Análise fitoquímica e potencial inseticida de Eragrostis plana NEES sobre Drosophila melanogaster

Abstract

The capim-annoni-2 (Eragrostis plana Nees) is an exotic species belonging to the Poaceae family and is considered invasive to pastures with accidental introduction in Rio Grande do Sul in the late 1950. The objective was to determine the capim-annoni2 insecticidal activity against the fruit fly (Drosophila melanogaster), identify, and quantify chemical compounds present in the aerial parts capim- annoni-2 in three years of storage. For the phytochemical analysis, it was prepared a methanol extract at a concentration of 2 g.10 mL-1 and by high-performance liquid chromatography (HPLC) quantified and identified phenolics (caffeic acid, chlorogenic acid, gallic acid and ellagic acid), flavonoids (quercetin and rutin) and total tannins (catechin, epicatechin and apigenin). For bioassays (insecticide) were prepared methanol, hydroalcoholic and aqueous extracts in the concentration of 2 g. 10 mL-1 and, the extracts application occurred in two different bioassays, where the first bioassay, the extract was resuspended in 3 mL of distilled water used in the culture medium; in the second bioassay, the extract was resuspended in 3 mL of dimethylsulfoxide (DMSO) applied on filter paper containing sucrose solution 5%. After performing the bioassays, it was detected that the first death did not occur in the different extracts; early as the second with the application the filter paper, there was a mortality of 100% compared to control. Possibly this effect is due to the presence of allelochemicals found in the methanol extract of capim-annoni-2 especially quercetin, a flavonoid with insecticidal activity. Still, the phytochemical analysis was detected as major components caffeic acid and chlorogenic acid (phenol) followed by the flavonoids quercetin and rutin, being that, for all secondary compounds, the concentration reduced with storage time except ellagic acid, rutin and catechin in the last year of storage. The phytochemical profile of the species may be related to possible biological activities in the same Bioma Pampa.