Characterizing New Zealand forest grown ginseng (Panax ginseng C.A. Meyer and Panax quinquefolius L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Palmerston North, New Zealand
Ginseng is a slow-growing perennial herbaceous plant of the genus Panax (Araliaceae family). Ginseng root has been a significant source for natural medicines and has been used for thousands of years in East Asia. Ginsenosides are the unique and bioactive components in ginseng. They are affected by the growing environment and conditions. With the increasing demand for ginseng, wild ginseng is becoming rare, and most of the world’s supply of ginseng is from farmed ginseng. In New Zealand (NZ), ginseng has been grown as a secondary crop under a pine tree canopy with an open wild environment for more than 15 years. However, there is neither research on the chemical composition of NZ grown ginseng, nor reports on its biological activity. In this thesis, an LC-QTOF-MS/MS method was developed for characterizing and quantifying ginsenoside components of NZ-grown ginseng. A total of 102 ginsenosides were detected and identified from NZ-grown P. ginseng. The total content of ginsenosides in various parts of ginseng varied and was not dependent on age. In the underground parts, ginsenosides Rb1, mRb1, and Re were the main components. Furthermore, the average content of total ginsenosides in NZ-grown ginseng was 40.1 ± 3.2 mg/g (n = 14), which showed significantly (p < 0.05) higher concentration than that of China-grown ginseng (16.5 ± 1.2 mg/g, n = 113) and Korea-grown ginseng (21.1 ± 1.6 mg/g, n = 106). The individual ginsenosides Rb1, Re, Rf, and Rg1 from NZ-grown ginseng were 2.2, 2.9, 1.7, and 1.3 times higher than that of ginseng grown in China, respectively. In addition, fifty and forty-three ginsenosides were identified from various parts of NZ-grown P. ginseng and NZ-grown P. quinquefolius L., respectively, and 29 ginsenosides were found in both ginseng species. In both plants, concentration of Rb1 was highest in the underground parts (fine root, rhizome, and main root), and ginsenoside Re was highest in the aboveground parts (stem and leaf). In terms of improving the use of ginseng resources, ginseng leaves can be made into black ginseng leaves by steaming for ginsenoside transformation, and the less-polar ginsenoside (Rg3) can be greatly enriched through converting major ginsenosides in the post-harvest process, such as high temperature treatment at low pH. THP-1 cell line was used to evaluate the effects of different NZ-grown ginseng fractions on the productions of inflammatory cytokines. Less-polar ginsenoside fraction extracts (LPG) showed stronger anti-inflammatory effects than high-polar ginsenoside fraction extracts (HPG) on inhibiting pro-inflammatory cytokine (TNF-α, IL-1β, and IL-6) production. Particularly, 100 µg/mL LPG not only significantly inhibited the production of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, but also remarkably enhanced the production of anti-inflammatory cytokine IL-10. This thesis fills a gap in the chemical composition and biological activity of NZ-grown ginseng and provides methods for improving active components through the post-harvest process.