Effect of Mollugin on Apoptosis and Adipogenesis of 3T3-L1 Preadipocytes

The effect of mollugin, isolated from the roots of Rubia cordifolia L., on cell viability, apoptosis and adipogenesis in 3T3-L1 preadipocytes was investigated. The inhibitory effect of mollugin (40-60 mu M) on cell viability was more significant in differentiated adipocytes than in 3T3-L1 preadipocytes. In 3T3-L1 cells, the cytotoxicity of mollugin was accompanied by apoptotic events including mitochondrial membrane potential (Delta psi m) loss and activation of caspase-9, -3 and -7, leading to PARP degradation. Although the presence of 20 mu M mollugin during induced adipocytic differentiation of 3T3-L1 cells for 6 days failed to affect the cell viability, it could almost completely abrogate the differentiation-associated morphology change and intracellular lipid accumulation. A similar level of inhibition was observed, when 20 mu M mollugin was present during the early stage (D0-D2) of the differentiation period. In addition, the expression of C/EBP alpha, PPAR gamma 1 and PPAR gamma 2 was significantly down-regulated. The presence of 20 mu M mollugin during either middle stage (D2-D4) or late stage (D4-D6) of the differentiation period, however, caused the inhibition to a lesser extent. These results indicated that mollugin at high concentrations (40-60 mu M) exerted cytotoxicity via inducing apoptosis, whereas mollugin at a low concentration (20 mu M) suppressed adipocytic differentiation without exerting cytotoxicity in 3T3-L1 preadipocytes. Copyright (C) 2010 John Wiley & Sons, Ltd.