Mogroside V inhibits LPS-induced COX-2 expression/ROS production and overexpression of HO-1 by blocking phosphorylation of AKT1 in RAW264.7 cells

Momordica grosvenori is a valuable edible plant with medicinal purposes, and it is widely used in medicated diets and traditional Chinese medicine in Asia. Mogroside V (MV), the main bioactive component from M. grosvenori, is commonly used as a natural sweetener. M. grosvenori extracts have been reported to exert potent anti-inflammatory property, however the underlying molecular mechanism still remains unknown. In the present study, the biological effect of MV in inflammation was investigated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The ELISA and western blot analysis results showed that MV significantly inhibited LPS-induced prostaglandin E2 (PGE2) production and cyclooxygenase-2 (COX-2) expression. MV markedly decreased the phosphorylation of IκB-α, increased IκB-α, and reduced nuclear p-65 and C/EBPδ. Furthermore, MV attenuated LPS-induced phosphorylation of MAPKs and AKT1, and only the phosphorylation status of AKT1 was found to be consistent with the expression trend of COX-2. Moreover, MV reduced ROS level and restored overexpressed HO-1 and AP-1 to basal level, which can be markedly reversed by AKT1 inhibitor LY294002. These results revealed that AKT1 plays a key role in LPS-induced COX-2 expression, and acts as a mediator to keep the redox balance in LPS-stimulated RAW264.7 cells. MV exerts anti-inflammatory property by blocking AKT1-mediated NF-κB and C/EBPδ activation, ROS generation and AP-1/ HO-1 expression. Therefore, the present study indicated that MV has a significant chemopreventive effect on the inflammatory lesions and suggested that AKT1 is a potential specific target of MV for relieving inflammation.