Incorporation of branched-chain fatty acid into cellular lipids and caspase-independent apoptosis in human breast cancer cell line, SKBR-3

BACKGROUND: 13-Methyltetradecanoic acid (13-MTD), an iso-C15 branched- chain saturated fatty acid, has been shown to induce apoptotic cell death of numerous human cancer cells. However, the mechanism for the induction of apoptosis has not been fully understood. This study described the incorporation of 13-MTD into cellular lipid of SKBR-3 breast cancer cells and apoptosis related event to gain more insight into the mechanism action of this fatty acid. RESULTS: Treatment of SKBR-3 cells with 13-MTD lowered the cell viability and induced apoptosis. Proportion of 13-MTD in the glycerolipids increased to saturation level within 6 hours. Triacylglycerol contained 13-MTD in higher concentration than phospholipid with positional preference to sn-2. 13-MTD caused no changes in the caspase activity and its gene expression. Furthermore, addition of caspase-inhibitor to culture medium did not prevent the cells from the cytotoxicity of 13-MTD. No-increase in the cellular calcium level was also noted with 13-MTD treatment. However, 13-MTD disrupted the mitochondrial integrity in 4 hours, and increased the nuclear translocation of apoptosis inducing factor. CONCLUSION: These results showed that 13-MTD disrupted the mitochondrial integrity, and induced apoptosis via caspase-independent death pathway

Taurine reduces the secretion of apolipoprotein B100 and lipids in HepG2 cells

<p>Abstract</p> <p>Background</p> <p>Higher concentrations of serum lipids and apolipoprotein B100 (apoB) are major individual risk factors of atherosclerosis and coronary heart disease. Therefore ameliorative effects of food components against the diseases are being paid attention in the affluent countries. The present study was undertaken to investigate the effect of taurine on apoB secretion and lipid metabolism in human liver model HepG2 cells.</p> <p>Results</p> <p>The results demonstrated that an addition of taurine to the culture media reduces triacylglycerol (TG)-mass in the cells and the medium. Similarly, cellular cholesterol-mass was decreased. Taurine inhibited the incorporation of [¹⁴C] oleate into cellular and medium TG, suggesting the inhibition of TG synthesis. In addition, taurine reduced the synthesis of cellular cholesterol ester and its secretion, suggesting the inhibition of acyl-coenzyme A:cholesterol acyltransferase activity. Furthermore, taurine reduced the secretion of apoB, which is a major protein component of very low-density lipoprotein.</p> <p>Conclusion</p> <p>This is a first report to demonstrate that taurine inhibits the secretion of apoB from HepG2 cells.</p

Antioxidant peptides purified and identified from the oil palm (Elaeis guineensis Jacq.) kernel protein hydrolysate

Protein extracted from oil palm kernel was hydrolyzed using pepsin-pancreatin (OPKH) and subsequently used to identify the potential antioxidative peptides. Then, the OPKH was purified sequentially by ultrafiltration, reversed-phase and semi-preparative HPLC. Antioxidant capacities (ACs) of the purified peptides from OPKH were evaluated using ferric reducing antioxidant power (FRAP), β-carotene-linoleate bleaching (BCB) assay and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity assay. Amino acid compositions of the purified peptide fractions were also determined. The amino acid sequence of the antioxidative peptide was identified by liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI-Q-TOF-MS/MS) using de novo sequencing. There were nine fractions purified and collected where F6 demonstrated the highest AC. Three antioxidative peptides, Val-Val-Gly-Gly-Asp-Gly-Asp-Val (VVGGDGDV), Val-Pro-Val-Thr-Ser-Thr (VPVTST) and Leu-Thr-Thr-Leu-Asp-Ser-Glu (LTTLDSE) were identified in fraction F6. These peptides did not show any similarity with other antioxidant peptides listed in BLAST database of NCBI. These peptides may be useful ingredients in food and pharmaceutical applications

Dietary effect of pomegranate seed oil rich in 9cis, 11trans, 13cis conjugated linolenic acid on lipid metabolism in obese, hyperlipidemic OLETF Rats

Conjugated fatty acid, the general term of positional and geometric isomers of polyunsaturated fatty acids with conjugated double bonds, has attracted considerable attention because of its potentially beneficial biological effects. In the present study, dietary effect of pomegranate seed oil rich in punicic acid (9cis, 11trans, 13cis-conjugated linolenic acid; 9c, 11t, 13c-CLNA) on lipid metabolism was investigated in obese, hyperlipidemic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. After 2 weeks feeding period, OLETF rats revealed obesity and hyperlipidemia compared with their progenitor LETO rats. Feeding of the diet supplemented with 9% safflower oil and 1% pomegranate seed oil (9c, 11t, 13c-CLNA diet) did not affect abdominal white adipose tissue weights and serum lipid levels compared with the diet supplemented with 10% safflower oil (control diet) in OLETF rats. However, the accumulated hepatic triacylglycerol was markedly decreased by 9c, 11t, 13c-CLNA diet in OLETF rats. Activities of hepatic enzymes related to fatty acid synthesis and fatty acid β-oxidation were not altered by 9c, 11t, 13c-CLNA diet. Levels of monounsaturated fatty acid (MUFA), major storage form of fatty acid, in serum triacylglycerol were markedly higher in obese, hyperlipidemic OLETF rats than in lean LETO rats. In addition, 9c, 11t, 13c-CLNA diet significantly decreased MUFA levels in OLETF rats. This is the first study showing that 9c, 11t, 13c-CLNA suppresses delta-9 desaturation in vivo, and we suggest that the alleviation of hepatic triacylglycerol accumulation by 9c, 11t, 13c-CLNA diet was, at least in part, attributable to the suppression of delta-9 desaturation in OLETF rats

Cytotoxicity effect of oil palm (Elaeis guineensis) kernel protein hydrolysates

This study was conducted to ascertain the cytotoxicity effect of oil palm (Elaeis guineensis) kernel protein hydrolysates (OPKHs) produced from its protein isolate. A modified microplate titer WST-1 [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium] assay was used to investigate the cytotoxicity of hydrolysates produced from protease and pepsin-pancreatin hydrolysis at various concentrations (0.1, 1, 10, 100 μg/ml and 1 mg/ml) using HepG2 cell model. Additionally, peptide stimulation test using OPKHs at 1 mg/ml was carried out to investigate whether OPKHs could serve as growth factor for HepG2 cells other than affecting its viability. As a result, oleic acid appeared to normalize the WST-1 readings of HepG2 cells treated with both hydrolysates at 1 mg/ml. The presence of amino acids in OPKHs could stimulate the growth and prolongs the viability of HepG2 cells. Both OPKHs were non-cytotoxic to HepG2 cells at all tested concentrations even at high concentrations. This study indicated that pepsin-pancreatin and protease hydrolysates produced from oil palm kernel protein were non-cytotoxic on HepG2 cells

The mechanism of dietary cholesterol effects on lipids metabolism in rats

<p>Abstract</p> <p>Background</p> <p>Cholesterol administration has been reported to influence hepatic lipid metabolism in rats. In the present study, the effect of dietary cholesterol on hepatic activity and mRNA expression of the enzymes involved in lipid metabolism were investigated. Fourteen male Wistar rats were randomly divided into 2 groups and fed 1% cholesterol or cholesterol free AIN76 diets for 4 weeks.</p> <p>Results</p> <p>The serum triglyceride and high density lipoprotein cholesterol levels were significantly decreased but the total cholesterol and non high density lipoprotein cholesterol levels were significantly increased in the cholesterol-fed rats compared with the control rats. And the concentrations of the hepatic total cholesterol and triglyceride increased about 4-fold and 20-fold separately by dietary cholesterol. The activities of hepatic malic enzyme, glucose-6-phosphate dehydrogenase, fatty acid synthase, phosphatidate phophatase and carnitine palmitoyl transferase were depressed by the cholesterol feeding (40%, 70%, 50%, 15% and 25% respectively). The results of mRNA expression showed that fatty acid synthase, carnitine palmitoyl transferase 1, carnitine palmitoyl transferase 2, and HMG-CoA reductase were down-regulated (35%, 30%, 50% and 25% respectively) and acyl-CoA: cholesterol acyltransferase and cholesterol 7α-hydroxylase were up regulated (1.6 and 6.5 folds) in liver by the cholesterol administration.</p> <p>Conclusions</p> <p>The dietary cholesterol increased the triglyceride accumulation in liver, but did not stimulate the activity and the gene expression of hepatic enzymes related to triglyceride and fatty acid biosynthesis.</p

Dietary saponins of sea cucumber alleviate orotic acid-induced fatty liver in rats via PPARα and SREBP-1c signaling

<p>Abstract</p> <p>Background</p> <p>Nonalcoholic fatty liver disease is the most common chronic liver disease in the world, and is becoming increasingly prevalent. Saponins of sea cucumber (SSC) are proven to exhibit various biological activities. Therefore, the present study was undertaken to examine the effect of saponins extracted from sea cucumber (Pearsonothuria graeffei) on the preventive activity of fatty liver in rats.</p> <p>Methods</p> <p>Male Wistar rats were randomly divided into five groups, including normal control group, fatty liver model group, SSC-treated group with SSC at levels of 0.01%, 0.03% and 0.05%. Model rats were established by administration with 1% orotic acid (OA). After the experiment period, serum total cholesterol (TC), triglyceride (TG), and hepatic lipid concentrations were determined. To search for a possible mechanism, we examined the changes of key enzymes and transcriptional factors involved in hepatic lipids biosynthesis, fatty acid β-oxidation.</p> <p>Results</p> <p>Both 0.03% and 0.05% SSC treatment alleviated hepatic steatosis and reduced serum TG and TC concentration significantly in OA fed rats. Hepatic lipogenic enzymes, such as fatty acid synthase (FAS), malic enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PDH) activities were inhibited by SSC treatment. SSC also decreased the gene expression of FAS, ME, G6PDH and sterol-regulatory element binding protein (SREBP-1c). Otherwise, the rats feeding with SSC showed increased carnitine palmitoyl transferase (CPT) activity in the liver. Hepatic peroxisome proliferator-activated receptor (PPARα), together with its target gene CPT and acyl-CoA oxidase (ACO) mRNA expression were also upregulated by SSC.</p> <p>Conclusions</p> <p>According to our study, the lipids-lowering effect of dietary SSC may be partly associated with the enhancement of β-oxidation via PPARα activation. In addition, the inhibited SREBP-1c- mediated lipogenesis caused by SSC may also contribute to alleviating fatty liver.</p

Short term effects of different omega-3 fatty acid formulation on lipid metabolism in mice fed high or low fat diet

BACKGROUND: Bioactivities of Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA) depend on their chemical forms. The present study was to investigate short term effects of triglyceride (TG), ethyl ester (EE), free fatty acid (FFA) and phospholipid (PL) forms of omega-3 fatty acid (FA) on lipid metabolism in mice, fed high fat or low fat diet. METHOD: Male Balb/c mice were fed with 0.7% different Omega-3 fatty acid formulation: DHA bound free fatty acid (DHA-FFA), DHA bound triglyceride (DHA-TG), DHA bound ethyl ester (DHA-EE) and DHA bound phospholipid (DHA-PL) for 1 week, with dietary fat levels at 5% and 22.5%. Serum and hepatic lipid concentrations were analyzed, as well as the fatty acid composition of liver and brain. RESULT: At low fat level, serum total cholesterol (TC) level in mice fed diets with DHA-FFA, DHA-EE and DHA-PL were significantly lower than that in the control group (P < 0.05). Hepatic TG level decreased significantly in mice fed diets with DHA-TG (P < 0.05), DHA-EE (P < 0.05) and DHA-PL (P < 0.05), while TC level in liver was significantly lower in mice fed diets with TG and EE compared with the control group (P < 0.05). At high fat level, mice fed diets with DHA-EE and DHA-PL had significantly lower hepatic TC level compared with the control diet (P < 0.05). Hepatic PL concentration experienced a significant increase in mice fed the diet with PL at high fat level (P < 0.05). Furthermore, both at low and high fat levels, hepatic DHA level significantly increased and AA level significantly decreased in all forms of DHA groups (P < 0.05), compared to control groups at two different fat levels, respectively. Additionally, cerebral DHA level in mice fed diets with DHA-FFA, DHA-EE and DHA-PL significantly increased compared with the control at high fat level (P < 0.05), but no significant differences were observed among dietary treatments for mice fed diets with low fat level. CONCLUSION: The present study suggested that not only total dietary fat content but also the molecular forms of omega-3 fatty acids contributed to lipid metabolism in mice. DHA-PL showed effective bioactivity in decreasing hepatic and serum TC, TG levels and increasing omega-3 concentration in liver and brain