Abstract: This study was conducted to optimize the fermentation conditions of wheat bran for improved yield of polysaccharides using response surface methodology and to investigate the anti-inflammatory effects of the polysaccharides extracted from fermented wheat bran in Wistar rats injected with diquat. Solid-sate fermentation of wheat bran was carried out with a mixed stater culture of Saccharomyces cerevisiae and Bacillus subtilis. The fermentation conditions (temperature, time, inoculum size and solid-to-water ratio) were optimized using response surface methodology. The anti-inflammatory effects were evaluated by measuring the levels of TNF-α, IL-6, IL-2 and IL-1β in the plasma and liver of rats challenged with diquat. The results showed that a temperature of 35.4 ℃, a fermentation time of 52.7 h, an inoculum size of 10.4% and a solid-to-water ratio of 1:1.16 (g/mL) were found to be the optimal conditions to obtain a higher yield of polysaccharides of 130.21 mg/g. Diquat significantly increased the levels of TNF-α, IL-6, IL-2 and IL-1β in the plasma and liver of rats (P < 0.05), and oral administration of the polysaccharides extracted from fermented wheat bran significantly decreased these cytokine levels in rats under oxidative stress by diquat (P < 0.05) and returned them to normal with its increasing concentration. In summary, the polysaccharides from fermented wheat bran can exert anti-inflammatory effects.

Key words: wheat bran polysaccharides, fermentation process, anti-inflammatory effects