Effect of soybean milk fermented with Lactobacillus plantarum HFY01 isolated from yak yogurt on weight loss and lipid reduction in mice with obesity induced by a high-fat diet

Abstract

Soybean milk fermented with Lactobacillus plantarum HFY01 (LP-HFY01) was used for weight and lipid reduction in mice with obesity induced by a high-fat diet. We evaluated the gastrointestinal tolerance in vitro, organ index, body fat rate, pathological changes, serum index, mRNA expression and changes of isoflavones in soybean milk. Results indicated that LP-HFY01 exhibited good tolerance to pH 3.0 artificial gastric juice (69.87 ± 0.04%) and 0.3% bile salt (15.94 ± 0.3%). LP-HFY01-fermented soybean milk reduced the body fat rate and liver index of obese mice (p < 0.05). Organ sections showed that LP-HFY01-fermented soybean milk improved fatty degeneration and liver cell damage caused by a high-fat diet. LP-HFY01-fermented soybean milk inhibited increases in low-density lipoprotein cholesterol (LDL-c), triglyceride (TG), alkaline phosphatase (AKP), and glutamic oxaloacetic transaminase (GOT) and the decrease in high-density lipoprotein cholesterol (HDL-c) in the serum of obese mice, and inhibited CCAAT/enhancer-binding protein-α (C/EBP-α) and peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA expression, as well as activated cuprozinc-superoxide dismutase (SOD1) and lipoprotein lipase (LPL) mRNA expression in the liver and epididymal fat of obese mice (p < 0.05). Daidzin, glycitin, daidzein, glycitein, genistein, and genistin contents in soybean milk were determined before and after fermentation by high-performance liquid chromatography (HPLC); the daidzin and genistin contents in the fermented soybean milk decreased, whereas the daidzein and genistein contents increased significantly. Therefore, the LP-HFY01-fermented soybean milk strongly inhibits obesity induced by a high-fat diet, and shows good potential for utilization.

Fig. 1. Observation of the epididymal fat section. (A) Normal group, (B) model group, (C) l-carnitine group, (D) LP-HFY01-fermented group, (E) LB-fermented group, (F) soymilk group (unfermented group), (G) comparison of adipocyte area in epididymis, (H) comparison of adipocyte mean diameter in epididymis. ^a–e Mean values with different letters in the same bar graph indicate significant differences (p < 0.05) as determined using Duncan's multiple range test.

Fig. 2. Observation of the liver section. (A) Normal group, (B) model group, (C) l-carnitine group, (D) LP-HFY01-fermented group, (E) LB-fermented group, (F) soymilk group (unfermented group). (G) Comparison of fat cavities area in liver, (H) comparison of fat cavities mean diameter in liver. ^a–e Mean values with different letters in the same bar graph indicate significant differences (p < 0.05) as determined using Duncan's multiple range test.

Fig. 3. HDL-c (A), LDL-c (B), TG (C), AKP (D) and GOT (E) content in serum. ^a–e Mean values with different letters in the same bar graph indicate significant differences (p < 0.05) as determined by Duncan's multiple range test.

Fig. 4. Gene expression in liver tissue. ^a–e Mean values with different letters in the same bar graph indicate significant differences (p < 0.05) as determined using Duncan's multiple range test.

Fig. 5. Gene expression level in adipose tissue. ^a–e Mean values with different letters in the same bar graph indicate significant differences (p < 0.05) as determined using Duncan's multiple range test.

Fig. 6. HPLC assay. (A) Mixed standard chromatograms; (B) soybean milk chromatograms; (C) LB-fermented soybean milk chromatograms; (D) LP-HFY01-fermented soybean milk chromatograms.

Fig. 7. Chemical structures of the 6 isoflavones. (1) Daidzin; (2) glycitin; (3) genistin; (4) daidzein; (5) glycitein; (6) genistein.