Effects of isomerisation and oxidation on the immunomodulatory activity of chlorogenic acid in RAW264.7 macrophages.

Summary: Chlorogenic acid (CA) is one of the major polyphenols in fruit that contributes to most bioactivities. However, it is susceptible to isomerisation and oxidation in processing and thus displays varied bioactivity. This study aimed to evaluate the isomerisation and oxidation effects of CA on the potential immunomodulatory activity in RAW264.7 macrophages through the NF‐E2‐related factor‐2 (Nrf2) and nuclear factor‐kappa B (NF‐κB) signalling pathways. The results showed that isomerisation significantly affected the immunomodulation of CA by reducing Nrf2 and increasing NF‐κB nuclear translocation. The oxidation of CA weakened the effect of immune regulation in macrophages through impacts on the nucleic translocation of Nrf2 and NF‐κB, cellular reactive oxygen species (ROS) accumulation, antioxidant enzyme (superoxide dismutase, SOD) activity and cytokine expression. Consequently, isomerisation and oxidation remarkably affect the immunomodulation of CA via the Nrf2 and NF‐κB pathways. [ABSTRACT FROM AUTHOR]