Bioguided extraction of polyphenols from grape marc by using an alternative supercritical-fluid extraction method based on a liquid solvent trap.

The biological activity of polyphenols extracted from grape marc was studied with a view to finding a new use for this winery waste. Polyphenols were extracted by using an alternative supercritical-fluid extraction method based on the use of a liquid trap that allows extracted polyphenols to be retained in a saline buffer, thus avoiding the need for the organic solvent required to elute polyphenols from a solid trap. The major extraction variables influencing the performance of the liquid trap (viz. CO(2) modifier content, flow-rate, extraction time and trap volume) were optimized. The proposed method was applied to the supercritical-fluid extraction extraction of 0.3 g grape marc with CO(2) modified with 3% methanol at 350 bar at 50 degrees C (CO(2) density 0.9 g mL(-1)) for 20 min, using a liquid flow-rate of 0.9 mL min(-1). The polyphenol extracts thus obtained exhibited cytotoxic effects that induced apoptosis in tumour cells.