Lipid lowering effect of antioxidant alpha-lipoic Acid in experimental atherosclerosis

Metagenomic Analysis of Gut Microbiota for Abdominal Aortic Aneurysm

Objectives: The pathophysiological mechanism of abdominal aortic aneurysm (AAA) remains unclear. We previously reported that Bifidobacterium adolescentis levels were reduced in the feces of patients with AAA by 16S ribosomal ribonucleic acid (RNA) gene sequencing. In this study, we increased the number of cases and conducted metagenomic analyses to examine bacterial genes associated with the pathophysiology of AAA. Methods: For gut microbiota data, feces from 55 patients with AAA and 52 patients with no history of AAA, lower extremity artery disease, or coronary artery disease (control group) were collected. Metagenomic analysis was performed by collecting raw stool samples from patients. For intestinal microbiota analysis, metagenomic analysis of the fecal samples was performed. Results: Oral bacteria, including Actinomyces oris (p <0.0001), Streptococcus salivarius (p <0.001), Lactobacillus salivarius (p <0.001), and Streptococcus sp. (p <0.001), were increased in the feces of patients with AAA. In addition, bacterial genes related to alpha lipoic acid (ALA) biosynthesis (M00882, M00883, and M00884, p <0.0001) were decreased in patients with AAA. Conclusions: In the feces of patients with AAA, there was an increase in oral bacteria, and the expression of bacterial genes related to ALA biosynthesis was reduced. The results suggest the possibility of developing gut microbial drug treatments for AAA.

Effects of alpha lipoic acid on metabolic syndrome: A comprehensive review

Metabolic syndrome (MetS) is a multifactorial disease with medical conditions such as hypertension, diabetes, obesity, dyslipidemia, and insulin resistance. Alpha-lipoic acid (α-LA) possesses various pharmacological effects, including antidiabetic, antiobesity, hypotensive, and hypolipidemia actions. It exhibits reactive oxygen species scavenger properties against oxidation and age-related inflammation and refines MetS components. Also, α-LA activates the 5' adenosine monophosphate-activated protein kinase and inhibits the NFκb. It can decrease cholesterol biosynthesis, fatty acid β-oxidation, and vascular stiffness. α-LA decreases lipogenesis, cholesterol biosynthesis, low-density lipoprotein and very low-density lipoprotein levels, and atherosclerosis. Moreover, α-LA increases insulin secretion, glucose transport, and insulin sensitivity. These changes occur via PI3K/Akt activation. On the other hand, α-LA treats central obesity by increasing adiponectin levels and mitochondrial biogenesis and can reduce food intake mainly by SIRT1 stimulation. In this review, the most relevant articles have been discussed to determine the effects of α-LA on different components of MetS with a special focus on different molecular mechanisms behind these effects. This review exhibits the potential properties of α-LA in managing MetS; however, high-quality studies are needed to confirm the clinical efficacy of α-LA.

Lipoic acid prevents mirtazapine-induced weight gain in mice without impairs its antidepressant-like action in a neuroendocrine model of depression

Mirtazapine (MIRT) is a multi-target antidepressant used in treatment of severe depression with promising efficacy, but also with important side effects, mainly sedation and weight gain. Thus, the present study aimed to test the effects of the neuroprotective antioxidant lipoic acid (ALA) in the reversal of weight and metabolic changes induced by MIRT in corticosterone-induced depression model in mice, as well as proposed mechanisms for their association antidepressant and pro-cognitive effects. To do these male Swiss mice received Tween 80 (control), corticosterone (CORT 20 mg / kg), MIRT (3 mg / kg) and ALA (100 or 200 mg / kg), alone or associated for 21 days. After this, the animals were subjected to behavioral tests for affective and cognitive domains. Daily weight changes, blood cholesterol fractions and corticosterone were measured. Also, hippocampus (HC) protein expression of the serotonin transporter (SERT), synaptophysin, protein kinase B-Akt (total and phosphorylated) and the cytokines IL-4 and IL-6 were investigated. CORT induced a marked depression-like behavior, memory deficits, metabolic changes (total cholesterol and LDL) and increased serum corticosterone. Also, CORT increased SERT expression in the HC. MIRT alone or combined with ALA sustained its antidepressant-like effect, as well as reversed CORT-induced impairment in spatial recognition memory. Additionally, the association MIRT+ALA200 reversed the weight gain induced by the former antidepressant, as well as reduced serum corticosterone levels and SERT expression in the HC. ALA alone induced significant weight loss and reduced total cholesterol and HDL fraction. Our findings provide promising evidence about the ALA potential to prevent metabolic and weight changes associated to MIRT, without impair its antidepressant and pro-cognition actions. Therefore, ALA+MIRT combination could represent a new therapeutic strategy for treating depression with less side effects.

Lipoic Acid Metabolism as a Potential Chemotherapeutic Target Against Plasmodium falciparum and Staphylococcus aureus

Lipoic acid (LA) is an organic compound that plays a key role in cellular metabolism. It participates in a posttranslational modification (PTM) named lipoylation, an event that is highly conserved and that occurs in multimeric metabolic enzymes of very distinct microorganisms such as Plasmodium sp. and Staphylococcus aureus, including pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase (KDH). In this mini review, we revisit the recent literature regarding LA metabolism in Plasmodium sp. and Staphylococcus aureus, by covering the lipoate ligase proteins in both microorganisms, the role of lipoate ligase proteins and insights for possible inhibitors of lipoate ligases.

Alpha lipoic acid supplementation affects serum lipids in a dose and duration-dependent manner in different health status

Background: Many studies have investigated the effect of ALA supplementation on lipid profile, and different results have been obtained from these studies. The current systematic review and dose-response meta-analysis was conducted to achive a strong conclusion about the effect of ALA supplementation on lipid profile including total cholesterol (TC), low- and high-density lipoprotein cholesterol (LDL, HDL) and triglyceride (TG). Methods: A systematic search was performed in PubMed, SCOPUS, ProQuest and Embase for randomized placebo-controlled human trials that examined the effect of ALA supplementation on lipid profile up to November 2020. The dose and duration of ALA supplementation for included studies were ranged between 300-1200 mg/d and 2-16 weeks respectively. Weighted mean differences (WMD) and 95% confidence intervals (CIs) were used to evaluate the effect size. Cochran's Q and I² tests were also used to assess between-study's heterogeneity. In addition, subgroup analysis was performed to investigate potential sources of heterogeneity. Dose-response relationship was done using fractional polynomial modeling. Results: Among all eligible studies, 12 studies with a total number of 548 participants were selected. ALA caused a significant reduction on TC (WMD): -10.78 mg/dl, 95% CI: -20.81, -0.74, P=0.002), LDL (WMD: -10.88 mg/dl, 95% CI: -19.52, -2.24, P=0.014) and TG (WMD: -31.02 mg/dl, 95% CI: -49.63, -12.42, P<0.001). There was also a non-significant increaes in HDL concentrations. In addition, dose-response analysis showed a positive association between LDL (P_{non-linearity}=0.026), TG (P_{non-linearity}<0.001) and duration of intervention in a non-linear model. Conclusion: The present meta-analysis revealed the beneficial effects of ALA supplementation on TC, LDL and TG levels. Moreover, the beneficial effects of ALA supplementation on LDL and TG levels was duration-dependent.

Citrus reticulata peel oil as an antiatherogenic agent: Hypolipogenic effect in hepatic cells, lipid storage decrease in foam cells, and prevention of LDL oxidation

BACKGROUND AND AIMS

Hypercholesterolemia and oxidative stress are two of the most important risk factors for atherosclerosis. The aim of the present work was to evaluate mandarin (Citrus reticulata) peel oil (MPO) in cholesterol metabolism and lipid synthesis, and its antioxidant capacity.

METHODS AND RESULTS

Incubation of hepatic HepG2 cells with MPO (15-60 μL/L) reduced cholesterogenesis and saponifiable lipid synthesis, demonstrated by [¹⁴C]acetate radioactivity assays. These effects were associated with a decrease in a post-squalene reaction of the mevalonate pathway. Molecular docking analyses were carried out using three different scoring functions to examine the cholesterol-lowering property of all the components of MPO against lanosterol synthase. Docking simulations proposed that minor components of MPO monoterpenes, like alpha-farnesene and neryl acetate, as well the major component, limonene and its metabolites, could be partly responsible for the inhibitory effects observed in culture assays. MPO also decreased RAW 264.7 foam cell lipid storage and its CD36 expression, and prevented low-density lipoprotein (LDL) lipid peroxidation.

CONCLUSION

These results may imply a potential role of MPO in preventing atherosclerosis by a mechanism involving inhibition of lipid synthesis and storage and the decrease of LDL lipid peroxidation.

The Beneficial Effects of Alpha Lipoic Acid Supplementation on Lp-PLA2 Mass and Its Distribution between HDL and apoB-Containing Lipoproteins in Type 2 Diabetic Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

Lipoprotein-associated phospholipase A₂ (Lp-PLA2) is a new specific vascular inflammation biomarker that is carried by the lipoproteins in the blood and plays a prominent role in the pathogenesis of atherosclerosis. Increased Lp-PLA2 levels and impaired Lp-PLA2 distribution across high-density lipoprotein (HDL) and non-HDL lipoproteins have been reported in diabetic patients, which is associated with the increase in cardiovascular disease (CVD) risk. This study is aimed at investigating the effect of alpha lipoic acid (ALA), as an antioxidant with potential cardioprotective properties, on the Lp-PLA2 mass and its distribution in diabetic patients. In a double-blind, randomized, placebo-controlled clinical trial, seventy diabetic patients were randomly allocated to ALA (1200 mg ALA as two 600 mg capsules/day) and placebo (two maltodextrin capsules/day) groups. The serum levels of total Lp-PLA2 mass, HDL-Lp-PLA2, oxidized low-density lipoproteins (ox-LDL), apolipoprotein A1 (apo A1), lipid profiles, fasting blood sugar (FBS), and insulin were measured, and apolipoprotein B- (apoB-) associated Lp-PLA2 and homeostasis model of assessment index (HOMA-IR) were calculated at the baseline and after 8 weeks of intervention. ALA significantly decreased the ox-LDL, total Lp-PLA2 mass, apoB-associated Lp-PLA2, and percent of apoB-associated Lp-PLA2 and triglyceride and increased the percent of HDL-Lp-PLA2 compared with the placebo group but had no significant effect on HDL-Lp-PLA2 mass, apo A1, lipid profiles, and glycemic indices. There was a positive correlation between the reduction in the ox-LDL level and total Lp-PLA2 mass in the ALA group. In conclusion, ALA may decrease the CVD risk by reducing the ox-LDL and Lp-PLA2 mass and improving the Lp-PLA2 distribution among lipoproteins in type 2 diabetic patients.

Discovery of a novel niacin-lipoic acid dimer N2L attenuating atherosclerosis and dyslipidemia with non-flushing effects

Niacin has been widely used as an antihyperlipidemic drug, but the flushing effect restricted its clinical application. Here, we developed novel niacin-lipoic acid dimers which lead to better lipid modulation, higher synergistic effects and less side effects. We utilized molecular docking simulation to design a novel series of niacin-lipoic acid dimers. The compound N-(2-(5-(1,2-dithiolan-3-yl)pentanamido)ethyl)nicotinamide (N2L) was selected for the in vitro and in vivo evaluation, including the agonist activity in CHO-hGPR109A cells, cell protective effects in HT22 and HUVECs cells, flushing effect in guinea pigs and rats, lipid modulation in C57BL/6 mice and high fat diet-rats and atherosclerotic lesions regulation in apolipoprotein E null mice. N2L worked as potent and selective agonists for the high affinity niacin receptor GPR109A. N2L retained antioxidation and cytoprotection of lipoic acid. In addition, N2L displayed a good therapeutic index regarding lipid modulation and atherosclerotic lesions regulation, and minimized niacin-induced vasodilation (flushing) effect in vivo. N2L showed effective treatment regarding to lipid regulation and atherosclerosis inhibition effects, also with excellent antioxidant effects, safety profiles and non-flushing. All these results suggest N2L promising application prospects in the drug development for the treatment of atherosclerosis.

Dietary total antioxidant capacity (TAC) among candidates for coronary artery bypass grafting (CABG) surgery: Emphasis to possible beneficial role of TAC on serum vitamin D

Aims

Recently, the clinical importance of total antioxidant capacity (TAC) and its protective role against several chronic diseases like cardiovascular disease, osteoporosis and several types of cancers has been reported. However, its association with cardio-metabolic risk factors among patients candidate for coronary artery bypass graft surgery (CABG) has not been evaluated yet. CABG is associated with increased oxidative stress and free radicals; so, the current study was aimed to evaluate the potential association of TAC with cardiovascular risk factors among patients candidate for CABG.

Methods and materials

In the current cross-sectional study, 454 patients aged 35–80 years as candidates of CABG and hospitalized in Tehran Heart Center were enrolled. Anthropometric and demographic characteristics were obtained from all participants. Total dietary antioxidant capacity (TAC) was calculated according to the findings of semi-quantitative food-frequency questionnaire (FFQ). Biochemical parameters including serum lipids, albumin, creatinine, HbA1C, C-reactive protein (CRP), lipoprotein (a), creatinine, blood urea nitrogen (BUN) and serum vitamin D concentrations were also assessed by commercial laboratory methods.

Results

Male patients in the top quintiles of TAC had significantly lower prevalence of hypertension (35.1% vs 45.9%). Moreover, male patients at fifth quintile of TAC were 2% more serum vitamin D concentrations, 3% lower serum cholesterol concentrations compared with lowest quintile. Top quintiles of TAC make patients more likely to have low hematocrit and high serum albumin concentrations compared with lowest quintiles (P < 0.05). However, in female participants, only serum creatinine concentration was in negative association with TAC. In comparison of clinical parameters, females in the fifth quintile of TAC had 9% higher EF compared with patients in the first quintile (P = 0.021).

Conclusion

To our findings, higher dietary antioxidant capacity was associated with lower prevalence of hypertension, lower hematocrit, total cholesterol and higher albumin and vitamin D concentrations. Therefore, high dietary TAC could be considered as a potent protective tool against cardio-metabolic risk factors in patients CABG candidate for especially in male patients.

Effect of alpha-lipoic acid supplementation on lipid profile: A systematic review and meta-analysis of controlled clinical trials

Several studies have shown the effect of alpha-lipoic acid (ALA) on lipid profile. However, findings remain controversial. This systematic review and meta-analysis was conducted to systematically summarize the available clinical trials that examined the effects ALA supplementation on the lipid profile of adults. A systematic search through PubMed and Scopus was done for studies published in English up to April 2017. Effect sizes were combined with fixed- or random-effects analysis, where appropriate. Between-study heterogeneity was evaluated by Cochran's Q test and I². Eleven clinical trials with 452 adults (51.5% women, 48.5% men) were included in this meta-analysis. Combining effect sizes of 10 studies on serum triacylglycerol (TG) concentrations revealed a significant effect of ALA supplementation on serum TG compared with the placebo group (weighted mean difference [WMD], -29.185 mg/dL; 95% confidence interval [CI], -51.454 to -6.916; P = 0.010). We also found significant changes in serum total cholesterol and low-density lipoprotein (WMD, -10.683 mg/dL; 95% CI, -19.816 to -1.550; P = 0.022, WMD, -12.906 mg/dL; 95% CI, -22.133 to -3.679; P = 0.006, respectively). Significant changes were not observed in serum high-density lipoprotein (WMD, -0.092 mg/dL; 95% CI, -3.014 to 2.831; P = 0.025). Supplementation dosage and body mass index were potential sources of heterogeneity, in which those with body mass index >30 kg/m² who received >600 mg/d ALA showed better improvements in lipid profile. Our findings showed that supplementation with ALA significantly decreased the serum concentrations of TG, total cholesterol, and low-density lipoprotein but did not affect serum levels of high-density lipoprotein in adults.

Chronic co-exposure to chlorpyrifos and deltamethrin pesticides induces alterations in serum lipids and oxidative stress in Wistar rats: mitigating role of alpha-lipoic acid

The study evaluated the effect of combination of chlorpyrifos (CPF) and deltamethrin (DLT) on serum lipid profiles and oxidative stress in rats, and the mitigating role of alpha-lipoic acid (ALA). Thirty male rats were used for the 120-day study. Serum samples obtained at termination were evaluated for the levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL), malondialdehyde (MDA), and the activities of antioxidant enzymes. The levels of low-density lipoprotein-cholesterol (LDL), very low-density lipoprotein-cholesterol (VLDL), and atherogenic index (AI) were calculated. The pesticide combination elevated the levels of TG, TC, LDL, VLDL, AI, and MDA, and decreased HDL level, and activities of CAT, SOD, and GPx. The alterations induced by CPF and DLT were alleviated by ALA, partly through its antioxidant properties. In conclusion, co-exposure to DLT and CPF altered serum lipids and increased oxidative stress changes in the rats, which were ameliorated by ALA.

THE MECHANISM OF ALPHA LIPOIC ACID ON REDUCING THE MDA LEVEL AND MCP-1 EXPRESSION IN ENDOTHELIAL DYSFUNCTION OF HYPERCHOLESTEROLEMIA RAT (Rattus norvegicus) MODEL

Endothelial dysfunction is an initial condition of atherosclerosis and other vascular diseases where one of the risk factors is hypercholesterolemia. Blood cholesterol levels is associated with an increase in the production of reactive oxygen species (ROS). The increasing of ROS production can cause increased oxidative stress which in turn resulting in endothelial dysfunction. Alpha lipoic acid (ALA) is one of the antioxidant compound that has been developed and studied. In this study we found that the use of ALA in Rattus norvegicus rats signifficantly lower the total cholesterol levels at dose 60 mg/kgBW (p=0.020). ALA also inhibit the expression of Monocyte Chemoattractant Protein-1 (MCP-1) at dose 60 mg/kgBW (p=0.044) and reduces the formation of Malondialdehyde (MDA) at dose 120 mg/kgBW (p=0.009), which is the initial stage of the atherogenic development and prognosis of events, thus, ALA can reduce the risk of further damage to the endothelium.

Chronic treatment of (R)-α-lipoic acid reduces blood glucose and lipid levels in high-fat diet and low-dose streptozotocin-induced metabolic syndrome and type 2 diabetes in Sprague-Dawley rats

(R)‐ α ‐lipoic acid (ALA), an essential cofactor in mitochondrial respiration and a potential antioxidant, possesses a wide array of metabolic benefits including anti‐obesity, glucose lowering, insulin‐sensitizing, and lipid‐lowering effects. In this study, the curative effects of ALA (100 mg/kg) on a spectrum of conditions related to metabolic syndrome and type 2 diabetes (T2D) were investigated in a high‐fat diet (HFD)‐fed and low‐dose streptozotocin (STZ)‐induced rat model of metabolic syndrome and T2D. The marked rise in the levels of glucose, triglycerides, total‐cholesterol, LDL‐cholesterol, and VLDL‐cholesterol in the blood of HFD‐fed and low‐dose STZ‐injected rats were significantly reduced by ALA treatment. Furthermore, ALA treatment significantly increased the serum HDL‐cholesterol levels and tended to inhibit diabetes‐induced weight reduction. Mathematical computational analysis revealed that ALA also significantly improved insulin sensitivity and reduced the risk of atherosclerotic lesions and coronary atherogenesis. This study provides scientific evidence to substantiate the use of ALA to mitigate the glucose and lipid abnormality in metabolic syndrome and T2D.

Biochemical effects of oleuropein in gentamicin-induced nephrotoxicity in rats

BACKGROUND

Oleuropein is a natural antioxidant and scavenging free radicals. In the present study, we examined effect of oleuropein on the paraoxonase 1 (PON1) activity, lipid peroxidation, lipid profile, atherogenic indexes, and relationship of PON1 activity by high-density lipoprotein-cholesterol (HDL-C) and atherogenic indices in gentamicin (GM)-induced nephrotoxicity in rats.

METHODS

This is a lab trial study in Khorramabad, Lorestan province of Iran (2013). 30 Sprague-Dawley rats were divided into three groups to receive saline; GM, 100 mg/kg/day; and GM plus oleuropein by 15 mg/kg intraperitoneal daily, respectively. After 12 days, animals were anesthetized, blood samples were also collected before killing to measure the levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), and very LDL (VLDL), HDL-C, atherogenic index, lipid peroxidation, and the activities of PON1 of all groups were analyzed. Data were analyzed, and P < 0.050 was considered significant.

RESULTS

Oleuropein significantly decreased lipid peroxidation, TG, TC, LDL, VLDL, atherogenic index, atherogenic coefficient (AC), and cardiac risk ratio (CRR). HDL-C level was significantly increased when treated with oleuropein. The activity of PON1 in treated animals was (62.64 ± 8.68) that it was significantly higher than untreated animals (47.06 ± 4.10) (P = 0.047). The activity of PON1 in the untreated nephrotoxic rats was significantly lower than that of control animals (77.84 ± 9.43) (P = 0.030). Furthermore, the activity of PON1 correlated positively with HDL-C and negatively with AC, CRR 1, and CRR 2 in the treated group with oleuropein.

CONCLUSION

This study showed that oleuropein improves PON1 activity, lipid profile, and atherogenic index and can probably decrease the risk of cardiovascular death in nephrotoxic patients.

Lipoicmethylenedioxyphenol Reduces Experimental Atherosclerosis through Activation of Nrf2 Signaling

Objective

Oxidative stress is implicated in the pathogenesis of atherosclerosis, and Nrf2 is the transcriptional factor central in cellular antioxidant responses. In the present study, we investigate the effect of a dihydrolipoic acid derivative lipoicmethylenedioxyphenol (LMDP) on the progression of atherosclerosis and test whether its effect on atherosclerosis is mediated by Nrf2.

Methods and Results

Both magnetic resonance imaging (MRI) scanning and en face analysis reveal that 14 weeks of treatment with LMDP markedly reduced atherosclerotic burden in a rabbit balloon vascular injury model. Myograph analyses show decreased aortic contractile response to phenylephrine and increased aortic response to acetylcholine and insulin in LMDP-treated animals, suggesting that LMDP inhibits atherosclerosis through improving vascular function. A role of Nrf2 signaling in mediating the amelioration of vascular function by LMDP was supported by increased Nrf2 translocation into nuclear and increased expression of Nrf2 target genes. Furthermore, chemotaxis analysis with Boydem chamber shows that leukocytes isolated from LMDP-treated rabbits had reduced chemotaxis, and knock-down of Nrf2 significantly reduced the effect of LMDP on the chemotaxis of mouse macrophages.

Conclusion

Our results support that LMDP has an anti-atherosclerotic effect likely through activation of Nrf2 signaling and subsequent inhibition of macrophage chemotaxis.

The protective effect of lipoic acid on selected cardiovascular diseases caused by age-related oxidative stress

Oxidative stress is considered to be the primary cause of many cardiovascular diseases, including endothelial dysfunction in atherosclerosis and ischemic heart disease, hypertension, and heart failure. Oxidative stress increases during the aging process, resulting in either increased reactive oxygen species (ROS) production or decreased antioxidant defense. The increase in the incidence of cardiovascular disease is directly related to age. Aging is also associated with oxidative stress, which in turn leads to accelerated cellular senescence and organ dysfunction. Antioxidants may help lower the incidence of some pathologies of cardiovascular diseases and have antiaging properties. Lipoic acid (LA) is a natural antioxidant which is believed to have a beneficial effect on oxidative stress parameters in relation to diseases of the cardiovascular system.

Complementary Cholesterol-Lowering Response of a Phytosterol/α-Lipoic Acid Combination in Obese Zucker Rats

To investigate the cholesterol-lowering effectiveness of a phytosterol/α-lipoic acid (PS/αLA) therapy, thirty-two male Zucker rats were randomly assigned to 1 of 4 diets for 30 days: (i) high fat diet (HF, 40% energy from fat); (ii) HF diet supplemented with 3% phytosterols; (iii) HF diet supplemented with 0.25% αLA; or (iv) HF diet supplemented with PS (3%) and αLA (0.25%, PS/αLA). Compared with the HF diet, combination PS/αLA proved more effective in reducing non-HDL cholesterol (-55%) than either the PS (-24%) or the αLA (-25%) therapies alone. PS supplementation did not affect LDL particle number, however, αLA supplementation reduced LDL particle number when supplemented alone (-47%) or in combination with PS (-54%). Compared with the HF-fed animals, evidence of increased HDL-particle number was evident in all treatment groups to a similar extent (21-22%). PS-mediated interruption of intestinal cholesterol absorption was evident by increased fecal cholesterol loss (+52%) and compensatory increase in HMG-CoA reductase mRNA (1.6 fold of HF), however, αLA supplementation did not affect fecal cholesterol loss. Hepatic mRNA and protein expression patterns suggested that αLA modulated multiple aspects of cholesterol homeostasis including reduced synthesis (HMG-CoA reductase mRNA, 0.7 fold of HF), reduced bile acid synthesis (CYP7a1 expression, 0.17 of HF), and increased cholesterol clearance (reduced PCSK9 mRNA, 0.5 fold of HF; increased LDLr protein, 2 fold of HF). Taken together, this data suggests that PS and αLA work through unique and complementary mechanisms to provide a superior and more comprehensive cholesterol lowering response than either therapy alone.

Alpha-lipoic acid reduces LDL-particle number and PCSK9 concentrations in high-fat fed obese Zucker rats

We characterized the hypolipidemic effects of alpha-lipoic acid (LA, R-form) and examined the associated molecular mechanisms in a high fat fed Zucker rat model. Rats (n = 8) were assigned to a high fat (HF) diet or the HF diet with 0.25% LA (HF-LA) for 30 days and pair fed to remove confounding effects associated with the anorectic properties of LA. Compared with the HF controls, the HF-LA group was protected against diet-induced obesity (102.5±3.1 vs. 121.5±3.6,% change BW) and hypercholesterolemia with a reduction in total-C (−21%), non-HDL-C (−25%), LDL-C (−16%), and total LDL particle number (−46%) and an increase in total HDL particles (∼22%). This cholesterol-lowering response was associated with a reduction in plasma PCSK9 concentration (−70%) and an increase in hepatic LDLr receptor protein abundance (2 fold of HF). Compared with the HF-fed animals, livers of LA-supplemented animals were protected against TG accumulation (−46%), likely through multiple mechanisms including: a suppressed lipogenic response (down-regulation of hepatic acetyl-CoA carboxylase and fatty acid synthase expression); enhanced hepatic fat oxidation (increased carnitine palmitoyltransferase Iα expression); and enhanced VLDL export (increased hepatic diacylglycerol acyltransferase and microsomal triglyceride transfer protein expression and elevated plasma VLDL particle number). Study results also support an enhanced fatty acid uptake (2.8 fold increase in total lipase activity) and oxidation (increased CPT1β protein abundance) in muscle tissue in LA-supplemented animals compared with the HF group. In summary, in the absence of a change in caloric intake, LA was effective in protecting against hypercholesterolemia and hepatic fat accumulation under conditions of strong genetic and dietary predisposition toward obesity and dyslipidemia.

Wheat germ oil and α-lipoic acid predominantly improve the lipid profile of broiler meat

In response to recent assertions that synthetic antioxidants may have the potential to cause toxic effects and to consumers' increased attention to consuming natural products, the poultry industry has been seeking sources of natural antioxidants, alone or in combination with synthetic antioxidants that are currently being used by the industry. The present study was conducted to determine the effect of α-lipoic acid, α-tocopherol, and wheat germ oil on the status of antioxidant enzymes, fatty acid profile, and serum biochemical profile of broiler blood. One-day-old (180) broiler birds were fed six different feeds varying in their antioxidant content: no addition (T1), natural α-tocopherol (wheat germ oil, T2), synthetic α-tocopherol (T3), α-lipoic acid (T4), α-lipoic acid together with natural α-tocopherol (T5), and α-lipoic acid together with synthetic α-tocopherol (T6). The composition of saturated and unsaturated fatty acids in the breast and leg meat was positively influenced by the different dietary supplements. The content of fatty acid was significantly greater in broilers receiving T2 both in breast (23.92%) and in leg (25.82%) meat, whereas lower fatty acid levels was found in broilers receiving diets containing T6 in the breast (19.57%) and leg (21.30%) meat. Serum total cholesterol (113.42 mg/dL) and triglycerides (52.29 mg/dL) were lowest in the group given natural α-tocopherol and α-lipoic acid. Wheat germ oil containing natural α-tocopherol alone or with α-lipoic acid was more effective than synthetic α-tocopherol in raising levels of antioxidant enzymes superoxide dismutase, catalase, and glutathione reductase while lowering plasma total cholesterol, low-density lipoprotein, and triglycerides and raising high-density lipoprotein and plasma protein significantly. It was concluded that the combination of wheat germ oil and α-lipoic acid is helpful in improving the lipid profile of broilers.

Antiatherosclerotic Effect of Canarium odontophyllum Miq. Fruit Parts in Rabbits Fed High Cholesterol Diet

The effect of C. odontophyllum (CO) fruit parts was investigated in hypercholesterolemic rabbits. Forty-nine rabbits, which were randomly divided into seven groups of seven animals (n = 7), received a diet containing different parts of CO fruit parts for 8 weeks. The groups were as follows: (1) normal diet: NC group and (2) hypercholesterolemic diet: PC, HS (10 mg/kg/day simvastatin), HPO (20 g kg(-1) oil extracted from the pulp of CO), HKO (20 g kg(-1) oil extracted from the kernel of CO), HF (50 g kg(-1) fullfat pulp of CO), and HD (50 g kg(-1) defatted pulp of CO). Among these groups, rabbits receiving defatted pulp of CO showed the greatest cholesterol lowering effect as it had reduced plasma LDL-C, TC, and thiobarbiturate reactive substance (TBARS) levels as well as atherosclerotic plaques. The presence of high dietary fiber and antioxidants activity are potential factors contributing to the cholesterol lowering effect. Consequently, these results indicate the potential use of CO defatted pulp as a cholesterol lowering and antioxidant agent.

Effects of oxidized cooking oil and α-lipoic acid on blood antioxidants: enzyme activities and lipid peroxidation in rats fed a high-fat diet

The effects of administration of oxidized rapeseed oil and α-lipoic acid on activities of blood antioxidant enzymes and malondialdehyde (MDA) concentration were studied in laboratory rats fed a high-fat diet. Addition of oxidized oil resulted in increased production of oxygen radicals, evidenced by elevated plasma MDA production. Such effect was counteracted by administration of α-lipoic acid. There was an increase of the activities of superoxide dismutase (total and Cu/Zn-SOD) and catalase in rats fed a high-fat diet to which 10% oxidized oil was added. Administration of α-lipoic acid resulted in a decrease of the activities of these enzymes.

Amelioration of lipid abnormalities by α-lipoic acid through antioxidative and anti-inflammatory effects

Recent data have revealed that oxidative products and inflammatory mediators are increased in the insulin-resistant states of obesity and type 2 diabetes mellitus (T2DM). Obese patients with impaired glucose tolerance (IGT) are at high risk for developing T2DM and have high incidence of dyslipidemia. α-Lipoic acid (ALA) is a potent antioxidant with insulin sensitizing activity. However, it is not clear whether ALA is effective on lipid parameters in humans. This study has investigated 22 obese subjects with IGT (obese-IGT), 13 of whom underwent 2-week ALA treatment, 600 mg intravenously once daily. Before and after the treatment, euglycemic-hyperinsulinemic clamps were used to measure insulin sensitivity. Meanwhile, plasma lipids, oxidative products, and chronic inflammatory markers were measured. After treatment of ALA in obese-IGT patients, insulin sensitivity was improved, insulin sensitivity index (ISI) impressively enhanced by 41%. Plasma levels of free fatty acids (FFAs), triglyceride (TG), total cholesterol (T-Chol), low density lipoprotein-cholesterol (LDL-Chol), small dense LDL-Chol (sd-LDL), oxidized LDL-Chol (ox-LDL-Chol), very low density lipoprotein-cholesterol (VLDL-Chol) were all significantly decreased (P < 0.01). At the same time, both plasma oxidative products (malondialdehyde (MDA), 8-iso-prostaglandin) and inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)) were remarkably decreased (P < 0.01), while adiponectin was increased (P < 0.01). There are significant negative correlations between ISI and plasma FFAs, sd-LDL-Chol, ox-LDL-Chol, MDA, 8-iso-prostaglandin, TNF-α, and IL-6, and positive correlations with HDL-Chol and adiponectin in obese-IGT patients. The results indicate that short-term treatment with ALA can improve insulin sensitivity and plasma lipid profile possibly through amelioration of oxidative stress and chronic inflammatory reaction in obese patients with IGT.

The effects of lipoic acid and α-tocopherol supplementation on the lipid profile and insulin sensitivity of patients with type 2 diabetes mellitus: a randomized, double-blind, placebo-controlled trial

Antioxidants probably play an important role in the etiology of type 2 diabetes (DM2). This study evaluated the effects of supplementation with lipoic acid (LA) and α-tocopherol on the lipid profile and insulin sensitivity of DM2 patients. A randomized, double-blind, placebo-controlled trial involving 102 DM2 patients divided into four groups to receive daily supplementation for 4 months with: 600 mg LA (n = 26); 800 mg α-tocopherol (n = 25); 800 mg α-tocopherol + 600 mg LA (n = 25); placebo (n = 26). Plasma α-tocopherol, lipid profile, glucose, insulin, and the HOMA index were determined before and after supplementation. Differences within and between groups were compared by ANOVA using Bonferroni correction. Student's t-test was used to compare means of two independent variables. The vitamin E/total cholesterol ratio improved significantly in patients supplemented with vitamin E+LA and vitamin E alone (p ≤ 0.001). There were improvements of the lipid fractions in the groups receiving LA and vitamin E alone or in combination, and on the HOMA index in the LA group, but not significant. The results suggest that LA and vitamin E supplementation alone or in combination did not affect the lipid profile or insulin sensitivity of DM2 patients.

Genetic reduction of lipoic acid synthase expression modestly increases atherosclerosis in male, but not in female, apolipoprotein E-deficient mice

OBJECTIVES

To evaluate the effects of a genetic reduction of Lias gene expression on atherosclerosis development.

METHODS AND RESULTS

Heterozygous knockout mice for the lipoid acid synthase gene (Lias(+/-)) were crossed with apolipoprotein E-deficient (ApoE(-/-)) mice, and the plaque size in aortic sinuses of Lias(+/-)ApoE(-/-)mice was evaluated at 6 months of age. Lesions at the aortic sinus in Lias(+/-)ApoE(-/-) males were significantly larger (1.5x) than those in Lias(+/+) ApoE(-/-) littermate males. The lesion size was inversely correlated with an increased erythrocyte reduced glutathione/oxidized glutathione (GSH/GSSH) ratio, a systemic index of body redox balance. Lias(+/-)ApoE(-/-)males also had significantly increased plasma cholesterol and reduced pyruvate dehydrogenase complex activity in the liver. Significant reductions in the expression of genes for antioxidant enzymes, including superoxide dismutase 1 (SOD1) and SOD2, were observed in aortas of Lias(+/-)ApoE(-/-)males. Female Lias(+/-)ApoE(-/-)also exhibited changes in these parameters, parallel to those observed in males. However, the Lias gene effects for the majority of these factors, including atherosclerotic lesion size, were not significant in females.

CONCLUSIONS

Our data provide evidence that Lias deficiency enhances atherosclerosis in male mice, at least in part due to reduced antioxidant capacity. The notable absence of such effects in females leaves open the possibility of a gender-specific protection mechanism.

Redox homeostasis of albumin in relation to alpha-lipoic acid and dihydrolipoic acid

Albumin represents the predominant circulating antioxidant agent in plasma exposed to continuous oxidative stress and a change in serum albumin structure accounts for its antioxidant properties. Alterations in the redox status of albumin may result in impairments of its biological properties. Alpha-lipoic acid (LA), a naturally occurring thiol compound found in virtually all species, is a potent antioxidant with high efficacy which is also involved in the chelation of metal ions, regeneration of antioxidants, and repair of oxidatively damaged proteins. In human body LA is rapidly reduced to dihydrolipoic acid (DHLA) after intake into the cell. Both, LA and DHLA are amphipathic molecules which act as antioxidants both in hydrophilic and lipophilic environments. The present study aimed to investigate the antioxidant/pro-oxidant effects of LA and DHLA due to their concentrations in metal-catalyzed protein oxidation (MCO) of human serum albumin (HSA). Progressive oxidative modification of albumin was found in MCO system by an increased content of protein hydroperoxides (POOH), protein carbonyl groups (PCO) which is the former's major breakdown product, and other protein oxidation markers such as advanced oxidized protein products (AOPP) and protein thiol groups (P-SH). The possible antioxidant protective effects of LA and DHLA were observed with 25 microM and 50 microM; DHLA being more influential. Protein oxidation parameters were found to be lower and P-SH levels seemed higher. However, prooxidant effects of both LA and DHLA came on the scene with increased concentrations of 75 microM and 100 microM where the latter seemed the most hazardous with contradicted results. It is clear that the loss of biological activity of human serum albumin by MCO system appears of medical relevance and if LA exerts similar effects seen in the present study, it is possible that cellular prooxidant activity can also result consuming this unique antioxidant in certain doses.