Rust-spotted North American Ginseng Roots: Phenolic, Antioxidant, Ginsenoside, and Mineral Nutrient Content

Abstract

Rusty root is a major problem in ginseng production worldwide as it reduces root quality. Full characterization of rusty root is unavailable, and necessary for development of effective control measures. A comparison of phenolics, antioxidants, ginsenosides, and mineral nutrient content of rusted and non-rusted tissue from disease-free roots is reported. Periderm and adjacent tissues of 4-year-old North American ginseng roots (Panax quinquefolius L.) had a total phenolic content of 3.05 mg·g-1 dry weight (as gallic acid equivalents), which was increased 53% by rust-spotting. Antioxidant activity increased with phenolic content and was 33% higher (3.6 vs. 2.7 mg·g-1 dry weight as ascorbic acid equivalents) in rust-spotted tissue. Total ginsenoside content was higher (139.1 vs. 119.4 mg·g-1) in healthy than in rust-spotted tissue, the latter reflecting a significant decrease in four of the major ginsenosides (Rb2, Rc, Rd, and Re). The Rg group was higher (38.0 vs. 29.9 mg·g-1) in healthy than in rust-spotted tissue. The mineral elements N, P, Ca, Mg, Zn, Mn, and Fe were higher, and K lower (21%) in rust-spotted tissue than in healthy tissue.