Alleviation of
fatigue has been emerging as a serious issue that requires urgent attention. Health professionals and sports physiologists have been looking for active natural products and synthetic compounds to overcome
fatigue in humans. This study was designed to define the anti-
fatigue property of Rubus parvifolius L. (RPL) by characterization of active constituents using a mouse forced swimming test model. Four RPL fractions with different polarities containing anti-
fatigue activity were sequentially isolated from the
n-butanol RPL extract, followed by elution of 50%
ethanol-water fraction from D101 macroporous resin chromatography to obtain nigaichigoside F1,
suavissimoside R1 and coreanoside F1. Active constituents of the 50%
ethanol-water eluate of RPL were total
saponins. The fractions were examined based on the effect on weight-loaded swimming capacity of mice. Serum levels of
urea nitrogen (SUN),
triglyceride fatty acids (TG),
lactate dehydrogenase (LDH),
lactic acid (LA),
ammonia and
hepatic glycogen (HG) were also examined for potential mechanisms underlying the anti-
fatigue effect of RPL extracts. During the experiment, two inflammatory markers,
interleukin-6 (IL-6) and
tumor necrosis factor (TNF-α) in serum, were measured. We found that total
saponins from RPL possess potent capabilities to alleviate mouse
fatigue induced by forced swimming and that nigaichigoside F1 was responsible for the pharmacological effect. The underlying mechanisms include delays of SUN and LA accumulation, a decrease in TG level by increasing fat consumption, increases in HG and LDH so that
lactic acid accumulation and
ammonia in the muscle were reduced, and suppression of increased immune activation and inflammatory
cytokine production. Our findings will be helpful for functional identification of novel anti-
fatigue components from natural medicinal herbs.