Anti-inflammatory effects of seed ethanolic extracts of the common buckwheat and tartary buckwheat are mediated through the suppression of inducible nitric oxide synthase and pro-inflammatory cytokines in LPS-induced RAW 264.7 macrophage cells

The ethanolic seed extracts of the common buckwheat (CB) and tartary buckwheat (TB) were examined for their anti-oxidant and anti-inflammatory effects on lipopolysaccharide (LPS)-induced RAW 264.7 cells. In this study, it was observed that the rutin content of TB extracts was 65-78 times higher than the CB extracts, while quercetin was only detected in the TB extracts. In addition, TB extracts were observed to have 1.8-2.0 times higher flavonoid and polyphenolic content than the CB extracts. Cytotoxicity was not observed when both the buckwheat extracts were evaluated at concentrations in the range of 6.25-400 μg/mL. The treatment with TB extracts significantly suppressed the LPS-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression at the protein and mRNA levels. The TB extracts more potently inhibited the LPS-induced production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 than the CB extracts. The mRNA levels of TNF-α, IL-1β, and IL-6 were also significantly inhibited both by the TB and CB extracts in a pattern similar to their production.