Hydroxytyrosol acetate (Hd-Ac) is a polyphenol that is present in the olive fruit and oil at a concentration similar to that of hydroxytyrosol (Hd). The effects of Hd-Ac on adipogenesis, lipolysis, and glucose consumption in 3T3-L1 cells were investigated. Treatment with Hd-Ac at concentrations of 0-75 μmol/L inhibited 3T3-L1 differentiation and lipid accumulation in a dose-dependent manner. At the same concentration range, no effect on cell viability was observed in the MTT assay. Inhibition of adipogenesis was associated with the downregulation of PPARγ, C/EBPα, SREBP-1c, and their downstream target genes (GLUT4, CD36, and FAS) as revealed by qRT-PCR. On the other hand, Hd-Ac dose dependently activated glycerol release in fully differentiated 3T3-L1 adipocytes, indicating lipolysis. This stimulation of lipolysis was mediated via the activation of hormone-sensitive lipase (HSL) by phosphorylation at Ser563 and Ser660, and the phosphorylation of perilipin. Further investigation of the in vitro activities of this polyphenol showed that Hd-Ac has the capability to increase glucose consumption in 3T3-L1 adipocytes and C2C12 myotubes.
Keywords: C/EBPα; HSL; Hydroxytyrosol acetate; PPARγ; Perilipin; SREBP-1c.
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