Estudo químico e avaliação da atividade antidiabética dos extratos das cascas da Cassia bakeriana Craib

Abstract

Cassia bakeriana is a species found in Thailand and belongs to the Fabaceae family and the Cassia genus, which has great importance within this family. Several specialized metabolites have been isolated from Cassia species, in addition to the reports of the use of many parts of this plant in traditional medicine, for the treatment of hanseniasis, mycoses, eye infections, skin, and hepatic diseases. As C. bakeriana does not have many studies published in the literature, in this work, we evaluated the chemical composition, the antioxidant activities, and the biologic activities of the bark. Then, the hexane extract (EH) and ethanol extract (EE) were prepared by maceration, and the fractionation by liquid-liquid extraction of the EE with solvents of increasing polarity, obtaining the dichloromethane fractions (FD), ethyl acetate (FEA), n-butanol (FB) and water (FA). Regarding the tests, the antioxidant capacity was evaluated by ORAC and DPPH methods. In the ORAC method, the values obtained for the EE and for FD, FAE and FB were well above the values obtained for the control (ascorbic acid), and the best results were FD with 4514.37 ± 176.03 μmol troloxeq gsample–1. Regarding the DPPH method, the IC50 values were slightly above those observed for the control, the best result was FAE with 93,30% of radical inhibition and IC50 de 25.90 ± 3.2 μg mL–1. Also, the capacity inhibitory activities of α-amylase and α-glucosidase enzymes from extracts and fractions were evaluated. The most important result was the α-amylase inhibition by FEA with 94.00±1.13% of inhibition and IC50 of 1.05±0.21 μg mL–1. Another activity evaluated was the glycation inhibitory capacity, with FB showing the most promising value with inhibition of 85.15±2.47% and IC50 of 76.95±5.87 μg mL–1. By Mass Spectrometry (MS) it was possible to identify many of the compounds in the EE, FEA, FD, and FB, which were the most active ones. The main classes of the identified metabolites were flavonoids, proanthocyanidins and anthraquinones, which can be the responsible for the activities shown in the extracts and fractions. It was the first time that the antioxidant and antidiabetic activities for the bark were evaluated and the first complete chemical composition for the EE and other fractions. These studies showed that extracts and fractions on the C. bakeriana are promising sources of bioactive compounds, in addition to the contribution to the chemosystematics of the genre.