Prospecção química de compostos produzidos por Senna alata com atividade alelopática

Senna alata é uma espécie daninha frequente em pastagens da região amazônica. Suas folhas apresentam propriedades medicinais capazes de influenciar a germinação e o desenvolvimento de outras plantas. Objetivou-se neste estudo a prospecção química e a avaliação da atividade alelopática dos compostos presentes nas folhas de S. alata. O material vegetal foi seco, triturado e submetido à extração exaustiva, com solução água:metanol (3:7). O extrato obtido foi então fracionado por coluna cromatográfica por via úmida. As frações mais puras foram submetidas à espectroscopia de Ressonância Magnética Nuclear, para determinação das fórmulas estruturais das moléculas. Na avaliação dos efeitos das substâncias químicas isoladas, utilizaram-se as concentrações de 50, 100, 150 e 200 ppm, tendo como eluente solução hidrometanólica (3:7 v/v). As frações foram adicionadas em placas de Petri e seus efeitos avaliados sobre a germinação de sementes e o alongamento da radícula e hipocótilo de três espécies daninhas de áreas de pastagens: Mimosa pudica, Senna obtusifolia e a própria S. alata. Os compostos com atividade alelopática encontrados em folhas de S. alata pertencem à classe dos flavonoides glicosilados, cujo núcleo aromático é um kaempferol, e causaram maior inibição sobre o crescimento da radícula e sobre a germinação de S. obtusifolia e M. pudica. Já os efeitos autotóxicos desse composto são pouco significativos para o desenvolvimento da plântula e nulos sobre a germinação.

Estudo da atividade antioxidante do extrato e do óleo essencial obtidos das folhas de alfavaca (Ocimum gratissimum L.)

O isolamento e a identificação de antioxidantes naturais, extraídos de plantas, contribuem para a descoberta de novas fontes de compostos químicos. A alfavaca (Ocimum gratissimum L.) é uma planta conhecida por seus aspectos medicinais e pelo uso na culinária. A atividade antioxidante do extrato bruto e do óleo essencial das folhas de alfavaca foi comprovada através do método do tiocianato férrico. A porcentagem de inibição da oxidação lipídica foi de 96,89% para o extrato bruto e de 92,44% para o óleo essencial, ambos na concentração de 0,02%. O extrato bruto foi purificado através da cromatografia em coluna com sílica-gel e fase móvel hexano:acetato de etila em diferentes proporções. Para a identificação, foram utilizadas análises espectrais (infravermelho, ressonância magnética de hidrogênio e carbono 13). A substância isolada foi o eugenol, que apresentou 86,56% de atividade antioxidante. Alguns constituintes do óleo essencial foram caracterizados por cromatografia de fase gasosa, sendo o eugenol o principal componente (53,90%). Desta forma, a alfavaca apresenta-se como uma nova fonte de eugenol e, conseqüentemente, de antioxidante natural.

Hemiparesia congênita e adquirida na criança: interrelação entre presença de crises epilépticas, os achados eletrencefalográficos e de neuroimagem por ressonância nuclear magnética

The purpose of this paper was to study patients with congenital and acquired hemiparesis, their clinical aspects, the presence or not of epileptic seizures, and electroencephalographic (EEG) and Magnetic Resonance Imaging (MRI) findings. We analyzed the interrelation between etiology, the presence and seriousness of epileptic seizures (ES) and the possible causes of refractoriness. This is a prospective study using the clinical diagnosis of a child neurologist, who attested to the presence of unilateral motor lesions. We compared the electroencephalographic findings in patients with or without epileptic seizures, and investigated if among the former, these seizures were controlled or not, their likely etiology and risks of refractoriness. EEG background activity on the lesion and contralateral side was analyzed, in addition to the presence of concomitant epileptiform activity. Encephalon MRIs of all the patients were studied to correlate etiology and the control or not of epileptic seizures. The disorganization of bilateral EEG activity correlated with the difficult-to-control epileptic seizures. Suitably organized background activity contralateral to the lesion is a good prognosis in relation to epileptic seizures. Focal epileptogenic activity does not necessarily predispose to epileptic manifestation. The MRI is more important in determining etiology than in prognosing epileptic seizures. This study used a multidisciplinary approach involving child neurologists, a physical therapist and a neuroradiologist. This meets the criteria of multidisciplinarity of the Postgraduate Program in Health Sciences

Sobre a relação entre rotação, atividade crosmosférica e abundância de lítio em estrelas subgigantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Evolução da atividade cromosférica, abundância de lítio e rotação das estrelas análogas e gêmeas solares

The study of solar-type stars also includes the familiar solar analogs and twins. These objects have been one of the major research subjects in astrophysics nowadays. A direct comparison of solar activity with chromospheric activity indices for a set of stars very similar to the Sun (twins and analogs) provides an excellent opportunity to study the evolution of stellar activity on timescales of the order of the lifetime on the main sequence. This work deals with the relationship between the abundance of lithium, chromospheric activity, X-ray emission and rotation period in terms of stellar ages. We explore the influence of stellar evolution in the global properties of the stars and the aspects linked to its coronal, chromospheric and magnetic activity. Our main objective is to probe the law of decay of each of these parameters based on a sample of stars classified as well-connected as analogs stars and solar twins.

Sobre a relação entre rotação, atividade crosmosférica e abundância de lítio em estrelas subgigantes

The connection between rotation, CaII emission flux and lithium abundance is analyzed for a sample of subgiant stars, with evolutionary status was determined from the Toulouse-Geneve code and HlPPARCOS trigonometric parallax measurements. We noted that the distribution of rotation and CaII emission flux, as a function of effective temperature, shows a discontinuity located around the same spectral type, F8IV. Stars located blueward of this spectral type, exhibit a large spread of values of rotation and CaII flux, whereas stars redward of F8lV show essentially low ratation anel low CaII flux. The strength of these declines nevertheless, depends on stellar mass. The distribution of lithium abundances also shows a discontinuity, however with behavior a little more complex for subgiants with mass lower than about 1.2 Solar Masses, this decrease is observed later than that in rotation and CaII flux, whereas for masses higher than 1.2 Solar Masses the decrease in lithium abundance is located around the spectral type F8IV. The discrepancy between the location of the discontinuities of rotation and CaII flux and log n(Li) for stars with masses lower than 102 Solar Masses, seems to reflect the sensitivity of these phenomena to the mass of the convective envelope. The drop in rotation, which results mostly from a magnetic braking, requires an increase in the mass of the convective envelope less than that required for the decrease in lithium abundance The location of the discontinuity in log n( Li) in the same region of the discontinuity ties in rotation and CaII flux, for stars with masses higher than 1.2 Solar Masses, may also be explained by the behavior of the deepening of the convective envelope. In contrast to the relationship between rotation and CaII flux the relationship between lithium abundance and rotation shows no dear tendency toward linear behavior. Similarly, the same tendency is observed in the relationship between lithium abundance and CaII flux in spite of these facts, subgiants with high lithium content also have high rotation and high CaII emission flux. We also observed that stars with high lithium content present, in its majority, an undeveloped convective envelope, whereas stars with low lithium content have a developed convective envelope. In the case of the rotation, stars with undeveloped convective envelope, show rotational velocities as much high as low, whereas stars with developed convective envelope only present low rotation

Alterações da default mode network provocadas pela ingestão de Ayahuasca investigadas por Ressonância Magnética Funcional

Ayahuasca is psychotropic beverage that has been used for ages by indigenous populations in South America, notably in the Amazon region, for religious and medicinal purposes. The tea is obtained by the decoction of leaves from the Psychotria viridis with the bark and stalk of a shrub, the Banisteriopsis caapi. The first is rich in N-N-dimethyltryptamine (DMT), which has an important and well-known hallucinogenic effect due to its agonistic action in serotonin receptors, specifically 5-HT2A. On the other hand, β-carbolines present in B. caapi, particularly harmine and harmaline, are potent monoamine oxidase inhibitors (MAOi). In addition, the tetrahydroharmine (THH), also present in B. caapi, acts as mild selective serotonin reuptake inhibitor and a weak MAOi. This unique composition induces a number of affective, sensitive, perceptual and cognitive changes in individuals under the effect of Ayahuasca. On the other hand, there is growing interest in the Default Mode Network (DMN), which has been consistently observed in functional neuroimaging studies. The key components of this network include structures in the brain midline, as the anterior medial frontal cortex, ventral medial frontal cortex, posterior cingulate cortex, precuneus, and some regions within the inferior parietal lobe and middle temporal gyrus. It has been argued that DMN participate in tasks involving self-judgments, autobiographical memory retrieval, mental simulations, thinking in perspective, meditative states, and others. In general, these tasks require an internal focus of attention, hence the conclusion that the DMN is associated with introspective mental activity. Therefore, this study aimed to evaluate by functional magnetic resonance imaging (fMRI) changes in DMN caused via the ingestion of Ayahuasca by 10 healthy subjects while submitted to two fMRI protocols: a verbal fluency task and a resting state acquisition. In general, it was observed that Ayahuasca causes a reduction in the fMRI signal in central nodes of DMN, such as the anterior cingulate cortex, the medial prefrontal cortex, the posterior cingulate cortex, precuneus and inferior parietal lobe. Furthermore, changes in connectivity patterns of the DMN were observed, especially a decrease in the functional connectivity of the precuneus. Together, these findings indicate an association between the altered state of consciousness experienced by individuals under the effect of Ayahuasca, and changes in the stream of spontaneous thoughts leading to an increased introspective mental activity

Atividade antiinflamatória de uma heterofucana da alga marrom Padina gymnospora

Fucans, sulfated polysaccharides extracted from brown algae and some echinoderms, have been extensively studied for its diverse biological activities and because of its interference with molecular mechanisms of cell to cell recognition, including leukocyte trafficking from blood vessels into sites of inflammation mediated by selectin, a family of adhesion molecules. In the present study, we examined structural features of a heterofucan extracted from brown algae Padina gymnospora and its effect on the leukocyte migration to the peritoneum. The sulfated polysaccharides were extracted from the brown seaweed by proteolysis with the proteolytic enzyme maxatase. The presence of protein and uronic acid contamination was detected in the crude polysaccharide extract. Fractionation of the crude extract with growing concentrations of acetone produced five fractions with different concentrations of fucose, xylose, uronic acid, galactose, glucose and sulfate. The fraction precipitated with 1.5 volumes of acetone was characterized by infrared and nuclear magnetic resonance, through which can be observed the presence of sulfate groups in the C4 of -L-fucose. The anti-inflammatory action of this composite was assessed by a sodium thioglycollate-induced peritonitis assay and through nitric oxide production by the peritoneal macrophages using Griess reagent. Fraction F1.5 was efficient in reducing leukocyte influx into the peritoneal cavity when 10 mg/kg and 25mg/kg were used, resulting in a decrease of 56 and 39%, respectively. A decrease of nitric oxide production occurred when high concentrations of fucana were used. The cytotoxicity of the composite was also assessed using the reduction of 3-(4,5 dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT). Fraction F1.5 had no cytotoxicity when 500 μg/mL of the fraction was used. This study suggests the use of fraction F1.5 (heterofucan) as an anti-inflammatory

Bioprospecção de atividade antioxidante e antimicrobiana da casca de Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae)

The aim of this work was to evaluate the class of secondary metabolites responsible for the antioxidant and antimicrobial activities of bark extracts of Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae), a plant widely used in folk medicine in Brazil. Extracts of the bark were prepared with 50% ethanol, 70% ethanol, acetone:water (7:3, v/v) and chloroform. Antioxidant activity was prospected by spraying thin-layer chromatographs of the extracts with 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and measuring the DPPH radical scavenging capacity by spectrophotometry. Antibacterial activity was revealed by the agar diffusion method and bioautography. TLC spots assigned to tannins in the polar extracts showed antioxidant activity by DPPH radical scavenging and the chloroform extract showed the least scavenging activity. Antimicrobial activity was indicated by the bacterial growth inhibition haloes around polar extracts and bioautography showed activity in the TLC spots assigned to tannins. It was concluded that polar extracts of the bark of S. adstringens possessed antioxidant and antimicrobial activities which were due to secondary metabolite derived from the tannin class, which are the main constituent of these bark extracts, according to the literature.

Estudo químico e atividade mutagênica e antiradicalar e Paepalanthus chiquitensis Herzog (ERIOCAULACEAE)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo químico de Jatropha curcas e de Jatropha gossypifolia nativas e cultivadas: avaliação de ciclopeptídeos em função de habitat e hábito : prospecção e atividade biológica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Síntese, caracterização e atividade antifúngica de derivados anfifílicos de dietilaminoetil-quitosana contra Aspergillus flavus e Aspergillus parasiticus

Pós-graduação em Química - IBILCE

Investigação estrutural e atividade tuberculostática de complexos mononucleares e binucleares de paládio (II)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da atividade biológica de compostos de paládio (II)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

β-glucanas de isolados fúngicos do gênero Botryosphaeria: produção, caracterização química e atividade anticoagulante

Pós-graduação em Ciências Biológicas (Microbiologia Aplicada) - IBRC