Estudo químico da resina de Amburana cearensis (Fabaceae)

Abstract

Amburana cearensis(Fr. All.) AC Smith (Fabaceae), popularly known as amburana de cheiro, cerejeira and cumaruis typical of the Caatinga and widely distributed in northeastern of Brazil. It is used in folk medicine to treat inflammations of the respiratory tract such as influenza, asthma and bronchitis. This work aimed the chemical investigation of the resin of Amburana cearensis and evaluate its antioxidant potential. Chromatographic profileanalysis using HPLC-DAD showed the presence of phenolic compounds. Chromatographic fractionation with Sephadex LH-20 followed by HPLC resulted in the isolation of twelve substances, comprising seven isoflavones identified as 7,8,3'- trihydroxy- 4'-methoxyisoflavone (Re-1), 7,8,3'-trihydroxy-6,4’-dimethoxyisoflavone (Re-2), 7,3'-dihydroxy-8,4'-dimethoxyisoflavone (Re-3) 7,3'-dihydroxy-4'-methoxyisoflavone (Re-4), 7,3'-dihydroxy-6,4'-dimethoxyisoflavona (Re-5), 3'-Hydroxy-7,8,4' trimethoxyisoflavone (Re-9) and 7,8,3',4'-tetramethoxyisoflavone (Re-12), one new isoflavonolignan identified as (2S,3S)-2,3-trans-3-(4’’-hydroxy-3’’,5’’-dimethoxyphenyl) – 8 – (3’-hydroxy-4’- methoxyphenyl)-2-hydroxymethyl-5-methoxy-2,3-dihydro - 7H-1,4 - dioxin [2,3h] chromen-7-one Re-7) and three chalcones identified as 2',3,4,4’-tetrahidroxi-trans-chalcone (Re-6), 2',4,4’-trihydroxy-3-methoxy-trans-chalcone (Re-11) and 2',4,4’-trihydroxy-trans-chalcone (Re-10) and a quinone identified as 3',4'-dimethoxy-1'- (7-methoxy-4-oxo-4H-romen-3-yl) benzo-2',5'-quinone (Re-8). The structures of these compounds were estabilished on the basis of 1D (1H and APT) and 2D (1H-1H COSY, HMQC, HMBC and NOESY) NMR spectroscopy. To evaluate the antioxidant potential of methanolic extract of the resin were carried out tests with DPPH, ABTS and the β-carotene / linoleic acid system. The test results showed that the resin showed promising activity antiradical front of DPPH (EC50 = 6.1 ± 0.06) and ABTS (EC50 = 10.42 ± 0.11), and good oxidation inhibitory activity across the β-carotene / linoleic acid system (69.09 ± 0.7, t = 60 min).