Immunomodulatory effects of feruloylated oligosaccharides from rice bran

Feruloylated oligosaccharides (FOs), the ferulic acid ester of oligosaccharides, can be released either by the enzymatic or mild acid hydrolysis of arabinoxylans present in cereal bran, and are usually considered as natural antioxidants. However, no related research is available to explain their immunomodulatory effects. This report elucidated their immunomodulatory effects through the variations of pro-inflammatory mediators in vitro. FOs were obtained from the mild acid hydrolysis of rice bran. We found that FOs (0.1-100 μg/ml) induced tumour necrosis factor alpha (TNF-α), IL-1β, IL-6, nitric oxide (NO) and PGE(2) production in unstimulated macrophages, RAW264.7 cells. Furthermore, pre- and post-treated FOs (0.1-100 μg/ml) dose-dependently suppressed TNF-α, IL-1β, IL-6 and NO production, and induced IL-10 production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells without exerting cytotoxicity. As a result anti-inflammatory and therapeutic activities were revealed. It is noteworthy that prostaglandin E(2) (PGE(2)) production was significantly suppressed at an FO level of 100 μg/ml. The in vitro assessment of inflammatory mediators should be useful in further characterising the effects of FOs on immunomodulation. Moreover, it will create the economical value of rice bran, which has long been considered as conventional agricultural wastes.