Large-scale supercritical fluid chromatography (SFC) can be used for the purification and concentration of natural samples. The aim of the present work was the concentration of two important antioxidants, mangiferin and quercetin, from mango leaf extracts by using this technique at a pilot plant scale. First of all, the influence of experimental conditions (pressure, temperature, mobile phase composition, isocratic/gradient mode) on the elution profile of the aforementioned compounds and two typical phenolic compounds presented in natural extracts (gallic acid, methyl gallate) was analyzed. The most favorable conditions selected, at the range studied of 10-40 MPa and 40-60 degrees C, were 40 MPa and 40 degrees C using as mobile phase the mixture of CO2 + modifier (0.5% formic acid in methanol) in a gradient mode by increasing the concentration of modifier from 5% to 50% (w/w). In a second step, the fractionation of a natural extract obtained by high-pressure extraction was realized. At these conditions, it is possible to multiply the concentration of mangiferin by a factor of five with respect to the original extract. (C) 2014 Elsevier B.V. All rights reserved.