Black rice anthocyanin-rich extract and rosmarinic acid, alone and in combination, protect against DSS-induced colitis in mice

Abstract

The aim of this study was to investigate the effect of black rice anthocyanin-rich extract (BRAE) and rosmarinic acid (RA), alone and in combination, on dextran sulfate sodium (DSS)-induced colitis in mice. Results showed that administration of BRAE and RA, alone and in combination, significantly decreased the disease activity index (DAI) and the histological score of colons in DSS-induced colitis mice. Moreover, the administration of BRAE and RA, alone and in combination, not only reduced myeloperoxidase (MPO) and nitric oxide (NO) levels, but also inhibited the expression of pro-inflammatory mediators including interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Our results showed that BRAE decreased the histological score and TNF-α mRNA expression in a dose-dependent manner, while BRAE + RA dose-dependently attenuated the histological score and mRNA expression of IL-6. However, the benefits of RA were not dose-dependent within the dose range of 25–100 mg kg⁻¹. The combination of BRAE and RA showed better inhibitory effect on the NO content and iNOS mRNA expression than BRAE or RA given alone, and was the most effective in ameliorating DSS-induced colitis at 100 mg kg⁻¹. Notably, the BRAE and RA combination exhibited additive interactions in reducing MPO and NO levels, as well as the expression of some pro-inflammatory mediators (IL-6, IL-1β and iNOS), especially at 100 mg kg⁻¹. In conclusion, dietary BRAE and RA, alone and in combination, alleviate the symptoms and inflammation of DSS-induced colitis in mice, and may provide a promising dietary approach for the management of inflammatory bowel disease.