Antioxidative effects of a new lychee fruit-derived polyphenol mixture, oligonol, converted into a low-molecular form in adipocytes

In this study we investigated the antioxidative effects of Oligonol (Amino Up Chemical Co., Ltd., Sapporo, Japan), a new polyphenol, in adipocytes. The levels of reactive oxygen species (ROS) and the expression of adipokine genes decreased in HW mouse white adipocytes upon treatment with Oligonol as compared to control cells. The transcriptional activity of nuclear factor-kappaB (NF-κB) and the activation of extracellular signal-regulated kinase (ERK) 1/2 were also down-regulated by Oligonol. In addition, when C57BL/6J mice were fed a high fat diet (HFD) for 5 weeks, the levels of epididymal white adipose tissue (WAT) mass and lipid peroxidation in WAT both increased, but Oligonol intake clearly inhibited such HFD-induced increases. Furthermore, dysregulated expression of genes for adipokines in WAT of mice fed solely a HFD was attenuated by Oligonol intake. These results suggest that Oligonol has antioxidative effects and that it attenuates HFD-induced dysregulated expression of genes for adipokines in adipocytes.