Analysis of ginsenosides in Panax ginseng in high pressure microwave-assisted extraction

High pressure microwave assisted extraction (HPMAE) was applied to extract the ginsenosides from Panax ginseng root. The influences of extraction solvent, extraction pressure and extraction time were individually investigated. HPMAE has been compared with other extraction methods, including Soxhlet extraction, ultrasound-assisted extraction and heat reflux extraction. The determination of ginsenosides was performed by HPLC-ESI-MS. The results indicated that the HPMAE not only took a shorter time but also afforded higher extraction yields of ginsenosides, especially ginsenoside Rb-1, Rc, Rb-2 and Rd. Furthermore, the neutral ginsenosides and malonyl ginsenosides in Panax ginseng root extracts by HPMAE were investigated. The malonyl ginsenoside m-Rb-1, m-Rc, m-Rb-2 and m-Rd degraded in HPMAE at 400 kPa (109-112 degrees C) in 70% (v/v) ethanol-water and at 600 kPa (112-115 degrees C) in methanol, and transformed into corresponding neutral ginsenoside Rb-1, Rc, Rb-2 and Rd. Using water as extraction solution, tile neutral ginsenosides degraded under HPMAE at 400 kPa (135-140 degrees C), and transformed into less polarity rare ginsenosides. (c) 2008 Elsevier Ltd. All rights reserved.