Key Components In Fats And Oils Improving Lipid Accumulation And Oxidative Stress In HepG2 Cells

Edible fats and oils are the food raw material the most closely related to disease caused by the disorders of lipid metabolism.Scientific selection and reasonable intake of edible fats and oils become particularly important with the public's increasing demand for health.Fatty acids,the main components of edible fats and oils,are generally considered to play a decisive role in the functionality of edible fats and oils.With the deep study of edible fats and oils,more and more researchers have begun to pay attention to the functionality of minor components in them.In this study,the effects of fats and oils types and cooking methods on the lipid accumulation and oxidative stress in HepG2 cells were investigated by the combined method of cell culture and in vitro digestion tests.Moreover,the key components(fatty acids and minor components)of edible fats and oils improving the lipid accumulation and oxidative stress in HepG2 cells were selected using the modeling and analysis method of multivariate data set,and their mechanism were investigated preliminarily.This study will provide an in-depth knowledge on the nutritional effects of the fats and oils components.Furthermore,this study will serve as a theoretical underpinning to develop the edible blending oil for the people at a high risk of lipid metabolic disorders.The main results are shown as follows:Eight kinds of edible fats and oils,including lard(LO),soy oil(SO),rice bran oil(RO),palm oil(PO),coconut oil(CO),Pu'er tea seed oil(TO),olive oil(OO)and flaxseed oil(FO),were used as the materials.Then the effect of fats and oils types on the lipid accumulation and oxidative stress in HepG2 cells were investigated by both the digestion test in vitro and the cell assays.The results showed that the total polyphenol and flavone contents in OO were 238.36 mg/kg and 26.57 mg/kg,respectively,which was much higher than that of other seven kinds.The total phytosterol,squalene and tocopherol/tocotrienol contents in RO were the highest of the tested materials,while the contents of stigmasta-3,5-diene and parkeol in TO were much higher than that of the others.The cell culture test results showed that the level of lipid accumulation and oxidative stress in HepG2 cells increased after the treatment,and different kinds of fats and oils showed different effects.When the cells were treated at the concentration of 200 ?mol/L,the triglyceride(TG)content in HepG2 cells treated with LO increased by 71.79%,while the TG content in cells treated with CO increased by 10.17% compared with the control,respectively.However,at the same concentration,the TG content in cells treated with TO was slightly lower than that of the controls.It revealed that the lipid accumulation increased with the increment of the treated concentrations of fats or oils.However,the images of the Oil red O-stained cells showed that when the treatment concentration increased to 500 ?mol/L,there was little lipid accumulation in the cells treated by CO and TO.The effect of LO on the oxidative stress in the cells was the highest among the eight samples.The reactive oxygen species(ROS)and malondialdehyde(MDA)contents in HepG2 cells treated with LO increased by 9.97% and 94.45%,respectively,while there was no significant difference in ROS and MDA contents when treated with TO,OO and FO.Meanwhile,the activities of four antioxidases in the cells treated with TO or OO were significantly lower than those of the other six samples.The oxidative stability and the composition of the different fats and oils were analyzed and compared after three differents methods,i.e.stir-frying(160°C,5 min),pan-frying(170°C,5 min)and deep-frying(180°C,3 min at a time,frying at intervals of half an hour,a total of three times).Moreover,the effects of these treated samples on the lipid accumulation and oxidative stress in HepG2 cells were investigated after different cooking treatments.The results showed that the acid values,peroxide values,anisidine values and total polar components in all the fried samples increased,and these values of the deep-frying treatment samples were the higheset,revealing the worst oxidative stability.The FO samples after frying showed the least oxidative stability.Also,the peroxide values of FO increased by 44.44%,and the content of total polar components was 11.50%.In addition,the contents of polyunsaturated fatty acids and minor components in all the treated samples significantly decreased when fried at the high temperature.The loss rates of ergosta-4,7,22-trien-3-one in RO,and the total polyphenols and tocopherol/tocotrienols in CO were more than 99% after the deep-frying.When the Hep G2 cells were treated at the same concentration(200 ?mol/L)by the fried samples,the cytotoxicity of the fried samples was higher than that of non-fried ones,and the effects of fried samples on the intracellular lipid accumulation and oxidative stress were more significant,which depended on the kinds of the samples.The TG and total cholesterol(TC)contents in the cells treated with the fried samples were significantly lower than those of the non-fried samples.The intracellular TG content in TO after deep-frying treatment was the lowest.However,the intracellular TG content in TO after deep-frying treatment increased by 101.03% compared to that of the non-fried.The intracellular TG content in FO after deep-frying treatment increased by 104.24%.The intracellular ROS content in LO after deep-frying treatment showed the highest increasing rate(35.93%)of all the fried samples.The intracellular MDA content in TO and FO after deep-frying treatment showed a higher increasing rate(62.92% and 60.78%)than the others,and the decrease of antioxidase activities of these two samples was more significant than those of the other groups.Meanwhile,the analysis method of multivariate data set was applied to investigate the key components in edible fats and oils improving the lipid accumulation and oxidative stress in HepG2 cells.The results showed that the effects of the minor components in fats and oils on improving the lipid accumulation and oxidative stress was more significant than that of fatty acids.The key fatty acid components in edible fats and oils improving the lipid accumulation in HepG2 cells were cis-unsaturated fatty acid,C18:3cis,C20:1cis,C12:0 and C14:0,and the key minor components were(3?,22E)-ergosta-7,22-dien-3-yl,cycloartenol,dihydro-cis-?-copaene-8-ol,squalene and ?-tocopherol.The results of two-way orthogonal projections to latent structures(O2PLS)analysis showed that the vip important in projection and regression coefficients of minor components were both higher than those of fatty acids.The key components in edible fats and oils improving the oxidative stress in HepG2 cells were squalene,parkeol,?-sitosterol,campesterol and stigmasterol.Seven kinds of edible oils with high unsaponifiable matters(USMs),including TO,sunflower seed oil,wheat germ oil,SO,OO,RO and FO,were used as the raw materials to investigate the key components in USMs extracted from edible fats and oils improving the lipid accumulation and oxidative stress in HepG2 cells.The USMs were extracted from the seven edible oils using the saponification method,and model control group of oleic acid-induced lipid accumulation and oxidative stress in HepG2 cells was established.The USMs were delivered to the HepG2 cells through nanoemulsion delivery system stabilized by the whey protein hydrolysates/sodium caseinate/gum arabic,and the effects of USMs extracted from the seven samples on the lipid accumulation and oxidative stress in HepG2 cells were determined and compared.Simultaneously,the key components in USMs extraction improving the lipid accumulation and oxidative stress in HepG2 cells were investigated.The results showed that the cell absorption rate of nanoemulsin delivery system was significantly higher than the conventional DMSO dissolution method.USMs extracted from OO and RO showed the most significant improving effect on the lipid accumulation in HepG2 cells: the TG contents treated by the USMs extracted from OO and RO decreased by 83.19% and 84.61%,respectively,and the TC contents decreased by 78.18% and 80.37%,respectively.USMs extracted from TO,RO and FO showed far more significant improving effect on the oxidative stress in HepG2 cells.The MDA contents in the cells treated with USMs extracted from TO,RO and FO decreased by 36.14%,39.22% and 32.69%,respectively,while their glutathione peroxidase activities increased by 46.87%,53.72% and 52.17%,which was much higher than those of other USMs extraction samples.The key components in USMs extracted from the seven edible fats and oils improving lipid accumulation and oxidative stress in HepG2 cells were ?-tocotrienol,dihydro-cis-?-copaene-8-ol,squalene and parkeol.Finally,the effective concentration and action mechanism of one of the key components,that is parkeol,in improving the lipid accumulation and oxidative stress in HepG2 cells were investigated.The results showed that the effective concentration of parkeol was 15-20 ?mol/L.When the concentration was 20 ?mol/L,it effectively inhibited the fatty acid synthesis,and promoted the fatty acid oxidation,glycolysis,energy metabolism and amino acid catabolism.Meanwhile,parkeol regulated the intracellular expression of genes FASN,ACSL1,CPT1 A and PIK3 CB to improve the lipid accumulation,and regulated the expression of genes NQO-1,PRXL2 A,NF-kB2 and TXNRD1 to improve the intracellular oxidative stress.Moreover,parkeol regulated the signaling pathways in HepG2 cells including glutathione metabolism,fatty acid biosynthesis,sterol synthesis,aging,longevity,AMPK and FoxO signaling pathways.In summary,the effect of the minor components in fats and oils on improving the lipid accumulation and oxidative stress was more significant than that of the fatty acids.The key components in edible fats and oils improving the lipid accumulation and oxidative stress in HepG2 cells were minor components including ?-tocotrienol,dihydro-cis-?-copaene-8-ol,squalene and parkeol.