Astragalus membranaceus is a well known oriental medicinal herb. The polysaccharides of the aboveground parts (AMA) and the radix (AMR) of A. membranaceus are the most important functional constituents. Methods and Results: The aim of this study was to determine the effects of AMA and AMR on the oxidative damage induced in the skeletal muscle of rats subjected to exhaustive exercise. Sprague-Dawley rats were randomly divided into exercise and non-exercise groups; in the groups receiving the test compounds, AMA and AMR were administered orally for 30 days. Skeletal muscle samples were collected from each rat after running to exhaustion on a treadmill to determine the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) and the concentation of malondialdehyde (MDA). The antioxidant enzyme activities of SOD and GSH-Px of skeletal muscle of AMA- and AMR-treated groups were significantly higher than those of the control and commercial sports drink (SPD)-treated groups in exhaustive exercise rats. In addition, MDA concentrations in the skeletal muscle of the AMA- and AMR-treated groups were significantly lower than those of the control and SPD-treated groups. In the present study, the effects of AMA and AMR on exercise endurance capacity were also evaluated in mice subjected to a swimming exercise test. AMA and AMR supplementation prolonged the swimming time of mice and enhanced exercise endurance capacity. AMA and AMR possess the ability to retard and lower the production of blood lactate, and prevent the decrease of serum blood glucose. Conclusions: These results showed that, AMR and AMA exerted beneficial effect in mice, increasing the activity of the antioxidant systems and inhibiting oxidative stress induced by exhaustive exercise. The compounds improved exercise performance and showed anti-fatigue effects against exhaustive exercise.

Background: Polysaccharides are the most important functional constituent in Astragalus membranaceus. The purpose of the present study was to evaluate the effect of polysaccharides isolated from the aboveground parts of A. membranaceus (AMA) and polysaccharides isolated from the roots of A. membranaceus (AMR) immune function by modulated cytotoxic T cell and Th1- and Th2- related cytokines kinetics. Methods and Results: Sprague-Dawley rats were randomly divided into exhaustive exercise case groups and non-exercise case, AMA and AMR samples were administered orally for 30 days (500 ㎎/㎏/day and 10 ㎎/㎏/day, respectively) and were compared to those rats in the groups fed commercial sports drink (SPD) and vehicle. Both exhaustive exercise groups and non-exercise groups had a lower ratio of CD4+ and CD8+ cells in the spleens of the rat fed AMA and AMR compared to those in the rats fed SPD and vehicle group. These results suggested that AMA and AMR promote an increase in the proportion of cytotoxic T cells. The IL-4- producing T lymphocytes decreased significantly in the AMR (10 ㎎/㎏/day) group compared to SPD and vehicle, whereas the AMA group increased the IL-4 concentration more than the SPD and vehicle in exhaustive exercise group. However, the populations of IFN-γ-producing T lymphocytes of AMR and AMA increased. AMA decreased the concentration of IFN-γ to inhibit the Th1 response and thereby increased the concentration of IL-4 to induce a Th2 response that was related to humoral immunity in the non-exercise group. Conclusions: These results showed that, in addition to Th1/Th2 regulation, AMR and AMA played an important immuno-modulatory role after exhaustive exercise-induced Th1/Th2 lymphocyte imbalance, which might be correlated with cytokine producing immunoregulatory cells.