Extraction of parishin B and parishin C from Gastrodiae Rhizoma by subcritical water technology

Subcritical water extraction (SWE) was used to extract bioactive parishin B (PB) and parishin C (PC) from Gastrodiae Rhizoma. Extraction conditions were optimized by Box-Behnken design (BBD) of response surface methodology (RSM). The highest yield of PB was 7.46 ± 0.18 mg/g when the solid/liquid ratio (SLR) was 4.5 mg/mL at an extraction temperature of 118 °C and extraction time of 50 min, and the highest yield of PC was 5.27 ± 0.07 mg/g when the SLR was 22 mg/mL at an extraction temperature of 145 °C and extraction time of 23 min. Compared with heating reflux extraction the yield of PB was about 1.3 times higher, and that of PC about 2.6 times higher; Compared with ultrasound assisted extraction the yield of PB was about 3 times higher, and that of PC about 6 times higher. Degradation of parishin A by SWE showed that the increasing mechanism of PB and PC mainly attributed to the conversion of PA into PB and PC. This study suggests that SWE was an efficient and green way to extract natural products with greater values.