Structure of isobavachalcone (IBC) and effect of IBC on adipocyte growth and differentiation. (A) Structure of IBC isolated from A. keiskei (AK); (B) 3T3-L1 preadipocytes were differentiated with differentiation medium (MDI) in the presence or absence of IBC (0, 2, 10, or 40 μM). On differentiation day 0, 2, or 8 (D0, D2, or D8), cells were subjected to MTT assay; and (C) 3T3-L1 cells were differentiated with IBC at indicated concentration. Cells were stained with Oil Red O (ORO) on D8, and intracellular lipid contents were quantified as described in Materials and Methods. Adipocytes stained with ORO (magnification, 40×) were visualized by light microscopy. Scale bar = 100 μm. Data are means ± standard deviation (SD) of triplicate experiments. # p < 0.01 vs. control (no differentiation, ND); * p < 0.01 vs. MDI only.