Bioprospecção fitoquímica, toxicidade e atividades antioxidante e anticolinesterásica de extratos da Parkia Platycephala (Benth.)

Abstract

Despite the historical use of plants for therapeutic purposes in Brazil, the progress in research that justifies such pharmacological effects is still negligible in the face of the vast national flora. With a view to indicating the Parkia platycephala species in the treatment of Alzheimer's disease, two methods of hot extraction (hydroethanolic and sequential) of the leaf, bark, flower and seed of this species were carried out to carry out chemical bioprospecting (liquid chromatography “LC”, gas chromatography “GC”), determine the antioxidant capacity (DPPH•), anticholinesterase activity (Ellman) and toxicity (Artemia salina, Allium cepa) of these extracts. The crude extracts of the leaf (LE), bark (BE), flower (FE) and seed (SE) of Parkia platycephala were obtained after hydroethanolic extraction at reflux (Soxlhet), using ethanolic solution (70%) for a period of 5h. Sequential extraction started with hexane solvent under reflux for 5h. After 12 hours of drying in a hood, the same sample underwent a new extraction with methanolic solvent. The methodology was repeated, to finish the extraction with ethanolic solution (70%). Thus, the methanolic and ethanolic extracts of the leaf (LEM, LEE), bark (BEM, BEE), flower (FEM, FEE) and seed (SEM, SEE) were obtained, respectively. The presence of tannins, flavonoids, saponins, phytosterols/triterpenoids and alkaloids were detected in the phytochemical screening of both methodologies. The antioxidant activity of the extracts was influenced by the methodologies, mainly for the bark, whose BEE extract (IC50=10.69 ± 0.35 μg. mL-1) showed an antioxant capacity superior to the rutin standard (IC50=15.85 ± 0.08μg. mL-1). The chemical characterization of the sequential extracts indicated a diversity of compounds, evidencing urs- 12-ene and 1,2,3 benzenotriol, in leaf extracts, linoelaidic acid, (Z)-9-octadecenamide and (Z)-7-hexadecenal, in seed extracts, trilinolein, (Z)-9-octadecenamide, in bark extracts and 3- o-methyl-d-glucose and (methylsulfinyl)(methylthio)-methane in flower extracts. For the crude extracts, three steroids and two triterpenoids were identified by GC-MS. Analysis by CL-DAD revealed the presence of naringin and kaempferol in all parts of the plant, in addition to phenolic acids (leaf, bark and flower). Among the analyzed extracts, the bark and the seed showed the highest levels of toxicity against Artemia salina, while in relation to Allium cepa, the seed extracts inhibited root growth from 250 μg. mL-1. Such results are indicative of antitumor activity. Although all extracts showed potential anticholinesterase activity, the crude seed extract and the sequential extracts of the flower stood out. We conclude that the sequential ethanol extracts showed better results in the antioxidant (bark), of toxicity (leaf) and anticholinesterase (flower) assays, while the crude seed extract stood out in terms of toxicity and anticholinesterase activity.