| The epidemiology in the related research results show that the increase of the intake of whole grain can prevent and improve hyperlipidemia, cardiovascular disease, atherosclerosis and diabetes. Compared with the fine grain, whole grain is rich in vitamin and fiber value because of rice bran, especially phenolic compounds. The bioactive compounds have long been undervalued compared with the fruits and vegetables. So, the brown rice was taken as objects of study, and rice bran as a raw material, macroporous adsorptive resins were used to purify the rice bran extract. To investigate the effects of phenolics on the lipid metabolism in hyperlipemia mice, and probe into its molecular mechanisms regulating lipid metabolism by test the gene expression level. The research is of great significance of guiding the whole grain dietary pattern. The concrete research content is as follows:(1) Separation purification of phenolic compunds in brown rice by macroporous resin: The static adsorption and desorption, dynamic adsorption and desorption of 9 macroporous resins with different polarities to phenolic compunds in brown rice were compared. Comparison the total polyphenols, flavonoids, total sugar, protein, fat, ash and moisture content before and after purification. The phenolic profiles in brown rice extract before and after resin purification were analyzed by HPLC analysis. And the antioxidant activity was valued by oxygen radical absorption capacity(ORAC) and cellular antioxidant activity(CAA). The results showed that Macroporous resin HPD-300 exhibited the best capability of adsorption and desorption to brown rice phenolics. The optimized purification parameters were as follows: the phenolic concentration of loading sample is 1 mg GAE/m L; sampling rate is 3.0 BV/h; sampling volume is 3.5 BV; eluent is 70% ethanol; flow velocity is 3.0 BV/h. After HPD-300 resin purification, the total phenolic and total flavonoids content were 320.72 μg GAE/ mg and 133.67 μg CE/ mg, respectively. The total sugar, protein, fat, ash and moisture content in brown rice extract reduced by 34.8%, 35.7%, 67.4%, 65.3% and 69.21%. The phenolic profiles of the extract were not changed after HPD-300 resin purification but the concentrations of 10 phenolic compounds increased by 0.4-2.4 times. The ORAC and CAA antioxidant activity of the extract increased by 1.4 and 2.2 times, respectively. In conclusion, HPD-300 macroporous resin can enrich whole grain brown rice phenolics effectively.(2) Effect of brown rice pheolics in regulating lipid metabolism: The brown rice phenolic extract separation purification by macroporous resin were taken as material. C57BL/6J male mice were randomly divided into four groups: Normal control group(NC), high fat diet group(HF), high fat diet +low dose brown rice phenolics group(HF+LP), high fat diet +high dose brown rice phenolics group(HF+HP). HF+LP and HF+HP mice were given doses of 200 mg/kg·d and 400 mg/kg·d of brown rice phenolics extract. 16 weeks later, the levels of serum and liver lipid metabolism related indicator were analyzed. Liver and adipose tissue lipid accumulation were analyzed by pathological observation. The results showed that after BRPE intervention, the body weight and organ indexes were decreased in mice, and serum TC, TG, LDL-c and FFA content decreased significantly(P<0.05), while HDL-c content increased significantly(P<0.05). Hepatic TC and TG content also decreased significantly(P<0.05). The pathological results of liver and epididymal adipose showed that brown rice phenolic can obviously improve the liver steatosis and reduce fat deposition in hyperlipidemia mice. Meanwhile, BRPE can improve the oxidation damage, the serum and hepatic MDA content decreased significantly(P<0.05), and SOD activity increased significantly(P<0.05). The hepatic GSH content and GSH-px and CAT activity increased significantly(P<0.05). In conclusion, BRPE can improve the lipid metabolism in hyperlipemia mice effectively.(3) Molecular mechanisms of brown rice pheolics in regulating lipid metabolism: Through the animals experiments, the hormones and adipocytokins were analyzed by ELISA, and the gene expressions were analyzed by Q-PCR and Western Blot. The results showed that, the BRPE can improve insulin resistance and leptin resistance, and increase adiponectin content(P<0.05). The expression of AMPKα m RNA and the phosphorylation of AMPKα protein were increased significantly; the expression of PPARα and CPT1 a increased significantly, and the expression of SREBP1 c, ACC, SCD and HMGR decreased significantly. In conclusion, the mechanism of brown rice polyphenols regulate lipid metabolism is to increase serum adiponectin, and promote the phosphorylation of AMPKα, and activate PPARα, and then upregulate CPT1 a expression, thus promote the fatty acid oxidant. On the other hand, brown rice polyphenols can downregulate SREBP1 c, ACC, SCD and HMGR expression, thus inhibit the synthesis of lipids. |
