Composition and systemic immune activity of the polysaccharides from an herbal tea (Lycopus lucidus Turcz)

This study was undertaken to characterize the water-soluble polysaccharides isolated from an herbal tea, the leaves of L. lucidus Turcz. HPLC analysis showed that L. lucidus polysaccharides (LLPs) were mainly composed of galactose (50.1 mol %), followed by galacturonic acid (14.2 mol %), accounting for 64.3 mol % of all quantitative nine monosaccharides. Furthermore, we evaluated the systemic immunological efficacy of LLPs in mice. Mice were intragastrically administered once daily with low-dose (50 mg/kg), intermediate-dose (100 mg/kg), and high-dose (300 mg/kg) of LLPs, respectively, for 30 consecutive days. In comparison with vehicle, LLPs significantly enhanced the plaque-forming cells (PFCs), and serum hemolysin level, and delayed-type hypersensitivity (DTH) in response to sheep red blood cells (SRBC) in a dose-dependent manner (p < 0.01). In LLPs-treated mice, phagocytosis capacity and concanavalin A-induced spleenocyte proliferation were remarkably increased (p < 0.05). The intermediate- and high-dose of LLPs also caused a significant increase in the indices of thymus and spleen organs of mice (p < 0.05). This suggests that the polysaccharides derived from the tea leaves of L. lucidus improves the immune system and might be regarded as a biological response modifier.