Oligonol, a new lychee fruit-derived low-molecular form of polyphenol, enhances lipolysis in primary rat adipocytes through activation of the ERK1/2 pathway.

The effect of Oligonol, a phenolic product from lychee fruit polyphenol (LFP) containing catechin-type monomers and lower oligomers of proanthocyanidin, on lipolysis in primary adipocytes was investigated in order to examine the possible mechanism underlying the regulation of in vivo metabolism in fat. Oligonol significantly increased lipolysis, which was accompanied by both activation of extracellular signaling-related kinase 1/2 (ERK1/2) and down-regulation of perilipin protein expression, without an increase in intracellular cAMP production. The increase in lipolysis with Oligonol was prevented completely by pretreatment with either PD98059 or U0126, selective ERK1/2 inhibitors, which also prevented the reduction in the expression of perilipin protein. Tumor necrosis factor-alpha also down-regulated the expression of perilipin protein. However, there was no significant alteration in the expression of Galphai protein with Oligonol. These findings indicate that Oligonol enhances lipolysis in primary adipocytes, independent of cAMP production, but its effect is dependent on activation of the ERK1/2 pathway, leading to down-regulation of perilipin protein expression.