Isolation of functional ingredients from rosemary by preparative-supercritical fluid chromatography (Prep-SFC)

A supercritical fluid extract of rosemary has been fractionated under supercritical conditions by using a preparative-SFC system. In this work, the optimum conditions have been evaluated to achieve a selective isolation of the compounds responsible for both, antioxidant and antimicrobial activities. A 25 cm × 10 mm i.d. LC-Diol packed column (dp = 5 μm) has been used and the separation took place at 80 °C of column temperature, 130 bar of pressure, and 10% of ethanol as modifier of the mobile phase (CO2). Two cyclones were employed to collect the fractions which were subsequently characterized by HPLC-DAD, GC, and in vitro antioxidant and antimicrobial assays. By a careful selection of the separation conditions it is possible to obtain two different fractions, one enriched with antioxidant and antimicrobial compounds (with an improvement of about 20% and 40% of antioxidant and antimicrobial activity, respectively, compared to the original extract) collected in cyclone 2 and with no residual rosemary aroma and another one containing the essential oil.