Rutin was enzymatically polymerized by laccase and the rutin polymer fraction (RPF) was collected by ultrafiltration with a molecular cut off of 3 kDa. The RPF contained a range of oligomer size varying from hexamer (m/z 3650) to octamer (m/z 4866). The Fourier transform infrared spectrum indicated that various linkages such as hydrogen bonds (OH), aromatic groups (C=C), and ether bonds (C-O) were involved in rutin polymer formation. RPF more effectively suppressed triglyceride accumulation compared to the rutin monomer in 3T3-L1 adipocytes at all tested concentrations (p < 0.05). The anti-adipogenic effect of RPF was mediated by down-regulation of the expression of adipogenic transcriptional factors including peroxisome proliferator-activated receptor (PPAR gamma), CCATT/enhancer binding protein (C/EBP alpha), sterol regulatory binding protein (SREBP1C) and fatty acid synthase (FAS) while up-regulating lipolysis and adiponectin expression in 3T3-L1 adipocytes. These results suggest that RPF has a potential protective effect in the development of obesity and that enzyme-catalyzed polymerization could be useful in improving flavonoids bioactivity. (C) 2014 Elsevier Ltd. All rights reserved.