Corosolic acid isolation from the leaves of Eriobotrta japonica showing the effects on carbohydrate metabolism and differentiation of 3T3-L1 adipocytes.

The extracts of Eriobotrta japonica leaves with the 3H-glucose uptaking activity in 3T3-L1 adipocytes were separated by TLC for two times. On the basis of UV-vis spectral, NMR and MS data, corosolic acid was identified as activity components. Moreover, the effects of corosolic acid on carbohydrate metabolism and differentiation of 3T3-L1 adipocytes was studied. The results showed that 3H-glucose uptaking rate in different concentrations of corosolic acid (15 micromol/L, 30 micromol/L, and 45 micromol/L) group were increased to 108.1%, 112.2% ,118.6%, respectively, compared to control group (without corosolic acid) (p<0.01). Corosolic acid suppressed the differentiation of 3T3-L1 pre-adipocytes and down-regulated the expression of PPAR-gamma and C/EBP-alpha mRNA (p<0.01, vs control group). Corosolic acid promotes the 3H-glucose uptaking, suppresses the differentiation and downregulates the expression of PPAR-gamma and C/EBP-alpha mRNA in 3T3-L1 adipocytes.