Journal List > J Nutr Health > v.48(1) > 1081375

Lee, Kyoung, Kim, and Kwon: Effects of an aqueous extract of purple sweet potato on nonalcoholic fatty liver in high fat/cholesterol-fed mice∗

Abstract

Purpose:

Anthocyanins from purple sweet potato (PSP) have been investigated in vitro and in animals and found to have a protective effect against oxidative hepatic damage. In this study, we investigated that aqueous extract of PSP can ameliorate the dysfunction of lipid metabolism in mice fed a high fat/cholesterol diet.

Methods:

Forty C57BL/6J mice were randomly divided into 5 groups (n = 8) and fed one of the following diets for 8 weeks; normal fat (NF) diet; high fat/ cholesterol (HFC) diet; HFC with 1.25% PSP (HFPL) diet; HFC with 2.5% PSP (HFPM) diet; HFC with 5% PSP (HFPH) diet.

Results:

Nonalcoholic fatty liver was manifested in the HFC group by showing increased levels in plasma alanine aminotransferase (ALT) activity, total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), increased level of TC and presence of many large lipid droplets in the liver, and increased fat cell size in the HFC group compared with the NF group. However, administration of HFC induced a significant decrease in food intake, resulting in decrease in fat mass. Coadministration of PSP did not lead to reversal of body weight changes, ALT activity, and lipid levels in plasma and the liver, but suppressed excess enlargement of the fat cell size through increasing carnitine palmitoyltransferase-1 (CPT-1) gene expression in the liver. Accordingly, the number of fat droplets in the liver was reduced in PSP administered groups.

Conclusion:

Taken together, these results suggest that PSP may have a protective effect on the dysfunction of lipid metabolism. Conduct of further studies on the coordinated regulation of PSP for lipid metabolic homeostasis at the liver-adipose tissue axis is needed.

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Fig. 1.
Effects of purple sweet potato extract on food intake and body weight in high fat/cholesterol diet-fed C57BL/6 mice: (A) food intake, (B) energy intake, (C) total body weight gain and (D) body weight changes by week. NF, normal fat control; HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM; HFC + PSP 2.5%; HFPH, HFC + PSP 5%. Values are expressed as Mean ± SE (n = 8 for each group). Means with different letters on the bar are significantly different from each other at p < 0.05 by Duncan's multiple range test.
jnh-48-1f1.tif
Fig. 2.
Effects of purple sweet potato extract on liver enzymes in plasma and liver histology in high fat/cholesterol-fed C57BL/6 mice: (A) AST, (B) ALT and (C) liver histology. NF, normal fat control; HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM; HFC + PSP 2.5%; HFPH, HFC + PSP 5%. Values are expressed as Mean ± SE (n = 8 for each group). Means with different letters on the bar are significantly different from each other at p < 0.05 by Duncan's multiple range test. Histology bar represents 50 μm.
jnh-48-1f2.tif
Fig. 3.
Effects of purple sweet potato extract on plasma lipid levels in high fat/cholesterol-fed C57BL/6 mice: (A) TG, (B) TC, and (C) LDL-C. NF, normal fat control; HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM; HFC + PSP 2.5%; HFPH, HFC + PSP 5%. Values are expressed as Mean ± SE (n = 8 for each group). Means with different letters on the bar are significantly different from each other at p < 0.05 by Duncan's multiple range test.
jnh-48-1f3.tif
Fig. 4.
Effects of purple sweet potato extract on lipid and mRNA levels in the liver of high fat/cholesterol-fed C57BL/6 mice: (A) TC, (B) TG, and (C) mRNA levels. NF, normal fat control; HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM; HFC + PSP 2.5%; HFPH, HFC + PSP 5%; SREBP-1c, sterol regulatory element-binding protein-1c; FAS, fatty acid synthase; CPT-1, carnitine palmitoyltransferase-1. Values are expressed as Mean ± SE (n = 8 for each group). Means with different letters on the bar are significantly different from each other at p < 0.05 by Duncan's multiple range test.
jnh-48-1f4.tif
Fig. 5.
Effects of purple sweet potato extract on fat mass and epididymal fat tissue histology in high fat/cholesterol-fed mice: (A) adipose tissue weight and (B) adipose tissue histology. NF, normal fat control; HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM; HFC + PSP 2.5%; HFPH, HFC + PSP 5%. Values are expressed as Mean ± SE (n = 8 for each group). Means with different letters on the bar are significantly different from each other at p < 0.05 by Duncan's multiple range test. Histology bar represents 50 μm.
jnh-48-1f5.tif
Table 1.
Composition of experimental diets1)(Unit: g/kg diet)
Ingredients Group NF High-fat/cholesterol diet
HFC HFPL HFPM HFPH
Cornstarch 150 150 150 150 150
Sucrose 500 337 324.5 312 287
Casein 200 200 200 200 200
Corn oil 50 30 30 30 30
Lard 0 170 170 170 170
Cholesterol 0 10 10 10 10
Sodium cholate 0 3 3 3 3
Cellulose 50 50 50 50 50
Mineral mix#2000002) 35 35 35 35 35
Vitamin mix#3000503) 10 10 10 10 10
DL-Methionine 3 3 3 3 3
Choline Bitrate 2 2 2 2 2
Purple sweet potato 0 0 12.5 25 50
Total 1,000 1,000 1,000 1,000 1,000
Total calorie (kcal) 3,920 4,708 4,708 4,708 4,708
Carbohydrates (% as k kcal) 67.5 42 42 42 42
Protein (% as kcal) 20.8 17 17 17 17
Lipid (% as kcal) 11.7 41 41 41 41

1) NF, normal fat control (AIN 73A diet); HFC, high fat control; HFPL, HFC + PSP 1.25%; HFPM, HFC + PSP 2.5%; HFPH, HFC + PSP 5% 2) Mineral mixture (g/kg mix): CaHPO4 500; NaCl 74; K2H6O7H2O 220; K2SO4 52; MgO 24; MnCO3 3.50; Fe(C6H5O7)·6H2O6; ZnCO3 1.6; CuCO3 0.3; KIO3 0.01; Na2SeO3·5H2O 0.01; CrK(SO4)2 0.55; sucrose, finely powdered 118 3) Vitamin mixture (g/kg mix): thi-amin·HCl 0.6; riboflavin 0.6; pyridoxin·HCl 0.7; niacin 3.0; calcium pantothenate 1.6; folic acid 0.2; biotin 0.02; vitamin B12 (0.1%) 1.0; vitamin A palmitate (500,000 IU/g) 0.8; vitamin D3 (400,000 IU/g)0.25; vitamin E acetate (500 IU/g) 10.0; menadione sodium bisulfate 0.08; sucrose finely powdered 981.15

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