Anti-Obesity and Lipid Metabolism Effects of Ulmus davidiana var. japonica in Mice Fed a High-Fat Diet

Abstract

The root bark of Ulmus davidiana var. japonica (Japanese elm) is used in Korea and other East Asian countries as a traditional herbal remedy to treat a variety of inflammatory diseases and ailments such as edema, gastric cancer and mastitis. For this study, we investigated the lipid metabolism and anti-obesity efficacy of ethyl alcohol extract of Ulmus davidiana var. japonica root bark (UDE). First, HPLC was performed to quantify the level of (+)-catechin, the active ingredient of UDE. In the following experiments, cultured 3T3-L1 pre-adipocytes and high-fat diet (HFD)-fed murine model were studied for anti-obesity efficacy by testing the lipid metabolism effects of UDE and (+)-catechin. In the test using 3T3-L1 pre-adipocytes, treatment with UDE inhibited adipocyte differentiation and significantly reduced the production of adipogenic genes and transcription factors PPARγ, C/EBPα and SREBP-1c. HFD-fed, obese mice were administered with UDE (200 mg/kg per day) and (+)-catechin (30 mg/kg per day) by oral gavage for 4 weeks. Weight gain, epididymal and abdominal adipose tissue mass were significantly reduced, and a change in adipocyte size was observed in the UDE and (+)-catechin treatment groups compared to the untreated control group (***p < 0.001). Significantly lower total cholesterol and triglyceride levels were detected in UDE-treated HFD mice compared to the control, revealing the efficacy of UDE. In addition, it was found that lipid accumulation in hepatocytes was also significantly reduced after administration of UDE. These results suggest that UDE has significant anti-obesity and lipid metabolism effects through inhibition of adipocyte differentiation and adipogenesis.

Keywords: (+)-catechin; 3T3-L1; Ulmus davidiana var. japonica; anti-obesity; high-fat diet.

Fig. 1

Identification of (+)-catechin in UDE using HPLC chromatogram.

Fig. 2. Effects of UDE and (+)-catechin on cell viability and differentiation of 3T3-L1 preadipocytes.

(A) An MTT assay was performed for analysis of cell viability after treatment with UDE (10, 50, 100, 250, 500, and 1,000 μg/ml) or (B) (+)-catechin (10, 25, 50, 75, 100, and 200 μM) for 48 h. The average value of three independent experiments is shown. All data are expressed as the mean ± SD of the experiment. *p < 0.05, **p < 0.01, and ***p < 0.001 compared to the control group. (C) Intracellular lipids were stained with oil Red O (200× magnification) and quantified. Treatment with UDE and (+)-catechin resulted in reduced formation of adipocytes. The data are presented as the mean percentage compared to DMSO-treated cells. All data are expressed as the mean ± SD of the experiment. **p < 0.01 and ***p < 0.001 compared to the MDI control group.

Fig. 3. Effect of UDE and (+)-catechin on adipogenic transcription factors in 3T3-L1 cells.

(A) 3T3-L1 cells were treated with UDE (50, 100, 200 μg/ml) or (+)-catechin (50 μM) for 48 h in adipocyte-induction media. Western blot using GAPDH as a loading control was performed for analysis of whole cell lysates. (B) Quantification of the band intensity ratios of PPAR-γ, (C) SREBP-1c, and (D) C/EBPα relative to GAPDH. The data are presented as the mean percentage compared to DMSO-treated cells. All data are expressed as the mean ± SD of the experiment. ^##p < 0.01 and ^###p < 0.001 compared to the control group; **p < 0.01 and ***p < 0.001 compared to the MDI control group.

Fig. 4. Effect of UDE and (+)-catechin on mRNA levels of proteins regulating synthesis, transport and storage of fatty acid.

3T3-L1 cells were treated with UDE (50, 100, and 200 μg/ml) or (+)-catechin (50 μM) for 48 h in adipocyte-induction media. Adipocyte RNA was isolated, and real-time PCR analysis was performed to determine mRNA expressions of ACS1, FAS, FATP1, and perilipin. GAPDH was used as an internal control. All data are expressed as the mean ± SD of the experiment. ^###p < 0.001 compared to the control group; **p < 0.01 and ***p < 0.001 compared to the MDI control group.

Fig. 5. Regulation of body weight gain, food efficiency ratio (FER), weight and histology of adipose tissue by UDE in high-fat diet (HFD)-fed mice.

(A) Body weight gain at the end of the treatment period. (B) FER as the body weight gain (g/day) divided by food intake (g/day). (C) White adipose tissue weights in HFD-fed mice. All values are expressed as mean ± SD (n = 6). Different letters are significantly different at p < 0.05 by Duncan’s multiple range test. (D) Adipose tissue histology. Representative adipose tissue sections stained with hematoxylin-eosin (original magnification ×200). (E) Average diameter of adipocytes in adipose tissue from each group. All data are expressed as the mean ± SD of the experiment. ^###p < 0.001 compared to the LFD group; ***p < 0.001 compared to the HFD control group.

Fig. 6. Changes in circulating AST, ALT, triglycerides, and total cholesterol by UDE in high-fat diet-fed mice.

(A) Serum concentrations of AST and ALT, and (B) triglycerides and total cholesterol measured as mean ± SD (n = 6). Different letters are significantly different at p < 0.05 by Duncan’s multiple range test.

Fig. 7. Inhibition of hepatic lipid accumulation by UDE in high-fat diet-fed mice.

(A) Representative liver sections stained with hematoxylin-eosin (original magnification × 200). (B) Representative liver sections stained with Oil Red O (original magnification × 200).

Fig. 8. Effect of UDE and (+)-catechin on adipogenic transcription factors in liver tissue.

(A) Western blot analysis using GAPDH as the loading control was performed for measurement of PPAR-γ and SREBP-1c protein expression in liver tissue. (B) Quantification of the band intensity ratios of PPAR-γ and (C) SREBP-1c relative to GAPDH. The data are presented as the mean percentage compared to DMSO-treated cells. All data are expressed as the mean ± SD of the experiment. ##p < 0.01 compared to the LFD group; **p < 0.01 compared to the HFD group.