Role of capsaicin, curcumin and dietary n-3 fatty acids in lowering the generation of reactive oxygen species in rat peritoneal macrophages.

Reactive oxygen species (ROS) generated by activated macrophages play an important role in the initiation of inflammation. Ten different spice principles, some of which with known anti-inflammatory properties, were tested for their effect on generation of superoxide anions, hydrogen peroxide and nitrite radical generation by activated rat peritoneal macrophages. Preincubation of macrophages with 10 microM capsaicin (from red pepper) or 10 microM curcumin (from turmeric) completely inhibited the superoxide anions, hydrogen peroxide and nitrite radical production in vitro by macrophages. Higher concentrations (500 microM) of eugenol (from clove) and piperine (from pepper) were required to completely inhibit superoxide anion and hydrogen peroxide release by macrophages. Capsaicin and curcumin were then fed to rats which were on a diet containing 8 wt% of coconut oil or olive oil or peanut oil or cod liver oil for 8 weeks, by gavage for 2 weeks. The peritoneal macrophages isolated from these animals produced lower levels of ROS compared to the macrophages from the control groups fed with the oil alone. Macrophages from cod liver oil fed animals generated lower levels of superoxide anions (76%), hydrogen peroxide (70%) and nitrite radicals (88%) compared to those isolated from coconut oil fed animals. Peanut oil and olive oil feeding also lowered the extent of ROS generation in macrophages compared to those from coconut oil fed animals. Capsaicin and curcumin feeding further lowered the generation and release of ROS. It is concluded that capsaicin or curcumin in combination with dietary fatty acids differentially lowers the production of ROS in macrophages.