Extract of curry powder and its components protect against diesel exhaust particle-induced inflammatory responses in human airway epithelial cells

Measures for protecting against PM2.5 (particulate matter with aerodynamic diameters ≤2.5 µm), which exacerbates respiratory diseases, have not been established. The present study investigated the effects of extracts of curry powder and its components on pro-inflammatory responses, extracellular and intracellular reactive oxygen species (ROS) production, induced by the PM2.5 component, DEP (diesel exhaust particles). Airway epithelial cells were exposed to DEP in the presence of curry powder, or its major and/or anti-inflammatory components, clove and turmeric. Curry powder, clove, and turmeric inhibited DEP-induced IL-6 release and extracellular ROS; in the absence of clove and turmeric, these effects of curry powder were mild but similar. Among the other curry spices, cinnamon decreased IL-6 and extracellular ROS, and coriander decreased IL-6 alone. This is the first report on the protective effects of extracts of curry powder and its components, against PM2.5-induced airway inflammation, which may be partly through inhibition of extracellular ROS.