A química das plantas: uma abordagem investigativa para o ensino

Abstract

According to the Ministry of Health, around 40% of all medicines have vegetables as their active ingredient. However, knowledge of the beneficial effects of plants is not widely disseminated, therefore, teaching practices that seek to contextualize this empirical knowledge with scientific knowledge are necessary. Therefore, this study aims to develop and apply an investigative teaching sequence (SEI) about plant chemistry for undergraduate students in biological sciences. Divided into groups, the students were presented with the guiding question “Why do some plants have medicinal or pesticide action and others do not?”. Initially, students raised hypotheses, sought support in scientific literature, collected and identified plant material through the Picture This App. They were later challenged to present the research carried out and play the board game “Phytochemical Profile”. In the laboratory, the hydroalcoholic extract of the collected leaves was prepared by the students for phytochemical prospecting, in which they investigated the presence of the main classes of metabolites: tannins, flavonoids, alkaloids, saponins, triterpenoids and steroids in the samples, through simple qualitative tests. The antioxidant potential was also determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) test. The students analyzed the collected data, compared them with the literature and concluded about the initial problematization. Finally, the students were evaluated through a questionnaire with discursive questions covering the content covered in the SEI. All stages were recorded with a smartphone and transcribed to analyze the verbal and non-verbal context constructed in the classroom. SEI provided significant learning and the development of conceptual skills in the area of phytochemistry, but also attitudinal and procedural skills. The results found reinforce the benefits of using active methodologies that prioritize research for teaching phytochemistry.