Cinnamyl Alcohol, the Bioactive Component of Chestnut Flower Absolute, Inhibits Adipocyte Differentiation in 3T3-L1 Cells by Downregulating Adipogenic Transcription Factors

The extract of chestnut (Castanea crenata var. dulcis) flower (CCDF) has antioxidant and antimelanogenic properties, but its anti-obesity properties have not been previously examined. In this study, we tested the effect of CCDF absolute on adipocyte differentiation by using 3T3-L1 cells and determining the bioactive component of CCDF absolute in 3T3-L1 cell differentiation. CCDF absolute (0.1-100 mu g/mL) did not change 3T3L1 cell viability. At 50 mu g/mL and 100 mu g/mL, the absolute significantly reduced the accumulation of lipid droplets in 3T3-L1 cells that were induced by culture in medium containing 3-isobutyl-1-methylxanthine/dexamethasone/insulin (MDI). GC/MS analysis showed that CCDF absolute contains 10 compounds. Among these compounds, cinnamyl alcohol (3phenyl- 2-propene-1-ol) dose-dependently inhibited the increased accumulation of lipid droplets in MDI-contained medium-cultured 3T3-L1 cells at a concentration range of 0.1 mu g/ mL to 10 mu g/mL that did not cause cytotoxicity in 3T3-L1 cells. The inhibitory effect was significant at 5 mu g/mL (70: 27 +/- 1: 50% of response in MDI alone-treated state, P < 0: 005) and 10 mu g/mL (28: 94 +/- 1: 76% of response in MDI alone-treated state, P < 0: 005). Moreover, the enhanced expression of obesity-related proteins (PPAR gamma, C/EBP alpha, SREBP-1c, and FAS) in MDI medium-cultivated 3T3-L1 cells was significantly attenuated by the addition of cinnamyl alcohol at 5 mu g/mL and 10 mu g/mL. These findings demonstrate that cinnamyl alcohol suppresses 3T3-L1 cell differentiation by inhibiting anti-adipogenesis-related proteins, and it may be a main bioactive component of CCDF absolute, exerting antidifferentiation action in 3T3-L1 cells. Therefore, cinnamyl alcohol, as well as CCDF absolute, may be potential candidates for the prevention or treatment of obesity.