Estudo fitoquímico e avaliação da atividade anticolinesterásica de extratos da casca da raiz da Mimosa tenuiflora (Willd.) Poiret

Abstract

Mimosa tenuiflora (Willd.) Poiret (jurema preta) is a species in the Fabaceae family, native to the Caatinga, found throughout the Brazilian Northeast. In folk medicine, the shells of the stem and root of jurema preta are used in treatment of several diseases, as burns and inflammations, besides being maid traditionally as drink in indigenous rituals. Regarding to the root bark, there are few studies described in the literature about its phytochemical profile and biological properties. In this way, the present study has proposed perform a phytochemical study of the extracts from the root bark of Mimosa tenuiflora. For this, it was performed the fractionation of chloroformic extract from the column chromatography (CC), and the structural determinations of the isolated compounds were carried out by technique of nuclear magnetic resonance (NMR) of 1H and 13C, besides the identification and quantification of phenolic substances in the chloroformic extracts and the ethyl acetate from the high-efficiency liquid chromatography with diode arrangement detector (HPLC-DAD) and consequent validation of applied analytical method. Were also carried out assessment of anticholinesterasic activity of the extracts by the method of Ellman and quantification of the total flavonoid content of the crude extract through spectrophotometric method using as reactant aluminum chloride (AlCl3) and standard curve with quercetin. As a result, were obtained from the chloroformic extract a mixture of the β-sitosterol and stigmasterol steroids and the betulinic acid triterpene. From of the HPLC-DAD were identified polyphenols such as catechin, epicatechin and procyanidin B2 beyond the gallic acid in the ethyl acetate extract and procyanidin B2, in the chloroformic extract of this species. With the validation of the analytical method, this proved to be reliable and suitable for the quantification of the substance catechin and epicatechin in the ethyl acetate extract, according to criteria recommended by the National Health Surveillance Agency – NHSA. Regarding the anticholinesterasic activity, among the tested extracts of black jurema, the gross and the ethyl acetate were the ones who showed greater inhibition capacity on the enzyme acetylcholinesterase (AChE) in relation to other, presenting percentages of 89% + 0,31 and 93,8% + 0,4, respectively, what classifies this species as a potent inhibitor. The total flavonoids content quantified in the crude extract of Mimosa tenuiflora was of 1,386g/100g extract. Thus, this work indicates that the species Mimosa tenuiflora is a promising source of bioactive substances of chemical-medicinal interest, besides being a strong natural candidate that can aid in the treatment of Alzheimer's disease. It is important to mention that the present study provides an unprecedented contribution about the chemical composition of root bark of black jurema, since to date no records were found in the literature on phenolic constituents of this part of the plant.