ANTIOXIDANT ACTIVITY OF Erythrina americana Miller ALKALOIDS

Abstract

Alkaloids are chemical compounds with pharmacologic properties at low concentrations. In this study, the antioxidant activity of free alkaloids fractions in hexane and methanol, liberated in methanol and in erysodine, obtained from seeds of Erythrina americana Miller, was evaluated using the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method; the reaction was measured by UV-Visible spectroscopy. The liberated alkaloid fraction showed the highest antioxidant activity (0.1593 mg mL^-1± 0.0305), though all three crude fractions inhibited more than 50 % of the DPPH concentration. Pure erysodine was isolated from the fraction of liberated alkaloids by column chromatography, using dichloromethane:methanol at different polarities; this alkaloid was identified by thin-layer chromatography and 1H-NMR. Erysodine showed a strong DPPH inhibition which is comparable to the ascorbic acid inhibition (CI₅₀ = 0.0212 mg mL^-1 ± 0.008 and CI₅₀ = 0.0068 mg mL^-1 ± 0.0007, respectively). Also, erysodine at 0.5 mg mL^-1 inhibited up to 94% of DPPH.