Inhibitory effect of diosmetin on inflammation and lipolysis in coculture of adipocytes and macrophages.

The interaction between adipocytes and macrophages in obese tissues plays a critical role in the onset of metabolic syndromes. This study aimed to evaluate the modulatory effect of diosmetin on anti-inflammatory and anti-lipolytic activities in the coculture of macrophages and adipocytes. The secretion of inflammatory mediators increased in a coculture medium, however, diosmetin significantly reduced the levels of these inflammatory mediators such as nitric oxide (NO), tumor necrosis factor-α, and monocyte chemoattractant protein. Diosmetin down-regulated the protein expression of inducible NO synthase in cocultured macrophages and adipocytes, and inhibited the phosphorylation of mitogen-activated protein kinases and the translocation of p65 and p50 to the nucleus. Moreover, it suppressed the phosphorylation of hormone-sensitive lipase and the production of fatty acid-binding protein 4, and increased the mRNA expression of adiponectin in cocultured adipocytes by 18%-35%. These results indicate that diosmetin inhibited inflammation and lipolysis in the crosstalk between adipocytes and macrophages; diosmetin-containing foods could be used in dietary therapy for the prevention of obesity-related metabolic syndromes. PRACTICAL APPLICATIONS: Diosmetin occurs naturally in citrus fruits that have a high inhibitory effect on inflammation in cocultured adipocytes and macrophages via the inactivation of the MAPKs/NF-kB pathway. Diosmetin also inhibited lipolysis via the reduction of FFA and free glycerol. The present study suggests that treatment of diosmetin may be useful for the prevention of obesity and inflammation-related metabolic syndromes.