Anti-fatigue effects of proteins isolated from Panax quinquefolium

American ginseng (Panax quinquefolium) is an obligate shade perennial plant that belongs to Araliaceae ginseng species, and is native to eastern USA and Canada. Ginseng proteins are reported to have several pharmaceutical properties. However, such properties of American ginseng proteins (AGP) have seldom been reported. Also, anti-fatigue properties of AGP have not been studied. Therefore, we examined the anti-fatigue effects of AGP in mice. The molecular weight and protein contents of AGP were determined by SDS-PAGE, while the amino acid composition was analyzed by HPLC. The mice were divided into four groups. The control group was administered distilled water by gavage every day for 28 days. The other groups, designated as AGP treatment groups, were administered 125, 250 and 500 mg/kg of body weight, respectively of AGP by gavage every day for 28 days. Anti-fatigue activity was estimated using forced swimming test, and biochemical indices were determined using available kits. The subunit molecular weight of AGP ranged from 8–66 kD and the protein content measured by Bradford assay was 1.86 mg/mL. The forced swimming time of low, intermediate and high groups were found to be longer as compared to the control group. AGP significantly decreased blood lactate (BLA) and serum urea nitrogen (SUN) levels, and increased hepatic glycogen (GLU) level. Additionally, AGP lowered malondialdehyde (MDA) content and increased the levels of glutathione peroxidase (GPx) and superoxide dismutase (SOD). AGP shows anti-fatigue activity in mice, as measured by the physiological indices for fatigue.