Antifungal Activity of Fibrate-Based Compounds and Substituted Pyrroles That Inhibit the Enzyme 3-Hydroxy-methyl-glutaryl-CoA Reductase of Candida glabrata (CgHMGR), Thus Decreasing Yeast Viability and Ergosterol Synthesis.

Due to the emergence of multidrug-resistant strains of yeasts belonging to the Candida genus, there is an urgent need to discover antifungal agents directed at alternative molecular targets. The aim of the current study was to evaluate the capacity of three different series of synthetic compounds to inhibit the Candida glabrata enzyme denominated 3-hydroxy-methyl-glutaryl-CoA reductase and thus affect ergosterol synthesis and yeast viability. Compounds 1c (α-asarone-related) and 5b (with a pyrrolic core) were selected as the best antifungal candidates among over 20 synthetic compounds studied. Both inhibited the growth of fluconazole-resistant and fluconazole-susceptible C. glabrata strains. A yeast growth rescue experiment based on the addition of exogenous ergosterol showed that the compounds act by inhibiting the mevalonate synthesis pathway. A greater recovery of yeast growth occurred for the C. glabrata 43 fluconazole-resistant (versus fluconazole-susceptible) strain and after treatment with 1c (versus 5b). Given that the compounds decreased the concentration of ergosterol in the yeast strains, they probably target ergosterol synthesis. According to the docking analysis, the inhibitory effect of 1c and 5b could possibly be mediated by their interaction with the amino acid residues of the catalytic site of the enzyme. Since 1c displayed higher binding energy than α-asarone and 5b, it is the best candidate for further research, which should include structural modifications to increase its specificity and potency. The derivatives could then be examined with in vivo animal models using a therapeutic dose. IMPORTANCE Within the context of the COVID-19 pandemic, there is currently an epidemiological alert in health care services due to outbreaks of Candida auris, Candida glabrata, and other fungal species multiresistant to conventional antifungals. Therefore, it is important to propose alternative molecular targets, as well as new antifungals. The three series of synthetic compounds herein designed and synthesized are inhibitors of ergosterol synthesis in yeasts. Of the more than 20 compounds studied, two were selected as the best antifungal candidates. These compounds were able to inhibit the growth and synthesis of ergosterol in C. glabrata strains, whether susceptible or resistant to fluconazole. The rational design of antifungal compounds derived from clinical drugs (statins, fibrates, etc.) has many advantages. Future studies are needed to modify the structure of the two present test compounds to obtain safer and less toxic antifungals. Moreover, it is important to carry out a more in-depth mechanistic approach.

A review of the studies on food-derived factors which regulate energy metabolism via the modulation of lipid-sensing nuclear receptors.

Obesity is one of the most important risk factors for chronic metabolic disorders. Molecular mechanisms underlying obesity-related metabolic disorders have not been completely elucidated. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily and are key metabolic regulators of the whole-body energy metabolism. Certain enzymes involved in carbohydrate and lipid metabolism are directly regulated by PPARs via their interaction with specific response elements in their gene promoters. Many food factors act as ligands of PPARs and regulate carbohydrate and lipid metabolism by regulating the activities of these nuclear receptors, leading to the attenuation of obesity-related metabolic disorders. In this review, we describe our current knowledge of the role of PPARs in the regulation of whole-body energy metabolism and several examples of food factors that act as ligands of PPARs, which may be useful in the management of obesity and the accompanying energy metabolism abnormalities. Abbreviations: WAT: white adipose tissue; PPAR: Peroxisome proliferators-activated receptor; RXR: retinoid X receptors; mTORC1: mechanistic target of rapamycin complex 1; PPRE: PPAR-responsive regulatory elements; NAFLD: nonalcoholic fatty liver disease; LPL: lipoprotein lipase; FGF21: fibroblast growth factor 21; BAT: brown adipose tissue; UCP1: uncoupling protein 1; LPC(16:0): 1-palmitoyl lysophosphatidylcholine; C/EBP: CCAAT-enhancer binding proteins; STAT5A: signal transduction and activator of transcription 5A; APO apolipoptotein; CBP: cAMP response element-binding protein-binding protein; PGC1A: PPARγ coactivator protein 1a; HFD: high-fat diet; TG: triglyceride; VLDL: very low density lipoprotein; HDL: high density lipoprotein.

Fatty Acid Binding Proteins Expressed at the Human Blood-Brain Barrier Bind Drugs in an Isoform-Specific Manner.

PURPOSE: To examine the expression of fatty acid binding proteins (FABPs) at the human blood-brain barrier (BBB) and to assess their ability to bind lipophilic drugs. METHODS: mRNA and protein expression of FABP subtypes in immortalized human brain endothelial (hCMEC/D3) cells were examined by RT-qPCR and Western blot, respectively. FABPs that were found in hCMEC/D3 cells (hFABPs) were recombinantly expressed and purified from Escherichia coli C41(DE3) cells. Drug binding to these hFABPs was assessed using a fluorescence assay, which measured the ability of a panel of lipophilic drugs to displace the fluorescent probe compound 1-anilinonaphthalene-8-sulfonic acid (ANS). RESULTS: hFABP3, 4 and 5 were expressed in hCMEC/D3 cells at the mRNA and protein level. The competitive ANS displacement assay demonstrated that, in general, glitazones preferentially bound to hFABP5 (Ki: 1.0-28 µM) and fibrates and fenamates preferentially bound to hFABP4 (Ki: 0.100-17 µM). In general, lipophilic drugs appeared to show weaker affinities for hFABP3 relative to hFABP4 and hFABP5. No clear correlation was observed between the molecular structure or physicochemical properties of the drugs and their ability to displace ANS from hFABP3, 4 and 5. CONCLUSIONS: hFABP3, 4 and 5 are expressed at the human BBB and bind differentially to a diverse range of lipophilic drugs. The unique expression and binding patterns of hFABPs at the BBB may therefore influence drug disposition into the brain.

Environmental pollutants directly affect the liver X receptor alpha activity: Kinetic and thermodynamic characterization of binding.

Liver X receptor is a ligand-activated transcription factor, which is mainly involved in cholesterol homeostasis, bile acid and triglycerides metabolism, and, as recently discovered, in the glucose metabolism by direct regulation of liver glucokinase. Its modulation by exogenous factors, such as drugs, industrial by-products, and chemicals is documented. Owing to the abundance of these synthetic molecules in the environment, and to the established target role of this receptor, a number of representative compounds of phthalate, organophosphate and fibrate classes were tested as ligands/modulators of human liver X receptor, using an integrated approach, combining an in silico molecular docking technique with an optical SPR biosensor binding study. The compounds of interest were predicted and proved to target the oxysterols-binding site of human LXRα with measurable binding kinetic constants and with affinities ranging between 4.3 × 10(-7) and 4.3 × 10(-8)M. Additionally, non-cytotoxic concentration of these chemicals induced relevant changes in the LXRα gene expression levels and other target genes (SREBP-1c and LGK) in human liver hepatocellular carcinoma cell line (HepG2), as demonstrated by q-RT-PCR.

A simple and sensitive method for the determination of fibric acids in the liver by liquid chromatography.

Fibrates are used in biochemical and pharmacological studies as bioactive tools. Nevertheless, most studies have lacked information concerning the concentrations of fibric acids working inside tissues because a simple and sensitive method is not available for their quantitation. This study aimed to develop a simple and sensitive bioanalytical method for the quantitation of clofibric, bezafibric and fenofibric acids in samples of very small portions of tissues. Fibric acids were extracted into n-hexane-ethyl acetate from tissue homogenates (10 mg of liver, kidney or muscle) or serum (100 µL) and were derivatized with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC with fluorescence detection. These compounds were separated isocratically on a reversed phase with acetonitrile-water. Standard analytical curves were linear over the concentration range of 0.2-20 nmol/10 mg of liver. Precision and accuracy were within acceptable limits. Recovery from liver homogenates ranged from 93.03 to 112.29%. This method enabled the quantitation of fibric acids in 10 mg of liver from rats treated with clofibric acid, bezafibric acid or fenofibrate. From these analytical data, it became clear that there was no large difference in ratio of acyl-CoA oxidase 1 (Acox1) mRNA level to fibric acid content in the liver among the three fibric acids, suggesting that these three fibric acids have similar potency to increase expression of the Acox1 gene, which is a target of peroxisome proliferator-activated receptor α. Thus, the proposed method is a simple, sensitive and reliable tool for the quantitation of fibric acids working in vivo inside livers.

The human liver fatty acid binding protein T94A variant alters the structure, stability, and interaction with fibrates.

Although the human liver fatty acid binding protein (L-FABP) T94A variant arises from the most commonly occurring single-nucleotide polymorphism in the entire FABP family, there is a complete lack of understanding regarding the role of this polymorphism in human disease. It has been hypothesized that the T94A substitution results in the complete loss of ligand binding ability and function analogous to that seen with L-FABP gene ablation. This possibility was addressed using the recombinant human wild-type (WT) T94T and T94A variant L-FABP and cultured primary human hepatocytes. Nonconservative replacement of the medium-sized, polar, uncharged T residue with a smaller, nonpolar, aliphatic A residue at position 94 of the human L-FABP significantly increased the L-FABP α-helical structure content at the expense of ß-sheet content and concomitantly decreased the thermal stability. T94A did not alter the binding affinities for peroxisome proliferator-activated receptor α (PPARα) agonist ligands (phytanic acid, fenofibrate, and fenofibric acid). While T94A did not alter the impact of phytanic acid and only slightly altered that of fenofibrate on the human L-FABP secondary structure, the active metabolite fenofibric acid altered the T94A secondary structure much more than that of the WT T94T L-FABP. Finally, in cultured primary human hepatocytes, the T94A variant exhibited a significantly reduced extent of fibrate-mediated induction of PPARα-regulated proteins such as L-FABP, FATP5, and PPARα itself. Thus, while the T94A substitution did not alter the affinity of the human L-FABP for PPARα agonist ligands, it significantly altered the human L-FABP structure, stability, and conformational and functional response to fibrate.

Estimation of the PPARα agonism of fibrates by a combined MM-docking approach.

Fibrates are peroxisome proliferator-activated alpha receptor (PPARα) activators derived from fibric acid and are the most clinically used therapeutics in the treatment of hypertriglyceridemia. Recently, we reported a computational approach for the investigation of the binding properties of fibrates, characterized by similar carboxylic heads but differing in the size and orientation of the hydrophobic portion. This procedure is based on a combination of standard docking and molecular mechanics approaches to better describe the adaptation of the protein target to the bound ligand. The application of our approach to a set of 23 fibrates and the use of an effective regression procedure, allowed the development of predictive models of the PPARα agonism. The obtained models are characterized by good performances realizing a fair trade-off between accuracy and computational costs. The best model is more specialized in the ranking of fibrate agonists whose binding is mainly controlled by steric rather than by electronic modulation. Here, we describe in details the application of this computational procedure for the prediction of PPARα agonism of fibrate ligands.

Nutritional and metabolic status of HIV-positive patients with lipodystrophy during one year of follow-up.

OBJECTIVES: The aim of this prospective study was to compare changes in lipid metabolism and nutritional status after either 6 and 12 months of follow-up in subjects with lipodystrophy syndrome after traditional lifestyle therapy with or without fibric acid analogue intervention (bezafibrate and clofibrate). METHODS: Food intake, alterations in body composition and metabolic abnormalities were assessed in subjects with lipodystrophy syndrome at the beginning of the study. The nutritional status and metabolic alterations of the subjects were monitored, and the subjects received nutritional counseling each time they were seen. The subjects were monitored either two times over a period no longer than six months (Group A; n = 18) or three times over a period of at least 12 months (Group B; n = 35). All of the subjects underwent nutrition counseling that was based on behavior modification. The fibric acid analogue was only given to patients with serum triglyceride levels above 400 mg/dL. RESULTS: After six months of follow-up, Group A showed no alterations in the experimental parameters. After twelve months, there was a decrease in serum triglyceride levels (410.4 ± 235.5 vs. 307.7 ± 150.5 mg/dL, p < 0.05) and an increase in both HDLc levels (37.9 ± 36.6 vs. 44.9 ± 27.9 mg/dL, p,0.05) and lean mass (79.9 ± 7.8 vs. 80.3 ± 9.9 %, p < 0.05) in Group B. CONCLUSION: After one year of follow-up (three sessions of nutritional and medical counseling), the metabolic parameters of the subjects with lipodystrophy improved after traditional lifestyle therapy with or without fibric acid analogue intervention.

Prediction of the PPARα agonism of fibrates by combined MM-docking approaches.

Fibrates are peroxisome proliferator-activated alpha receptor (PPARα) activators derived from fibric acid and are the most clinically used therapeutics in the treatment of hypertriglyceridemia. Long standing studies on these drugs have accumulated a large body of experimental data about their biological activity and, more recently, on the molecular mechanism mediating their PPARα agonism. An immense interest for the discovery of new fibrates with improved potency and PPARα selectivity has stimulated many investigations toward a deeper understanding of structure-activity relationships controlling their activity. The present study aimed at investigating the binding properties of a set of 23 fibrates, characterized by similar carboxylic heads but differing in the size and orientation of the hydrophobic portion, using computational approaches. We combined standard docking and molecular mechanics approaches to better describe the adaptation of the protein target to the bound ligand. The agonist potencies were then regressed against the calculated binding energies to elaborate predictive model equations. The obtained models were characterized by good performances realizing a fair trade-off between accuracy and computational costs. The best model was obtained with a regression procedure allowing automatic generation of a training subset from the whole set of trials and filtering out outliers, thus highlighting the importance of regression strategies.

Iatrogenic hyperhomocysteinemia in patients with metabolic syndrome: a systematic review and metaanalysis.

Metabolic syndrome (MetS) is associated with increased cardiovascular mortality and its management incorporates hypolipidemic, antidiabetic and antihypertensive drugs. However, several classes of these drugs, such as biguanides, fibrates and hydrochlorothiazide have been reported to raise circulating total homocysteine (tHcy) levels. During the last decades, numerous large-scale epidemiological studies have identified Hcy as a moderate independent cardiovascular risk factor. Therefore, drug-induced hyperhomocysteinemia in MetS patients may add one cardiovascular risk factor in these high-risk patients. The present systematic review summarizes data from studies which investigated the effects of the above-mentioned drugs on tHcy, and calculates the treatment effect of each drug class on tHcy levels. We also discuss the underlying pathophysiology and the issues that should be addressed in the future.

Nutritional and metabolic status of HIV-positive patients with lipodystrophy during one year of follow-up

OBJECTIVES: The aim of this prospective study was to compare changes in lipid metabolism and nutritional status after either 6 and 12 months of follow-up in subjects with lipodystrophy syndrome after traditional lifestyle therapy with or without fibric acid analogue intervention (bezafibrate and clofibrate). METHODS: Food intake, alterations in body composition and metabolic abnormalities were assessed in subjects with lipodystrophy syndrome at the beginning of the study. The nutritional status and metabolic alterations of the subjects were monitored, and the subjects received nutritional counseling each time they were seen. The subjects were monitored either two times over a period no longer than six months (Group A; n = 18) or three times over a period of at least 12 months (Group B; n = 35). All of the subjects underwent nutrition counseling that was based on behavior modification. The fibric acid analogue was only given to patients with serum triglyceride levels above 400 mg/dL. RESULTS: After six months of follow-up, Group A showed no alterations in the experimental parameters. After twelve months, there was a decrease in serum triglyceride levels (410.4 ± 235.5 vs. 307.7 ± 150.5 mg/dL, p< 0.05) and an increase in both HDLc levels (37.9±36.6 vs. 44.9 ±27.9 mg/dL, p,0.05) and lean mass (79.9 ± 7.8 vs. 80.3 ± 9.9 percent, p< 0.05) in Group B. CONCLUSION: After one year of follow-up (three sessions of nutritional and medical counseling), the metabolic parameters of the subjects with lipodystrophy improved after traditional lifestyle therapy with or without fibric acid analogue intervention.

Optimal pharmacologic approach to patients with hypertriglyceridemia and low high-density lipoprotein-cholesterol: randomized comparison of fenofibrate 160 mg and niacin 1500 mg.

OBJECTIVES: Atherogenic dyslipidemia is emerging as a target of lipid-modifying therapy. However, an optimal pharmacologic approach has not yet been established. The aim of this study is to compare the efficacy and tolerability of the typical doses of fenofibrate and niacin. METHODS: After an eight-week dietary run-in, 201 patients who had triglyceride (TG) levels of 150-499 mg/dL, high-density lipoprotein-cholesterol (HDL-C) levels of <45 mg/dL and low-density lipoprotein-cholesterol (LDL-C) levels of <130 mg/dL were randomly assigned to one of two treatment groups for 16 weeks: fenofibrate 160 mg or niacin extended release 1500 mg (starting at 500 mg and up-titrated at the fifth and ninth weeks). RESULTS: One hundred forty patients completed the study. The percent reductions in apoB/A1 were not different between the two groups (-20% and -22% in the fenofibrate and niacin groups, respectively, p=0.47). The effects of the two regimens on HDL-C were similar (24% and 20%, respectively, p=0.22), while fenofibrate reduced TG more than did niacin (-53% and -48%, respectively, p=0.045). Niacin was more effective at lowering LDL-C, Lp (a), and hs-CRP. However, niacin worsened the parameters of glycemic control, whereas fenofibrate improved them. Niacin showed more frequent adverse events including pruritus and skin flushing. CONCLUSIONS: These two regimens have largely comparable lipid-modifying effects. However, their effects on glucose metabolism and inflammation, and their adverse events need to be considered additionally. Our results underscore more individualized pharmacologic approaches to patients with atherogenic dyslipidemia.

Tratamiento de la hipertrigliceridemia: fibratos frente a ácidos grasos omega-3 / Treatment of hypertriglyceridemia: fibrates versus omega-3 fatty acids

Por ser un componente del síndrome metabólico y de la diabetes, entidades que en la actualidad son epidémicas, la hipertrigliceridemia (HTG) asociada con valores bajos de colesterol unido a lipoproteínas de alta densidad (cHDL) es la dislipidemia de presentación clínica más frecuente. Además, es la alteración lipídica característica de pacientes con enfermedad cardiaca coronaria. La HTG se debe a un aumento de la síntesis hepática de las lipoproteínas de muy baja densidad (VLDL), en general por un exceso de grasa visceral, o a un defecto en el aclaramiento de VLDL por hipoactividad de la lipoproteinlipasa (LPL) de causa genética o adquirida, y con frecuencia hay un defecto doble. Además del cHDL bajo, la HTG se asocia con la formación de partículas LDL densas y pequeñas, que son muy aterogénicas. Esto justifica que la HTG sea un factor de riesgo cardiovascular independiente y deba tratarse con la misma intensidad que la hipercolesterolemia. Actualmente, se recomiendan como deseables unas cifras de triglicéridos (TG) <150 mg/dl. El tratamiento conservador de la HTG con dieta y normalización del peso es muy eficaz, pero difícil de realizar en la práctica. El tratamiento farmacológico convencional de la HTG son los fibratos, agentes que activan el factor de transcripción PPAR-α. Esto promueve la oxidación de ácidos grasos y estimula la actividad LPL, lo que reduce los TG, y aumenta la síntesis de apoproteínas de las HDL, lo que incrementa las cifras de cHDL. En promedio, los fibratos reducen los TG un 36% y aumentan el cHDL un 8%. En dosis de 2-4 g/día, los ácidos grasos n-3 (AGn-3) de origen marino son tan eficaces como los fibratos en la reducción de TG y carecen de efectos secundarios. Los AGn-3 también son ligandos de PPAR-α, pero reducen la síntesis de ácidos grasos por mecanismos independientes, lo cual justifica que su efecto de reducción de los TG sea complementario del de los fibratos. La eficacia de los AGn-3 en la reducción de TG se ha demostrado en monoterapia y en tratamiento combinado con estatinas. En la HTG grave del síndrome de quilomicronemia, los AGn-3 añaden su efecto al de los fibratos, con lo que se consiguen reducciones adicionales de los TG de hasta un 50% y se minimiza el riesgo de pancreatitis. Por tanto, los fibratos y los AGn-3 no están enfrentados, sino que son complementarios (AU)

Hypertriglyceridemia (HTG) combined with a low highdensity lipoprotein (HDL) cholesterol level is the characteristic lipid abnormality in two prevalent conditions: the metabolic syndrome and diabetes. Moreover, it is also the commonest dyslipidemia in patients with coronary heart disease. HTG is caused by increased hepatic synthesis of very-low-density lipoprotein (VLDL), usually due to excess visceral fat, or to defective VLDL clearance secondary to genetic or acquired impairment of lipoprotein lipase activity (LPL). Frequently, there is both excess VLDL input to the circulation and reduced clearance. In addition to a low HDL cholesterol level, HTG is also associated with the formation of small dense low-density lipoprotein (LDL) particles that are particularly atherogenic. This explains why HTG is an independent cardiovascular risk factor that must be treated as intensively as hypercholesterolemia. At present, a triglyceride concentration < 150 mg/dL is regarded as desirable. Conservative treatment of HTG by lifestyle modification involving diet and weight loss is very effective but difficult to implement. Fibrates are the conventional pharmacological treatment for HTG. These agents are activators of transcription factor PPAR-α, and consequently promote fatty acid oxidation and enhance LPL. This, in turn, reduces the serum level and stimulates synthesis of HDL apolipoproteins, thereby increasing the HDL cholesterol level. On average, fibrates reduce the level by 36% and increase HDL cholesterol by 8%. Given at a dose of 2-4 g/day, marine omega-3 fatty acids are as effective as fibrates in lowering the triglyceride level. Moreover, they are devoid of side effects. In addition, omega-3 fatty acids also interact with PPAR-α, although they decrease fatty acid synthesis by alternative mechanisms. This explains why the lowering effect of omega-3 fatty acids is complementary to that of fibrates. Omega-3 fatty acids have been found to be effective in lowering the, triglyceride level when given either as monotherapy or in combination with statins. In the severe HTG found with chylomicronemia syndromes, the effect of omega-3 fatty acids is additive to that of fibrates, resulting in an additional reduction in levels of up to 50% beyond that induced by fibrates alone, thereby minimizing the risk of acute pancreatitis. Consequently, fibrates and omega-3 fatty acids do not have opposing actions. Instead, they complement each other when used for the treatment of hypertriglyceridemia (AU)