Anti-obesity effect of an isoflavone fatty acid ester on obese mice induced by high fat diet and its potential mechanism

Abstract

Background: The novel compound 1a is one of the isoflavone fatty acid esters. In order to investigate the anti-obesity effect of compound 1a and its potential mechanism of influence in adipocyte differentiation, Obese male C57BL/6J mice induced by high-fat diet (HFD) and rat preadipocytes (3T3-L1 cell) were used.

Methods: After 4-week HFD induction, the obese model was made successfully. After treatment with compound 1a, mice plasma biochemistry parameters were analyzed. In addition, mice hepatic tissue slice was observed. In in vitro research, 3T3-L1 cell differentiation by Oil-Red-O staining and adipocyte apoptosis was detected by flow cytometry.

Results: The in vivo results implied that compound 1a significantly decreased the body weight, white adipose tissue weight of obesity mice (p<0.05), reduced leptin and TG in plasma (p<0.05), elevated HDL-C in serum (p<0.05). The in vitro results suggested that compound 1a could significantly suppress the adipocyte viability and lipid accumulation in the differentiation of preadipocyte, and induce apoptosis in both preadipocytes and mature adipocytes (p<0.05).

Conclusion: Compound 1a regulates serum lipid profiles, decreases adipose tissue mass and body weight gain by inducing adipocyte apoptosis in high fat diet induced mice. Thus, it may be used to treat obese patients with hypercholesterolemia and hypertriglyceridemia.

Figure 1

Structural formula of compound 1a.

Figure 2

Effects of compound 1a on C57BL/6J mice. A: Effects of compound 1a on the weight of the mice after treatment. B: Effects of compound 1a on the weight of the adipose tissue after treatment. Normal group: low fat diet; Model group: high fat diet; Low dosage group: high fat diet+50 mg·kg^-1 compound 1a; High dosage group: high fat diet+100 mg·kg^-1 compound 1a; Control group: high fat diet+200 mg·kg^-1 Inositol Hexanicotinate. All values are mean ± SD (n = 10), * presents P < 0.05 compared with model group. ** presents P < 0.05 compared with normal group

Figure 3

Effects of compound 1a on serum lipids and leptin. A: Changes in TG, TC, LDL-C and HDL-C by compound 1a in high-fat diet fed obese mice. Compound 1a-treated mice had significantly lower serum concentration of triglycerides and higher HDL-C compared with high-fat diet alone. B: Effects of compound 1a on serum leptin. Serum leptin concentration was reduced by compound 1a in a concentration dependent manner. Normal group: low fat diet; Model group: high fat diet; Low dosage group: high fat diet+50 mg·kg^-1 compound 1a; High dosage group: high fat diet+100 mg·kg^-1 compound 1a; Control group: high fat diet+200 mg·kg^-1 Inositol Hexanicotinate. All values are mean ± SD (n = 10), * presents P < 0.05 compared with model group. ** presents P < 0.05 compared with normal group.

Figure 4

Inhibition of hepatic lipid accumulation by compound 1a in high-fat diet-fed obese mice. Histological analyses of hepatic lipid accumulation. Representative HE-stained liver sections are shown (original magnification 200×). A presents the normal hepatocyte appearance. High fat diet induced hepatocytes necrosis was shown in B. After the treatment of compound 1a, necrosis hepatocytes are reduced, especially in D. Small lipid drops were seen C. There were obvious lipid drops in E. A: low fat diet (normal group); B: high fat diet (model group); C: high fat diet+50 mg·kg^-1 compound 1a (low dosage group); D: high fat diet+100 mg·kg^-1 compound 1a (high dosage group); E: high fat diet+200 mg·kg^-1 Inositol Hexanicotinate (control group).

Figure 5

Effect of compound 1a on the inhibition of cell viability in 3T3-L1 preadipocytes. After the influence reached 80%, 3T3-L1 preadipocytes were incubated with compound 1a, at the indicated concentration (1 × 10^-7, 1 × 10^-6, 1 × 10^-5, 1 × 10^-4mol L^-1) for 48 h; growth rate was assessed by MTT assay. The inhibition ratio was calculated by formula 1. All values are mean ± SD (n = 3)

Figure 6

Effect of compound 1a on lipid adipogenesis. A: Effect of compound 1a on lipid accumulation in 3T3-L1 adipocytes. At two days after confluence, 3T3-L1 cells were differentiated by MDI. At day 8 compound 1a was given to the cells at series of concentrations. Ten days after differentiation, we measured triglyceride content of 3T3-L1 cells treated with compound 1a by Oil-Red-O staining. The inhibition ratio was calculated by formula 1. B: Effect of vehicle, compound 1a, Inositol Nicotinate on the lipid accumulation by Oil-Red-O staining. Images of the stained lipid droplets were collected on a fluorescence microscope. Lipid accumulation was significantly decreased treated by compound 1a. All values are mean ± SD (n = 3).

Figure 7

Apoptosis ratios (apoptosis cell number in treatment group/apoptosis cell number in blank group) after 24 h were shown in this picture. With the concentration increase, the apoptosis ratio was raised both in preadipocytes and mature adipocytes. The phenomenon was more notable in mature adipocytes induced by 1 × 10^-4 mol·L^-1 compound 1a, whose apoptosis ratio reached almost 206% compared with DMSO group.