Enrichment of ginsenoside (Rg3) from ginseng by post-harvest processing and extraction
Background: Previous studies showed that New Zealand-grown ginseng contains an abundance of ginsenosides and that rare less polar ginsenosides, such as Rg3, exhibit more pharmacological activities than polar ginsenosides, which are the major components of ginseng.
Methods: The ginsenoside profile of New Zealand-grown Panax ginseng was manipulated by treatment with acetic acid, sodium hydroxide, pH, and high temperature. The abundance of 23 ginsenosides extracted by different treatments was quantified using high-performance liquid chromatography.
Results: Treatment with 0.5 mol/L acetic acid can stimulate the degradation of polar ginsenosides to less polar ginsenosides (5.6% Rg3 was accumulated, P < 0.0001). Furthermore, when ginseng root was treated at 121 °C for 100 min in a pH 3.0 acetic acid aqueous solution, the majority of the polar ginsenosides were converted into less polar ginsenosides. Specifically, 83.46 ± 3.69% (P = 0.0360) of the less polar ginsenosides and 41.01 ± 2.39% (P = 0.0412) of Rg3 were enriched. In contrast, alkali treatment did not convert the polar ginsenosides into less polar ginsenosides at mild temperature and less conversion was observed compared with acid treatment at high temperature.
Conclusion: This is the first attempt to manipulate the ginsenoside profile of New Zealand-grown ginseng. The conditions (high temperature with low pH) may be modified to produce and enrich the less polar ginsenoside fraction (especially Rg3) from the total ginseng extract.