Subcritical water extraction of bioactive components from ginseng roots (Panax ginseng C.A. Mey)

The feasibility of applying subcritical water extraction (SWE), which is considered to be an environmentally friendly and efficient extraction technology for the extraction of bioactive components from ginseng roots, was evaluated by comparing it with conventional water (WE) and ethanol (EE) extraction methods SWE was conducted at different temperatures ranging from 120 to 200 °C, and WE and EE were performed by solid-liquid heating extraction methods using water or 70% (v/v) aqueous ethanol as a solvent, respectively. SWE showed significantly and markedly higher extraction yields of total sugar (TS), total protein (TPro), phenolic components (TP), and more potent antioxidant activities than WE and EE. The optimized temperature for TS, TP, and antioxidant activities was 200 °C, and that for TPro was 180 °C. Although vanillin-perchloric acid colorimetric quantification showed that SWE yielded more total ginsenosides (TG) than WE and EE, ultrafast liquid chromatography tandem mass spectroscopy (UFLC-MS/MS) analysis revealed that SWE induced extensive hydrolysis of the ginsenosides, except for Rg2. At 160 °C, SWE yielded 9.7- and 6.2-fold more Rg2 than WE and EE, respectively. In comparison, the extraction yields of R1, Rb1, Rb2, Rb3, Rc, Rd, Re, Rg1, and Ro decreased significantly with the increase of SWE temperature. These findings suggested that SWE is a promising environmentally friendly and efficient technology for extracting bioactive polysaccharides, proteins, TP, and Rg2 from ginseng roots, but it has potency to induce extensive hydrolysis of ginsenosides, such as Rb1 and Re.