The study on synthesis and vitro hypolipidemic activity of novel berberine derivatives nitric oxide donors.

Berberine was used as the lead compound in the present study to design and synthesize novel berberine derivatives by splicing bromine bridges of different berberine carbon chain lengths coupled nitric oxide donors, and their lipid lowering activities were assessed in a variety of ways. This experiment synthesized 17 new berberine nitric oxide donor derivatives. Compared with berberine hydrochloride, most of the compounds exhibited certain glycerate inhibitory activity, and compounds 6a, 6b, 6d, 12b and 12d showed higher inhibitory activity than berberine, with 6a, 6b and 6d having significant inhibitory activity. In addition, compound 6a linked to furazolidone nitric oxide donor showed better NO release in experiments; In further mechanistic studies, we screened and got two proteins, PCSK9 and ACLY, and docked two proteins with 17 compounds, and found that most of the compounds bound better with ATP citrate lyase (ACLY), among which there may be a strong interaction between compound 6a and ACLY, and the interaction force was better than the target drug Bempedoic Acid, which meaning that 6a may exert hypolipidemic effects by inhibiting ACLY; moreover, we also found that 6a may had the better performance in gastrointestinal absorption, blood-brain barrier permeability, Egan, Muegge class drug principle model calculation and bioavailability.

Active post-transcriptional regulation and ACLY-mediated acetyl-CoA synthesis as a pivotal target of Shuang-Huang-Sheng-Bai formula for lung adenocarcinoma treatment.

BACKGROUND: New therapeutic approaches are required to improve the outcomes of lung cancer (LC), a leading cause of cancer-related deaths worldwide. Chinese herbal medicine formulae widely used in China provide a unique opportunity for improving LC treatment, and the Shuang-Huang-Sheng-Bai (SHSB) formula is a typical example. However, the underlying mechanisms of action remains unclear. PURPOSE: This study aimed to confirm the efficacy of SHSB against lung adenocarcinoma (LUAD), which is a major histological type of LC, unveil the downstream targets of this formula, and assess the clinical relevance and biological roles of the newly identified target. METHODS: An experimental metastasis mouse model and a subcutaneous xenograft mouse model were used to evaluate the anti-cancer activity of SHSB. Multi-omics profiling of subcutaneous tumors and metabolomic profiling of sera were performed to identify downstream targets, especially the metabolic targets of SHSB. A clinical trial was conducted to verify the newly identified metabolic targets in patients. Next, the metabolites and enzymes engaged in the metabolic pathway targeted by SHSB were measured in clinical samples. Finally, routine molecular experiments were performed to decipher the biological functions of the metabolic pathways targeted by SHSB. RESULTS: Oral SHSB administration showed overt anti-LUAD efficacy as revealed by the extended overall survival of the metastasis model and impaired growth of implanted tumors in the subcutaneous xenograft model. Mechanistically, SHSB administration altered protein expression in the post-transcriptional layer and modified the metabolome of LUAD xenografts. Integrative analysis demonstrated that SHSB markedly inhibited acetyl-CoA synthesis in tumors by post-transcriptionally downregulating ATP-citrate lyase (ACLY). Consistently, our clinical trial showed that oral SHSB administration declined serum acetyl-CoA levels of patients with LC. Moreover, acetyl-CoA synthesis and ACLY expression were both augmented in clinical LUAD tissues of patients, and high intratumoral ACLY expression predicted a detrimental prognosis. Finally, we showed that ACLY-mediated acetyl-CoA synthesis is essential for LUAD cell growth by promoting G1/S transition and DNA replication. CONCLUSION: Limited downstream targets of SHSB for LC treatment have been reported in previous hypothesis-driven studies. In this study, we conducted a comprehensive multi-omics investigation and demonstrated that SHSB exerted its anti-LUAD efficacy by actively and post-transcriptionally modulating protein expression and particularly restraining ACLY-mediated acetyl-CoA synthesis.

Two New Oleanane-Triterpenoid Saponins from Clinopodium gracile.

Two new oleanane-triterpenoid saponins, clinograsaponins A (1) and B (2), together with twelve known ones (3-14), were isolated from the whole herb of Clinopodium gracile (Bentham) Matsumura. Their structures were determined by spectroscopic analysis and chemical method. All the isolated compounds were evaluated for their activities against ATP-citrate lyase (ACLY) and nuclear factor kappa B (NF-κB).

Regulation on Citrate Influx and Metabolism through Inhibiting SLC13A5 and ACLY: A Novel Mechanism Mediating the Therapeutic Effects of Curcumin on NAFLD.

Upregulated de novo lipogenesis (DNL) plays a pivotal role in the progress of the nonalcoholic fatty liver disease (NAFLD). Cytoplasmic citrate flux, mediated by plasma membrane citrate transporter (SLC13A5), mitochondrial citrate carrier (SLC25A1), and ATP-dependent citrate lyase (ACLY), determines the central carbon source for acetyl-CoA required in DNL. Curcumin, a widely accepted dietary polyphenol, can attenuate lipid accumulation in NAFLD. Here, we first investigated the lipid-lowering effect of curcumin against NAFLD in oleic and palmitic acid (OPA)-induced primary mouse hepatocytes and high-fat plus high-fructose diet (HFHFD)-induced mice. Curcumin profoundly attenuated OPA- or HFHFD-induced hyperlipidemia and aberrant hepatic lipid deposition via modulating the expression and function of SLC13A5 and ACLY. The possible mechanism of curcumin on the citrate pathway was investigated using HepG2 cells, HEK293T cells transfected with human SLC13A5, and recombinant human ACLY. In OPA-stimulated HepG2 cells, curcumin rectified the dysregulated expression of SLC13A5/ACLY possibly via the AMPK-mTOR signaling pathway. Besides, curcumin also functionally inhibited both citrate transport and metabolism mediated by SLC13A5 and ACLY, respectively. These findings confirm that curcumin improves the lipid accumulation in the liver by blocking citrate disposition and hence may be used to prevent NAFLD.

Cytosolic Acetyl-CoA Generated by ATP-Citrate Lyase Is Essential for Acetylation of Cell Wall Polysaccharides.

Plant cell wall polysaccharides, including xylan, glucomannan, xyloglucan and pectin, are often acetylated. Although a number of acetyltransferases responsible for the acetylation of some of these polysaccharides have been biochemically characterized, little is known about the source of acetyl donors and how acetyl donors are translocated into the Golgi, where these polysaccharides are synthesized. In this report, we investigated roles of ATP-citrate lyase (ACL) that generates cytosolic acetyl-CoA in cell wall polysaccharide acetylation and effects of simultaneous mutations of four Reduced Wall Acetylation (RWA) genes on acetyl-CoA transport into the Golgi in Arabidopsis thaliana. Expression analyses of genes involved in the generation of acetyl-CoA in different subcellular compartments showed that the expression of several ACL genes responsible for cytosolic acetyl-CoA synthesis was elevated in interfascicular fiber cells and induced by secondary wall-associated transcriptional activators. Simultaneous downregulation of the expression of ACL genes was demonstrated to result in a substantial decrease in the degree of xylan acetylation and a severe alteration in secondary wall structure in xylem vessels. In addition, the degree of acetylation of other cell wall polysaccharides, including glucomannan, xyloglucan and pectin, was also reduced. Moreover, Golgi-enriched membrane vesicles isolated from the rwa1/2/3/4 quadruple mutant were found to exhibit a drastic reduction in acetyl-CoA transport activity compared with the wild type. These findings indicate that cytosolic acetyl-CoA generated by ACL is essential for cell wall polysaccharide acetylation and RWAs are required for its transport from the cytosol into the Golgi.

Earlier Degraded Tapetum1 (EDT1) Encodes an ATP-Citrate Lyase Required for Tapetum Programmed Cell Death.

In flowering plants, the tapetum cells in anthers undergo programmed cell death (PCD) at the late meiotic stage, providing nutrients for further development of microspores, including the formation of the pollen wall. However, the molecular basis of tapetum PCD remains elusive. Here we report a tapetum PCD-related mutant in rice (Oryza sativa), earlier degraded tapetum 1 (edt1), that shows complete pollen abortion associated with earlier-than-programmed tapetum cell death. EDT1 encodes a subunit of ATP-citrate lyase (ACL), and is specifically expressed in the tapetum of anthers. EDT1 localized in both the nucleus and the cytoplasm as observed in rice protoplast transient assays. We demonstrated that the A and B subunits of ACL interacted with each other and might function as a heteromultimer in the cytoplasm. EDT1 catalyzes the critical steps in cytosolic acetyl-CoA synthesis. Our data indicated a decrease in ATP level, energy charge, and fatty acid content in mutant edt1 anthers. In addition, the genes encoding secretory proteases or lipid transporters, and the transcription factors known to regulate PCD, were downregulated. Our results demonstrate that the timing of tapetum PCD must be tightly regulated for successful pollen development, and that EDT1 is involved in the tapetum PCD process. This study furthers our understanding of the molecular basis of pollen fertility and fecundity in rice and may also be relevant to other flowering plants.

Fermented Castanea crenata Inner Shell Extract Increases Fat Metabolism and Decreases Obesity in High-Fat Diet-Induced Obese Mice.

The anti-obesity effects of fermented Castanea crenata inner shell extract (FCCE) were investigated using high-fat diet (HFD)-induced obese mice. In the FCCE intake groups, body weight gain and adipocyte area were significantly reduced, especially body weight gain in the 250 mg/kg FCCE group (G4) decreased by 37%, respectively, compared with negative control group (G2, HFD group). After oral administration of the FCCE, the increase of serum low-density lipoprotein (LDL)-cholesterol induced by HFD was suppressed significantly, as well as the level of aspartate aminotransferase, and alanine aminotransferase, which are markers of hepatitis induced by obesity. Serum leptin in G4 group was significantly decreased to less than that of G2 group. Also, in G4 and 500 mg/kg FCCE group (G5), enzymes-related lipogenesis, citrate synthase, and ATP citrate lyase were decreased, whereas the level of enoyl-CoA hydratase used for ß-oxidation was significantly increased in comparison with normal diet group. Furthermore, the FCCE stimulated the expression of lipolytic regulators, especially AMP-activated protein kinase. In conclusion, we suggest that the FCCE may ameliorate in diet-induced obesity by regulating lipid metabolism.

Prevention of Diet-Induced Metabolic Dysregulation, Inflammation, and Atherosclerosis in Ldlr-/- Mice by Treatment With the ATP-Citrate Lyase Inhibitor Bempedoic Acid.

OBJECTIVE: Bempedoic acid (ETC-1002, 8-hydroxy-2,2,14,14-tetramethylpentadecanedioic acid) is a novel low-density lipoprotein cholesterol-lowering compound. In animals, bempedoic acid targets the liver where it inhibits cholesterol and fatty acid synthesis through inhibition of ATP-citrate lyase and through activation of AMP-activated protein kinase. In this study, we tested the hypothesis that bempedoic acid would prevent diet-induced metabolic dysregulation, inflammation, and atherosclerosis. APPROACH AND RESULTS: Ldlr-/- mice were fed a high-fat, high-cholesterol diet (42% kcal fat, 0.2% cholesterol) supplemented with bempedoic acid at 0, 3, 10 and 30 mg/kg body weight/day. Treatment for 12 weeks dose-dependently attenuated diet-induced hypercholesterolemia, hypertriglyceridemia, hyperglycemia, hyperinsulinemia, fatty liver and obesity. Compared to high-fat, high-cholesterol alone, the addition of bempedoic acid decreased plasma triglyceride (up to 64%) and cholesterol (up to 50%) concentrations, and improved glucose tolerance. Adiposity was significantly reduced with treatment. In liver, bempedoic acid prevented cholesterol and triglyceride accumulation, which was associated with increased fatty acid oxidation and reduced fatty acid synthesis. Hepatic gene expression analysis revealed that treatment significantly increased expression of genes involved in fatty acid oxidation while suppressing inflammatory gene expression. In full-length aorta, bempedoic acid markedly suppressed cholesteryl ester accumulation, attenuated the expression of proinflammatory M1 genes and attenuated the iNos/Arg1 ratio. Treatment robustly attenuated atherosclerotic lesion development in the aortic sinus by 44%, with beneficial changes in morphology, characteristic of earlier-stage lesions. CONCLUSIONS: Bempedoic acid effectively prevents plasma and tissue lipid elevations and attenuates the onset of inflammation, leading to the prevention of atherosclerotic lesion development in a mouse model of metabolic dysregulation.

ATP-citrate lyase: genetics, molecular biology and therapeutic target for dyslipidemia.

PURPOSE OF REVIEW: ATP-citrate lyase (ACLY) has re-emerged as a drug target for LDL cholesterol (LDL-C) lowering. We review ACLY as a therapeutic strategy, its genetics, its molecular and cellular biology, and also its inhibition. RECENT FINDINGS: ACLY is a critical enzyme linking glucose catabolism to lipogenesis by providing acetyl-CoA from mitochondrial citrate for fatty acid and cholesterol biosynthesis. Human genetic variants have been associated with enhanced growth and survival of several cancers, and with attenuated plasma triglyceride responses to dietary fish oil. In mice, liver-specific Acly deficiency protects from hepatic steatosis and dyslipidemia, whereas adipose tissue-specific Acly deletion has no phenotype, supporting therapeutic inhibition of ACLY. A lipid-regulating compound, bempedoic acid, was discovered to potently inhibit ACLY, and in animal models, it prevents dyslipidemia and attenuates atherosclerosis. Phase 2 clinical trials revealed that bempedoic acid effectively lowers LDL-C as monotherapy, combined with ezetimibe, added to statin therapy and in statin-intolerant hypercholesterolemic patients. SUMMARY: The efficacy of bempedoic acid as an LDL-C-lowering agent has validated ACLY inhibition as a therapeutic strategy. Positive results of phase 3 patient studies, together with long-term cardiovascular disease outcome trials, are required to establish ACLY as a major new target in cardiovascular medicine.

Activating PPARα prevents post-ischemic contractile dysfunction in hypertrophied neonatal hearts.

RATIONALE: Post-ischemic contractile dysfunction is a contributor to morbidity and mortality after the surgical correction of congenital heart defects in neonatal patients. Pre-existing hypertrophy in the newborn heart can exacerbate these ischemic injuries, which may partly be due to a decreased energy supply to the heart resulting from low fatty acid ß-oxidation rates. OBJECTIVE: We determined whether stimulating fatty acid ß-oxidation with GW7647, a peroxisome proliferator-activated receptor-α (PPARα) activator, would improve cardiac energy production and post-ischemic functional recovery in neonatal rabbit hearts subjected to volume overload-induced cardiac hypertrophy. METHODS AND RESULTS: Volume-overload cardiac hypertrophy was produced in 7-day-old rabbits via an aorto-caval shunt, after which, the rabbits were treated with or without GW7647 (3 mg/kg per day) for 14 days. Biventricular working hearts were subjected to 35 minutes of aerobic perfusion, 25 minutes of global no-flow ischemia, and 30 minutes of aerobic reperfusion. GW7647 treatment did not prevent the development of cardiac hypertrophy, but did prevent the decline in left ventricular ejection fraction in vivo. GW7647 treatment increased cardiac fatty acid ß-oxidation rates before and after ischemia, which resulted in a significant increase in overall ATP production and an improved in vitro post-ischemic functional recovery. A decrease in post-ischemic proton production and endoplasmic reticulum stress, as well as an activation of sarcoplasmic reticulum calcium ATPase isoform 2 and citrate synthase, was evident in GW7647-treated hearts. CONCLUSIONS: Stimulating fatty acid ß-oxidation in neonatal hearts may present a novel cardioprotective intervention to limit post-ischemic contractile dysfunction.

Inactivation of ATP citrate lyase by Cucurbitacin B: A bioactive compound from cucumber, inhibits prostate cancer growth.

Prostate cancer, a leading cause of cancer-related deaths in males, is well recognized as having late disease on-set (mostly at age 60-70) and showing slow/latent disease development, and strategies to prevent cancer formation in late manhood may have significant health impacts. Cucurbitacin B (CuB) is a naturally occurring compound that is found abundantly in cucumbers and other vegetables, and it is known to exert anti-cancer activities (primarily via apoptosis-induction) in several human cancers. However, its chemopreventive potential for prostate cancer has not yet been investigated. Here, we reported that CuB significantly and specifically inhibited prostate cancer cell growth with low IC50 (~0.3 µM; PC-3 and LNCaP), accompanied by marked apoptosis (Caspase 3/7 activation, PARP cleavage, increase of Annexin V-Alexa Fluor 488 (Alexa488)+ cells and accumulation of Sub-G0/G1 population), whereas normal human prostate epithelial cells (PrEC) were CuB-insensitive. Using a chemopreventive model, pre-treatment of mice with CuB (2 weeks before PC-3 prostate cancer cell implantation) significantly reduced the rate of in vivo tumor-formation. A 79% reduction in tumor size (accompanied by marked in situ apoptosis) was observed in the CuB-treated group (with no noticeable toxicity) vs. controls at day 31. Strikingly, mechanistic investigations demonstrated that CuB drove dose-dependent inhibition of ATP citrate lyase phosphorylation (ACLY; an important enzyme for cancer metabolism) both in vitro and in the CuB-chemopreventive mouse model. Importantly, ACLY over-expression abrogated CuB's apoptotic effects in prostate cancer cells, confirming ACLY as a direct target of CuB. Thus, CuB harbors potent chemopreventive activity for prostate cancer, and we revealed a novel anti-tumor mechanism of CuB via inhibition of ACYL signaling in human cancer.

AMP-activated protein kinase and ATP-citrate lyase are two distinct molecular targets for ETC-1002, a novel small molecule regulator of lipid and carbohydrate metabolism.

ETC-1002 (8-hydroxy-2,2,14,14-tetramethylpentadecanedioic acid) is a novel investigational drug being developed for the treatment of dyslipidemia and other cardio-metabolic risk factors. The hypolipidemic, anti-atherosclerotic, anti-obesity, and glucose-lowering properties of ETC-1002, characterized in preclinical disease models, are believed to be due to dual inhibition of sterol and fatty acid synthesis and enhanced mitochondrial long-chain fatty acid ß-oxidation. However, the molecular mechanism(s) mediating these activities remained undefined. Studies described here show that ETC-1002 free acid activates AMP-activated protein kinase in a Ca(2+)/calmodulin-dependent kinase ß-independent and liver kinase ß 1-dependent manner, without detectable changes in adenylate energy charge. Furthermore, ETC-1002 is shown to rapidly form a CoA thioester in liver, which directly inhibits ATP-citrate lyase. These distinct molecular mechanisms are complementary in their beneficial effects on lipid and carbohydrate metabolism in vitro and in vivo. Consistent with these mechanisms, ETC-1002 treatment reduced circulating proatherogenic lipoproteins, hepatic lipids, and body weight in a hamster model of hyperlipidemia, and it reduced body weight and improved glycemic control in a mouse model of diet-induced obesity. ETC-1002 offers promise as a novel therapeutic approach to improve multiple risk factors associated with metabolic syndrome and benefit patients with cardiovascular disease.

High dose of Garcinia cambogia is effective in suppressing fat accumulation in developing male Zucker obese rats, but highly toxic to the testis.

We investigated the ability of Garcinia cambogia extract containing (-)-hydroxycitric acid (HCA) to suppress body fat accumulation in developing male Zucker obese (fa/fa) rats. We also examined histopathologically the safety of its high doses. Diets containing different levels of HCA (0, 10, 51, 102 and 154 mmol/kg diet) were fed to 6-week-old rats for 92 or 93 days. Each diet group was pair-fed to the 154 mmol HCA/kg diet group. Epididymal fat accumulation and histopathological changes in tissues were observed. The highest dose of HCA-containing Garcinia cambogia (154 mmol HCA/kg diet) showed significant suppression of epididymal fat accumulation in developing male Zucker obese rats, compared with the other groups. However, the diets containing 102 mmol HCA/kg diet and higher (778 and 1244 mg HCA/kg BW/d, respectively) caused potent testicular atrophy and toxicity, whereas diets containing 51 mmol HCA/kg diet (389 mg HCA/kg BW/d) or less did not. Accordingly, 51 mmol HCA/kg diet (389 mg HCA/kg BW/d) was deemed to be the no observed adverse effect level (NOAEL).

Improving estimates of trophic shift in Nile tilapia, Oreochromis niloticus (L.), using measurements of lipogenic enzyme activities in the liver.

To test whether the measurement of selected enzyme activities could be used to estimate more precisely the trophic shift of C isotopes, Nile tilapia (Oreochromis niloticus) were fed semi-synthetic diets differing in their lipid contents (1.7%, 5.0%, 10.8% and 20.0%). The diets were formulated to contain the same amount of nitrogen and metabolizable energy and were made from casein, wheat starch, corn germ oil supplemented with vitamins, minerals and L-arginine. The influence of the different diets on the activity of two lipogenic enzymes, ATP-citrate lyase and malic enzyme, on delta13C values in the whole fish, the liver and their correlation was investigated. There was a strong positive correlation between delta13C values in the lipids of whole fish and those of their livers. The activities of lipogenic enzymes increased significantly with increasing trophic shift of C isotopes (Deltadelta13Cdiet-fish values) in the lipids. If the relationship between trophic shift and enzyme activity can be confirmed in situations where feed quantity and quality are not known, the determination of enzyme activities would enable better estimates of the trophic shift to be made thus significantly improving back-calculation of diets from stable isotope data.

Dose- and time-dependent effects of a novel (-)-hydroxycitric acid extract on body weight, hepatic and testicular lipid peroxidation, DNA fragmentation and histopathological data over a period of 90 days.

(-)-Hydroxycitric acid (HCA), a natural extract from the dried fruit rind of Garcinia cambogia (family Guttiferae), is a popular supplement for weight management. The dried fruit rind has been used for centuries as a condiment in Southeastern Asia to make food more filling and satisfying. A significant number of studies highlight the efficacy of Super CitriMax (HCA-SX, a novel 60% calcium-potassium salt of HCA derived from Garcinia cambogia) in weight management. These studies also demonstrate that HCA-SX promotes fat oxidation, inhibits ATP-citrate lyase (a building block for fat synthesis), and lowers the level of leptin in obese subjects. Acute oral, acute dermal, primary dermal irritation and primary eye irritation toxicity studies have demonstrated the safety of HCA-SX. However, no long-term safety of HCA-SX or any other (-)-hydroxycitric acid extract has been previously assessed. In this study, we have evaluated the dose- and time-dependent effects of HCA-SX in Sprague-Dawley rats on body weight, hepatic and testicular lipid peroxidation, DNA fragmentation, liver and testis weight, expressed as such and as a % of body weight and brain weight, and histopathological changes over a period of 90 days. The animals were treated with 0, 0.2, 2.0 and 5.0% HCA-SX as feed intake and the animals were sacrificed on 30, 60 or 90 days of treatment. The feed and water intake were assessed and correlated with the reduction in body weight. HCA-SX supplementation demonstrated a reduction in body weight in both male and female rats over a period of 90 days as compared to the corresponding control animals. An advancing age-induced marginal increase in hepatic lipid peroxidation was observed in both male and female rats as compared to the corresponding control animals. However, no such difference in hepatic DNA fragmentation and testicular lipid peroxidation and DNA fragmentation was observed. Furthermore, liver and testis weight, expressed as such and as a percentage of body weight and brain weight, at 30, 60 and 90 days of treatment, exhibited no significant difference between the four groups. Taken together, these results indicate that treatment of HCA-SX over a period of 90 days results in a reduction in body weight, but did not cause any changes in hepatic and testicular lipid peroxidation, DNA fragmentation, or histopathological changes.

Diets rich in polyunsaturated fatty acids: effect on hepatic metabolism in rats.

OBJECTIVE: We investigated the effect of diets rich in omega-6 and omega-3 fatty acids on hepatic metabolism. METHODS: Male Wistar rats, just weaned, were fed ad libitum for 8 wk with one of the following diets: rat chow (C), rat chow containing 15% (w/w) soybean oil (S), rat chow containing 15% (w/w) fish oil (F), and rat chow containing 15% soy bean and fish oil (SF; 5:1, w/w). Casein was added to the fatty diets to achieve the same content of protein (20%) as the control chow. The rats were killed by decapitation, and the hepatic tissue was removed and weighed. Tissue lipid, glycogen, and protein content, in vivo lipogenesis rate, and adenosine triphosphate citrate lyase and malic enzyme activities were evaluated. Plasma total lipids, triacylglycerol, and cholesterol concentrations were assessed. RESULTS: Body weight gain was higher in F and SF than in C and S rats. Liver weight, lipid content, and lipogenesis rate increased in F and SF rats, although adenosine triphosphate citrate lyase activity decreased. Glycogen concentration decreased in S, F, and SF rats compared with C rats. Plasma total lipids and triacylglycerol concentrations were lower in F and SF than in C rats. Total and high-density lipoprotein cholesterol (HDL-C) plasma levels decreased in F rats, with maintenance of the total:HDL-C ratio. In SF rats, an increase in HDL-C led to a lower total:HDL-C ratio. CONCLUSIONS: These results indicated that an enrichment of the diet with omega-3 polyunsaturated fatty acids produces hypolipidemia but may cause changes in liver metabolism that favor lipid deposition. They also suggested that the addition of a small amount of eicosapentaenoic and docosahexaenoic polyunsaturated fatty acids to an omega-6-rich diet further improve the circulating lipid profile, in comparison with an omega-3-rich diet, but it does not prevent excess liver lipid accumulation.

Correlation of ATP/citrate lyase activity with lipid accumulation in developing seeds of Brassica napus L.

The temporal distribution of ATP/citrate lyase (ACL) activity in developing seeds of Brassica napus L. closely paralleled both that of acetyl-CoA carboxylase and the overall rate of lipid biosynthesis. Maximum ACL activities (250 nmol acetyl-CoA formed min-1.g fresh seed) were recorded between 35 to 42 d after pollination and, if the in vitro data could be extrapolated to the situation in vivo, could account for half of the acetyl-CoA required for the measured rate of fatty acid biosynthesis during seed development. The enzyme appeared to be localized in a subcellular compartment, which was clearly separated from mitochondria on a sucrose gradient and by differential centrifugation, and which corresponded to the chloroplast organelle.

Polyunsaturated fatty acid-mediated suppression of insulin-dependent gene expression of lipogenic enzymes in rat liver.

The effects of dietary polyunsaturated fat on insulin-dependent gene expression of lipogenic enzymes and a possible mechanism for PUFA-mediated suppression of the gene expression have been investigated in rat livers. When diabetic rats were injected with insulin, the insulin dose-dependent induction of lipogenic enzyme mRNAs were markedly reduced with increasing dietary corn oil. On the other hand, the PUFA-mediated suppression of the mRNA concentrations was partially restored by treatment with pioglitazone, a candidate for increasing insulin receptor phosphorylation. Moreover, insulin binding to receptors of liver, receptor autophosphorylation, and kinase activity toward exogenous substrate were lower in the corn oil diet group than in the hydrogenated fat group. The PUFA-mediated suppression of insulin binding was somewhat restored by pioglitazone, and the suppression of insulin receptor phosphorylation was significantly restored. It is suggested that the PUFA-mediated suppression of insulin-dependent gene expression of lipogenic enzymes can be ascribed to a decrease in insulin receptor binding primarily and also to receptor phosphorylation. Thus, PUFA appears to suppress the lipogenic enzyme gene expression stimulated by insulin.

Influence of dietary medium- and long-chain triglycerides on fat deposition and lipogenic enzyme activities in rats.

The present study investigates fat deposition, variances of fatty acid (FA) composition, and lipogenic enzyme activities through dietary medium- and long-chain triglyceride (MCT and LCT) supplementation in growing rats. Eighteen male Wistar rats were divided into three groups and fed isocalorically for 4 weeks with control (based on AIN 76), MCT (C8:0 26%), or LCT (corn oil 25%) diets. Compared to the control group with 0.28 +/- 0.01, feed efficiency was lower in the MCT rats and greater in the LCT rats (0.24 +/- 0.01 and 0.33 +/- 0.01, respectively). Weights of perirenal and epididymal adipose tissue pads of the MCT rats were similar to those of the control group, but were significantly lower than those of the LCT group. Whole-body carcass components data of MCT rats showed the decrease in moisture and protein contents compared to those of control and LCT rats. Fat content of LCT rats was 25-30% higher than those of the MCT and control group. Glucose-6-phosphate dehydrogenase, citrate cleavage enzyme, and malic enzyme activities of liver and epididymal adipose tissue were markedly low in LCT rats. In the MCT group, however, lipogenic enzyme activities were not suppressed, and malic enzyme activity was drastically increased. FA composition of whole-body triglycerides and epididymal adipose tissue in MCT rats showed that C16:0 and C16:1 levels were higher than those of the LCT rats. In contrast, FA composition of the LCT group presented high C18:2 content.(ABSTRACT TRUNCATED AT 250 WORDS)