Nutritional Evaluation Of Different Ratios Of N-6/n-3 Polyunsaturated Fatty Acids In Vitro

Polyunsaturated fatty acids(PUFAs) are important nutriments which are essential for human growth and health.PUFAs can be classified in n-3 and n-6 PUFAs,their main physiological role :antioxidant,prevent cardiovascular disease,anti-inflammation,lower blood cholesterol and triglyceride levels,etc.People always focus on the dietary intake of n-6 and n-3propertion.The recommendation ratio of n-6/n-3 PUFAs was inconsistent in many countries at present,and there were some disputations.The optimal ratio of n-6/n-3 PUFAs was also different in vivo and vitro.In this research,Hep G2 cells was selected as research object,refered nutrition recommendation, choosed the typically n-6 PUFAs(LA) and n-3PUFAs(ALA) which mainly exist in vegetable oil to set up different ratios(group1-7:LA、10:1LA/ALA、5:1 LA/ALA、1:1 LA/ALA 、1:5 LA/ALA、1:10 LA/ALA、ALA) to study the effect of different ratios of n-6/n-3 PUFAs on antioxidation capability, inflammatory cytokines and lipid metabolism of Hep G2 cells,to provide theoretical basis for the optimal nutrition ratio recommendations of LA/ALA.The main contents of this study were as follows:Firstly,investigated the effect of different ratios of LA/ALA on antioxidant system in Hep G2 cells.Selected 60μM different ratios of LA/ALA on Hep G2 cells 24 h to subsequent experiments by MTT.After co-cultrue the 60μM different ratios of LA/ALA and Hep G2 cells,found they can decrease the level of ROS and MDA contents,increase the antioxidant enzymes GST and GSH-Px activity, group4(1:1 LA/ALA) was the best one.And group4-group7 can increase the content of GSH. While the total antioxidant capacity(T-AOC)of Hep G2 cells was not affected by the experiment groups.It means that 60μM different ratios of LA/ALA did not cause the oxidative damage of Hep G2 cells,and although different ratios of LA/ALA did not affect the T-AOC,but can affect the antioxidant content and antioxidant enzymes activity of the series of glutathione which associated with antioxidant.Sencondly,investigated the effect of different ratios of LA/ALA on inflammatory cytokine in Hep G2 cells.The results showed that the 60μM different ratios of LA/ALA can reduce the level of pro-inflammatory cytokine:TNF-α and IL-6,increase the level of anti-inflammatory:IL-10 and LXA4 by enzyme immunoassay(ELISA),group4 was the best one.Finally,investigated the effect of different ratios of LA/ALA on lipid metabolism of Hep G2 cells.The results showed:(1)GC showed that 60μM different ratios of LA/ALA can significantly change the fatty acid composition of Hep G2 cells: group1-group3 increased the contents of LA and AA,group5-group7 increased the contents of ALA and EPA,group4(1:1LA/ALA) increased the contents of LA,ALA and EPA.(2)60μM different ratios of LA/ALA affected lipids level of Hep G2 significantly:After Hep G2 cells co-cultured with different ratios of LA/ALA,the level of TC、TG and LDL-C of Hep G2 cells were decreased,group4(1:1LA/ALA) was the best one.Group4-7 increased the HDL-C concentrations of Hep G2 cells compared with the other groups.(3)60μM different ratios of LA/ALA affected secretion of apolipoproteins of Hep G2 cells:ELISA results showed,secretion of Apo B was decreased by different ratios of LA/ALA,group4(1:1 LA/ALA) was the best one,secretion of Apo A-I wasincreased by group4-group7.(4)RT-PCR results showed that 60μM different ratios of LA/ALA reduced TG concentrations by inhibited the m RNA level of SREBP-1 and FAS,group4(1:1LA/ALA) was the best one.The experiment groups reduced the TC and LDL-C concentrations by down-regulated HMG-CR m RNA level and up-regulated LDLr m RNA level,group4(1:1LA/ALA) was the best one.Group4-group7 increased HDL-C concentrations,inceased RCT of cholesterol by up-regulated SR-B1 m RNA level.In summary,after co-cultrue the 60μM different ratios of LA/ALA with Hep G2 cells24 h,they did not cause the oxidative damage of Hep G2 cells,and can strengthen the antioxidant of the series of glutathione;improve inflammation of Hep G2 cells;decrease the lipid levels of Hep G2 cells by affect the gene expression which associated with lipid metabolism.The optimum ratio of LA/ALA was 1:1.