Inhibitory Effects of Apple Polyphenols on Differentiation of 3T3-L1 Cells into Adipocytes

Abstract

A crude apple polyphenol (CAP) fraction partially purified from unripe apples was found to inhibit adipose differentiation in mouse fibroblast 3T3-L1 cells. CAP inhibited the increase in intracellular levels of glycerophosphate-3-dehydrogenase (GPDH), one of the most important enzymes in the pathway for triacylglycerol biosynthesis, that occurs upon differentiation of 3T3-L1 cells into adipocytes and decreased the triglyceride content of the cells. In particular, apple condensed tannins (ACT), purified from CAP, inhibited the increase in GPDH activity when these cells differentiated. In contrast, phloridzin, (+)-catechin, and (-)-epicatechin, which were also present in the CAP fraction, decreased the triglyceride content of the cells but did not inhibit the increase in GPDH activity. These results suggest that ACT such as procyanidins inhibit the differentiation of preadipocytes into adipocytes.