Anti-inflammatory effect of strawberry extract against LPS-induced stress in RAW 264.7 macrophages

A common denominator in the pathogenesis of most chronic inflammatory diseases is the involvement of oxidative stress, related to ROS production by all aerobic organisms. Dietary antioxidants from plant foods represent an efficient strategy to counteract this condition. The aim of the present study was to evaluate the protective effects of strawberry extracts on inflammatory status induced by E. Coli LPS on RAW 264.7 macrophages by measuring the main oxidative and inflammatory biomarkers and investigating the molecular pathways involved. Strawberry pre-treatment efficiently counteracted LPS-induced oxidative stress reducing the amount of ROS and nitrite production, stimulating endogenous antioxidant enzyme activities and enhancing protection against lipid, protein and DNA damage (P < 0.05). Strawberry pre-treatment exerted these protective effects primarily through the activation of the Nrf2 pathway, which is markedly AMPK-dependent and also by the modulation of the NF-kB signalling pathway. Finally, an improvement in mitochondria functionality was also detected. The results obtained in this work highlight the health benefit of strawberries against inflammatory and oxidative stress in LPS-stimulated RAW 264.7 macrophages, investigating for the first time the possible involved molecular mechanisms.