Optimization of the extraction of Curcuma longa L. oleoresin with supercritical CO2

The fresh rhizomes and flour of turmeric (Curcuma longa L.) have been used for centuries in traditional medicine to treat ailments. In recent years, attention has been paid to the beneficial properties of turmeric such as the prevention and control of diabetes. The objectives of this study were to optimize the extraction parameters of turmeric oleoresin (TO) with supercritical CO2 and ethanol (SC-CO2), and to evaluate the antioxidant activity and hypoglycemic activity in vitro and in vivo. The results showed that the optimal conditions for oleoresin extraction using SC-CO2 were 188 bar, 65°C and 180 min; the yield obtained under optimal conditions was 16.09 ± 0.57g oleoresin/100 g turmeric flour; antioxidant activity (ABTS) was 2224.96±26.33 µmol TE/g oleoresin; the mean inhibitory concentration of α-glucosidase (IC50) was 11.59 ± 2.05 µg/mL; and the greatest hypoglycemic effect in vivo in mice was obtained at the concentration of 200 mg of TO /kg body weight. This work shows the optimized conditions to extract the greatest amount of TO with the highest content of curcuminoids and antioxidant activity, and the in vitro and in vivo hypoglycemic effect of TO, for its possible use in functional foods.