Poly‐γ‐glutamate isolated from fermented soy products changes omega‐3 fatty acid contents of liver and brain in diet‐induced obese rats

Abstract

The study was carried out to evaluate the effects of poly‐gamma‐glutamate (γ‐PGA) on the omega‐fatty acids of liver and brain in diet‐induced obese rats. The gamma‐PGA isolated from a Korean fermented soybean product, Cheongkukjang is an anionic biopolymer. Ten‐weeks‐old Sprague‐Dawley male rats (n=64) were divided into two groups and induced obesity by providing the low 10% fat control and high 45% fat diets for 4 weeks. Then, they were randomly blocked into four groups in each fat diet and provided four different diets containing no PGA control, PGA, PGA‐Ca, and PGA‐Mg. The gamma‐PGA content of the diets was 0.1% that was determined as appropriate by previous studies. After 4 week feeding, rats were decapitated and the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents of liver and brain were analyzed by gas chromatography. The low fat groups fed with three different types of PGA showed higher liver DHA content than the control and the high fat groups with PGA showed higher liver EPA content (p<0.05). In the brain, the high fat groups fed with PGA showed significantly higher EPA contents in cerebellum except in cerebrum and brain stem, and showed higher DHA contents in all three brain regions. The results suggest that gamma‐PGA accumulates EPA and DHA in liver and brain. The binding forms of PGA may not influence the omega‐fatty acid accumulation. (This study was supported by 2007 Seoul R& D Program).