We evaluated the bioactivity of Morinda citrifolia L., Rubiaceae on Tuta absoluta (Lepidoptera: Gelechiidae) and quantified the phenolic components. Ethanolic extracts of leaves and fruits were used in five concentrations (0.01, 0.02, 0.03, 0.04 and 0.05 mg / L). The leaves of the plants were immersed in the solution (10 s) and placed in contact with five caterpillars of the same instar in Petri dishes. The caterpillars were kept under controlled conditions, temperature of 25 ± 1 ° C, and relative humidity of 65 ± 10%, photophase of 12 h. The experimental design was completely randomized with five concentrations, five replicates with two different extracts, the control being distilled water. The phenolic composition of the extracts was determined by high-performance liquid chromatography (HPLC) based on the retention times using the standard external method. Leaf extracts and fruits of M. citrifolia had bioinseticidal activity against caterpillars (leaves at 0.02 mg / L gave 100% mortality and fruits at 0.03 mg / L gave 46.08% mortality). The greater efficiency of leaves can be attributed to their high percentage of phenolic compounds and flavonoids. Eleven phenolic compounds were identified and quantified in extracts of leaves and fruits that showed significant bioactivity.
Volume 3, Número 2 (mai./ago. 2018) pp: 412-428. www.kentron.ifal.edu.br/index.php/diversitas_journal © Diversitas Journal DIVERSITAS JOURNAL. Santana do Ipanema/AL. vol 3, n. 2, p.412-428, mai./ago. 2018. Página | 412 Página | 412 Avaliação da atividade antioxidante do extrato etanólico de Melochia tomentosa Linaeus (1735) Evaluation of the antioxidant activity of the ethanol extract of Melochia tomentosa Linaeus (1735). RESUMO:O Brasil possui a maior biodiversidade do mundo e ainda não há estudos acerca de diversas espécies da flora brasileira. Nesse contexto, o gênero Melochia tem sido estudado como possível fonte de antioxidante natural alternativo. O presente trabalho teve como objetivo investigar a atividade antioxidante do extrato etanólico das partes aéreas (folhas e talos) do candieiro (Melochia tomentosa L.) e compará-la a outros antioxidantes naturais e sintéticos. Para tanto, foram realizados os testes DPPH Trolox e DPPH Quantitativo, FRAP, Teor de compostos fenólicos totais e flavonoides totais, e Prospecção fitoquímica. Comparou-se a ação antioxidante do extrato etanólico com Trolox, Ácido gálico, Quercetina e BHA, bem como com fontes de antioxidantes naturais encontradas na literatura. Os valores obtidos para compostos fenólicos totais e flavonoides foram respectivamente 1833,73 mg de equivalente ácido gálico/g de extrato seco e 133, 35 mg de equivalente de quercetina/g de extrato seco. Foi obtido para o teste do Poder Redução do Ferro (FRAP) uma concentração de 3692,76 μmol de equivalente Trolox/g de extrato seco. Foram encontradas altas atividades de sequestro para o radical DPPH com percentual de atividade antioxidante de 84,89% na concentração de 75 μg/mL, e com EC50 (Concentração da substância antioxidante necessária para reduzir em 50% a concentração inicial do DPPH) de 37,3 μg/mL. Os resultados indicaram um teor elevado de compostos fenólicos, um alto potencial no sequestro do radical DPPH e de redução do ferro, sugerindo ao candieiro elevada atividade antioxidante. PALAVRAS-CHAVE: extrato vegetal; flavonoides; fenóis totais. ABSTRACT: Brazil has the greatest biodiversity in the world and there are no studies on several species of Brazilian flora. In this context, the genus Melochia has been studied as a possible source of alternative natural antioxidant. The objective of the present work was to investigate the antioxidant activity of the aerial parts (leaves and stems) of the candle (Melochia tomentosa L.) and to compare it with other natural and synthetic antioxidants. For that, the DPPH Trolox and DPPH Quantitative, FRAP, Total phenolic compounds and total flavonoids, and Phytochemical Prospection tests were performed. It was compared the antioxidant action of the ethanolic extract with Trolox, Gallic Acid, Quercetin and BHA, as well as with sources of natural antioxidants found in the literature. The values obtained for total phenolic compounds and flavonoids were respectively 1833.73 mg of gallic acid equivalent / g of dry extract and 133, 35 mg of quercetin equivalent / g of dry extrac...
Allelopathy is characterized by effects on plant germination or development caused by chemicals released by other plants. This work aimed to verify the allelopathic activity of Scoparia dulcis leaves and roots in weeds and lettuce, as well as to determine the phenolic compounds present in the studied plant. The experiment was arranged in a 2 x 5 factorial design, with six replications of 15 seeds each. The seeds were placed to germinate in agar layers, and after ten days were evaluated the germination percentage, shoot length and root primary length. Phytochemical analysis using high performance liquid chromatography was also carried out, in which the samples were injected three times in the chromatographic system to obtain the average concentrations and retention times, allowing to identify and quantify the studied metabolites. The results showed that this species has allelopathic potential, as it interfered in the development of all receiving plants studied, and the inhibitory action exerted by the leaves was more significant/ou intense on the analyzed variables. On the other hand, the roots presented a larger total amount of phenolic compounds, being caffeic acid found in greater amount both in the roots and leaves.
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