Anti-inflammatory effect of black rice in Aggregatibacter actinomycetemcomitans stimulated macrophages via inhibition of NF-κB pathway

Abstract

Periodontitis, which results from infection and inflammation, is one of the most common inflammatory diseases. Some studies have shown that plant extracts can inhibit inflammation in periodontitis. However, the anti-inflammatory effects of black rice extract (BRE) have not yet been investigated. Here, we investigated the anti-inflammatory activity of BRE in vitro on Aggregatibacter actinomycetemcomitans (A. a) stimulated RAW 264.7 macrophages. The results showed that BRE did not affect cell viability at concentrations ranging from 0.015 to 0.5 mg/mL, but toxicity was observed >1 mg/mL. A. a-induced nitric oxide (NO) production and iNOS protein expression were inhibited by treatment with BRE. In addition, BRE inhibited the gene expression of pro-inflammatory cytokines, such as IL-6, IL-1β and TNF-α, and blocked NF-κB p65 translocation as well as IκBα and IKK α/β phosphorylation. Moreover, the DPPH and ABTS radical scavenging activity results showed that BRE exhibits strong antioxidant activity in a dose-dependent manner. This study found that BRE exerts anti-inflammatory activity via inhibition of NF-κB signaling and antioxidant activity. The above finding suggests that BRE can be used as a potential therapeutic agent for treating inflammation in periodontitis.