Potential anti-inflammatory and anti-oxidative properties of Thai colored-rice extracts

In Thailand, there has been growing interest in the use of colored rice extracts as a new source of anti-oxidative and anti-inflammatory effects. This study investigates the effects of different colored rice extracts in terms of their biological content, anti-oxidative activity, and their ability to reduce pro-inflammatory cytokines and matrix metalloproteinase (MMP) expression. Various colored rice from different rice cultivating areas in Thailand were used to obtain ethanolic extracts. The biological compounds in colored-rice extracts were determined by Folin-Ciocalteu colorimetric and pH-differential methods. To determine the anti-oxidative properties of colored-rice extract, DPPH radical scavenging, ferrous reducing power, and lipid peroxidation assays were used. The cytotoxicity of colored rice extracts was determined by MTT assay on a human promyelocytic leukemia (HL-60) cell line in vitro. The inhibition of pro-inflammatory cytokines (IL-6, TNF-α, NF-κB) and MMP expression in LPS-induced HL-60 cells was determined by ELISA assay. Moreover, MMP activity was determined by gelatinolytic zymography. The results found that red (Mun Poo, MP) rice exhibited high anti-oxidative activity and reduced pro-inflammatory cytokines and MMP-2 expression in LPS-induced HL-60 cells. This study provides new insights into the potential use of Thai colored rice extracts, especially red rice, as a source of anti-oxidants and anti-inflammation.