Structural characteristics and anti-fatigue mechanisms of a homogeneous polysaccharide from green tea (Camellia sinensis (L.) O. Kuntze)

This study investigated the structural features and anti-fatigue mechanisms of TPS4-1, a homogeneous polysaccharide derived from Tianzhu Xianyue roasted green tea. Structural analysis revealed that TPS4-1 was primarily composed of arabinose, galactose, glucuronic acid, glucose, and mannose. Its backbone structure was characterized by the repeating units →1)-α-L-Araf-(3→, →1)-α-L-Araf-(5→, →1)-β-D-Manp-(4→,→1)-β-D-Galp-(3→, and →1)-β-D-Galp-(4 → with a side chain connected to the C-6 position of the →1)-β-D-Glcp-(3,6 → residue. In an exhaustive swimming mouse model, TPS4-1 extended swimming duration by 71.2 %, alleviating fatigue through enhanced hepatic (52.7 %) and muscle glycogen (47.1 %) levels, reduced blood lactate (24.3 %) and urea nitrogen (28.6 %) concentrations, and oxidative stress mitigation via increased SOD (25.1 %) and GSH-Px (53.3 %) activity with decreased MDA (33.1 %). Emerging evidence indicated that physical fatigue was influenced by central fatigue mechanisms mediated by serotonin (5-HT). Notably, TPS4-1 suppressed exercise-induced 5-HT elevation in the brain, correlating with improved endurance. This dual regulatory mechanism involved: (1) the promotion of gut-derived short-chain fatty acids, and (2) the regulation of tryptophan metabolism to restrict 5-HT synthesis. The findings highlight the unique dual-action potential of TPS4-1, targeting both peripheral metabolic regulation and central fatigue pathways, thereby positioning it as a promising functional anti-fatigue agent.