Avaliação farmacognóstica e otimização da extração de flavonoides de flores de Tagetes patula através de planejamento de misturas

Abstract

Tagetes patula L. (Asteraceae), commonly known as marigold, has its flowers used in folk medicine as an antiseptic, diuretic, purifying the blood and insect repellent, as well as widely used as ornamental. This study was conducted to develop the pharmacognostic evaluations for T. patula flowers, as well as to optimize the extraction process, based on the total flavonoid content, through statistical mixture design simplex-centroid, which allowed to evaluate the effect of the solvents water, ethanol and acetone, as well as mixtures thereof, on this response. Also were tested dry residue and antioxidant capacity of the extracts produced. These evaluations were performed according to the Brazilian Pharmacopoeia and/or specialized literature. Colorimetric assays detected the presence of flavonoids, tannins and simple phenolics. By thin layer chromatography and high performance liquid chromatography it was possible to determine the presence of the substance quercetin. The results for loss on drying, total ash content, extractives content and total flavonoid content were, respectively: 9.35%±0.2 (2.10%), 5.51%±0.2 (3.61%), 39.55%±0.52 (1.31%) e 5.24%±0.08 (1.51%). The extract with acetone had the highest total flavonoid content 25.13%±1.02 (4.07%) and better antioxidant capacity, with IC50 of 15.74 μg/mL±1.09 (6.92%), but with lower dry residue, 6.62%±1.33 (20.10%). The extracts containing water as extractor liquid exhibited higher values of dry residue, but with the total flavonoid content and antioxidant capacity smaller than extract with acetone. The correlation between the total flavonoid content and antioxidant capacity of the extracts showed that flavonoids contribute significantly to this capacity. Thus, the statistical mixture design allowed the optimization of the extraction of flavonoids from the flowers of T. patula, with acetone as the best liquid extractor.