The aim of this study was to explore the lipolysis-stimulating activity of soy protein isolate (SPI) hydrolysate using 3T3-L1 adipocytes. Intracellular triglyceride residue (TR) was employed as a marker for lipolysis in cells. The lower TR represents the better lipolysis-stimulating activity. SPI was hydrolysed with Flavourzyme for 2 h to obtain the hydrolysate FH2h, which showed lipolysis-stimulating activity in adipocytes at 400-1600 ppm levels. The sequential fractionation of FH2h with 30-0.3 kDa molecular weight cut-off (MWCO) membranes in order to obtain a 1 kDa retentate resulted in further enhancement of its lipolysis-stimulating activity in the cells. The TR decreased significantly from 2.73 to 2.30 μmole/mg protein at the 400 ppm level (p < 0.05). Based on the western immunoblot and immunostaining analysis, the 1 kDa retentate promotes lipolysis by increasing phosphorylation and translocation of the hormone-sensitive lipase in 3T3-L1 adipocytes. ? 2012 Elsevier Ltd. All rights reserved.
