The Anti-Obesity Effect of Polysaccharide-Rich Red Algae (Gelidium amansii) Hot-Water Extracts in High-Fat Diet-Induced Obese Hamsters

Abstract

This study investigated the anti-obesity effect of a polysaccharide-rich red algae Gelidium amansii hot-water extract (GHE) in high-fat (HF) diet-induced obese hamsters. GHE contained 68.54% water-soluble indigestible carbohydrate polymers. Hamsters were fed with a HF diet for 5 weeks to induce obesity, and then randomly divided into: HF group, HF with 3% guar gum diet group, HF with 3% GHE diet group, and HF with orlistat (200 mg/kg diet) group for 9 weeks. The increased weights of body, liver, and adipose in the HF group were significantly reversed by GHE supplementation. Lower plasma leptin, tumor necrosis factor-α, and interleukin-6 levels were observed in the GHE+HF group compared to the HF group. GHE also increased the lipolysis rate and decreased the lipoprotein lipase activity in adipose tissues. GHE induced an increase in the phosphorylation of AMP-activated protein kinase (AMPK) and the protein expressions of peroxisome proliferator-activated receptor alpha (PPARα) and uncoupling protein (UCP)-2 in the livers. The decreased triglyceride and total cholesterol in the plasma and liver were also observed in obese hamsters fed a diet with GHE. These results suggest that GHE exerts a down-regulation effect on hepatic lipid metabolism through AMPK phosphorylation and up-regulation of PPARα and UCP-2 in HF-induced obese hamsters.

Keywords: Gelidium amansii hot-water extracts; adipocytokines; guar gum; lipoprotein lipase; obesity; orlistat.

Figure 1

Effects of GHE on body weight in hamsters fed different diets for 14 weeks during induction period (weeks 0–5) and experimental period (weeks 6–14). Data are presented as mean ± SD (n = 8). Con: Normal control group; HF: Obese hamsters fed a high-fat diet; GG: Obese hamsters fed 3% guar gum in the high-fat diet; GHE: Obese hamsters fed 3% Gelidium amansii hot-water extract in the high-fat diet; OL: Obese hamsters fed a high-fat diet with orlistat (200 mg/kg diet) in the diet. Values denoted by different letters differ significantly (p < 0.05) among one another.

Figure 2

Effects of GHE on triglyceride content per gram (A) and total (B) paraepididymal and perirenal fat pads in hamsters fed different experimental diets for 9 weeks. Data are presented as mean ± SD (n = 8). Con: Normal control group; HF: Obese hamsters fed a high-fat diet; GG: Obese hamsters fed 3% guar gum in the high-fat diet; GHE: Obese hamsters fed 3% Gelidium amansii hot-water extract in the high-fat diet; OL: Obese hamsters fed a high-fat diet with orlistat (200 mg/kg diet) in the diet. Values denoted by different letters differ significantly (p < 0.05) among one another.

Figure 3

Effects of GHE on lipolysis rate (A) and lipoprotein lipase activity (B) of paraepididymal and perirenal fat pads in hamsters fed different experimental diets for 9 weeks. Data are presented as mean ± SD (n = 8). Con: Normal control group; HF: Obese hamsters fed a high-fat diet; GG: Obese hamsters fed 3% guar gum in the high-fat diet; GHE: Obese hamsters fed 3% Gelidium amansii hot-water extract in the high-fat diet; OL: Obese hamsters fed a high-fat diet with orlistat (200 mg/kg diet) in the diet. Values denoted by different letters differ significantly (p < 0.05) among one another.

Figure 4

Effects of GHE on the protein expressions of phosphorylated AMPK (A), PPARα (B), and UCP-2 (C) in the livers of hamsters fed different experimental diets for 9 weeks. Data are presented as mean ± SD for 4–5 Syrian hamsters. Con: Normal control group; HF: Obese hamsters fed a high-fat diet; GG: Obese hamsters fed 3% guar gum in the high-fat diet; GHE: Obese hamsters fed 3% Gelidium amansii hot-water extract in the high-fat diet; OL: Obese hamsters fed a high-fat diet with orlistat (200 mg/kg diet) in the diet. Values denoted by different letters differ significantly (p < 0.05) among one another.