , Animais , Masculino , Camundongos , Nigéria , Sono/efeitos dos fármacos
8.
An. acad. bras. ciênc ; 71(2): 189-201, jun. 1999. ilus, graf
Artigo em Inglês | LILACS | ID: lil-234513

RESUMO

Although recently developed drugs have brought significant improvement, the treatment of psychotic disorders still presents serious drawbacks. Since inherent complexity and lack of satisfactory understanding of the underlying pathophysiology impose limits for rational drug design, resourceful approaches in the search for antipsychotics are pertinent. This paper reports pharmacological properties of alstonine, a heteroyohimbine type alkaloid, Which exbitited an antipsychotic-like profile, inhibiting amphetamine-induced lethaly, apomorphine-induced steotypy and potentiating barbiturate-induced slleping time. Atypical features of alstonine were the prevention of haloperidol-induced catalepsy and lack of direct interaction with D1, D2 and 5-HT2A receptors, classically linked to antipsychotic mechanism of action.


Assuntos
Animais , Masculino , Camundongos , Antipsicóticos/farmacologia , Plantas Medicinais , Alcaloides de Triptamina e Secologanina/farmacologia , Anfetamina/antagonistas & inibidores , Apomorfina/antagonistas & inibidores , Barbitúricos/antagonistas & inibidores , Estimulantes do Sistema Nervoso Central/antagonistas & inibidores , Clorpromazina/farmacologia , Clozapina/farmacologia , Diazepam/farmacologia , Eméticos/antagonistas & inibidores , Haloperidol/farmacologia , Hipnóticos e Sedativos/antagonistas & inibidores , Nigéria , Pentobarbital/farmacologia , Reserpina/farmacologia , Sono/efeitos dos fármacos , Estereotipagem , Sulpirida/farmacologia
9.
Pharmacol Biochem Behav ; 60(1): 133-41, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9610935

RESUMO

Although recently developed drugs have brought significant improvement, the treatment of psychotic disorders still presents serious drawbacks. Because inherent complexity and lack of satisfactory understanding of the underlying pathophysiology impose limits for rational drug design, resourceful approaches in the search for antipsychotics are pertinent. This article reports pharmacological properties of alstonine, a heteroyohimbine-type alkaloid, which exhibited an antipsychotic-like profile, inhibiting amphetamine-induced lethality, apomorphine-induced stereotypy, and potentiating barbiturate-induced sleeping time. Atypical features of alstonine were the prevention of haloperidol-induced catalepsy and lack of direct interaction with D1, D2 and 5-HT2A receptors, classically linked to antipsychotic mechanism of action.


Assuntos
Antipsicóticos/farmacologia , Comportamento Animal/efeitos dos fármacos , Alcaloides de Triptamina e Secologanina/farmacologia , Anfetamina/antagonistas & inibidores , Anfetamina/toxicidade , Animais , Apomorfina/antagonistas & inibidores , Catalepsia/induzido quimicamente , Catalepsia/prevenção & controle , Avaliação Pré-Clínica de Medicamentos , Haloperidol/antagonistas & inibidores , Haloperidol/farmacologia , Masculino , Camundongos , Ratos , Ratos Wistar , Receptores de Dopamina D1/efeitos dos fármacos , Receptores de Dopamina D2/efeitos dos fármacos , Receptores de Serotonina/efeitos dos fármacos , Sono/efeitos dos fármacos , Comportamento Estereotipado/efeitos dos fármacos
10.
J Ethnopharmacol ; 51(1-3): 111-9; discussion 119-20, 1996 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9213607

RESUMO

Brazil is a gene rich country, host to 24% of known primate species, between 10 and 15 million species of insects, and 22% of the world's higher plant species. The debate over how and by whom these resources should be protected has intensified over the last few years due to a growing awareness of the links between sustainable utilization of natural resources, conservation of biodiversity, and economic development. Within this context the pharmaceutical exploitation of natural products for drug development has a prominent place. For a significant portion of Brazilian society, fair cooperation is welcome and can facilitate drug discovery. Nevertheless, the complexity of the consequences of patenting and utilization of natural resources calls for a thorough cost/benefit analysis in order to promote policies that can ensure significant and long term benefits for the country.


Assuntos
Conservação dos Recursos Naturais , Cooperação Internacional , Farmacognosia , Plantas Medicinais/genética , Brasil , Conservação dos Recursos Naturais/economia , Conservação dos Recursos Naturais/legislação & jurisprudência , Análise Custo-Benefício , Países em Desenvolvimento/economia , Indústria Farmacêutica/economia , Economia , Ecossistema , Propriedade Intelectual , Patentes como Assunto , Preparações Farmacêuticas/isolamento & purificação , Farmacognosia/economia , Política Pública , Impostos
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