Anti-Inflammatory Potential of Rape Flower in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

The present study was undertaken to investigate the anti-inflammatory potential and mechanism of action of the rape flower extract (RFE) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. RFE inhibited nitric oxide (NO), prostaglandin E-2 (PGE(2)), interleukin-1a (IL-1a), and IL-6 production in a concentration-dependent manner. RFE effectively attenuated the expression of inflammation-mediating enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), at the protein level in a concentration-dependent manner. Additionally, the attenuation of inflammatory responses in RAW 264.7 cells by RFE was closely associated with the suppression of the phosphorylation of extracellular signal-regulated kinase (ERK), eventually blocking the activation of downstream elements contributing to inflammation. RFE HPLC fingerprint indicated the presence of coumestrol. The coumestrol content in RFE was 2.614 iM. To evaluate the safety of RFE and its effects on the human skin, human skin primary irritation tests were performed on the normal skin (upper back) of 32 volunteers to determine if any constituent of RFE presented an irritation or sensitization potential. RFE did not induce any adverse reactions. Taken together, our results suggest that RFE may be considered as an anti-inflammatory candidate for topical application.