Immunomodulatory Activities of Polysaccharides from Lobaria kurokawae Yoshim
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Abstract:
The aim of this study was to determine the immunomodulatory activities of the neutral polysaccharide LKY-I extracted from Lobaria kurokawae Yoshim. The polysaccharide LKY-I was isolated sequentially using ultrasonic-assisted water extraction, ethanol precipitation, diethylaminoethyl cellulose (DEAE-52) ion-exchange chromatography, and gel permeation chromatography. We investigated the immunomodulatory activities using different concentrations of LKY-I. The polysaccharide LKY-I at a concentration range of 31.25–500 μg/mL had no obvious in vitro toxic effects in macrophages (RAW 264.7). The phagocytic ability of macrophages treated with 500 μg/mL LKY-I was higher than that of the macrophages in the positive control group treated with lipopolysaccharide (LPS); absorbance, 1.39. In addition, LKY-I induced the production of nitric oxide (NO) up to 55.42 ± 1.79 μM. Compared with the control group, the LKY-I group showed an increase in the secretion of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) by 102.3% and 289.5%, respectively. Furthermore, LKY-I at a dose of 125–500 μg/mL showed a marked increase in the mRNA expression levels of inducible nitric oxide synthase (iNOS), TNF-α, and interleukin 6 (IL-6). LKY-I in combination with LPS or concanavalin A (ConA) significantly promoted the proliferation of lymphocytes. Thus, our findings suggest that LKY-I has immunomodulatory effects and can be used as a health-promoting food supplement.
