Cytotoxic effects of essential oils from three Lippia gracilis Schauer genotypes on HeLa, B16, and MCF-7 cells and normal human fibroblasts

This study aimed to evaluate the chemical composition of the essential oils from three genotypes of Lippia gracilis Schauer (Verbenaceae) and investigate the cytotoxic activities of these oils. Essential oils were extracted from the leaves using a Clevenger-type apparatus, and chemical analysis was performed using a gas chromatograph coupled to a mass spectrometer and flame ionization detector. 3T3, MRC5, B16, HeLa, and MCF-7 cell lines were used to study the in vitro cytotoxicity of the essential oils, and the level of cell death was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test with three replicates. The cytotoxic activity was expressed as the concentration that inhibited 50% of cell growth. The main compound in the essential oil of LGRA-106 was thymol (40.52%), while LGRA-109 and LGRA-201 contained 45.84 and 32.60% carvacrol, respectively, as their major compound. The essential oils of L. gracilis showed cytotoxic activity against both normal and tumor cells at concentrations below 100 μg/mL; this demonstrated the antitumor potential of these essential oils, which should be further investigated

Re-Elaboration of Chemical Concepts by Chemistry Undergraduate Students Interning a High School

Na graduação os licenciandos em química estudam diversos conceitos químicos de forma aprofundada. Quando exercem a função de professor necessitam ensinar tais conceitos no ensino médio e portanto, é necessária uma adequação para o ensino neste nível de ensino. O conceito de equilíbrio químico é um dos mais difíceis de ensinar e aprender, segundo a literatura. Esta tese pretende elucidar como se dá o processo de reelaboração do conceito de equilíbrio químico pelo licenciando em química ao ter que planejar atividades para o ensino médio. O campo empírico foi o grupo Programa Institucional de Bolsa de Iniciação à Docência (PIBID) da CAPES, da Licenciatura em Química da Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto da Universidade de São Paulo (FFCLRP-USP). A organização do PIBID proporciona momentos de interação entre licenciandos em química, professores de ensino médio e professores universitários. No PIBID, os licenciandos elaboram atividades didáticas para os alunos de ensino médio juntamente com os professores supervisores da escola e o coordenador da universidade. Durante este processo, muitos conceitos das diferentes áreas da química são revisitados e reelaborados visando a contextualização dos conceitos para sala de aula. A questão central é: como ocorre a reelaboração de conceitos de equilíbrio químico dentro do grupo PIBID? A fundamentação teórica apoiou-se na perspectiva histórico-cultural e na Teoria da Atividade. A pesquisa participante foi a metodologia adotada e como instrumento de análise adotamos o método dialético. Para responder à questão de pesquisa, as reuniões de planejamento e as realizações de atividades de ensino do grupo realizadas tanto na universidade como na escola pública parceira foram vídeo-gravadas. Pelas análises realizadas observou-se que os licenciandos ao ter que planejar uma atividade de ensino de equilíbrio químico tentam encontrar contextos que acreditam envolver o assunto em questão. Ainda no processo de reelaboração, os licenciando buscam estratégias dinâmicas e mesmo assim a tendência é o licenciando recorrer as estratégias de ensino que ele experienciou nas aulas da graduação. Constatou-se que há dificuldade de ultrapassar o nível simbólico e atômico-molecular, até porque o conteúdo equilíbrio químico, não é de fácil compreensão no nível macroscópico. A utilização de analogias é recorrente. Para se inteirar do ensino médio o licenciando consulta os livros e os materiais destinados a este nível. Notou-se ainda que concomitante a processo de reelaboração vem a consciência da responsabilidade em ser professor. Os dados e discussões presentes nesta tese podem contribuir para melhoria dos cursos de formação inicial de professores de química, a medida que pode dar pistas sobre como a abordagem de conteúdos químicos nas disciplinas específicas da química poderia considerar a facilitação do processo de reelaboração conceitual.On the undergraduate program, preservice chemistry students delve into various chemical concepts. Nevertheless, when performing as teachers, they need to develop those concepts in the middle school setting; therefore, adjustments to such educational level are necessary. According to the literature, the notion of chemical equilibrium poses a significant challenge for both teaching and learning experiences. The present thesis aims to elucidate how the re-elaboration process of the chemical equilibrium concept in the light of pre-service undergraduates in chemistry on devising activities for high school education. The empirical field was the PIBID group (Programa Institucional de Bolsa de Iniciação à Docência) - Institutional Scholarship Program for the Introduction to Teaching - by CAPES, within the Undergraduate and Pre-service Program in Chemistry held at the Faculty of Philosophy, Liberal Arts and Sciences of Ribeirão Preto at the University of São Paulo (USP-FFCLRP). The design of PIBID renders synergy among their members, high school teachers and university professors. In the PIBID, the pre-service students elaborate educational activities for high school students under the supervision of teachers at the school and the academic coordinator. Along that process, numerous concepts from various areas of chemistry are revisited and re-elaborated aiming at the re-contextualization of those notions for the classroom environment. The central question is: How does the re-elaboration of chemical equilibrium concepts occur within the PIBID group? The theoretical foundation relied on the historical-cultural perspective and the Theory of Activity. The participatory action research was the methodology adopted and as an analytical tool, we adopted the dialectical method. For responding the research question, planning meetings, as and the performances of educational activities of the group carried out both at the university and in the public school partner, were video-recorded. By the analyses performed, it was observed that the pre-service undergraduates, when required to plan a teaching activity on chemical balance, try to find contexts in which they believe should involve the issue at hand. Also in the re-elaboration process, pre-service undergraduates seek dynamic strategies and still tend to use teaching strategies that they had experienced in their graduation classes. It was noted that there was difficulty in surpassing the symbolic and atomic-molecular level; chemical equilibrium content is not easily understandable at the macroscopic level. The use of analogies is recurring. As to learn about the high school environment, the pre-service undergraduates consult books and materials for that level. Also, it was noted that concomitant to the re-elaboration process, there comes the awareness of the responsibility of being a teacher. The data and discussion in this thesis can contribute to the improvement of initial training courses for chemistry teachers, as it can offer clues on how the approach of chemical contents in specific disciplines of chemistry could consider facilitating the conceptual re-elaboration process