High Molecular Weight Poly-Gamma-Glutamic Acid Regulates Lipid Metabolism in Rats Fed a High-Fat Diet and Humans
2011
Park, J.H., Kookmin University, Seoul, Republic of Korea | Choi, J.C., BioLeaders Corporation, Daejeon, Republic of Korea | Sung, M.H., BioLeaders Corporation, Daejeon, Republic of Korea | Kang, J.H., Inje University Seoul Paik Hospital, Seoul, Republic of Korea | Chang, M.J., Kookmin University, Seoul, Republic of Korea
We investigated the effect of high molecular weight poly-gamma-glutamic acid (hm γ-PGA) on adiposity and lipid metabolism of rats in the presence of an obesity-inducing diet. Thirty-two Sprague Dawley rats were fed either a normal-fat (11.4% kcal fat, NFC) or high-fat (51% kcal fat, RFC) diet. After 5 weeks, half of each diet-fed group was treated with hm γ-PGA (NFP or HFP) for 4 weeks. The HFC group had significantly higher body weight, visceral fat mass, fasting serum levels of total cholesterol, LDL cholesterol, and leptin, and lower serum HDL cholesterol level compared with those of the NFC group (p less than 0.05). Treatment with hm γ-PGA decreased body weight gain and perirenal fat mass (p less than 0.05), fasting serum total cholesterol, and mRNA expression of glucose-6-phosphate dehydrogenase (G6PD), regardless of dietary fat contents (p less than 0.01). However, hm γ-PGA increased serum HDL cholesterol in the HFC group (p less than 0.05). In vitro, 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase activity was suppressed by the addition of hm γ-PGA. In agreement with observations in animal study, the supplementation of hm γ-PGA (150 mg/day) to 20 female subjects in an 8-week double-blind, placebo-controlled study resulted in a tendency to decrease total cholesterol and LDL cholesterol concentrations. We thus conclude that dietary supplementation of hm γ-PGA may act as a hypocholestrolemic agent, secondary to its inhibitor effect on HMG-CoA reductase, and decrease abdominal adiposity by decreasing hepatic lipogenesis. The present study is an important first step in establishing the effect of hm γ-PGA on cholesterol levels in rats and humans.
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