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

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

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

Analise fitoquimica de Platymiscium floribundum var.latifolium e Lonchocarpus montanus : isolamento, determinação estrutural e atividade biologica

Orientador: Eva Gonçalves MagalhãesTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: Platymiscium floribundum va. latifolium e Lanchocarpus montanus são duas espécies de plantas nativas, fitoquimicamente inéditas que pertencem à família Leguminosae e sub-família Papilionoideae. A análise do extrato hexânico do cerne das raízes de P. floribundum var. latifolium resultou no isolamento e/ou identificação de uma mistura de triglicerídeos 19, mistura de cis e trans-3,4-dimetoxicinamato de metila 21 e 20, mistura de b-osina 27, tomentina 11, escoparona 10, isoscopoletina 33, formononetina 34, odoratina 35, além da mistura 21 e 20. Análises cromatográficas por CCP de uma alíquota do extrato diclorometânico metilado com diazometano resultou no isolamento da afrormosina 27, 7-O-metilafrormosina 28, 6,7,8,4'-tetrametoxi-isoflavona 29, 7,8,4'-trimetoxi-isoflavona 30, 5,6,7-trimetoxicumarina 31 e 7,4'-di-O-metildaidzeína 32. A reação de acetilação da tomentina 11 produziu o respectivo derivado acetilado que é inédito. Analogamente, no extrato éter de petróleo das raízes de L. montanus, foi possível isolar e/ou identificar 24 compostos. Lonchocarpina 49, pongamol 177, derriobtusona A 47, isolachocarpina 79, 4'-metóxi-isolonchocarpina 80, 6-metóxi-isolonchocarpina 97, lanceolatina B 109, 2'',2''-dimetilcromeno-(5'',6'':8,7)-flavona 112, 4'-metóxi-furano-(2'',3'':7,8)-flavona 182, 2'-metóxi-8-(a,a-dimetilalil)-furano-(2'',3'':4',5')-dibenzoilmetano 55, variabilina 184, anidrovariabilina 185, purpurenona 60, medicarpina 143, isopongaflavona 188, mistura de b-sitosterol 186 e estigmasterol 187 e uma mistura de ácidos graxos 190 são conhecidos, enquanto 2'-hidróxi-furano-(2'',3'':3',4')-dibenzoilmetano 178, 2'-hidróxi-8-(a,a-dimetilalil)-2'',2''-dimetilcromeno (5'',6'':3',4')-dibenzoimetano 179,2'-metóxi-8- (a,a-dimetilalil)-2'',2''-dimetilcromeno (5'',6'':3',4')-dibenzoilmetano 181, 4'-metóxi-2'',2''-dimetilcromeno-(5'',6'':8,7)-flavona 183, [2-metóxi-furano-(2'',3'':3:4)-fenil]-fenil-metanona 180 e 2''-(1-hidróxi-1-metiletil)-furano-(2,3:8,7)-flavona 189 são inéditos na literatura. Uma fração do extrato diclorometânico forneceu 4'-metóxi-furano-(2'',3'':7,8)-flavona 182, enquanto o lupeol 22 também foi isolado do extrato metanólico. As estruturas moleculares das substâncias inéditas 178-181,183 e 189 foram determinadas através da análise dos dados espectrais de UV, IV EM RMN (de H, de C, DEPT, diferença de NOE) e RMN-2D (COSY, HSQC e HMBC). As substâncias conhecidas foram identificadas pela comparação com os dados da literatura. Análises por CLAE permitiram amirina 18 e lupeol 22, olean-12-en-3b-acetoxi-28-oato de metila 23 e misturas de ácidos graxos 24 e 25. O extrato diclorometânico forneceu trans-ferulato de metila 26, afrorm a identificação dos flavonóides 177, 47, 79, 109 e 143 nos cromatogramas referentes aos extratos éter de petróleo e diclorometânico além, da quantificação dos flavonóides mais abundantes nos extratos destacando-se o pongamol 177, um dibenzoilmetano anti-cancerígeno que ocorre em alta concentração (19%) no extrato éter de petróleo e é raramente encontrado na natureza. Durante a análise das duas espécies, novos dados espectroscópicos foram obtidos para algumas das substãncias conhecidas. Os extratos de P. floribundum var. latifolium e L. montanus e algumas substâncias mostraram resultados positivos no teste de letalidade contra Artemia salina. Tanto os extratos como o pongamol 177 foram submetidos ao ensaio para avaliação da atividade inseticida contra larvas de Musca domestica. Os resultados sugerem que os flavonóides são os responsáveis pela maior atividade observada para o extrato éter de petróleo. Os extratos e as substâncias 20 e 21, 27, 31, 10, 11, 49, 177, 179, 47, 79, 109, 112, 182, 60 e 143 também foram submetidos ao teste de bioautografia, mostrando que o extrato diclorometânico de P. floribundum var. latifolium, os extratos éter de petróleo e diclorometânico de L. montanus juntamente com as substâncias 177, 47, 79, 109 e 143 apresentaram atividade bactericida contra Staphylococcus aureus. O extrato metanólico de P. floribundum var. latifolium apresentou atividade fungicida contra Aspergillus fumigatus, enquanto os compostos 11, 179, 112 e 182 apresentaram atividade contra o fungo Fusarium oxysporium. O flavonóide 112 apresentou atividade fungicida contra Rhizopus oryzae. O composto 177 também foi ativo contra a bactéria Bacillus subtilis e o fungo Cladosporium cladosporioides.Abstract: Platymiscium floribundum var. latifolium and Lonchocarpus montanus are native species belonging to Leguminosae family and Papilionoideae sub-family. Both are phytochemically unknown. The analysis of hexane extract from the roots of P. floribundum var. latifolium resulted in the isolation and/or identification of a triglycerides 19, a mixture of cis/trans methyl 3,4-dimethoxycinnamte 21 and 20, a mixture of b-amyrin 18 and lupeol 22, methyl olean-12-en-3b-acetoxy-28-oate 23, the mixture of fatty acids 24 and 25. The corresponding dichloromethane extract furnished methyl trans-ferulate 26, afrormosin 27, tomentin 11, scoparone 10, isoscopoletin 33, formonetin 34, odoratin 35, besides the mixture of 21 and 20. A sample of dichloromethane extract (previously methylated with diazomethane) was submitted to preparative layer chromatography resulting in the isolation of afrormosin 27, 7-O-methylafrormosin 28, 6,7,8,4'-tetramethoxyisoflavone 29, 7,8,4'-trimetoxyisoflavone 30, 5,6,7-trimethoxycoumarin 31 and 7,4' -di-O-methyldaidzein 32. The acetoxy derivative of tomentin 11 is now being described for the first time. Analogously in the petrol extract of L. montanus roots 24 metabolites were isolated and/or identified. Lonchocarpin 49, pongamol 177, derriobtusone A 47, isolonchocarpin 79, 4'-methoxyisolonchocarpin 80, 6-methoxyisolonchocarpin 97, lanceolatin B 109, 2",2"-dimethylcromene-(5",6":8,7)-flavone 112, 4'-methoxy-furan-(2",3":7,8)-flavone 182, 2'-methoxy-8-(a,a-dimethylallyl)-furan-(2",3":4',5')-dibenzoylmethane 55, variabilin 184, anhydrovariabilin 185, purpurenone 60, medicarpin 143, isopongaflavone 188, mixture of b-sitosteroI186 and stigmasterol 187 and the mixture of fatty acids 190 are all known in the literature while 2'-hydroxy- furan-(2",3":3',4')-dibenzoylmethane 178, 2'-hydroxy-8-(a,a-dimethylallyl)-2",2"-dimethylcromene (5",6":3',4')-dibenzoylmethane 179, 2'-methoxy-8-(a,a-dimethylallyl)-2",2"-dimethylcromene (5",6":3',4')-dibenzoylmethane 181, 4'-methoxy-2",2" -dimethylcromene-(5",6":8,7)-flavone 183, [2-methoxy-furan-(2",3":3:4)-phenyl]-phenyl-methanone 180 e 2"-(1-hydroxy-1-methylethyl)-furan-(2,3:8,7)-flavone 189 are new compounds. A fraction obtained from dichloromethane extract furnished 182 while 22 was also isolated from the methanol extract. The molecular structures of the new compounds (178-181, 183 and 189) were determined through the analysis of the corresponding spectral data UV, IV, MS, NMR (H, C, DEPT, NOE) and 2D-NMR (COSY, HSQC and HMBC). The known substances were identified through the comparison of the respective spectral data with those in the literature. HPLC analysis allowed the identification of 177, 47, 79, 109 and 143 in the chromatograms corresponding to petrol and dichloromethane extracts. The most abundant compounds (177, 47 and 109) were also quantified where pongamol 177 an anti cancer dibenzoylmethane rarely found in nature corresponds to 19% of the petrol extract. During the analysis of the two species mentioned above, spectral data of some known compounds were added to those already published. P. floribundum varo latifolium and L. montanus extracts and some substances showed positive results in the Artemia salina lethality bioassay. The extracts and pongamol 177 were submitted to insecticide activity with Musca domestica larva. The results suggesting the flavonoids are responsable to the petrol extract activity. The extracts and 20 and 21, 27, 31, 10, 31, 49, 177, 179, 47, 79, 109, 112, 182, 60 and 143 were tested through the bioautography method. P. floribundum var. latifolium dichloromethane extrac, L. montanus petrol and dichloromethane extracts and compounds 177, 47, 79, 109 e 143 showed bactericide activity against Staphylococcus aureus. P. floribundum var. latifolium methanol extract showed fungicide activity against Aspergillus fumigatus, while compounds 11, 179, 112 e 182 showed activity against fungi Fusarium oxysporium. The flavonoid 112 showed fungicide activity against Rhizopus oryzae. The compound 177 was active against bacteria Bacillus subtilis and fungi Cladosporium cladosporioides.Doutorad