Acylcarnitines: Nomenclature, Biomarkers, Therapeutic Potential, Drug Targets, and Clinical Trials.

Acylcarnitines are fatty acid metabolites that play important roles in many cellular energy metabolism pathways. They have historically been used as important diagnostic markers for inborn errors of fatty acid oxidation and are being intensively studied as markers of energy metabolism, deficits in mitochondrial and peroxisomal ß -oxidation activity, insulin resistance, and physical activity. Acylcarnitines are increasingly being identified as important indicators in metabolic studies of many diseases, including metabolic disorders, cardiovascular diseases, diabetes, depression, neurologic disorders, and certain cancers. The US Food and Drug Administration-approved drug L-carnitine, along with short-chain acylcarnitines (acetylcarnitine and propionylcarnitine), is now widely used as a dietary supplement. In light of their growing importance, we have undertaken an extensive review of acylcarnitines and provided a detailed description of their identity, nomenclature, classification, biochemistry, pathophysiology, supplementary use, potential drug targets, and clinical trials. We also summarize these updates in the Human Metabolome Database, which now includes information on the structures, chemical formulae, chemical/spectral properties, descriptions, and pathways for 1240 acylcarnitines. This work lays a solid foundation for identifying, characterizing, and understanding acylcarnitines in human biosamples. We also discuss the emerging opportunities for using acylcarnitines as biomarkers and as dietary interventions or supplements for many wide-ranging indications. The opportunity to identify new drug targets involved in controlling acylcarnitine levels is also discussed. SIGNIFICANCE STATEMENT: This review provides a comprehensive overview of acylcarnitines, including their nomenclature, structure and biochemistry, and use as disease biomarkers and pharmaceutical agents. We present updated information contained in the Human Metabolome Database website as well as substantial mapping of the known biochemical pathways associated with acylcarnitines, thereby providing a strong foundation for further clarification of their physiological roles.

Medium & long-chain acylcarnitine's relation to lipid metabolism as potential predictors for diabetic cardiomyopathy: a metabolomic study.

BACKGROUND: Acylcarnitine is an intermediate product of fatty acid oxidation. It is reported to be closely associated with the occurrence of diabetic cardiomyopathy (DCM). However, the mechanism of acylcarnitine affecting myocardial disorders is yet to be explored. This current research explores the different chain lengths of acylcarnitines as biomarkers for the early diagnosis of DCM and the mechanism of acylcarnitines for the development of DCM in-vitro. METHODS: In a retrospective non-interventional study, 50 simple type 2 diabetes mellitus patients and 50 DCM patients were recruited. Plasma samples from both groups were analyzed by high throughput metabolomics and cluster heat map using mass spectrometry. Principal component analysis was used to compare the changes occurring in the studied 25 acylcarnitines. Multivariable binary logistic regression was used to analyze the odds ratio of each group for factors and the 95% confidence interval in DCM. Myristoylcarnitine (C14) exogenous intervention was given to H9c2 cells to verify the expression of lipid metabolism-related protein, inflammation-related protein expression, apoptosis-related protein expression, and cardiomyocyte hypertrophy and fibrosis-related protein expression. RESULTS: Factor 1 (C14, lauroylcarnitine, tetradecanoyldiacylcarnitine, 3-hydroxyl-tetradecanoylcarnitine, arachidic carnitine, octadecanoylcarnitine, 3-hydroxypalmitoleylcarnitine) and factor 4 (octanoylcarnitine, hexanoylcarnitine, decanoylcarnitine) were positively correlated with the risk of DCM. Exogenous C14 supplementation to cardiomyocytes led to increased lipid deposition in cardiomyocytes along with the obstacles in adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathways and affecting fatty acid oxidation. This further caused myocardial lipotoxicity, ultimately leading to cardiomyocyte hypertrophy, fibrotic remodeling, and increased apoptosis. However, this effect was mitigated by the AMPK agonist acadesine. CONCLUSIONS: The increased plasma levels in medium and long-chain acylcarnitine extracted from factors 1 and 4 are closely related to the risk of DCM, indicating that these factors can be an important tool for DCM risk assessment. C14 supplementation associated lipid accumulation by inhibiting the AMPK/ACC/CPT1 signaling pathway, aggravated myocardial lipotoxicity, increased apoptosis apart from cardiomyocyte hypertrophy and fibrosis were alleviated by the acadesine.

Phosphate stress triggers the conversion of glycerol into l-carnitine in Pseudomonas fluorescens.

Glycerol, a by-product of the biofuel industry is transformed into l-carnitine when the soil microbe Pseudomonas fluorescens is cultured in a phosphate-limited mineral medium (LP). Although the biomass yield was similar to that recorded in phosphate-sufficient cultures (HP), the rate of growth was slower. Phosphate was completely consumed in the LP cultures while in the HP media, approximately 35 % of the initial phosphate was detected at stationary phase of growth. The enhanced production of α-ketoglutarate (KG) in HP cultures supplemented with manganese was recently reported (Alhasawi et al., 2017). l-carnitine appeared to be a prominent metabolite in the spent fluid while the soluble cellular-free extract was characterized with peaks attributable to lysine, γ-butyrobetaine (GB), acetate and succinate in the LP cultures. Upon incubation with glycerol and NH4Cl, the resting cells readily secreted l-carnitine and revealed the presence of such precursors like GB, lysine and methionine involved in the synthesis of this trimethylated moiety. Functional proteomic studies of select enzymes participating in tricarboxylic acid cycle (TCA), oxidative phosphorylation (OP), glyoxylate cycle and l-carnitine synthesis revealed a major metabolic reconfiguration evoked by phosphate stress. While isocitrate dehydrogenase-NAD+ dependent (ICDH-NAD+) and Complex I were markedly diminished, the activities of γ-butyrobetaine aldehyde dehydrogenase (GBADH) and l-carnitine dehydrogenase (CDH) were enhanced. Real-time quantitative polymerase chain reaction (RT-qPCR) analyses pointed to an increase in transcripts of the enzymes γ-butyrobetaine dioxygenase (bbox1), S-adenosylmethionine synthase (metK) and l-carnitine dehydrogenase (lcdH). The l-carnitine/γ-butyrobetaine antiporter (caiT) was enhanced more than 400-fold in the LP cultures compared to the HP controls. This metabolic reprogramming modulated by phosphate deprivation may provide an effective technology to transform glycerol, an industrial waste into valuable l-carnitine.

Prospective diagnosis of MT-ATP6-related mitochondrial disease by newborn screening.

Elevated citrulline and C5-OH levels are reported as part of the newborn screening of core and secondary disorders on the Recommended Uniform Screening Panel (RUSP). Additionally, some state laboratory newborn screening programs report low citrulline levels, which may be observed in proximal urea cycle disorders. We report six patients who were found on newborn screening to have low citrulline and/or elevated C5-OH levels in whom confirmatory testing showed the combination of these two abnormal analytes. Mitochondrial sequencing revealed known pathogenic variants in MT-ATP6 at high heteroplasmy levels in all cases. MT-ATP6 at these heteroplasmy levels is associated with Leigh syndrome, a progressive neurodegenerative disease. Patients were treated with supplemental citrulline and, in some cases, mitochondrial cofactor therapy. These six patients have not experienced metabolic crises or developmental regression, and early diagnosis and management may help prevent the neurological sequelae of Leigh syndrome. The affected mothers and siblings are asymptomatic or paucisymptomatic (e.g. intellectual disability, depression, migraines, obsessive-compulsive disorder, and poor balance) despite high heteroplasmy or apparent homoplasmy of the familial variant, thus expanding the clinical spectrum seen in pathogenic variants of MT-ATP6. Confirmatory plasma amino acid analysis and acylcarnitine profiling should be ordered in a patient with either low citrulline and/or elevated C5-OH, as this combination appears specific for pathogenic variants in MT-ATP6.

Safety indicators of a novel multi supplement based on guarana, selenium, and L-carnitine: Evidence from human and red earthworm immune cells.

Neurodegenerative diseases are associated with chronic inflammatory states. There is evidence to support the design of novel supplements based on guarana (G) (Paullinia cupana), selenium (S), and L-carnitine (C), the use of which, potentially attenuates neuro oxi-inflammatory conditions. Therefore, this study analyzed the cytotoxic and redox effects of GSC on human leucocytes, the inflammatory activation of microglia BV-2 cells, and effect on mortality, oxidative metabolism, and the immune modulation of red earthworms (Eisenia fetida). The GSC concentrations tested in cell culture were in the range of 0.04-2.1 mg/mL. All the GSC-supplemented samples tested, reverted H2O2 oxidation in DNA molecules, suggesting its genoprotective potential. GSC did not induce mortality in leucocyte cultures. On the contrary, a reduction in the levels of oxidation of lipids, proteins, and cell apoptosis was observed, via downregulation of caspase 3 and 8 genes. GSC showed a dual effect on microglia, decreasing the cellular proliferation at lower concentrations (<0.24 mg/mL) and increasing the cellular proliferation mainly at concentrations > 1.0 mg/mL. GSC did not have a toxic effect on red earthworms, but induced an increase in amoebocyte cells and in brown body formation, indicating immune response activation. The results suggest that GSC could be safe for human consumption.

A redox-activatable biopolymer-based micelle for sequentially enhanced mitochondria-targeted photodynamic therapy and hypoxia-dependent chemotherapy.

A tumor redox-activatable micellar nanoplatform based on the naturally occurring biomacromolecule hyaluronic acid (HA) was developed for complementary photodynamic/chemotherapy against CD44-positive tumors. Here HA was first conjugated with l-carnitine (Lc)-modified zinc phthalocyanine (ZnPc) via disulfide linkage and then co-assembled with tirapazamine (TPZ) to afford the physiologically stable micellar nanostructure. The mitochondria-targeted photodynamic activity of ZnPc-Lc could efficiently activate the mitochondrial apoptosis cascade and deplete the oxygen in the tumor intracellular environment to amplify the hypoxia-dependent cytotoxic effect of TPZ.

L-carnitine supplementation in culture media improves the pregnancy rate of in vitro produced embryos with sexed semen from Bos taurus indicus cows.

The in vitro embryo production industry in the actual world presents some difficulties related to low embryonic production rates, a problem that could be associated with in vitro culture conditions that differed from the in vivo (oviductal) conditions, mainly related to cytoplasmic lipid accumulation. L-carnitine is known as a modulator of ß-oxidation in the developing embryo, as it has been demonstrated that it improves embryo quality without affecting the in vitro embryo production rate. The aim of the present work was to evaluate the effect of L-carnitine supplemented during the in vitro maturation and culture processes on the implantation rate of in vitro produced embryos. Supplementation with 3.8 mM of L-carnitine was used during in vitro maturation, and later, during late in vitro culture, it was added at 1.5 mM. A control group contained no L-carnitine supplementation. Bovine oocytes obtained by ultrasound-guided follicle aspiration from healthy Bos taurus indicus cows were matured, fertilized and cultured in vitro. Multiparous F1 (Bos taurus taurus × Bos taurus indicus) cows were used as recipients. Overall, 460 oocytes were processed in three independent replicates from in vitro maturation until day 8 of the in vitro culture. No significant difference was found between treatments of in vitro embryo production. However, pregnancy rate at days 45 and 72 was significantly higher in blastocysts derived from L-carnitine treatment (31.55 ± 9.78%) compared to the control group (18.68 ± 6.31%). In conclusion, addition of L-carnitine at 3.8 mM and 1.5 mM in the maturation, and culture medium after day 3 of in vitro production process, significantly improved pregnancy rate after embryo transfer.

Fermented Wild Ginseng by Rhizopus oligosporus Improved l-Carnitine and Ginsenoside Contents.

We conducted this study to investigate the beneficial effects of Rhizopus oligosporus fermentation of wild ginseng on ginsenosides, l-carnitine contents and its biological activity. The Rhizopus oligosporus fermentation of wild ginseng was carried out at 30 °C for between 1 and 14 days. Fourteen ginsenosides and l-carnitine were analyzed in the fermented wild ginseng by the ultra high pressure liquid chromatography-mass spectrometry (UPLC-MS) system. Our results showed that the total amount of ginsenosides in ginseng increased from 3,274 to 5,573 mg/kg after 14 days of fermentation. Among the 14 ginsenosides tested, the amounts of 13 ginsenosides (Rg1, Rb2, Rb3, Rc, Rd, Re, Rf, Rg2, Rg3, Rh1, compound K, F1 and F2) increased, whereas ginsenoside Rb1 decreased, during the fermentation. Furthermore, l-carnitine (630 mg/kg) was newly synthesized in fermented ginseng extract after 14 days. In addition, both total phenol contents and DPPH radical scavenging activities showed an increase in the fermented ginseng with respect to non-fermented ginseng. These results show that the fermentation process reduced the cytotoxicity of wild ginseng against RAW264.7 cells. Both wild and fermented wild ginseng showed anti-inflammatory activity via inhibition of nitric oxide synthesis in RAW264.7 murine macrophage cells.

L-Carnitine Is Involved in Hyperbaric Oxygen-Mediated Therapeutic Effects in High Fat Diet-Induced Lipid Metabolism Dysfunction.

Lipid metabolism dysfunction and obesity are serious health issues to human beings. The current study investigated the effects of hyperbaric oxygen (HBO) against high fat diet (HFD)-induced lipid metabolism dysfunction and the roles of L-carnitine. C57/B6 mice were fed with HFD or normal chew diet, with or without HBO treatment. Histopathological methods were used to assess the adipose tissues, serum free fatty acid (FFA) levels were assessed with enzymatic methods, and the endogenous circulation and skeletal muscle L-carnitine levels were assessed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, western blotting was used to assess the expression levels of PPARα, CPT1b, pHSL/HSL, and UCP1. HFD treatment increased body/adipose tissue weight, serum FFA levels, circulation L-carnitines and decreased skeletal muscle L-carnitine levels, while HBO treatment alleviated such changes. Moreover, HFD treatment increased fatty acid deposition in adipose tissues and decreased the expression of HSL, while HBO treatment alleviated such changes. Additionally, HFD treatment decreased the expression levels of PPARα and increased those of CPT1b in skeletal muscle, while HBO treatment effectively reverted such changes as well. In brown adipose tissues, HFD increased the expression of UCP1 and the phosphorylation of HSL, which was abolished by HBO treatment as well. In summary, HBO treatment may alleviate HFD-induced fatty acid metabolism dysfunction in C57/B6 mice, which seems to be associated with circulation and skeletal muscle L-carnitine levels and PPARα expression.

Carnitine in Human Muscle Bioenergetics: Can Carnitine Supplementation Improve Physical Exercise?

l-Carnitine is an amino acid derivative widely known for its involvement in the transport of long-chain fatty acids into the mitochondrial matrix, where fatty acid oxidation occurs. Moreover, l-Carnitine protects the cell from acyl-CoA accretion through the generation of acylcarnitines. Circulating carnitine is mainly supplied by animal-based food products and to a lesser extent by endogenous biosynthesis in the liver and kidney. Human muscle contains high amounts of carnitine but it depends on the uptake of this compound from the bloodstream, due to muscle inability to synthesize carnitine. Mitochondrial fatty acid oxidation represents an important energy source for muscle metabolism particularly during physical exercise. However, especially during high-intensity exercise, this process seems to be limited by the mitochondrial availability of free l-carnitine. Hence, fatty acid oxidation rapidly declines, increasing exercise intensity from moderate to high. Considering the important role of fatty acids in muscle bioenergetics, and the limiting effect of free carnitine in fatty acid oxidation during endurance exercise, l-carnitine supplementation has been hypothesized to improve exercise performance. So far, the question of the role of l-carnitine supplementation on muscle performance has not definitively been clarified. Differences in exercise intensity, training or conditioning of the subjects, amount of l-carnitine administered, route and timing of administration relative to the exercise led to different experimental results. In this review, we will describe the role of l-carnitine in muscle energetics and the main causes that led to conflicting data on the use of l-carnitine as a supplement.

Boric acid and Borax Supplementation Reduces Weight Gain in Overweight Rats and Alter L-Carnitine and IGF-I Levels.

The aim of this study was to investigate the effects of boric acid (BA) and borax (BX) on live weight and obesity associated molecules including leptin, L-carnitine, insulin-like growth factor 1 (IGF-I), and heat shock proteins 70 (HSP70) in rats fed with high-fat diet. A total of 60 rats were equally allocated as ND (normal diet), HF (high-fat diet), HF+BA, HF+BX, ND+BX, ND+BA. Body weight increases in HF+BA (85 g) and HF+BX (86 g) were significantly lower (p<0.05) compared to HF group (126 g). Boron treatment decreased serum L-carnitine level in high-fat diet (HF+BA 11.12 mg/L, HF+BX 10.51 mg/L, p<0.05) compared to HF group (15.57 mg/L), while no change was observed in groups ND+BA (7.55 mg/L) and ND+BX (7.57 mg/L) compared to group ND (8.29 mg/L). Neither BA nor BX supplementation in ND and HF groups altered the serum levels of HSP70 and leptin. BA and BX supplementation in rats fed HF resulted in a significant reduction in live weight. Boron compounds altered L-carnitine and IGF-1 levels in rats. These results indicate that boron compounds are beneficial in the treatment of obesity as well as in the prevention of high-fat diet-induced weight increase. Alterations in serum L-carnitine and IGF-1 levels in boron treated rats also indicate possible role of boron compounds in energy metabolism in response to high fat diet.

Heat-inactivated coelomic fluid of the earthworm Perionyx excavatus is a possible alternative source for fetal bovine serum in animal cell culture.

Fetal Bovine Serum (FBS) is used as a major supplement in culturing animal cells under in vitro conditions. Due to ethical concern, high cost, biosafety, and geographical as well as batchwise result variations, it is important to reduce or replace the use of FBS in animal cell culture. The major objective of this work is to evaluate the feasibility of heat-inactivated coelomic fluid (HI-CF) of the earthworm, Perionyx excavatus as a possible alternative for FBS in animal cell culture experiments. The coelomic fluid (CF) was extruded from the earthworm using electric shock method and used for the experiments. Electric shock method is a simple non-invasive technique, which has no harmful effect on earthworms. Mouse primary fibroblast and HeLa cell lines were used in this study. Among HI-CF, autoclaved CF and crude CF, the supplement of medium with HI-CF shows positive results. The processed HI-CF (90°C for 5 min) at 10% supplement in cell culture medium promote maximum cell growth but cells need the initial support of FBS for the attachment to the culture flask. Microscopic observation and immunofluorescence assay with actin and lamin A confirm that the cellular and molecular morphology of the cells is maintained intact. The HI-CF of earthworm, P. excavatus has shown better cellular viability when compared with FBS and making it possible as an alternative supplement to minimize the use of FBS.

Development of High Capacity Enterosorbents for Aflatoxin B1 and Other Hazardous Chemicals.

Previously, a calcium montmorillonite clay (NovaSil) included in the diet of animals has been shown to bind aflatoxin B1 (AfB1) and reduce the symptoms of aflatoxicosis. To investigate and improve the capacity and efficacy of clay-based materials as aflatoxin sorbents, we developed and tested calcium and sodium montmorillonite clays amended with nutrients including l-carnitine and choline. Also, we determined the sorption of AfB1 by isothermal analysis and tested the ability of these amended sorbents to protect adult hydra from AfB1 toxicity. The results showed that exchanging montmorillonite clays with l-carnitine and choline inhibited swelling of the clays and increased the sorption capacity and efficacy of clay surfaces for AfB1. Results from dehydroxylated and heat-collapsed clays suggested that AfB1 was primarily adsorbed in the clay interlayer, as predicted from thermodynamic calculations and computational modeling. The hydra bioassay further indicated that the modified clays can significantly protect adult hydra from AfB1 with as low as 0.005% clay inclusion. This enterosorbent therapy may also be applied to screen hazardous chemicals such as pesticides and PAHs based on similar sorption mechanisms. Taken together, enterosorbent therapy could be delivered in nutritional supplements, foods that are vulnerable to aflatoxin contamination, flavored liquids and animal feeds during emergencies and outbreaks of acute aflatoxicosis, and as a screening model for hazardous environmental chemicals.

Cryosurvival of in vitro produced bovine embryos supplemented with l-Carnitine and concurrent reduction of fatty acids.

Lipid accumulation is associated with reduced embryonic quality, causing limited survival after cryopreservation. Therefore, in the present study we aimed to reveal the effects of supplementation of a lipid reducing agent, l-carnitine and the removal of fatty acids during in vitro culture on the morphological as well as on the molecular level. To accomplish that, presumptive zygotes were cultured in 4 contrasting groups: namely SOFaa medium supplemented with BSA, (BSA), SOFaa medium supplemented with fatty acid free BSA (FAF), SOFaa medium supplemented with BSA as well as l-Carnitine (BSA + LC) and SOFaa medium concurrently supplemented with fatty acid free BSA and l-Carnitine (FAF + LC). Considering the developmental rates, no impact of different treatments was observed. Conversely, treatment groups clearly affected lipid content, with the lowest amounts detected in embryos derived from FAF and BSA + LC groups, implicating that both removal of fatty acids and supplementation of LC reduces lipid content effectively. Importantly, survival rates after cryopreservation show that LC significantly affects the kinetics of re-expansion, with the highest hatching rates detected for embryos cultured in FAF + LC (p < 0.05). Noteworthy, the highest cryotolerance did not go along with lowest lipid contents. Finally, metabolic alterations between the groups were reflected in different abundances of selected candidate genes related to lipid metabolism and oxidative stress response, like AMPKA1, ACC and PGC1 α or KEAP1 and SOD1. All in all, highly beneficial effects on survival rates after cryopreservation have been detected when embryos were cultured in absence of fatty acids and concurrent presence of l-Carnitine. Highest cryotolerance, however, did not correlate with lowest lipid contents.

Identification of l-carnitine and its impurities in food supplement formulations by online column-switching liquid chromatography coupled with linear ion trap mass spectrometry.

The identification of impurities in l-carnitine by mass spectrometry is difficult because derivative reagents or ion pair reagents are usually used to separate and increase the retention of l-carnitine on the reversed-phase column. In this study, four impurities including 3-chloro-2-hydroxy-N,N,N-trimethylpropan-1-aminium, 3-cyano-2-hydroxy-N,N,N-trimethylpropan-1-aminium, 3-carboxy-N,N,N-trimethylprop-2-en-1-aminium, and 4-chloro-2,3,4-trihydroxy-N,N,N-trimethylbutan-1-aminium were identified in l-carnitine and its tablets by using two-dimensional column-switching high-performance liquid chromatography coupled with linear ion trap mass spectrometry. The first column was a C8 column at a flow rate of 0.15 mL/min; the detection wavelength was 220 nm. The second column was an Acclaim Q1 column using a gradient elution program with aqueous 30 mM ammonium acetate (pH 5.0) and acetonitrile as the mobile phase at a flow rate of 0.5 mL/min. The mass fragmentation patterns and structural assignments of impurities were studied, and the quantitative validation of three impurities was further investigated. The linearity (r2 ) was found to be >0.99, with ranges from 0.2 to 50 ng/mL and 0.1 to 10 ng/mL. The method was used successfully for determination of impurities in five samples of l-carnitine and tablets.

Effects of weight loss using supplementation with Lactobacillus strains on body fat and medium-chain acylcarnitines in overweight individuals.

Our previous study showed that supplementation with a combination of Lactobacillus curvatus (L. curvatus) HY7601 and Lactobacillus plantarum (L. plantarum) KY1032 reduced the body weight, body fat percentage, body fat mass and L1 subcutaneous fat area in overweight subjects. We aimed to evaluate whether the changes in adiposity after supplementation with Lactobacillus strains were associated with metabolic intermediates. A randomized, double-blind, placebo-controlled study was conducted on 66 non-diabetic and overweight individuals. Over a 12-week period, the probiotic group consumed 2 g of probiotic powder, whereas the placebo group consumed the same product without the probiotics. To investigate metabolic alterations, we performed plasma metabolomics using ultra-performance liquid chromatography and mass spectrometry (UPLC-LTQ/Orbitrap MS). Probiotic supplementation significantly increased the levels of octenoylcarnitine (C8:1), tetradecenoylcarnitine (C14:1), decanoylcarnitine (C10) and dodecenoylcarnitine (C12:1) compared with the levels from placebo supplementation. In the probiotic group, the changes in the body weight, body fat percentage, body fat mass and L1 subcutaneous fat area were negatively associated with changes in the levels of C8:1, C14:1, C10 and C12:1 acylcarnitines. In overweight individuals, probiotic-induced weight loss and adiposity reduction from the probiotic supplementation were associated with an increase in medium-chain acylcarnitines.

Developmental regulation and modulation of apoptotic genes expression in sheep oocytes and embryos cultured in vitro with L-carnitine.

The objective of this study was to find out the impact of L-carnitine (10 mM) on developmental regulation of preimplantation sheep embryos cultured in vitro when supplemented in maturation medium and post-fertilization medium separately. Subsequent objective was to observe the L-carnitine-mediated alteration in expression of apoptotic genes (Bcl2, Bax, Casp3 and PCNA) in sheep oocytes and developing embryos produced in vitro. Oocytes matured with L-carnitine showed significantly (p < .05) higher cleavage (67.23% vs 43.12%), morula (47.65% vs 28.58%) and blastocysts (32.12% vs 13.24%) percentage as compared to presumptive zygotes cultured with L-carnitine during post-fertilization period. So it is suggested to use L-carnitine during maturation than post-fertilization period. Antiapoptotic and proliferative effects of L-carnitine were confirmed by inducing culture medium with actinomycin D (apoptotic agent) and TNFα (antiproliferative agent), respectively, with and without L-carnitine. Oocytes and embryos cultured with actinomycin D and TNFα showed developmental arrest with significant (p < .05) decrease in morula and blastocysts percentage but supplementation of L-carnitine to actinomycin D and TNFα induced culture medium showed similar result as that of control. L-carnitine supplementation during IVM significantly (p < .05) upregulated the expression of Bcl2 and PCNA genes in majority of the developmental stages. Although L-carnitine upregulated the expression of Bax in initial developmental stages but downregulated at latter part, whereas the expression of Casp3 was upregulated upto 16-cell stage but after that there was no difference in expression. Expression of GAPDH gene was not affected by L-carnitine supplementation. In conclusion, L-carnitine acted as an antiapoptotic and proliferative compound during embryo development and supplementation of L-carnitine during IVM altered the expression of apoptotic genes in the developmental stages of embryos.

Medium-chain dicarboxylic acylcarnitines as markers of n-3 PUFA-induced peroxisomal oxidation of fatty acids.

SCOPE: Omega-3 polyunsaturated fatty acids (n-3 PUFA) found in fish oil activate PPAR-α, stimulate peroxisomal fatty acid (FA) ß-oxidation and prevent impairments on glucose homeostasis. METHODS AND RESULTS: Glucose metabolism and FA oxidation were studied in C57/Bl6 mice fed with diets containing either 3.6 and 31.5% fish oil or lard. To assess the effects of peroxisomal proliferation on FA oxidation independent of n-3 PUFA intake, mice were treated with the PPAR-α agonist WY-14643. n-3 PUFA-fed mice were protected from glucose intolerance and dyslipidemia compared to animals fed a lard-based high-fat diet. Most importantly, mice fed on the hyperlipidic diet based on fish oil as well as the WY-14643 treated mice showed twofold increase of odd, medium-chain, dicarboxylic acylcarnitines in the liver suggesting that not only ß-oxidation, but also α- and ω-oxidation of FA were increased. Finally, an oxidation assay using liver homogenates and palmitic acid as substrate revealed an over tenfold increased production of similar acylcarnitines, indicating that FA are their precursors. CONCLUSION: This study shows at the metabolite level that peroxisome proliferation induced either by fish oil or WY-14643 is associated with increased α- and ω-oxidation of FA producing specific acylcarnitines that can be utilized as biomarkers of peroxisomal FA oxidation.

L-carnitine is a calcium chelator: a reason for its useful and toxic effects in biological systems.

BACKGROUND: Investigation of the direct link between l-carnitine (LC), a quaternary ammonium compound that facilitates the passage of unsaturated fatty acids into the mitochondrial matrix, and free calcium (Ca2+) is needed to explain a number of varying results obtained from different in vitro and in vivo studies of LC as a supplement. METHODS: The chemical structure of LC, which contains oxygen ligand atoms, prompted to measure its activity asa Ca2+ chelator. The measurement was carried out spectrophotometri cally by measuring the reduction in the formation of Ca2+-o-cresolphthalein complexone (Ca-CPC) in the presence of different doses of LC (0.075, 0.75, and 7.5 mM) compared to the control (0.0 mM LC). RESULTS: The effect of LC was measured as a free entity in solution and when added to human serum. Our results showed a significant decrease (p < 0.05) in the average absorbance of Ca-CPC in the presence of LC compared to the control. CONCLUSIONS: In conclusion, LC exhibits a significant Ca2+ chelating activity. As Ca2+ is vital in the biochemical and physiological processes of living cells, LC could be affecting the calcium-dependent biological systems by limiting the levels of free Ca2+. Examples include decelerating the blood clotting process, amplifying the effect of anticoagulants, reducing nitric oxide synthase activity, inhibiting

Targeted metabolomic study indicating glycyrrhizin's protection against acetaminophen-induced liver damage through reversing fatty acid metabolism.

The present study aimed to give a short report on a possible mechanism of glycyrrhizin to acetaminophen-induced liver toxicity. Seven-day intraperitoneal administration of glycyrrhizin (400 mg/kg/day) to 2- to 3-month-old male C57BL/6N mice (mean weight 27 g) significantly prevents acetaminophen-induced liver damage, as indicated by the activity of alanine transaminase and aspartate aminotransferase. Metabolomics analysis and principal component analysis (PCA) using ultra-fast liquid chromatography coupled to triple time-of-flight mass spectrometer were performed. PCA separated well the control, glycyrrhizin-treated, acetaminophen-treated, and glycyrrhizin+acetaminophen-treated groups. Long-chain acylcarnitines were listed as the top ions that contribute to this good separation, which include oleoylcarnitine, palmitoylcarnitine, palmitoleoylcarnitine, and myristoylcarnitine. The treatment of glycyrrhizin significantly reversed the increased levels of long-chain acylcarnitines induced by acetaminophen administration. In conclusion, this metabolomic study indicates a significant glycyrrhizin protection effect against acetaminophen-induced liver damage through reversing fatty acid metabolism.