Regulation of acyl-CoA:cholesterol acyltransferase activity in normal and atherosclerotic rabbit aortas: role of a cholesterol substrate pool

Antimicrobial and therapeutic potentials of the blackberry extracts against Escherichia coli infection in male albino rats

BACKGROUND

Blackberries have garnered attention recently due to their high concentration of bioactive components like anthocyanin and their health advantages. Therefore, this study aims to determine the bioactive profile, antioxidant and antibacterial effects of blackberry extracts (BBEs). Then, evaluate the protective effect of BBEs (20%, 30% and 40%) in a rat model of 2 mL of 4-8 × 106 Escherichia coli ATTC 25922 strain colony-forming unit mL-1 oral infection on the seventh day of the experiment.

RESULTS

Rats were divided into six groups: G1: control (C-: normal or negative group), G2: (C+: infected or positive group), G3: infected-treated group by 20% BBE, G4: infected-treated group by 30% BBE, G5: infected-treated group by 40% of BBE and G6: infected-treated group by Gentamicin. The results showed that BBE had a high content of total phenolic compounds, flavonoid, anthocyanin contents, and different vitamins (vitamins A, E and C), reaching 450, 186, 58.83 mg 100 g-1, 2.68, 2.14 and 107.46 mg 100g-1 fresh weight, respectively, which showed great antioxidant and antibacterial effects. Therefore, liver enzymes, kidney function and lipid profiles were significantly higher in the infected group than in the control or infected-treated groups. Furthermore, BBE ameliorated inflammation of the intestine and hepatocyte damage compared to the infected control group.

CONCLUSION

These results suggest that consistent intake of BBE might alleviate hepatic inflammation and the gut microbiota in ways that could significantly impact human health. © 2024 Society of Chemical Industry.

Kaempferol ameliorates metabolic syndrome by inhibiting inflammation and oxidative stress in high-fat diet-induced obese mice

BACKGROUND/OBJECTIVES

Kaempferol (Ka) is one of the most widely occurring flavonoids found in large amounts in various plants. Ka has anti-obesity, antioxidant, and anti-inflammatory effects. Despite the numerous papers documenting the efficacy of Ka, some controversy remains. Therefore, this study examined the impact of Ka using 3T3-L1 and high-fat diet-induced obese mice.

MATERIALS/METHODS

3T3-L1 cells were treated with 50 μM Ka from the initiation of 3T3-L1 differentiation at D0 until the completion of differentiation on D8. Thirty male mice (C57BL/6J, 4 weeks old) were divided into 3 groups: normal diet (ND), high-fat diet (HFD), and HFD + 0.02% (w/w) Ka (Ka) group. All mice were fed their respective diets ad libitum for 16 weeks. The mice were sacriced, and the plasma and hepatic lipid levels, white adipose tissue weight, hepatic glucose level, lipid level, and antioxidant enzyme activities were analyzed, and immunohistochemistry staining was performed.

RESULTS

Ka suppressed the hypertrophy of 3T3-L1 cells, and the Ka-supplemented mice showed a significant decrease in perirenal, retroperitoneal, mesenteric, and subcutaneous fat compared to the HFD group. Ka supplementation in high-fat diet-induced obese mice also improved the overall blood lipid concentration (total cholesterol, non-high-density lipoprotein-cholesterol, phospholipids, and apolipoprotein B). Ka supplementation in high-fat-induced obesity mice reduced hepatic steatosis and insulin resistance by modulating the hepatic lipid (glucose-6-phosphate dehydrogenase, fatty acid synthase, malic enzyme, phosphatidate phosphohydrolase, and β-oxidation) activities and glucose (glucokinase, phosphoenolpyruvate carboxykinase, and G6pase)-regulating enzymes. Ka supplementation ameliorated the erythrocyte and hepatic mitochondrial H2O2 and inflammation levels (plasma tumor necrosis factor-alpha, monocyte chemoattractant protein-1, interleukin-6, and interferon-gamma and fibrosis of liver and epididymal fat).

CONCLUSION

Ka may be beneficial for preventing diet-induced obesity, inflammation, oxidative stress, and diabetes.

The effects of melatonin against atherosclerosis-induced endothelial dysfunction and inflammation in hypercholesterolemic rats

The aim of this study was to investigate the effects of melatonin on the serum asymmetric dimethylarginine (ADMA) levels and the expressions of vaspin, visfatin, dimethylarginine dimethylaminohydrolase (DDAH), and signal transducer and activator of transcription-3 (STAT-3) for evaluation of endothelial function and inflammation in the hypercholesterolemic rats. Rats were divided into 5 groups: (1) control, (2) hypercholesterolaemia, (3) melatonin administrated concurrently with cholesterol diet, (4) melatonin administrated only last 2 weeks and fed with cholesterol diet, (5) atorvastatin administered only last 2 weeks fed with cholesterol diet. Although an increase was observed in the expressions of visfatin and STAT-3 and the serum ADMA levels, the vaspin and DDAH protein expressions were found to decrease with hypercholesterolemic diets. Melatonin was determined to restore all the parameters to the normal levels. In conclusion, melatonin may have protective and therapeutic effects on hypercholesterolaemia by regulating vaspin, STAT-3, DDAH, and ADMA signalling pathways and create similar effects with atorvastatin.

Nifuroxazide modulates hepatic expression of LXRs/SR-BI/CES1/CYP7A1 and LDL-R and attenuates experimentally-induced hypercholesterolemia and the associated cardiovascular complications

Hyperlipidemia is a serious disorders affecting the metabolism of fats in the human body, and it is usually associated with some serious cardiovascular complications increasing the risk for sudden death. Nifuroxazide (NFR) is an oral nitrofuran antibiotic that has long been used for management of diarrhea and recently various recent out merging valuable therapeutic impacts were reported. The current study sought the concept of repositioning nifuroxazide in management of hyperlipidemia. Hyperlipidemia was induced in male rabbits using cholesterol enriched diet for 9 weeks and starting from the beginning of 5th week; NFR (100 and 300 mg/kg) were administered once daily for the further 5 weeks; till the end of the 9th week of the experiment. NFR significantly recovered balanced lipid profile as serum cholesterol, total glycerides, LDL significantly declined with significant elevation in serum HDL. Meanwhile, serum LDH, CK, ALT and AST activities were significantly corrected. These biochemical changes were correlated with significant improvement in the histopathological examination of hepatic, cardiac and aortic specimen with decreased expression of CD68 and Ki67 in the myocardium and the aorta implying retraction in macrophages' infiltration and tissue regeneration. Myocardial specimen confirmed significant recovery with preservation of cardiac muscle fibers. Aortic specimen confirmed retraction in the aortic thickness and fewer deposition of fat globules. In conclusion, NFR attenuated experimentally-induced hyperlipidemia with significant recovery of serum profile and tissue necrotic changes. The histopathological examination of hepatic, myocardial and aortic specimen confirmed the onset of tissues' recovery alongside biochemical improvement.

Fisetin Alleviates Hepatic and Adipocyte Fibrosis and Insulin Resistance in Diet-Induced Obese Mice

The present study aimed to investigate the protective role of the flavonoid fisetin (FI) on inflammation-mediated metabolic diseases, especially tissue fibrosis and insulin resistance (IR) in high-fat diet (HFD)-induced obese mice. C57BL/6J mice were fed with normal-fat diet, HFD (40 kcal% fat), or HFD +0.02% (w/w) FI for 16 weeks. Dietary FI supplementation improved hepatic steatosis by restricting lipogenesis, while promoting lipolysis in the liver. FI also prevented adiposity via an increase in the expression of genes involved in FA oxidation and a decrease in the expression of genes involved in lipogenesis in white adipose tissue. In addition, FI increased brown adipose tissue (BAT) and skeletal muscle weights, thermogenic gene mRNA expression in BAT, and tricarboxylic acid cycle-related gene expression in skeletal muscle, which may be linked to the prevention of nonalcoholic fatty liver disease as well as adiposity. Moreover, FI supplementation decreased excessive reactive oxygen species production by increasing paraoxonase activity, adipokine dysregulation, proinflammatory cytokine production, and extracellular matrix amassment in the liver. FI supplementation ameliorated IR, in part, by normalizing pancreatic islet dysfunction, and it declined hepatic gluconeogenesis and proinflammatory responses. Taken together, the present findings indicate that FI can protect against HFD-induced inflammation-mediated disorders, including fibrosis and IR.

Supplementation of Non-Dairy Creamer-Enriched High-Fat Diet with D-Allulose Ameliorated Blood Glucose and Body Fat Accumulation in C57BL/6J Mice

D-allulose, which has 70% of the sweet taste of sucrose but nearly no calories, has been reported to inhibit the absorption of lipids and suppress body weight gain in obese mice. Fats in non-dairy creamer consist of highly saturated fatty acids, which can cause various lipid disorders when consumed over a long period. We investigated whether D-allulose supplementation alleviates the effects of a non-dairy creamer-enriched high-fat diet on lipid metabolism. High-fat diets enriched with non-dairy creamer were administered to C57BL/6J mice with or without D-allulose supplementation for eight weeks by the pair-feeding design. Lipid metabolic markers were compared between the non-dairy creamer control group (NDC) and non-dairy creamer allulose group (NDCA). Body, adipose tissue, and liver weights, and fasting blood glucose levels, were significantly lower in the NDCA group than in the NDC group. Fecal fatty acid and triglyceride levels were significantly higher in the NDCA group than in the NDC group. Supplementing a non-dairy creamer-enriched high-fat diet with D-allulose improved overall lipid metabolism, including the plasma and hepatic lipid profiles, hepatic and adipose tissue morphology, and plasma inflammatory adipokine levels in mice. These results suggest that D-allulose can be used as a functional food component for preventing body fat accumulation from a high-fat diet that includes hydrogenated plant fats.

Ursolic Acid Attenuates Hepatic Steatosis, Fibrosis, and Insulin Resistance by Modulating the Circadian Rhythm Pathway in Diet-Induced Obese Mice

The aim of the current study was to elucidate the effects of long-term supplementation with dietary ursolic acid (UR) on obesity and associated comorbidities by analyzing transcriptional and metabolic responses, focusing on the role of UR in the modulation of the circadian rhythm pathway in particular. C57BL/6J mice were divided into three groups and fed a normal diet, high-fat diet, or high-fat + 0.05% (w/w) UR diet for 16 weeks. Oligonucleotide microarray profiling revealed that UR is an effective regulator of the liver transcriptome, and canonical pathways associated with the "circadian rhythm" and "extracellular matrix (ECM)⁻receptor interactions" were effectively regulated by UR in the liver. UR altered the expression of various clock and clock-controlled genes (CCGs), which may be linked to the improvement of hepatic steatosis and fibrosis via lipid metabolism control and detoxification enhancement. UR reduced excessive reactive oxygen species production, adipokine/cytokine dysregulation, and ECM accumulation in the liver, which also contributed to improve hepatic lipotoxicity and fibrosis. Moreover, UR improved pancreatic islet dysfunction, and suppressed hepatic gluconeogenesis, thereby reducing obesity-associated insulin resistance. Therapeutic approaches targeting hepatic circadian clock and CCGs using UR may ameliorate the deleterious effects of diet-induced obesity and associated complications such as hepatic fibrosis.

Dietary Isoliquiritigenin at a Low Dose Ameliorates Insulin Resistance and NAFLD in Diet-Induced Obesity in C57BL/6J Mice

Isoliquiritigenin (ILG) is a flavonoid constituent of Glycyrrhizae plants. The current study investigated the effects of ILG on diet-induced obesity and metabolic diseases. C57BL/6J mice were fed a normal diet (AIN-76 purified diet), high-fat diet (40 kcal% fat), and high-fat diet +0.02% (w/w) ILG for 16 weeks. Supplementation of ILG resulted in decreased body fat mass and plasma cholesterol level. ILG ameliorated hepatic steatosis by suppressing the expression of hepatic lipogenesis genes and hepatic triglyceride and fatty acid contents, while enhancing β-oxidation in the liver. ILG improved insulin resistance by lowering plasma glucose and insulin levels. This was also demonstrated by the intraperitoneal glucose tolerance test (IPGTT). Additionally, ILG upregulated the expression of insulin signaling-related genes in the liver and muscle. Interestingly, ILG elevated energy expenditure by increasing the expression of thermogenesis genes, which is linked to stimulated mitochondrial biogenesis and uncoupled cellular respiration in brown adipose tissue. ILG also suppressed proinflammatory cytokine levels in the plasma. These results suggest that ILG supplemented at 0.02% in the diet can ameliorate body fat mass, plasma cholesterol, non-alcoholic fatty liver disease, and insulin resistance; these effects were partly mediated by increasing energy expenditure in high-fat fed mice.

Phlorizin Supplementation Attenuates Obesity, Inflammation, and Hyperglycemia in Diet-Induced Obese Mice Fed a High-Fat Diet

Obesity, along with its related complications, is a serious health problem worldwide. Many studies reported the anti-diabetic effect of phlorizin, while little is known about its anti-obesity effect. We investigated the beneficial effects of phlorizin on obesity and its complications, including diabetes and inflammation in obese animal. Male C57BL/6J mice were divided into three groups and fed their respective experimental diets for 16 weeks: a normal diet (ND, 5% fat, w/w), high-fat diet (HFD, 20% fat, w/w), or HFD supplemented with phlorizin (PH, 0.02%, w/w). The findings revealed that the PH group had significantly decreased visceral and total white adipose tissue (WAT) weights, and adipocyte size compared to the HFD. Plasma and hepatic lipids profiles also improved in the PH group. The decreased levels of hepatic lipids in PH were associated with decreased activities of enzymes involved in hepatic lipogenesis, cholesterol synthesis and esterification. The PH also suppressed plasma pro-inflammatory adipokines levels such as leptin, adipsin, tumor necrosis factor-α, monocyte chemoattractant protein-1, interferon-γ, and interleukin-6, and prevented HFD-induced collagen accumulation in the liver and WAT. Furthermore, the PH supplementation also decreased plasma glucose, insulin, glucagon, and homeostasis model assessment of insulin resistance levels. In conclusion, phlorizin is beneficial for preventing diet-induced obesity, hepatic steatosis, inflammation, and fibrosis, as well as insulin resistance.

Luteolin attenuates hepatic steatosis and insulin resistance through the interplay between the liver and adipose tissue in mice with diet-induced obesity

The flavonoid luteolin has various pharmacological activities. However, few studies exist on the in vivo mechanism underlying the actions of luteolin in hepatic steatosis and obesity. The aim of the current study was to elucidate the action of luteolin on obesity and its comorbidity by analyzing its transcriptional and metabolic responses, in particular the luteolin-mediated cross-talk between liver and adipose tissue in diet-induced obese mice. C57BL/6J mice were fed a normal, high-fat, and high-fat + 0.005% (weight for weight) luteolin diet for 16 weeks. In high fat-fed mice, luteolin improved hepatic steatosis by suppressing hepatic lipogenesis and lipid absorption. In adipose tissue, luteolin increased PPARγ protein expression to attenuate hepatic lipotoxicity, which may be linked to the improvement in circulating fatty acid (FA) levels by enhancing FA uptake genes and lipogenic genes and proteins in adipose tissue. Interestingly, luteolin also upregulated the expression of genes controlling lipolysis and the tricarboxylic acid (TCA) cycle prior to lipid droplet formation, thereby reducing adiposity. Moreover, luteolin improved hepatic insulin sensitivity by suppressing SREBP1 expression that modulates Irs2 expression through its negative feedback and gluconeogenesis. Luteolin ameliorates the deleterious effects of diet-induced obesity and its comorbidity via the interplay between liver and adipose tissue.

Antiobesity and vasoprotective effects of resveratrol in apoE-deficient mice

This study was performed to investigate the hypolipidemic, antiobese, and antiatherogenic effects of resveratrol in apoE-deficient mice fed an atherogenic diet (20% fat and 1% cholesterol). These animals were fed an atherogenic diet containing 0.02% lovastatin (w/w) or 0.02% resveratrol (w/w) for 12 weeks. Resveratrol and lovastatin supplementation significantly reduced either the body weight or epididymal fat weight without altering the food intake and food efficiency ratio. Resveratrol significantly decreased the plasma total cholesterol (total-C), low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C) concentrations, apoB/apoA-I ratio, hepatic cholesterol, and triglyceride (TG) contents, whereas significantly it increased the plasma HDL-C concentration compared with the control and lovastatin groups. Plasma and hepatic TG and plasma apoB levels were significantly lower in both the lovastatin and resveratrol groups than in the control group without altering the plasma apoA-I concentration. Both resveratrol and lovastatin significantly decreased hepatic fatty acid and TG synthesis, whereas they increased fatty acid oxidation (β-oxidation) except for the carnitine palmitoyltransferase activity compared with the control group. However, there was no difference in hepatic 3-hydroxyl-3-methylglutaryl-CoA reductase activity among the groups, although hepatic acyl-CoA: cholesterol acyltransferase activity was significantly lower in the lovastatin groups than in the control group. In epididymal adipose tissue, resveratrol supplementation led to an increase in β-oxidation and decrease in TG synthesis, compared with the control group. Tissue morphology revealed that there were dramatic decreases in hepatic lipid droplets and aortic fatty streaks by resveratrol and lovastatin supplementation. This study demonstrates that resveratrol exerts not only antiobesity and hypolipidemic effects, but also protective effects for the liver and aorta through the modulation of lipid metabolism in both the liver and white adipose tissues.

Kalpaamruthaa modulates oxidative stress in cardiovascular complication associated with type 2 diabetes mellitus through PKC-β/Akt signaling

This study aimed at investigating the efficacy of Kalpaamruthaa (KA) on cardiovascular damage (CVD) associated with type 2 diabetes mellitus in experimental rats by reducing oxidative stress and the modulation of the protein kinase C-β (PKC-β)/Akt signaling pathway. CVD-induced rats were treated with KA (200 mg·(kg body mass)(-1)·(day)(-1)) orally for 4 weeks. KA effectively reduced insulin resistance with alterations in blood glucose, hemoglobin, and glycosylated hemoglobin in CVD-induced rats. Elevated levels of lipids in CVD-induced rats were decreased upon KA administration. In CVD-induced rats the levels of lipoproteins were returned to normal by KA treatment. KA effectively reduced the lipid peroxidative product and protein carbonyl content in liver of CVD-induced rats. KA increased the activities and (or) levels of enzymatic and nonenzymatic antioxidants in liver of CVD-induced rats. KA treatment reduced the fatty inclusion and mast cell infiltration in liver of CVD-induced rats. Further, treatment with KA reduced the chromatin condensation and marginization in myocardium of CVD-induced rats. KA alters insulin signaling by decreasing PKC-β and increasing p-Akt and GLUT4 expressions in heart of CVD-induced rats. The above findings suggest that KA renders protection against CVD induced by type 2 diabetes mellitus by augmenting the cellular antioxidant defense capacity and modulating PKC-β and the p-Akt signaling pathway.

Long-term curcumin administration protects against atherosclerosis via hepatic regulation of lipoprotein cholesterol metabolism

SCOPE

Atherosclerosis is a major cause of cardiovascular disease caused by high cholesterol. Stains are widely prescribed to lower cholesterol levels, but natural dietary compounds may also be effective. Therefore, we studied the effect of the natural dietary compound curcumin on atherosclerosis and its underlying mechanisms based on plasma and hepatic lipid metabolism.

METHODS AND RESULTS

LDLR(-/-) mice were fed a high-cholesterol diet and treated with curcumin, lovastatin or control (n=10 per group) for 18 wk. Aortic arch sections revealed curcumin ameliorated early atherosclerotic lesions, lipid infiltration, ICAM-1 and VCAM-1 localization, similar to lovastatin treatment. Furthermore, curcumin lowered plasma cholesterol, triglycerides, LDL cholesterol and Apo B levels as well as CETP activity, while curcumin increased plasma HDL cholesterol and liver Apo A-I expression, similar to lovastatin treatment. Curcumin caused transcriptional inhibition of HMG-CoA reductase, independent of ACAT1 and ACAT2 expression. Hepatic PPARα and LXRα expression was upregulated by curcumin treatment. Hepatic complement factor D (Cfd) and systemic CRP levels, markers of immune complement pathway activation, were significantly reduced by curcumin treatment.

CONCLUSION

Long-term curcumin treatment lowers plasma and hepatic cholesterol and suppresses early atherosclerotic lesions comparable to the protective effects of lovastatin. The anti-atherogenic effect of curcumin is mediated via multiple mechanisms including altered lipid, cholesterol and immune gene expression.

Tannic acid is more effective than clofibrate for the elevation of hepatic β-oxidation and the inhibition of 3-hydroxy-3-methyl-glutaryl-CoA reductase and aortic lesion formation in apo E-deficient mice

The effects of tannic acid (TA) supplementation (0·02 %, wt/wt) were compared with the effects of clofibrate (CF) supplementation (0·02 %, wt/wt) in apo E-deficient (apo E(- / -)) mice fed a AIN-76 semi-synthetic diet (normal diet) over 20 weeks. The mice were monitored for the modulation of hepatic mRNA expression and the activities of lipid-regulating enzymes. Both TA and CF supplementation lowered hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) activity and prevented atherosclerotic lesion formation in comparison with the control group. Hepatic carnitine palmitoyl transferase and β-oxidation activities were significantly higher in the TA and CF groups than in the control group. Both CF and TA supplementation resulted in significant decreases in hepatic HMGR mRNA levels in association with its enzyme activity. However, in contrast to CF supplementation, TA supplementation seemed to decrease the accumulation of hepatic lipids in the apo E(- / -) mice without increasing liver weight. These results suggest that the overall effect of TA is more desirable than CF for the alleviation of hepatic lipogenesis and atherogenesis in apo E(- / -) mice.

Long-term adaptation of global transcription and metabolism in the liver of high-fat diet-fed C57BL/6J mice

SCOPE

This study investigated the global transcriptional and metabolic changes occurring at multiple time points over 24 wk in response to a high-fat diet (HFD).

METHODS AND RESULTS

C57BL/6J mice were fed a HFD or normal diet (ND) over 24 wk. HFD-fed mice developed early clinical indicators of obesity-related co-morbidities including fatty liver, insulin resistance, hyperglycemia and hypercholesterolemia. Time-course microarray analysis at eight time points over 24 wk identified 332 HFD responsive genes as potential targets to counteract diet-induced obesity (DIO) and related co-morbidities. Glucose regulating enzyme activity and gene expression were altered early in the HFD-fed mice. Fatty acid (FA) and triglyceride (TG) accumulation in combination with inflammatory changes appear to be likely candidates contributing to hepatic insulin resistance. Cidea seemed to be one of representative genes related to these changes.

CONCLUSION

Global transcriptional and metabolic profiling across multiple time points in liver revealed potential targets for nutritional interventions to reverse DIO. In future, new approaches targeting HFD responsive genes and hepatic metabolism could help ameliorate the deleterious effects of an HFD and DIO-related complication.

Actions of ferulic acid and vitamin E on prevention of hypercholesterolemia and atherogenic lesion formation in apolipoprotein E-deficient mice

This study was carried out to investigate whether dietary vitamin E and ferulic acid (FA) can exert possible interactions on preventions of hypercholesterolemia and atherogenic lesion formation in C57BL/65 apolipoprotein E-deficient (apo E(-/-)) mice. Four-week-old male apo E(-/-) mice were randomly divided into three groups and given one of three types of Western diets with various amounts of vitamin E (0.02%, 0%, or 0.2%) for 15 weeks. FA was added to vitamin E-free Western diet and vitamin E-rich Western diet at the 0.02% level. The plasma total cholesterol concentration was significantly lowered when FA was added to the vitamin E-free and vitamin E-rich Western diet as compared to the normal vitamin E Western diet (0.02% vitamin E), and this was accompanied with a decreased hepatic acyl-coenzyme A:cholesterol acyltransferase activity. The hepatic and erythrocyte thiobarbituric acid-reactive substances levels were significantly lowered when FA was added to the vitamin E-rich Western diet, which was attributable to increased activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and paraoxonase. Accordingly, vitamin E and/or FA are beneficial for prevention of hypercholesterolemia and atherogenesis in apo E(-/-) mice. In particular, dietary FA exhibited an anti-atherosclerotic property, and this effect was synergistically enhanced with the vitamin E supplement.

Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice

This study investigated the efficacy of chlorogenic acid on altering body fat in high-fat diet (37% calories from fat) induced-obese mice compared to caffeic acid. Caffeic acid or chlorogenic acid was supplemented with high-fat diet at 0.02% (wt/wt) dose. Both caffeic acid and chlorogenic acid significantly lowered body weight, visceral fat mass and plasma leptin and insulin levels compared to the high-fat control group. They also lowered triglyceride (in plasma, liver and heart) and cholesterol (in plasma, adipose tissue and heart) concentrations. Triglyceride content in adipose tissue was significantly lowered, whereas the plasma adiponectin level was elevated by chlorogenic acid supplementation compared to the high-fat control group. Body weight was significantly correlated with plasma leptin (r=0.894, p<0.01) and insulin (r=0.496, p<0.01) levels, respectively. Caffeic acid and chlorogenic acid significantly inhibited fatty acid synthase, 3-hydroxy-3-methylglutaryl CoA reductase and acyl-CoA:cholesterol acyltransferase activities, while they increased fatty acid beta-oxidation activity and peroxisome proliferator-activated receptors alpha expression in the liver compared to the high-fat group. These results suggest that caffeic acid and chlorogenic acid improve body weight, lipid metabolism and obesity-related hormones levels in high-fat fed mice. Chlorogenic acid seemed to be more potent for body weight reduction and regulation of lipid metabolism than caffeic acid.

Metabolic response of soy pinitol on lipid-lowering, antioxidant and hepatoprotective action in hamsters fed-high fat and high cholesterol diet

This study was performed to investigate the lipid-lowering, antioxidant, and hepato-protective effects of pinitol in dose-dependent manners in hamsters fed-high fat and high cholesterol (HFHC) diet. Pinitol supplementation (0.05%, P-I and 0.1% pinitol, P-II) with an HFHC diet (10% coconut oil plus 0.2% cholesterol) for 10 wks significantly lowered the white adipose tissue weights, hepatic lipid droplets, plasma glucose, total-cholesterol, nonHDL-cholesterol, total-cholesterol/HDL-cholesterol ratio, and hepatic lipid levels. Whereas it significantly increased the brown adipose tissue weight, plasma HDL-cholesterol, apolipoprotein A-I (apo A-I) concentrations, paraoxonase (PON) activity, and/or mRNA expression, compared to the HFHC control group. Plasma insulin and adiponectin levels were significantly lower and higher, respectively, in both P-I and P-II groups than the HFHC control group. Dietary pinitol significantly inhibited hepatic HMG-CoA reductase, acyl-CoA:cholesterol acyltransferase (ACAT), and cytochrome P4502E1 (CYP2E1) activities without altering their mRNA expressions compared to the control group. Pinitol significantly elevated the hepatic antioxidant enzyme activities, whereas it also significantly reduced the hepatic lipid peroxide and H2O2 production. Accordingly, these results indicate that both 0.05 and 0.1% pinitol supplementation may improve the lipid and antioxidant metabolism in HFHC diet-fed hamsters. In particular, pinitol supplementation was very effective on the elevation of antiatherogenic factors, including plasma HDL-cholesterol, apo A-I, adiponectin, and PON.

Effect of curcumin supplementation on blood glucose, plasma insulin, and glucose homeostasis related enzyme activities in diabetic db/db mice

We investigated the effect of curcumin on insulin resistance and glucose homeostasis in male C57BL/KsJ-db/db mice and their age-matched lean non-diabetic db/+ mice. Both db/+ and db/db mice were fed with or without curcumin (0.02%, wt/wt) for 6 wks. Curcumin significantly lowered blood glucose and HbA 1c levels, and it suppressed body weight loss in db/db mice. Curcumin improved homeostasis model assessment of insulin resistance and glucose tolerance, and elevated the plasma insulin level in db/db mice. Hepatic glucokinase activity was significantly higher in the curcumin-supplemented db/db group than in the db/db group, whereas glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities were significantly lower. In db/db mice, curcumin significantly lowered the hepatic activities of fatty acid synthase, beta-oxidation, 3-hydroxy-3-methylglutaryl coenzyme reductase, and acyl-CoA: cholesterol acyltransferase. Curcumin significantly lowered plasma free fatty acid, cholesterol, and triglyceride concentrations and increased the hepatic glycogen and skeletal muscle lipoprotein lipase in db/db mice. Curcumin normalized erythrocyte and hepatic antioxidant enzyme activities (superoxide dismutase, catalase, gluthathione peroxidase) in db/db mice that resulted in a significant reduction in lipid peroxidation. However, curcumin showed no effect on the blood glucose, plasma insulin, and glucose regulating enzyme activities in db/+ mice. These results suggest that curcumin seemed to be a potential glucose-lowering agent and antioxidant in type 2 diabetic db/db mice, but had no affect in non-diabetic db/+ mice.

Small Dense Low-Density Lipoprotein Concentration and Oxidative Susceptibility Changes after Consumption of Soybean Oil, Rice Bran Oil, Palm Oil and Mixed Rice Bran/Palm Oil in Hypercholesterolaemic Women

The effects of a diet containing soybean oil (SBO), rice bran oil (RBO), palm oil (PO) or a RBO/PO (3:1) mixture on the composition and oxidation of small dense low-density lipoproteins (sdLDL) in 16 hypercholesterolaemic women were investigated. During the 8-week control period, participants consumed a free-choice weight-maintaining diet comprising carbohydrate (55% energy), protein (15% energy) and fat (30% energy) with < 300 mg/day of cholesterol. During each 10-week study period, participants consumed this same diet but with the addition of one of the three test oils or the RBO/PO mixture. Total cholesterol and low-density lipoprotein (LDL)-cholesterol levels were significantly reduced during SBO, RBO and RBO/PO consumption, while high-density lipoprotein cholesterol was significantly decreased by SBO consumption. There was a significant reduction in sdLDL-cholesterol levels only after using SBO and it tended to be reduced during RBO/PO consumption, whereas it was significantly increased following PO consumption. The sdLDL oxidation lag time was significantly increased during PO, RBO/PO and RBO consumption, but significantly reduced following SBO. The results for the RBO/PO mixture suggest that this oil mixture might further reduce the risk of atherosclerosis.

Beneficial effects of curcumin on hyperlipidemia and insulin resistance in high-fat-fed hamsters

This study investigated the effect of curcumin (0.05-g/100-g diet) supplementation on a high-fat diet (10% coconut oil, 0.2% cholesterol, wt/wt) fed to hamsters, one of the rodent species that are most closely related to humans in lipid metabolism. Curcumin significantly lowered the levels of free fatty acid, total cholesterol, triglyceride, and leptin and the homeostasis model assessment of insulin resistance index, whereas it elevated the levels of high-density lipoprotein cholesterol and apolipoprotein (apo) A-I and paraoxonase activity in plasma, compared with the control group. The levels of hepatic cholesterol and triglyceride were also lower in the curcumin group than in the control group. In the liver, fatty acid beta-oxidation activity was significantly higher in the curcumin group than in the control group, whereas fatty acid synthase, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and acyl coenzyme A:cholesterol acyltransferase activities were significantly lower. Curcumin significantly lowered the lipid peroxide levels in the erythrocyte and liver compared with the control group. These results indicate that curcumin exhibits an obvious hypolipidemic effect by increasing plasma paraoxonase activity, ratios of high-density lipoprotein cholesterol to total cholesterol and of apo A-I to apo B, and hepatic fatty acid oxidation activity with simultaneous inhibition of hepatic fatty acid and cholesterol biosynthesis in high-fat-fed hamsters.

Hypolipidemic effect of dietary diacylglycerol oil in Sprague-Dawley rats fed a normal diet

The present study compared the effects of dietary diacylglycerol (DG) and triacylglycerol (TG) oil on lipid metabolism in rats fed a 5% fat (AIN-76) diet for 6 weeks. The plasma and hepatic lipids, hepatic cholesterol-regulating enzyme activity, and hepatic and adipose tissue fatty acid metabolism enzyme activities were determined. Among plasma lipids, triglyceride, free fatty acid, and phospholipid concentrations were significantly lower in the DG group than in the TG group. A lower plasma TG level was accompanied by an increase in adipocyte lipoprotein lipase activity. The hepatic triglyceride level was significantly (P < .001) lowered in the DG group, which was attributable to an increased fatty acid oxidation enzyme (beta-oxidation) activity and a reduced fatty acid synthesis enzyme (glucose-6-phosphate dehydrogenase) activity. The plasma cholesterol concentration was significantly lower in the DG group and was accompanied by a lower hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity. The DG oil used in this study was beneficial for enhancing lipid metabolism with apparent hypolipidemic effects.

Hypocholesterolemic and antioxidant properties of 3-(4-hydroxyl)propanoic acid derivatives in high-cholesterol fed rats

The purpose of the present study was to evaluate the in vivo efficacy of two cinnamic acid synthetic derivatives (allyl 3-[4-hydroxyphenyl]propanoate; HPP304, 1-naphthyl-methyl 3-[4-hydroxyphenyl]propanoate; HPP305) in high-cholesterol fed rats and compare their actions to that of cinnamic acid. Cinnamic acid and its synthetic derivatives were supplemented with a high-cholesterol diet for 42 days at a dose of 0.135 mmol/100g of diet. The supplementation of HPP304 and HPP305 significantly lowered cholesterol and triglyceride levels in the plasma and liver with a simultaneous increase in the HDL-cholesterol concentration, whereas cinnamic acid only lowered the plasma cholesterol concentration. Cinnamic acid lowered hepatic HMG-CoA reductase activity in high-cholesterol fed rats, however, its synthetic derivatives (HPP304 and HPP305) did not affect HMG-CoA reductase activity compared to the control group. Instead, the HPP304 and HPP305 supplements significantly lowered hepatic acyl coenzyme A:cholesterol acyltransferase activity and increased the fecal bile acid. The SOD activity of the erythrocytes and liver was not different between the groups, however, the activities of CAT and GSH-Px, and the level of GSH in the erythrocytes were significantly higher in the HPP304 and HPP305 groups than in the control group. On the other hand, the activities of CAT and GSH-Px, and the level of malondialdehyde in the liver were significantly lower in the HPP304 and HPP305 groups. The antioxidant activities of these cinnamic acid synthetic derivatives were similar to the cinnamic acid in the high-cholesterol fed rats. In addition, HPP304 and HPP305 lowered amniotransferase activity in the plasma. These results suggest that two cinnamic acid synthetic derivatives (HPP304 and HPP305) exert lipid-lowering action and antioxidant properties without hepatotoxicity in high-cholesterol fed rats.

Naringin time-dependently lowers hepatic cholesterol biosynthesis and plasma cholesterol in rats fed high-fat and high-cholesterol diet

The flavonoid naringin was investigated for its differential effects on hepatic cholesterol regulation when supplemented for 3 weeks and 6 weeks. Sprague-Dawley rats were fed a high-fat and high-cholesterol diet with or without 0.02% naringin supplement for 3 or 6 weeks. Supplementation with naringin resulted in a significant decrease in the plasma cholesterol and triglyceride concentrations in the 6-week trial. Although high-density lipoprotein (HDL)-cholesterol was not altered in either trial, the HDL-cholesterol/total cholesterol ratio (in percent) was significantly higher, and the atherogenic index was significantly lower in the naringin-supplemented groups in the 6-week trial. The hepatic cholesterol content was also lowered by naringin supplementation only in the 6-week trial. The hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity was lower in the rats supplemented with naringin for 6 weeks, while the hepatic acyl-coenzyme A:cholesterol acyltransferase activity was lower in both the 3-week and 6-week trials. Results indicate that supplementation with naringin for 3 weeks did not exhibit a hypolipidemic effect when given with a HFHC diet. Naringin can, however, be beneficial for lowering hepatic cholesterol biosynthesis and levels of plasma lipids when supplemented for 6 weeks in this animal model.

Effects of dietary oxysterols on coronary arteries in hyperlipidaemic hamsters

The aim of this study was to evaluate the effect of dietary oxysterols on coronary atherosclerosis and vasospasm. Golden Syrian hamsters were fed three diets with different lipid contents for 3 months: (1) a normolipidaemic diet containing 25 g corn oil–fish oil (4:1, w/w)/kg (group Low L); (2) a hyperlipidaemic diet composed of the normolipidaemic diet supplemented with 150 g lard+30 g cholesterol/kg (group High L); (3) a third diet, similar to the hyperlipidaemic diet, in which 4 g cholesterol/kg was replaced by a mixture of oxysterols (group High L+OS). The oxysterol mixture contained (g/kg): 5,6α-epoxycholesterol 211, 5,6β-epoxycholesterol 179, 7α-hydroxycholesterol 67, 7β-hydroxycholesterol (7βOH) 185, 7-ketocholesterol (7 K) 235; and trace amounts of 7-hydroperoxycholesterols (approximately 30 g/kg). Atherosclerosis was evaluated by measuring myocardial Ca, oxysterols and acyl-CoA cholesterol acyl transferase (ACAT) activity; furthermore, coronary reactivity to sodium nitroprusside (5×10-6 m) was measured and the morphology of coronary arteries was visualized by transmission electron microscopy. Coronary spasm was determined by evaluating reactivity to serotonin (5×10-6 m). Feeding the high-lipid diet (group High L) increased the plasma level of 7βOH, 7 K and cholestanetriol. The presence of oxysterols in the diet (group High L+OS) further increased the concentrations of 7βOH and 7 K in the plasma. However, as evidenced by myocardial Ca, ACAT activity and coronary reactivity to sodium nitroprusside, severe atherosclerosis did not develop during the 3-month diet. 7 K was increased in myocardial lipids of groups High L and High L+OS. Electron microscopy did not show the development of atherosclerosis in group High L, whereas vascular wall thickening, endothelial damage and smooth muscle cell proliferation and migration occurred when oxysterols were present in the food. Serotonin (5×10-6 m) induced exacerbated coronary vasoconstriction in group High L that was completely reversed by dietary oxysterols. In conclusion, dietary oxysterols exhibit anti-spasmodic properties, but they cannot be used as agents against excess dietary lipid-induced coronary spasm because of their atherogenic properties.

Hypocholesterolemic and antioxidative effects of naringenin and its two metabolites in high-cholesterol fed rats

This study was conducted to compare the hypocholesterolemic and antioxidant effects of naringenin (0.02%), and its metabolites, rho-hyproxyphenylpropionic acid (PHPP, 0.012%) and rho-hydroxybenzoic acid (PHB, 0.012%), in 1% cholesterol diet-fed rats. All supplements significantly lowered the plasma total-cholesterol (total-C), triglyceride (TG) and atherogenic index, and hepatic cholesterol levels compared with the control group. The plasma high-density lipoprotein-cholesterol (HDL-C) concentration was significantly higher in these supplemented groups. However, PHB group only affected the reduction of hepatic TG content. The hydroxyl-3-methylglutaryl-coenzyme A reductase (HMGR) activity was significantly lower in all supplemented groups, whereas only the naringenin group reduced the acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity compared with the control group. The fecal acidic sterol excretion and hepatic superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were significantly higher in all supplemented groups. All supplements also significantly decreased the contents of plasma and hepatic thiobarbituric acid reactive substances (TBARS). Accordingly, it was considered that naringenin and its metabolites were effective on improving the cholesterol and antioxidant metabolism.

Supplementation of whole persimmon leaf improves lipid profiles and suppresses body weight gain in rats fed high-fat diet

The objective of this study was to investigate the hypolipidemic effects of powdered whole persimmon leaf supplement in rats fed high-fat diet. Three groups of male Sprague-Dawley rats during 6 weeks were fed different diet: normal control (NC), high-fat (HF), and high-fat supplemented with powdered whole persimmon leaf (PL; 5%, wt/wt) groups. Body weight and relative weight of interscapular brown adipose tissue were significantly lower in the PL group than in the HF group, while plasma leptin concentration was higher. The supplementation of persimmon leaf significantly lowered the plasma total cholesterol and triglyceride concentrations, whereas elevated the ratio of HDL-C/total-C and improved the atherogenic index. Persimmon leaf supplementation led the hepatic cholesterol and triglyceride values to similar levels to the NC group. Accumulation of hepatic lipid droplets and the epididymal white adipocyte size of PL group were diminished comparing to the HF group. Hepatic HMG-CoA and ACAT activities were significantly higher in the PL group than in other groups. Contents of fecal triglyceride, cholesterol and acidic sterol were significantly higher in the PL group than in the HF group. Accordingly, we suggest that supplementation of the powdered whole persimmon leaf improves plasma and hepatic lipid levels profile partly via the increased fecal lipids in high-fat fed rats. These beneficial effects may be due to the properties of its phenolic compounds (1.15 g/100g) and high fiber (63.48 g/100g) content in the powdered persimmon leaf.

Vitamin E supplementation alters HDL-cholesterol concentration and paraoxonase activity in rabbits fed high-cholesterol diet: comparison with probucol

Vitamin E and probucol are well-known antioxidants that prevent cells from the oxidative stress, which is a risk factor of atherosclerosis. Male rabbits were fed either 0.03% vitamin E or 0.05% probucol in a 0.5% high-cholesterol (HC) diet for 8 weeks. Vitamin E and probucol significantly suppressed an increase in plasma total-cholesterol (total-C) and low-density lipoprotein cholesterol compared to HC-control group. However, plasma high-density lipoprotein-cholesterol (HDL-C) and HDL-C/total-C ratio levels and plasma paraoxonase activity were only significantly higher in vitamin E group after 8 weeks. Hepatic ACAT activity was significantly lower in both vitamin E and probucol groups than in HC-control group, while HMG-CoA reductase activity was the highest only in the probucol group. Total fecal sterol content was significantly higher in probucol and vitamin E groups than in the two control groups. Some atherogenic signs were discovered in the aortic fatty streak of HC-control group, yet not in other groups. Hepatic mRNA expressions of apo B-100 and apo C-III were significantly lower in probucol group than in other groups. Vitamin E supplementation was found to alter the plasma HDL-C-related factors; meanwhile, probucol supplementation was very effective in enhancing cholesterol metabolism, except for a negative effect that reduced plasma HDL-C concentration.

Mechanisms of dysregulation of low-density lipoprotein receptor expression in vascular smooth muscle cells by inflammatory cytokines

OBJECTIVE

Although inflammation is a recognized feature of atherosclerosis, the impact of inflammation on cellular cholesterol homeostasis is unclear. This study focuses on the molecular mechanisms by which inflammatory cytokines disrupt low-density lipoprotein (LDL) receptor regulation.

METHODS AND RESULTS

IL-1beta enhanced transformation of vascular smooth muscle cells into foam cells by increasing uptake of unmodified LDL via LDL receptors and by enhancing cholesterol esterification as demonstrated by Oil Red O staining and direct assay of intracellular cholesterol concentrations. In the absence of IL-1beta, a high concentration of LDL decreased LDL receptor promoter activity, mRNA synthesis and protein expression. However, IL-1beta enhanced LDL receptor expression, overriding the suppression usually induced by a high concentration of LDL and inappropriately increasing LDL uptake. Exposure to IL-1beta also caused overexpression of the sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP), and enhanced its translocation from the endoplasmic reticulum to the Golgi, where it is known to cleave SREBP, thereby enhancing LDL receptor gene expression.

CONCLUSIONS

These observations demonstrate that IL-1beta disrupts cholesterol-mediated LDL receptor feedback regulation, permitting intracellular accumulation of unmodified LDL and causing foam cell formation. The implication of these findings is that inflammatory cytokines may contribute to intracellular LDL accumulation without previous modification of the lipoprotein.

Diacylglycerol-enriched structured lipids containing CLA and capric acid alter body fat mass and lipid metabolism in rats

OBJECTIVE

The present study compared the effect of corn oil, diacylglycerol (DG) oil, and DG-enriched structured lipids (SL-DG) produced from corn oil, capric and conjugated linoleic acid on adiposity in rats fed an AIN-76 diet (5% fat) for 6 weeks.

METHODS

The plasma and hepatic lipids, adipose tissue weight, and enzyme activities related to fatty acid metabolism were determined.

RESULTS

The weights of the epididymal white adipose tissue (WAT), perirenal WAT, and interscapular WAT were significantly lower in the SL-DG group than in the DG group. Reduction of fat mass in the SL-DG group was related to suppressing fatty acid synthase activities and enhancing beta-oxidation activity in perirenal WAT. The plasma leptin was lower in the SL-DG group than in the DG group, plus a lower plasma TG level was accompanied by an increase in adipocyte LPL activity. Meanwhile the SL-DG supplement lowered the plasma and hepatic cholesterol level. In addition, the hepatic HMG-CoA reductase and ACAT activities were significantly lower in the SL-DG group than in the other groups.

CONCLUSION

The DG-enriched SL used in this study was effective in enhancing triglyceride metabolism in adipose tissue, especially as regards reducing the abdominal fat mass and cholesterol metabolism in the liver.

Anticholesterolemic effect of 3,4-di(OH)-phenylpropionic amides in high-cholesterol fed rats

Two amide synthetic derivatives of 3,4-di(OH)-hydrocinnamate (HC), 3,4-dihydroxyphenylpropionic (l-serine methyl ester) amide (E030) and 3,4-dihydroxyphenylpropionic (l-aspartic acid) amide (E076), were investigated to compare their lipid-lowering efficacy with HC. Male rats were fed a 1 g/100 g high-cholesterol diet for 6 weeks with supplements of either clofibrate (0.02%, w/w), HC (0.025%, w/w), E030 (0.039%, w/w) or E076 (0.041%, w/w). The clofibrate supplement was used as a positive control for the lipid-lowering efficacy. The food intakes and body weight gains were not significantly different among the groups. The plasma and hepatic cholesterol and triglyceride levels were lower in clofibrate, HC, E030, and E076-supplemented groups compared to the control group. The supplementation of HC and its amide derivatives was as effective as clofibrate in increasing the ratio of HDL-cholesterol to total plasma cholesterol and reducing the atherogenic index (AI). The hepatic cholesterol level in the HC and E076 groups was significantly lower than that in the clofibrate group. The hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA reductase) and acyl-CoA:cholesterol acyltransferase (ACAT) activities were significantly lower in the all test groups than in the control group. The excretion of neutral sterol was significantly higher in the HC, E030, and E076-supplemented groups compared to the control group. The plasma AST and ALT activities, indirect indexes of hepatic toxicity, were significantly lower in the HC, E030, and E076-supplemented groups than in the control group. Accordingly, the current results suggest that E030 and E076, two amide synthetic derivatives of HC, are effective in lowering lipid activity.

Effect of 3,4-di(OH)-cinnamate synthetic derivative on plasma and hepatic cholesterol level and antioxidant enzyme activities in high cholesterol-fed rats

The effect of 3,4-di(OH)-phenylpropionic acid (L-phenylalanine methyl ester) amide (SL-1063), a synthetic derivative of 3,4-di(OH)-cinnamate, on the cholesterol metabolism and antioxidant enzyme system was examined in rats. Diets that included either SL-1063 (0.046%, w/w) or lovastatin (0.02%, w/w) as a supplement, plus 1 g cholesterol/100 g diet were fed to rats ad libitum for 5 weeks. The total plasma cholesterol and triglyceride levels were significantly lowered by the SL-1063 supplement compared to the control group. Meanwhile, the levels of plasma HDL-cholesterol and ratio of HDL-cholesterol/total cholesterol (%) were significantly higher in the SL-1063 group than in the control group. However, the lovastatin supplement did not affect the plasma lipid level. The hepatic cholesterol level and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity were significantly lowered in the lovastatin group compared to the SL-1063 group; however, the hepatic triglyceride level did not differ among the groups. The activity of hepatic acyl CoA: cholesterol acyltransferase (ACAT), the enzyme that catalyzes hepatic cholesterol esterification, was significantly lower in the lovastatin and SL-1063 groups than in the control group. Furthermore, the SL-1063 supplement elevated the excretion of fecal sterols. As regards the hepatic antioxidant enzyme system, the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) activities were all significantly higher in the SL-1063 group compared to the control group, whereas only the GR activity was significantly increased by the lovastatin supplement. No marked difference in the GSH levels and glucose-6-phosphate dehydrogenase (G6PD) activities was observed among the groups. The levels of plasma and hepatic thiobarbituric acid reactive substances (TBARS) were lowered by the SL-1063 supplement compared to the control group. Accordingly, the current results suggest that SL-1063, a synthetic derivative of 3,4-di(OH)-cinnamate, is effective in lowering the plasma lipids and improving the antioxidant enzyme system.

Lipid-lowering efficacy of 3,4-di(OH)-phenylpropionicL-leucine in high-cholesterol fed rats

A preliminary study revealed that 3,4-di(OH)-hydrocinnamate (HC), a polyphenolic compound, lowered the plasma lipids in high-cholesterol fed rats. Accordingly, this study was designed to test the lipid-lowering efficacy of a synthetic derivative, 3,4-di(OH)-phenylpropionic (L-leucine) amide (PPLA), in rats fed a high-cholesterol (1%, wt/wt) diet. As such, HC or PPLA was given as supplement to a high-cholesterol diet for 6 weeks at a dose of 0.137 mmol/100 g diet. The supplementation of HC and PPLA significantly lowered the plasma and hepatic cholesterol and triglyceride levels compared to the control group. The activities of hepatic HMG-CoA reductase (164 +/- 9.12 and 124.74 +/- 17.09 pmol/min/mg protein vs. 245.41 +/- 13.01 pmol/min/mg protein, p < 0.05) and ACAT (411.49 +/- 11.48 and 334.35 +/- 17.68 pmol/min/mg protein vs. 490.41 +/- 16.69 pmol/min/mg protein, p < 0.05) were significantly lower in the HC- and PPLA-supplemented groups than in the control group. However, PPLA was more effective in inhibiting the enzyme activities than HC. The excretion of neutral sterol was significantly higher in HC- and PPLA-supplemented groups than in the control group. Therefore, these results indicate that PPLA, a leucine-attached version of HC, exhibited a similar significant hypocholesterolemic effect to HC in rats fed a high-cholesterol diet.