Extraction kinetics and parameters of Silybum Marianum seeds

In order to respond to the basic requirements of food and pharmaceutical industries, to reduce or eliminate organic solvent residues in the final products, several extraction techniques were tested from the standpoint of performance, with low energy consumption. The aim of this study was to determine biological activities such as antioxidant and antiproliferative activities of flavonolignans from Silybum Marianum. Quantitative study of two methods, solvent extraction (Soxhlet) and supercritical CO2 extraction has concluded that the best performance is obtained for the supercritical fluid extraction at high pressure and low temperature. This study enhances this technique which aims to an estimable amount of pure product. The effect of supercritical extraction parameters on extraction kinetics and yields were studied: pressure (100-220 bars), temperature (40-80°C), particule size, CO2flowrate, contact time (15-90 min), ethanol as cosolvent. The model chosen is those proposed by Reverchon [1] who introduced models based on the differential mass balance for the extractor vessel, this model describes mass transfer between a single spherical porous particles and the supercritical fluid. Fatty acids were analyzed by gas chromatography and flavonolignans (silychristin, silydianin and silybin) by an HPLC method in seed extracts obtained by organic solvents and SC-CO2 with cosolvent. The antioxidant activity was measured by two complementary tests (DPPH and ABTS) and confirmed that the extract with higher antioxidant effect is the extract obtained by SC-CO2 at 220 bar and 40°C (yield=32.3 %). The biological activity of standards flavonolignans and an extract (220 bar, 40°C, ethanol as cosolvent, yield= 30.8%) was demonstrated with respect to a colon cancer cell line Caco-2.[2] [1]E. Reverchon, G. Donsi, L.S Osseo, Modeling of supercritical fluid extraction from herbaceous matrices, Ind. Eng. Chem. Res. 32 (1993) 2721. [2] N.BenRahal PhD Thesis Université de Lorraine 5 octobre 2012