RESUMO:A atividade antioxidante, avaliada pelo método DPPH (1,1-difenil-2-picrilidrazila), e o teor em compostos fenólicos totais do extrato bruto metanólico e frações das folhas da espécie Palicourea rigida Kunth, Rubiaceae, foram quantificadas neste trabalho. Apesar da baixa atividade apresentada pelo extrato bruto (500 ppm), a fração acetato de etila apresentou atividade moderada (192 ppm) e o maior teor de fenólicos totais dentre as frações ensaiadas. Assim, a fração acetato de etila foi submetida a procedimentos cromatográficos o que resultou no isolamento dos flavonoides quercetina 3-O-β-D-glicosídeo, quercetina 3-O-soforosídeo e isoraminetina 3-glicosídeo, cujas estruturas foram elucidadas por análise espectroscópica, incluindo RMN (1D e 2D) e comparação com os dados da literatura.Unitermos: Rubiaceae, Palicourea, flavonoides, atividade antioxidante.ABSTRACT: "Flavonoids and antioxidant activity in Palicourea rigida Kunth, Rubiaceae". The antioxidant activity, evaluated by DPPH (1,1-difenil-2-picrilidrazila) method, and the determination of the total phenolic compounds of the crude methanolic extract and fractions of the Palicourea rigida Kunth, Rubiaceae, leaves were quantified in this work. Despite weak activity exhibited by crude extract (500 ppm), the fraction ethyl acetate showed moderate activity (192 ppm), and the largest value for the phenolic compounds among all the assayed fractions. Then, the ethyl acetate fraction was submitted to the chromatography procedures which led to the isolation of the flavonoid quercetin 3-O-D-glicoside, quercetin 3-O-sophoroside and isorhamnetin 3-glicoside, which had the structures elucidated by spectroscopy analysis, including RMN (1D and 2D) and comparison with literature data.

Verbena minutiflora (Verbenaceae) is popularly consumed as an infusion for the treatment of various diseases. However, so far there is no pharmacological or chemical validation to support its therapeutic applications. Therefore, the analysis of the chemical composition and pharmacological activities of V. minutiflora is crucial. In this study, extracts and infusions of the aerial parts of V. minutiflora (leaves, flowers and stems) were analyzed during four consecutive years. Extracts of leaves and flowers had significantly higher phenolic content and antiradical capacity than stems regardless of the year of collection. The infusions of leaves presented constant composition throughout the studied period with high levels of bioactive compounds and high antioxidant potential. Samples were analyzed by HPLC with photodiode array detector (HPLC-DAD) and by LC-ESI-MS/MS, and the potent antioxidants verbascoside and isoverbascoside (phenylpropanoids) and the iridoid hastatoside were tentatively identified in extracts and infusions of the aerial parts of V. minutiflora. PRACTICAL APPLICATIONSMedicinal plants are used since ancient times and are increasingly attracting worldwide attention as functional foods or beverages. Verbena minutiflora is popularly consumed as an infusion to reduce the levels of glucose and cholesterol in blood. Despite its popularity, so far there is no pharmaceutical or chemical validation to support their therapeutic applications. Therefore, it is extremely important to identify the main bioactive constituents of V. minutiflora in order for the plant to be safely used as a phytotherapeutic resource. All extracts showed high concentration of phenolic compounds and therefore potential antiradical capacity, especially the extracts of leaves and flowers. Despite lower amounts of phenolic and flavonoid compounds extracted by hot water, infusions showed high antiradical capacity that might be due to the presence of hastatoside, verbascoside and its isomers. This result justifies the popular intake of infusions of V. minutiflora as a source of antioxidant compounds.

The phytochemical study of the leaves, roots, and flowers of Palicourea rigida led to the isolation of the triterpenes betulinic acid (1) and lupeol (2), the diterpene phytol (3), and the iridoid glycosides sweroside (4) and secoxyloganin (5). These compounds were identified using NMR 1H and 13C and comparing the spectra with published data. We studied the antiedematogenic activity of crude extracts from the organs, and of different fractions, in mice and found that the n-hexane fraction of the leaf extract significantly inhibited the ear edema resulting from croton oil administration. The crude extract from leaves was not acutely toxic to the mice.

Brazilian-pine seeds, Quirera and Tapioca: from the shelves to work benches of chemistry laboratories. Alternative materials for chromatographic tests have been studied in order to develop methods for experimental organic chemistry classes. Chromatography is a technique that allows separation of the components of a mixture and is therefore commonly used for purification of compounds and for discussing concepts such as polarity and molecular interactions. The aim of this work is to expand studies in this field and to adapt low-cost materials for the development of liquid column chromatography. In this paper, a mixture of food dyes was used as sample and Brazilian-pine (Araucaria angustifolia) seeds, white quirera (ground corn), and grained tapioca (starch extracted from cassava root) as stationary phases. The separation of the different pigments from the sample was observed, which makes the selected materials efficient for application in the teaching of chromatography.

Beer is described as a drink susceptible to changes, so any modification in the production process will cause variations in the sensory profile and chemical composition. Alcohol removal during low-alcohol beer production may significantly influence the quality of the beverage. Development and physicochemical characterization of low-alcohol beers from modified processes were performed in this study. In order to obtain low-alcohol beers, modifications were carried out in stages of the production process, in relation to malt concentration, malt processing, and mashing temperature. Fractional factorial design was applied at two levels to an optimization study, demonstrating that only the parameters of extract content and alcohol content were significant, with systematic influence of these factors in the response. Alcohol content showed results of 4.93% in the standard beer and 0.97−2.35% in the samples with low-alcohol content.