2.5. Oil Red O staining of 3T3-L1 adipocytes

3T3-L1 cells were incubated in cell culture media containing with various concentrations of the fraction from D. racemosum, washed twice with PBS, and then fixed in 10% formaldehyde prepared for 1 h at room temperature (20℃). The cells were washed with distilled water (DW) three times, and stained with Oil red O solution for 2 h at room temperature. The cells were then washed in DW three times for 1 h each time. All photographs were taken using a Nikon Eclipse TS100 microscope at 400x magnification. The cells were eluted using 100% isopropanol, and OD was measured at 500 nm using a spectrophotometer (Milton Roy Company, New York, USA).