Good immunity is highly valued in modern society. Although yuja's efficacy in immunity enhancement has been elucidated, there have been few studies on its role. In this study, we investigate the immune enhancement activity of yuja juice extracts (YJEs) and yuja concentrate extracts (YCEs). The immunoregulatory potencies of YJE and YCE were examined by determining cell viability and the expression of cytokines and immune-related molecules in RAW264.7 cells and mouse primary splenocytes. YJE and YCE induced the production of inducible nitric oxide synthase and cytokines (IL-10, IL-4, IL-6, and IFN-γ) at 1000 μg/mL concentration in RAW 264.7 cells. In addition, in mice that were orally administered 3000 or 2000 mg/kg concentrations of YJE or YCE, immune-related cytokines in splenocytes were boosted to levels higher than those in control mice. Importantly, no liver toxicity was observed at all doses. Thus, our results suggest that compounds present in YJEs and YCEs represent novel natural immune-modulatory substances.
Keywords: Citrus junos Sieb. ex Tanaka; RAW264.7 cells; cytokines; immune-stimulatory; splenocyte; yuja.