Intestinal Immune-Modulating Activities of Polysaccharides Isolated from Commercial and Traditional Korean Soy Sauces

To characterize novel biologically-active ingredients in traditional Korean soy sauces, polysaccharide fractions were isolated from two different soy sauces made either commercially (CSP-0) or through a traditional Korean process (KTSP-0), after which their intestinal immune-modulating activities were examined. CSP-0 and KTSP-0 showed enhanced production of interleukine-6 (IL-6) in culture supernatant of Peyer's patch cells. However, KTSP-0 activity was more potent than that of CSP-0. Only KTSP-0 increased in vitro immunoglobulin A (IgA) production by Peyer's patch cells in a dose-dependent manner. KTSP-0 also showed the higher bone marrow cell proliferation activity through Peyer's patch cells than that of the CSP-0 group. To investigate the in vivo effects on the intestinal immune system, CSP-0 and KTSP-0 were administered orally to four experimental groups of mice (0.0, 0.5, 1.0, and 5.0 mg/mouse/day, 30 days). Oral administration of CSP-0 and KTSP-0 induced IgA production by Peyer's patch cells and increased IgA excretion into mouse stools in a dose-dependent manner. Peyer's patch cells from the mice administered both CSP-0 and KTSP-0 showed significantly higher IL-6 production than that of the untreated or CSP-0 groups. However, oral administration of KTSP-0 was more effective at the same dosage. KTSP-0 administration augmented IL-6 content in mouse sera, whereas CSP-0 did not show any effect on IL-6 induction. The above data lead us to conclude that the intestinal immune-stimulating activities of polysaccharides from Korean traditional soy sauce are much better than those of commercial ones.