Inflammation plays an important role in the immune defense against injury and infection agents. However, the inflammatory chronic process may lead to neurodegenerative diseases, atherosclerosis, inflammatory bowel diseases, or cancer. Flavanones present in citrus fruits exhibit biological activities, including anti-oxidative and anti-inflammatory properties. The beneficial effects of flavanones have been found based on in vitro cell cultures and animal studies. A suitable in vitro model for studying the inflammatory process are macrophages (RAW264.7 cell line) because, after stimulation using lipopolysaccharide (LPS), they release inflammatory cytokines involved in the immune response. We determined the nitrite concentration in the macrophage cell culture and detected ROS using chemiluminescence. Additionally, we measured the production of selected cytokines using the Bio-Plex Magnetic Luminex Assay and the Bio-PlexTM 200 System. For the first time, we have shown that methyl derivatives of flavanone inhibit NO and chemiluminescence generated via LPS-stimulated macrophages. Moreover, the tested compounds at 1-20 µM dose-dependently modulate proinflammatory cytokine production (IL-1β, IL-6, IL-12p40, IL-12p70, and TNF-α) in stimulated RAW264.7 cells. The 2'-methylflavanone (5B) and the 3'-methylflavanone (6B) possess the strongest anti-inflammatory activity among all the tested flavanone derivatives. These compounds reduce the concentration of IL-6, IL-12p40, and IL12p70 compared to the core flavanone structure. Moreover, 2'-methylflavanone reduces TNF-α, and 3'-methylflavanone reduces IL-1β secreted by RAW264.7 cells.
Keywords: cytokines; flavanones; inflammation; nitric oxide.