Evidence suggests that the immunomodulatory property of polyphenols may also contribute to the reduction of cardiovascular risk. In the present study, we investigated the polyphenol extraction (PE) from Syzygium brachythyrsum, a functional food resource in south China, regarding the protective effect on inhibiting foam cell formation and the underlying molecular mechanism based on an ox-LDL-induced RAW264.7 macrophage model. The results of Oil Red O staining, Dil-ox-LDL fluorescent staining, and cholesterol efflux experiments showed that PE, and its two phenolics brachythol B (BB) and ethyl gallate (EG), significantly inhibited the foam cell formation, which may be associated with reducing the expression of SR-A1 and CD36 while increasing expression of SR-B1, ABCG1, and PPARγ. In addition, BB and EG also reduce the inflammatory response by down-regulating the expression of NF-κB and MAPK signal pathway proteins, thereby inhibiting the expression of inflammatory factors. Altogether, PE and its two components BB and EG attenuated foam cell formation and macrophage inflammation response.
Keywords: Syzygium brachythyrsum; cholesterol; foam cell; inflammation; ox-LDL; polyphenols.