Effect of Carotenoids fromPhaeodactylum tricornutumon Palmitate-Treated HepG2 Cells

Non-alcoholic fatty liver disease represents the most common liver disease and is characterized by an excess of lipid accumulation in hepatocytes, mainly stored as triglycerides.Phaeodactylum tricornutumis a marine microalga, which is rich in bioactive molecules known to be hepatoprotective, such asn-3 long-chain polyunsaturated fatty acids and fucoxanthin. The aim of this study was to investigate the effects of a carotenoid extract fromP. tricornutumin a cellular model of non-alcoholic fatty liver disease induced by palmitate treatment. The combined effects of carotenoids and lipids, especiallyn-3 long-chain polyunsaturated fatty acids, were also investigated by using a total lipophilic extract. HepG2 cells were exposed for 24 h to 250 mu M palmitate with or without the addition of carotenoid extract (6 mu g/mL) or total lipophilic extract (100 mu g/mL). The addition of carotenoid extract or total lipophilic extract prevented the accumulation of triglycerides, total cholesterol and cholesterol esters. The carotenoid extract and total lipophilic extract also decreased the mRNA expression levels of genes involved in lipogenesis (ACACA,FASN,SCDandDGAT1) and cholesterol esterification (ACAT1/SOAT1). In addition, the total lipophilic extract also downregulated theLXR/NR1H3andSREBF1genes, which are involved in lipogenesis regulation. By contrast, the carotenoid extract increased the mRNA level ofCPT1A, a beta-oxidation related gene, and reduced the lipid droplet accumulation. In conclusion, this study highlights the preventive effects against non-alcoholic fatty liver disease of the two microalga extracts.