Effects of Blackberry and Blueberry Polyphenol Extracts on Nitric Oxide and Tumor Necrosis Factor-Alpha Production in Lipopolysaccharide-Stimulated RAW264.7 Macrophages

Plants are rich sources of polyphenols which are reported to play an important role in promotion of human health. Epidemiological studies have shown that populations who consume foods rich in polyphenols have lower incidence of chronic inflammatory diseases. For instance, polyphenols have been shown to modulate the inflammatory response by interacting with numerous molecular targets such as inhibiting nitric oxide (NO), and tumor necrosis factor-' (TNF-'). The objective of the present study was to investigate whether blackberry and blueberry polyphenols modulate the production of NO, TNF-' in lipopolysscharide (LPS)-stimulated RAW 264.7 macrophage cells. Berry polyphenols were extracted using ethanol and total phenolics were quantified according to the Folin-Ciocalteu method. Macrophages were treated with different doses of berry polyphenols (10, 100, 1000'g/ml) 1 hr prior to stimulation with 10ng/ml LPS for 6 hrs. Supernatants were then collected to measure NO and TNF-' production. Blackberry and blueberry extracts were confirmed to be rich in polyphenol (2000 and 3000mg/g expressed as gallic acid equivalents, respectively). Blackberry polyphenol-rich extract strongly inhibited NO production at doses of 10 and 100'g/ml by 56 and 59 %, respectively, without exerting cytotoxicity while blueberry polyphenol-rich extract had little effect on NO production. No significant decrease in TNF-' production was seen when LPS-stimulated RAW 264.7 macrophages were treated with different doses of berry extracts. These results of the present study indicate that polyphenol-rich extracts from blackberry and blueberry possess anti-inflammatory properties. In conclusion, our findings may suggest that regular consumption of polyphenol-rich berries promote human health.