Fig. 1

Decreased accumulation of lipid droplets in response to PPE in differentiated 3T3-L1 cells. a The cytotoxicities of PPE (1.0, 0.5, 0.25, 0.125, 0.0625 and 0.03125 mg/mL) and resveratrol (100, 50, 25 and 10 μM) against 3T3-L1 cells were analyzed by WST assay. The data are represented as relative cell viabilities compared to 3T3-L1 cells cultured without PPE (Control). b Time schedule of the culture with PPE during the cellular differentiation of 3T3-L1 cells. 3T3-L1 cells that reached confluence were cultured with or without PPE (1.0, 0.5 and 0.1 mg/mL) and IDM for 2 days. The medium was changed every 48 h to fresh medium containing 5 μg/mL insulin with or without PPE until day 8, followed by staining with Oil Red O. c The culture plate was photographed after staining. d Lipid droplets in differentiated 3T3-L1 cells cultured with PPE (1.0, 0.5 and 0.1 mg/mL) were stained with Oil Red O and imaged by bright field microscopy. e Stained lipid droplets were extracted with isopropanol and quantified by measuring the absorbance at 492 nm. Experiments were performed in triplicate, and the data are presented as the mean ± SEM (n = 3). **p < 0.01, ***p < 0.005 vs. Control. Experiments were repeated at least seven times, and representative results are shown