PERCEPÇÃO DOS ESTUDANTES EM AULAS DE QUÍMICA DO ENSINO SUPERIOR EM MODO REMOTO EMERGENCIAL

Chemistry is one of the subjects that is part of many higher education courses and as it is an area of science that has a theoretical-experimental character, there is a need for practical classes. The experimentation stage is important in teaching, as it can promote student autonomy and the development of cognitive skills. However, the restrictive measures due to the Covid-19 pandemic, implied in chemistry classes in an emergency remote mode, without experimental classes and the opportunity to handle atomic models for undergraduate students of the degree in Natural Sciences and Bachelor’s degree in Biotechnology at the University of São Paulo. Thus, in order to report and analyze the students' perception of not offering experimental classes and the absence of atomic models in two chemistry subjects, two questionnaires were applied to two classes from two different undergraduate courses. The first questionnaire was applied at the beginning of the semester and the second at the end of it. According to the analysis of the results, the students felt harmed without experimental classes, requiring greater commitment on their part, requiring the use of alternative materials to complement the classes.La Química es una de las asignaturas que forma parte de muchos cursos de la enseñanza superior y, al tratarse de un área de la ciencia que tiene un carácter teórico-experimental, son necesarias las clases prácticas. La etapa de experimentación es importante en la enseñanza, ya que puede promover la autonomía del alumno y el desarrollo de sus habilidades cognitivas. Sin embargo, las medidas restrictivas en función de la pandemia del Covid-19, implicaron en clases de Química en modalidad de emergencia a distancia, y sin clases experimentales para los alumnos del curso de Licenciatura en Ciencias de la Naturaleza y Licenciatura en Biotecnología de la Universidad de São Paulo. Así, para informar y analizar la percepción de los estudiantes de no ofrecer clases experimentales en las asignaturas de Química, se aplicaron dos cuestionarios a dos clases de dos cursos de grado diferentes. El primer cuestionario se aplicó al principio del semestre y el segundo al final del mismo. Según el análisis de los resultados, los alumnos se sintieron perjudicados sin las clases experimentales, exigiendo un mayor compromiso por su parte, requiriendo la necesidad de utilizar materiales alternativos para complementar las clases.A Química é uma das disciplinas que faz parte de muitos cursos superiores e por ser uma área da ciência, que possui um caráter teórico-experimental, existe a necessidade da realização de aulas práticas. A etapa de experimentação é importante no ensino, pois pode promover a autonomia dos estudantes e o desenvolvimento de habilidades cognitivas. No entanto, as medidas restritivas, em função da pandemia da Covid-19, implicaram em aulas de Química em modo remoto emergencial, sem aulas experimentais e oportunidade de manusear modelos atômicos para graduandos dos cursos de Licenciatura em Ciências da Natureza e Bacharelado em Biotecnologia da Universidade de São Paulo. Assim, a fim de relatar e analisar a percepção dos estudantes ao não oferecimento de aulas experimentais e ausência de modelos atômicos em duas disciplinas de Química, foram aplicados dois questionários para cada turma. O primeiro questionário foi aplicado no início do semestre e o segundo ao final deste. De acordo com a análise dos resultados, os alunos se sentiram prejudicados sem aulas experimentais, exigindo um maior empenho por parte deles, requerendo a necessidade do uso de materiais alternativos para complementar as aulas

Chemical profile of the polar extract of Paepalanthus microphyllus (Guill.) Kunth (Eriocaulaceae)

Do extrato etanólico dos capítulos de Paepalanthus microphyllus, isolou-se um derivado do ácido cafeico (1). Sua estrutura foi caracterizada por métodos espectroscópicos (RMN mono e bi-dimensionais) e por espetrometria de massas Electrospray. Foram, também, isolados outros três flavonóides (2-4) de interesse taxonômico, os quais foram identificados por métodos espectroscópicos e comparados com dados da literatura.From the ethanolic extract of the capitulae of Paepalanthus microphyllus, one caffeic acid derivative (1) was isolated. The structure of the compound was characterized by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as ESMS spectrometry. In addition, three flavonoids of taxonomic relevance were isolated and identified by comparison to literature data

Effect of Byrsonima crassa and Phenolic Constituents on Helicobacter pylori-Induced Neutrophils Oxidative Burst

Byrsonima crassa Niedenzu (Malpighiaceae) is used in Brazilian folk medicine for the treatment of diseases related mainly to gastric ulcers. In a previous study, our group described the gastric protective effect of the methanolic extract from the leaves of B. crassa. The present study was carried out to investigate the effects of methanolic extract and its phenolic compounds on the respiratory burst of neutrophils stimulated by H. pylori using a luminol-based chemiluminescence assay as well as their anti-H. pylori activity. The suppressive activity on oxidative burst of H. pylori-stimulated neutrophils was in the order of methyl gallate > (+)-catechin > methanol extract > quercetin 3-O-α-l-arabinopyranoside > quercetin 3-O-β-d-galactopyranoside > amentoflavone. Methyl gallate, compound that induced the highest suppressive activity with IC50 value of 3.4 μg/mL, did not show anti-H. pylori activity. B. crassa could be considered as a potential source of natural antioxidant in gastric ulcers by attenuating the effects on the damage to gastric mucosa caused by neutrophil generated reactive oxygen species, even when H. pylori displays its evasion mechanisms

Flavonoids Of Lonchocarpus Montanus A.m.g. Azevedo And Biological Activity.

The analysis of root extracts from Lonchocarpus montanus A.M.G. Azevedo resulted in the isolation of twenty three compounds chiefly flavonoids of which five (four flavonoids and one benzophenone) are described for the first time. The molecular structures of the new compounds (1-5) were determined through spectral analysis (UV, IR, MS and NMR) as being: 2'-hydroxy-8-(alpha,alpha-dimethylallyl)-2, 2-dimethylpyrano-(5,6:3',4')-dibenzoylmethane (1), 2'-methoxy-8-(alpha,alpha-dimethylallyl)-2, 2-dimethylpyrano-(5,6:3',4')-dibenzoylmethane (2), 4'-methoxy-2,2-dimethylpyrano-(5,6:8,7)-flavone (3), 2-(1-hydroxy-1-methylethyl)-furano-(4,5:8,7)-flavone (4) and [2'-methoxy-furano-(4,5:3',4')-phenyl]-phenylmethanone (5). Additionally, fifteen fatty acids were detected through GC-MS analysis of the corresponding methyl esters [(CH3)2CH(CH2)8COOH and CH3(CH2)nCOOH (n = 6, 12-24)]. Quantitative RP-HPLC showed that the most abundant flavonoids in the petroleum ether and dichloromethane extracts were pongamol (19%) and lanceolatine B (8.0%), respectively. In the bioautography assay, the extracts, pongamol (9), lanceolatine B (10), isolonchocarpin (14), derriobtusone A (17) and medicarpine (18) were active against Staphylococcus aureus whereas 9 also against Bacillus subtilis and Cladosporium cladosporioides. Compound 1, 2,2-dimethylpyrano-(5,6:8,7)-flavone (11) and furano-(1200,1300:7,8)- 4'-methoxy flavone (12) were active against Fusarium oxysporium whereas 11 also against Rhizopus orizae. The extracts, compounds 9, 10, 17 and (E)-7-O-methoxypongamol (23) displayed high toxicity in the brine shrimp lethality assay.79351-6

New flavone from the leaves of Neea theifera (Nyctaginaceae)

Neea theifera Oerst. (Nyctaginaceae) is widely used in Brazilian folk medicine for the treatment of gastric ulcers and inflammation. Phytochemical investigation of the leaves of Neea theifera afforded the isolation of the new flavone luteolin-7-O-[2″-O-(5‴-O-feruloyl)-β-D-apiofuranosyl]- β-D-glucopyranoside (1) besides the eight-known compounds vitexin, isovitexin, isoorientin, orientin, vicenin-2, chrysoeriol, apigenin and luteolin. Their chemical identification was established by NMR spectroscopic methods including 2D-NMR, as well as UV and ESI-MS analyses. ©2007 Sociedade Brasileira de Química

Anti-Helicobacter pylori activity and immunostimulatory effect of extracts from Byrsonima crassa Nied. (Malpighiaceae)

<p>Abstract</p> <p>Background</p> <p>Several <it>in vitro </it>studies have looked at the effect of medicinal plant extracts against <it>Helicobacter pylori </it>(<it>H. pylori</it>). Regardless of the popular use of <it>Byrsonima crassa </it>(<it>B. crassa</it>) as antiemetic, diuretic, febrifuge, to treat diarrhea, gastritis and ulcers, there is no data on its effects against <it>H. pylori</it>. In this study, we evaluated the anti-<it>H. pylori </it>of <it>B. crassa </it>leaves extracts and its effects on reactive oxygen/nitrogen intermediates induction by murine peritoneal macrophages.</p> <p>Methods</p> <p>The minimal inhibitory concentration (MIC) was determined by broth microdilution method and the production of hydrogen peroxide (H₂O₂) and nitric oxide (NO) by the horseradish peroxidase-dependent oxidation of phenol red and Griess reaction, respectively.</p> <p>Results</p> <p>The methanolic (MeOH) and chloroformic (CHCl₃) extracts inhibit, <it>in vitro</it>, the growth of <it>H. pylori </it>with MIC value of 1024 μg/ml. The MeOH extract induced the production H₂O₂and NO, but CHCl₃extract only NO.</p> <p>Conclusion</p> <p>Based in our results, <it>B. crassa </it>can be considered a source of compounds with anti-<it>H. pylori </it>activity, but its use should be done with caution in treatment of the gastritis and peptic ulcers, since the reactive oxygen/nitrogen intermediates are involved in the pathogenesis of gastric mucosal injury induced by ulcerogenic agents and <it>H. pylori </it>infections.</p

Triterpenes and antitubercular activity of Byrsonima crassa

We evaluated the potential antitubercular activity of triterpenes obtained from leaves and bark of Byrsonima crassa. From chloroform extracts of the leaves, by bioassay-guided fractionation, we obtained mixtures of known triterpenes: &#945;-amyrin, &#946;-amyrin and their acetates, lupeol, oleanolic acid, ursolic acid and &#945;-amyrinone. Tested against Mycobacterium tuberculosis, the triterpenes exhibited minimum inhibitory concentrations (MICs) of 31.25 - 312.25 µg/mL. &#946;-amyrin and friedelin, isolated from the chloroform extract of bark, showed MICs of 312.25 and 125 µg/mL respectively. This is the first report of the identification and determination of the activity of B. crassa triterpenes against M. tuberculosis

Avaliação química e da atividade antidiarréica das folhas de Byrsonima cinera DC. (Malpighiaceae)

Folhas e cascas de algumas especies do gênero Byrsonima (Malpighiaceae) são empregadas popularmente contra diarréia. Contudo, não existem dados na literatura à respeito de investigacões químicas ou farmacológicas dos extratos de B. cinera. Neste estudo, nós avaliamos a atividade antidiarreica dos extratos metanólico e hidrometanólico das folhas de B. cinera em ratos Swiss. Os resultados mostraram que ambos os extratos reduziram signitivamente a motilidade intestinal. Investigacão fitoquímica do extrato metanólico levou ao isolamento e identificacão da (+)-catequina e da quercetina-3-O-a-L-arabinopiranosídeo. A atividade observada pode estar correlacaionada com a presença dessas substâncias nos extratos.Leaves and bark of some Byrsonima species (Malpighiaceae) are popularly employed against diarrhoeal diseases. However, no data were reported in the literature about the chemisty and pharmacology of extracts from B. cinera leaves. In the present study we evaluated the anti-diarrhoeal activity of methanolic and hydromethanolic extracts obtained from the leaves of B. cinera in Swiss mice. Results showed that both extracts reduced significantly the gastrintestinal motility. Phytochemical evaluation of the methanolic extract led to the isolation and identification of (+)-catechin and quercetin-3-O-a-L-arabinopyranoside. The observed activity may be correlated to the presence of these compounds in the extract