Inhibition of preadipocyte differentiation and lipid accumulation by Orengedokuto treatment of 3T3-L1 cultures.

Obesity is a major cause of metabolic syndrome and is due to an increase in the number and hypertrophy of adipocytes. Accordingly, inhibition of the differentiation and proliferation of adipocytes may be used in the treatment and prevention of metabolic syndrome. This study investigated the effects of 50 commonly used Kampo medicines on the differentiation of 3T3-L1 preadipocytes to search for a drug with an antiobesity effect. Kampo medicines were screened, and the strongest differentiation-inhibitory effect was noted with Orengedokuto. To explore the active ingredients in Orengedokuto, the effects of four crude drug components of Orengedokuto were investigated. It was found that the differentiation-inhibitory effect of Orengedokuto was accounted for by Coptidis rhizome and Phellodendri cortex. Furthermore, berberine, a principal ingredient common to Coptidis rhizome and Phellodendri cortex, showed a differentiation-inhibitory effect. The effect of berberine involves an inhibition of the mRNA and protein expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα). Moreover, berberine inhibited lipid accumulation in adipocytes. These findings suggest that an antiobesity effect could be a new indication for Orengedokuto and that its active ingredient is berberine, with a mechanism involving the inhibition of PPARγ and C/EBPα expression.