Antioxidant activity and phytochemical screening of extracts of Erythroxylum suberosum A.St.-Hil (Erythroxylaceae)

Abstract

Erythroxylum suberosum (Erythroxylaceae) is used in traditional Brazilian medicine as antidiarrheal, astringent, antirheumatic, anesthetic and against indigestion. The objectives of this study were to perform classical phytochemical screening, determine the total phenolic content and the antioxidant activity of ethanol and ethyl acetate extracts of E. suberosum. The extracts of the leaves were obtained by maceration. Phytochemical screening was performed using Thin Layer Chromatography (TLC) and specific reactions. Total phenolic content was determined using the Folin-Ciocalteu method. The antioxidant activity of the extracts was performed by reduction of DPPH, reduction of Fe+3 and Cyclic Voltammetry (CV). Phytochemical screening suggested the presence of alkaloids, coumarins, flavonoids, anthocyanins and condensed tannins in ethanol extract and flavonoids and triterpenes/steroids in the ethyl acetate extract. The amount of total phenolics detected was expressive, especially in the ethanol extract (575.50±2.50 mg g-1 of ethanol extract and 242.20±9.53 mg g-1 of extract in ethyl acetate). The ethanol extract showed higher antioxidant activity in the three methodologies employed (DPPH: IC50 of 0.18 mg mL-1, reduction of metal ion at 0.3 mg mL-1: 0.903±0.006-absorbance at 700 nm, CV: Increase of anodic current at 1.0 V at 2 mg extract mL-1) in comparison with the extract in ethyl acetate (DPPH: IC50 of 0.74 mg mL-1, reduction of metal ion at 0.3 mg mL-1: 0.871±0.007-absorbance at 700 nm, CV: Lower increase of anodic current at 1.0 V at 2 mg extract mL-1). The highest antioxidant activity of the ethanol extract may be associated with a higher content of phenolic compounds.