Effect of pecan phenolics on the release of nitric oxide from murine RAW 264.7 macrophage cells

• Pecan phenolics impart anti-inflammatory activity to LPS-stimulated RAW 264.7 macrophages.
• Phenolic acids & small PACs have a dose-dependent effect at curbing inflammation in the cell model.
• The low-molecular-weight compounds comprise catechin, gallic acid and ellagic acid derivatives.
• Cytotoxicity and phenolic–LPS complexation are not responsible for the anti-inflammation.
• This is the first reporting of pecan phenolics possessing anti-inflammatory activity.

Inflammation is linked to numerous chronic disease states. Phenolic compounds have attracted attention because a number of these compounds possess anti-inflammatory properties. A phenolic crude extract was prepared from pecans and separated by Sephadex LH-20 column chromatography into low- and high-molecular-weight (LMW/HMW) fractions. Anti-inflammatory properties of these fractions were assessed in LPS-stimulated RAW 264.7 murine macrophage cells. NO and reactive oxygen species (ROS) production was monitored after 3 different experimental protocols: (1) pre-treatment with Escherichia coli O111:B4 lipopolysaccharide (LPS); (2) pre-treatment with a pecan crude extract and its fractions; and (3) co-incubation of LPS with a pecan crude extract and its fractions. The LMW fraction displayed a dose-dependent decrease in NO production and a significant decrease from the LPS control in ROS production when cells were either co-incubated with or pre-treated with LPS. The phenolics were characterized by HPLC to help identify those responsible for the observed effect.