Effects of Acipimox on the metabolism of free fatty acids and very low lipoprotein triglyceride

Metabolite profiling of arginase inhibitor activity guided fraction of Ficus religiosa leaves by LC-HRMS

Cardiovascular disease is one of the major causes of deaths worldwide. Increased arginase activity is associated with cardiovascular disease. The literature shows that plants are a good source of arginase inhibitors. Hence in the present work arginase inhibitor activity is studied from Ficus religiosa leaves. A fine powder of F. religiosa leaves was serially extracted in various solvents, viz. hexane, chloroform, ethyl acetate and methanol. Out of those four solvent extracts, the one showing highest arginase inhibitor activity was loaded onto the column for further fractionation. Among the collected fractions, the one showing the highest activity was subjected to identification of metabolites by using LC-HRMS. Total compounds including acipimox, edoxudine, levulinic acid, hydroxyhydroquinone, ramiprilglucuronide, berberine, antimycin A, swietenine and some short peptides were identified from the fraction showing the highest arginase inhibitory activity. Identification of these metabolites from F. religiosa and their biological importance may help to promote its use as medicinal plant. Further purification and characterization of therapeutically novel molecules will be the subject of future work.

The Opportunities and Challenges of Peroxisome Proliferator-Activated Receptors Ligands in Clinical Drug Discovery and Development

Peroxisome proliferator-activated receptors (PPARs) are a well-known pharmacological target for the treatment of multiple diseases, including diabetes mellitus, dyslipidemia, cardiovascular diseases and even primary biliary cholangitis, gout, cancer, Alzheimer's disease and ulcerative colitis. The three PPAR isoforms (α, β/δ and γ) have emerged as integrators of glucose and lipid metabolic signaling networks. Typically, PPARα is activated by fibrates, which are commonly used therapeutic agents in the treatment of dyslipidemia. The pharmacological activators of PPARγ include thiazolidinediones (TZDs), which are insulin sensitizers used in the treatment of type 2 diabetes mellitus (T2DM), despite some drawbacks. In this review, we summarize 84 types of PPAR synthetic ligands introduced to date for the treatment of metabolic and other diseases and provide a comprehensive analysis of the current applications and problems of these ligands in clinical drug discovery and development.

Acipimox, an inhibitor of lipolysis, attenuates atherogenesis in LDLR-null mice treated with HIV protease inhibitor ritonavir

OBJECTIVE

The advent of HIV protease inhibitors has greatly extended the life span of AIDS patients. With an aging HIV(+) population, the cardiometabolic side effects of these drugs are becoming increasingly important clinical concerns. The purpose of this study was to test the hypothesis that inhibition of adipose lipolysis will retard atherogenic lesion development induced by the antiviral protease inhibitors.

METHODS AND RESULTS

LDLR-null mice receiving ritonavir were compared with those receiving ritonavir plus lipolysis inhibitor acipimox or vehicle alone to determine how acipimox would affect ritonavir-induced atherogenesis. Intermittent high-fat high-cholesterol diet was used to facilitate optimal atheromatous lesion development. Drug effects were assessed as changes in aortic lesion score, plasma lipid and lipoprotein profile, body fat mass, and insulin-induced suppression of plasma fatty acid concentrations. Ritonavir increased aortic lesions, in association with decreased body fat mass, impaired antilipolysis action of insulin, and increased proatherogenic plasma lipoproteins. All these adverse effects were attenuated by cotreatment with acipimox.

CONCLUSIONS

Our results provide the first direct evidence that supports the hypothesis that dysregulation of adipose lipolysis is an important contributor to the proatherogenic role of selected HIV protease inhibitors.

A single 1-h bout of evening exercise increases basal FFA flux without affecting VLDL-triglyceride and VLDL-apolipoprotein B-100 kinetics in untrained lean men

Our group (Magkos F, Wright DC, Patterson BW, Mohammed BS, Mittendorfer B, Am J Physiol Endocrinol Metab 290: E355-E362, 2006) has recently demonstrated that a single, prolonged bout of moderate-intensity cycling (2 h at 60% of peak oxygen consumption) in the evening increases basal whole-body free fatty acid (FFA) flux and fat oxidation, decreases hepatic VLDL-apolipoprotein B-100 (apoB-100) secretion, and enhances removal efficiency of VLDL-triglyceride (TG) from the circulation the following day in untrained, healthy, lean men. In the present study, we investigated the effect of a single, shorter-duration bout of the same exercise (1 h cycling at 60% of peak oxygen consumption) on basal FFA, VLDL-TG, and VLDL-apoB-100 kinetics in seven untrained, healthy, lean men by using stable isotope-labeled tracer techniques. Basal FFA rate of appearance in plasma and plasma FFA concentration were approximately 55% greater (P < 0.05) the morning after exercise than rest, whereas resting metabolic rate and whole-body substrate oxidation rates were not different after rest and exercise. Exercise had no effect on plasma VLDL-TG and VLDL-apoB-100 concentrations, hepatic VLDL-TG and VLDL-apoB-100 secretion rates, and VLDL-TG and VLDL-apoB-100 plasma clearance rates (all P > 0.05). We conclude that in untrained, healthy, lean men 1) the exercise-induced changes in basal whole-body fat oxidation, VLDL-TG, and VLDL-apoB-100 metabolism during the late phase of recovery from exercise are related to the duration of the exercise bout; 2) single sessions of typical recreational activities appear to have little effect on basal, fasting plasma TG homeostasis; and 3) there is a dissociation between systemic FFA availability and VLDL-TG and VLDL-apoB-100 secretion by the liver.

Improved triglycerides and insulin sensitivity with 3 months of acipimox in human immunodeficiency virus-infected patients with hypertriglyceridemia

CONTEXT

Metabolic abnormalities such as hypertriglyceridemia remain a challenge for optimizing long-term health in HIV-infected patients.

OBJECTIVE

Elevation of free fatty acids (FFAs) may contribute to hyperlipidemia and insulin resistance in HIV. We evaluated the efficacy and safety of chronic inhibition of lipolysis in HIV-infected men and women with hypertrigyceridemia. We hypothesized that acipimox would lead to significant reductions in triglycerides and improved insulin sensitivity, compared with placebo.

DESIGN

A 3-month, randomized, double-blind, controlled trial of acipimox (250 mg thrice daily) vs. placebo was conducted in 23 HIV-infected men and women with hypertriglyceridemia (>150 mg/dl), abnormal fat distribution, and no current lipid-lowering therapy. The primary outcome variable was triglyceride concentration, and insulin sensitivity measured by hyperinsulinemic euglycemic clamp was a secondary outcome.

SETTING

The study was conducted at an academic medical center.

RESULTS

Acipimox resulted in significant reductions in FFAs [mean change -0.38 (0.06) vs. 0.08 (0.06) mEq/liter with placebo, -68 vs. +17% change from mean baseline, P < 0.0001], decreased rates of lipolysis (P < 0.0001), and a median triglyceride decrease from 238 mg/dl at baseline to 190 mg/dl, compared with an increase from 290 to 348 mg/dl in the placebo group (P = 0.01). Acipimox improved insulin sensitivity [acipimox +2.31 (0.74) vs. placebo -0.21 (0.90) mg glucose per kilogram lean body mass per minute, or +31 vs. -2% change from mean baseline values, P = 0.04]. Improvements in insulin sensitivity were significantly correlated with reductions in FFAs (r = -0.62, P = 0.003) and lipolysis (r = -0.59, P = 0.005).

CONCLUSIONS

Acipimox resulted in significant sustained reductions in lipolysis, improved glucose homeostasis, and significant but modest reductions in triglycerides in HIV-infected individuals with abnormal fat distribution and hypertriglyceridemia. Improvement in overall metabolic profile with acipimox suggests a potential clinical utility for this agent that requires further investigation.

Long-term follow-up of patients with acute hypertriglyceridemia-induced pancreatitis

BACKGROUND

An acute and potentially life-threatening complication of hypertriglyceridemia (HTG) is acute pancreatitis (AP). Hypertriglyceridemia, usually severe, may be primary in origin or secondary to alcohol abuse, diabetes mellitus, pregnancy, and use of drugs.

STUDY

The efficacy of treatment to prevent relapses in 17 patients with AP attributed to HTG was investigated in the current prospective study. The mean follow-up period of patients was 42 months. Hypertriglyceridemia-induced AP comprised 6.9% of all patients with AP (n = 246) hospitalized in our clinic during the study (6 years).

RESULTS

Causative conditions of HTG-induced AP were familial HTG in eight patients, HTG caused by uncontrolled diabetes mellitus in five, HTG aggravated by drugs in two (one by tamoxifen and one by fluvastatin), familial hyperchylomicronemia (HCM) in one, and lipemia of pregnancy in one. During the acute phase of pancreatitis, patients underwent standard treatment. Thereafter, HTG was efficiently controlled with high dosages of fibrates or a fibrate plus acipimox, except for the patient with HCM, who was on a specific diet (the only source of fat was a special oil consisting of medium chain triglyceride) and taking a high dosage of acipimox. One of the patients died during the acute phase of pancreatitis with acute respiratory distress syndrome. During follow-up, maintenance treatment was successful and only one patient relapsed, because he discontinued diet and drug treatment.

CONCLUSION

Appropriate diet and drug treatment, including dose titration, of severe HTG is very effective in preventing relapses of HTG-induced AP.