Polyphenolic compounds, antioxidant and anti-inflammatory effects of Abeliophyllum distichum Nakai extract

The present study was conducted to evaluate the antioxidant and anti-inflammatory activities of crude methanolic extract of Abeliophyllum distichum Nakai, and those of its partitioned fractions, including hexane, ethyl acetate, n-butanol, and aqueous. The antioxidant activities were analyzed by DPPH free radical scavenging and oxygen radical antioxidant capacity assay. Results showed that the BuOH fraction possessed a strong antioxidant activity through a hydrogen atom transfer reaction-based mechanism and a single electron transfer reaction-based mechanism. In lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, the BuOH fraction of A. distichum methanol extract exhibited a strong inhibitory effect on the nitric oxide production and inhibited the expression of pro-inflammatory mediators, including COX-2, TNF-alpha, and IL-6, through the inhibition of the MEK/ERK signaling pathway. In addition, the BuOH fraction inhibited the LPS-induced ROS level through the NADPH oxidase-independent mechanism. Furthermore, HPLC analysis identified chlorogenic acid, caffeic acid, gentisic acid, rutin, ferulic acid, and quercetin, and suggested that the antioxidant and anti-inflammatory activities of the BuOH fraction should be mediated by the presence of higher amounts of caffeic acid, rutin, and ferulic acid than other fractions. Taken together, these results suggest that A. distichum extract is a source of antioxidant and anti-inflammatory compounds, and could be developed as a potential source for functional food and dietary health supplement.