Fermentation of Chestnut (Catanea crenata Sieb) Inner Shell Enhances Anti-Obesity Effects in 3T3-L1 and C3H10T1/2 Adipocytes

Chestnut inner shell (CIS) is rich in phenols and flavonoids such as gallic acid and ellagic acid, which are known to exhibit effective antioxidant and anti-obesity properties. Fermentation using lactic acid bacteria can enhance the physiological activity by increasing the contents of such functional ingredients. In this study, we evaluated the anti-obesity effects of a CIS extract subjected to a fermentation process (fermented CIS [FCIS]). Treatment with CIS and FCIS extracts (125, 250, and 500 μg/mL) increased cell viability and did not induce apoptosis, indicating no toxicity. The extract suppressed the gene expression of adipogenic factors, peroxisome proliferation-activated receptor gamma, CCAAT/enhancer binding protein (C/EBP) alpha, and C/EBP beta (by 7.75% and 67.59%, 21.41% and 66.27% in 500 μg/mL, respectively), and consequently suppressed the expression of downstream lipogenic factors such as fatty acid synthase, stearoyl CoA desaturase-1, citrate synthase, and ATP citrate lyase. The expression of factors involved in fat catabolism and β-oxidation increased in a dose-dependent manner, thereby preventing fat accumulation. This observation was consistent with the significant decrease in the staining intensity for lipid droplets, which indicated that lipid accumulation was decreased by 15.46% and 29.44% in 3T3L-1 and 27.01% and 46.68% in C3H10T1/2. Together, these results demonstrate the higher anti-obesity effects of FCIS extract than that of CIS extract, indicating the potential applicability of FCIS as an effective natural raw material to curb obesity.