Ultrasound-Assisted Enzymatic Extraction of Anthocyanins from Raspberry Wine Residues: Process Optimization, Isolation, Purification, and Bioactivity Determination

Abstract

Raspberry wine residues (RWR) contain abundant anthocyanins. The extraction conditions for the ultrasound-assisted enzymatic extraction (UAEE) of anthocyanins from RWR were optimized using response surface methodology coupled with genetic algorithm. The optimum extraction parameters were extraction temperature of 44 °C, ultrasound power of 290 W, pectinase dosage of 0.16%, and extraction time of 30 min. Results showed that UAEE exhibited the highest anthocyanin yield (0.853 ± 0.009) mg/g and extraction efficiency (84.75 ± 2.11)% when compared with the other three conventional extraction methods (hot water-, acidified ethanol-, and enzymatic-assisted extractions). UAEE method was available for realizing high activities of DPPH (417.15 ± 11.83) Trolox equivalents/g extract and ABTS (520.07 ± 8.29) Trolox equivalents/g extract, and reducing power (412.79 ± 9.11) Trolox equivalents/g extract. AB-8 macroporous resin, Sephadex LH-20 column chromatography, and high-speed countercurrent chromatography (HSCCC) were used to separate and purify anthocyanins in turn. The main anthocyanins were identified by using HPLC-MS/MS and NMR. The two main anthocyanins (cyanidin-3-glucoside with the purity of 93.46% and cyanidin-3-rutinoside with the purity of 94.16%) were obtained from RWR. Ultimately, we further evaluated the anti-tumor activity of the main anthocyanins on lung cancer. Results showed that the anti-tumor effect of cyanidin-3-rutinoside on A549 cells was better than that of cyanidin-3-glucoside. In addition, cyanidin-3-rutinoside could memorably increase intracellular ROS levels and apoptosis of MCF-7 cells. The UAEE is an effective and rapid method. This method has a broad application prospect in the extraction of bioactive substances from natural plant resources.