Effects of population and age on ginsenoside content of American ginseng (Panax quinquefolium L.)

American ginseng (Panax quinquefolium) is valued in traditional Asian medicine, and its use in Western countries has increased in recent years. The value of artificially-cultivated ginseng is much lower than that of woods-cultivated or wild-collected ginseng, but populations of the latter are threatened throughout its range. Our goal is to identify what factors influence the concentration of the pharmacologically active ginsenosides. Age-related increase in ginsenosides have been reported by several authors but variation among wild populations has not been considered. Ginsenoside analysis via HPLC was performed on roots collected from 8 different NY State populations. Statistical analysis of the effects of population and age on ginsenoside content indicated that there was a significant effect of both on ginsenoside Re, a significant interaction between population and age for ginsenosides Rb1 and Rb2, and a significant three way interaction between population, age and root fresh weight for Re. Ginsenosides Rb1 and Rb2 increased with age for some populations, but not for other populations. We conclude that the prevailing generalization that ginsenosides increase with root age cannot be applied to wild North American ginseng without taking into consideration population differences. The effects of population on ginsenoside content is likely to be related not only to environmental differences among collection sites but also genetic differences since there was considerable (several fold) variation in the content of ginsenosides within single populations. It is likely therefore that selection and cloning of individual roots for higher ginsenoside content could be a useful strategy for improvement of this medicinal crop. These results also suggest that populations could be selected based on their sensitivity to age and fresh weight-related increase in ginsenosides concentration.