Rice protein hydrolysates (RPHs) inhibit the LPS-stimulated inflammatory response and phagocytosis in RAW264.7 macrophages by regulating the NF-κB signaling pathway

The antioxidant and anti-hypertension properties of rice peptides following hydrolysis by proteolytic enzymes have been investigated previously, but the anti-inflammatory and immune characteristics have not been fully explored. In this study, we investigated the inhibitory effects of trypsin-derived rice protein hydrolysates (RPHs) on the inflammatory response in LPS-stimulated RAW264.7 macrophages, and probed their underlying molecular mechanisms of action. Moreover, a fraction, RPHs-C-7-3, displayed significant inflammation suppression activity by inhibiting the release of nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). Transcription of TNF-alpha, inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and interleukin-1 beta (IL-1 beta) were decreased in a dose-dependent manner. Additionally, RPHs-C-7-3 attenuated iNOS and repressed the nuclear transcription factor (NF-kappa B) signaling pathway by impeding the nuclear translocation of p65. RPHs-C-7-3 also repressed the phagocytic ability of the activated macrophages. Our results demonstrated that RPHs exerted anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages and may therefore have potential for treating inflammation-related conditions.