Carnitine Analogs Research Articles

Study of the drug “Kapikor” influence on the endothelial dysfunction in rats with doxorubicin cardiomyopathy

Topicality. An alternative solution in terms of modern anti-ischemic therapy optimization is a combination of metabolic and hemodynamic concepts – joint use of precursors and carnitine analogs – meldonium and gamma-butyrobetaine (GBB). Pharmacodynamic benefits of these substances combined use are characterized by synergetic phenomenon in the form of mutual potentiation of their effects, it is displayed in the drug “Kapikor”.Aim. The aim of this work was the experimental study of the drug “Kapikor” on endothelial dysfunction in rats with doxorubicin cardiomyopathy.Materials and methods. The drug “Kapikor” and its cardioprotective properties study was carried out on the model of doxorubicin cardiomyopathy (DCM) in 90 white nonlinear rats.Results and discussion. At the conditions of doxorubicin cardiomyopathy development it was shown that the cardioprotective properties of the drug “Kapikor” course, which is associated with the presence of metabolic, endothelialprotective, anti-ischemic, antihypoxic, antioxidant and anticytolitic, preconditioning activity. According to the combination of studied parameters in this disease model “Kapikor” excels the objects of comparison Mildronat and GBB.Conclusions. The combined use of GBB and meldonium in the composition of “Kapikor” provides its monocomponents mutual modifying influence on indicators characterizing the inflammatory and destructive, degenerative-dystrophic and ischemic nature of myocardial dystrophy flow and has general protective influence on the cardioprotective effect level of the drug.

A comparative study of «Capicor» safety in acute experiment

One of the main reasons in the pathogenesis of chronic ischemia is endothelial dysfunction. Combined use of carnitine precursors and carnitine analogs (Meldonium and γ-butyrobetaine (GBB)) is an interesting decision in terms of optimization of modern anti-ischemic therapy. The presented concept became to the basis for the development of the original regulator of vascular endothelial function with the trade name «Capicor», which combines the advantages of Meldonium as metabolic cytoprotector and GBB as endothelial corrector. The results of experimental researches on comparative study of «Capicor» acute toxicity were presented in the article. «Capicor» is identical to the reference drug «Mildronate» by toxicological characteristics. Pre-clinical study results indicate that «Capicor» is practically non-toxic drug and allow to attribute «Capicor» to the V-th toxicity class according to K.K. Sidorov classification. There are practically non-toxic substances. This is the basis for further «Capicor» study for the purpose of introduction into clinical practice as a metabolic action for the treatment of diseases in the pathogenesis of which endothelial dysfunction has a leading position.

Over-expression in Escherichia coli, purification and reconstitution in liposomes of the third member of the OCTN sub-family: The mouse carnitine transporter OCTN3

pET-21a(+)-mOCTN3-6His was constructed and used for over-expression in Escherichia coli Rosetta(DE3)pLysS. After IPTG induction a protein with apparent molecular mass of 53kDa was collected in the insoluble fraction of the cell lysate and purified by Ni2+-chelating chromatography with a yield of 2mg/l of cell culture. The over-expressed protein was identified with mOCTN3 by anti-His antibody and reconstitution in liposomes. mOCTN3 required peculiar conditions for optimal expression and reconstitution in liposomes. The protein catalyzed a time dependent [3H]carnitine uptake which was stimulated by intraliposomal ATP and nearly independent of the pH. The Km for carnitine was 36μM. [3H]carnitine transport was inhibited by carnitine analogues and some Cys and NH2 reagents. This paper represents the first outcome in over-expressing, in active form, the third member of the OCTN sub-family, mOCTN3, in E. coli.

Update on critical evidence for use of carnitine analogs in clinical practice in CNS disorders

Update on critical evidence for use of carnitine analogs in clinical practice in CNS disorders Giovanna TrainaDepartment of Economics and Food Sciences, University of Perugia, Perugia, ItalyAbstract: L-carnitine (LC) is part of the carnitine shuttle system at the mitochondrial inner membrane (MIM) and transports long chain fatty acids over the MIM route. Acetyl-L -carnitine (ALC), the acetyl ester of LC, plays an essential role in intermediary metabolism. To ALC are ascribed neurotrophic actions, antioxidant and antiapoptotic activity, positive effects on mitochondrial metabolism, and stabilization of intracellular membranes. Acylcarnitine and LC supplementation have shown beneficial effects in the treatment of aging, chronic degenerative pathologies and the slowing of the progression of mental deterioration in neurodegenerative diseases, and painful neuropathies. ALC is reported to affect brain energy and phospholipid metabolism and to interact with cell membranes, proteins, and enzymes. It also shows a neuromodulatory effect on synaptic morphology and neurotransmitter synaptic transmission, including that of acetylcholine and dopamine. All these data suggest that ALC can affect several targets in the central nervous system. The roles and effects of LC and ALC have led researchers to investigate carnitine's involvement in a variety of neuropathological states and treatments, including autism, Parkinson's disease, Alzheimer's disease, Down's syndrome, Huntington's disease, cerebellar ataxia, age-associated mental decline, hepatic encephalopathy, and ammonia neurotoxicity. This review summarizes evidence that carnitine analogs play many roles in serious neurological pathologies.Keywords: L-carnitine, acetyl-L-carnitine, brain, neural disorders

Involvement of Carnitine/organic Cation Transporter OCTN2 (SLC22A5) in Distribution of its Substrate Carnitine to the Heart

This study was designed to clarify the pharmacological role of carnitine/organic cation transporter (Octn) family members in mouse heart. Immunohistochemical analysis revealed that Octn1 was exclusively expressed on endothelial cells in blood vessels. Octn2 was detected on the plasma membrane of cardiac muscle cells by immunoelectron microscopy. Octn3 was not detected in the heart. Integration plot analysis showed that coadministration of unlabeled L-carnitine reduced distribution of L-[3H]carnitine to the heart. L-[3H]Carnitine uptake in heart slices was reduced by carnitine analogs and various Octn2 substrates. L-[3H]Carnitine uptake by heart slices from juvenile visceral steatosis (jvs) mice, which have a hereditary octn2 gene deficiency, was negligible. Distribution of [3H]quinidine, another Octn2 substrate, to the heart was not reduced by L-carnitine, and [3H]quinidine uptake in heart slices was Na(-)-independent and inhibited by cationic drugs, but not carnitine analogs. [3H]Quinidine uptake by heart slices from jvs mice was similar to that of wild-type mice. These results demonstrate that OCTN2 is functionally expressed on the plasma membrane of muscle cells and is involved in distribution of carnitine to the heart. Some mechanism(s) other than OCTN2 is involved in the distribution of quinidine to the heart.

Effect of carnitines on Lactobacillus plantarum subjected to osmotic stress

We investigated the effect of carnitine analogues on the physiology of Lactobacillus plantarum subjected to salt stress. Salt stressed cells of L. plantarum accumulated exogenously provided carnitine and its structural analogues acetylcarnitine and propionylcarnitine to maximum concentrations of 466, 122 and 75 μmol (g dry weight of cells)−1, respectively. Addition of these carnitines to osmotically stressed medium increased growth rate. Furthermore, the intracellular amino acid pool, consisting of mainly aspartate and glutamate, was reduced when carnitine, acetylcarnitine or propionylcarnitine were included in the medium. This is the first study demonstrating a role for β-substituted acylcarnitine esters in osmoadaptation of a lactic acid bacterium.

Carnitine/organic cation transporter OCTN2-mediated transport of carnitine in primary-cultured epididymal epithelial cells

Carnitine is essential for the acquisition of motility and maturation of spermatozoa in the epididymis, and is accumulated in epididymal fluid. In this study, carnitine transport into primary-cultured rat epididymal epithelial cells was characterized to clarify the nature of the transporter molecules involved. Uptake of carnitine by primary-cultured epididymal epithelial cells was time, Na(+) and concentration dependent. Kinetic analysis of carnitine uptake by the cells revealed the involvement of high- and low-affinity transport systems with Km values of 21 microM and 2.2 mM respectively. The uptake of carnitine by the cells was significantly reduced by inhibitors of carnitine/organic cation transporter (OCTN2), such as carnitine analogues and cationic compounds. In RT-PCR analysis, OCTN2 expression was detected. These results demonstrated that the high-affinity carnitine transporter OCTN2, which is localized at the basolateral membrane of epididymal epithelial cells, mediates carnitine supply into those cells from the systemic circulation as the first step of permeation from blood to spermatozoa.

Gbu glycine betaine porter and carnitine uptake in osmotically stressed Listeria monocytogenes cells.

The food-borne pathogen Listeria monocytogenes grows actively under high-salt conditions by accumulating compatible solutes such as glycine betaine and carnitine from the medium. We report here that the dominant transport system for glycine betaine uptake, the Gbu porter, may act as a secondary uptake system for carnitine, with a K(m) of 4 mM for carnitine uptake and measurable uptake at carnitine concentrations as low as 10 microM. This porter has a K(m) for glycine betaine uptake of about 6 micro M. The dedicated carnitine porter, OpuC, has a K(m) for carnitine uptake of 1 to 3 microM and a V(max) of approximately 15 nmol/min/mg of protein. Mutants lacking either opuC or gbu were used to study the effects of four carnitine analogs on growth and uptake of osmolytes. In strain DP-L1044, which had OpuC and the two glycine betaine porters Gbu and BetL, triethylglycine was most effective in inhibiting growth in the presence of glycine betaine, but trigonelline was best at inhibiting growth in the presence of carnitine. Carnitine uptake through OpuC was inhibited by gamma-butyrobetaine. Dimethylglycine inhibited both glycine betaine and carnitine uptake through the Gbu porter. Carnitine uptake through the Gbu porter was inhibited by triethylglycine. Glycine betaine uptake through the BetL porter was strongly inhibited by trigonelline and triethylglycine. These results suggest that it is possible to reduce the growth of L. monocytogenes under osmotically stressful conditions by inhibiting glycine betaine and carnitine uptake but that to do so, multiple uptake systems must be affected.

Functional relevance of carnitine transporter OCTN2 to brain distribution of L-carnitine and acetyl-L-carnitine across the blood-brain barrier.

Transport of L-[3H]carnitine and acetyl-L-[3H]carnitine at the blood-brain barrier (BBB) was examined by using in vivo and in vitro models. In vivo brain uptake of acetyl-L-[3H]carnitine, determined by a rat brain perfusion technique, was decreased in the presence of unlabeled acetyl-L-carnitine and in the absence of sodium ions. Similar transport properties for L-[3H]carnitine and/or acetyl-L-[3H]carnitine were observed in primary cultured brain capillary endothelial cells (BCECs) of rat, mouse, human, porcine and bovine, and immortalized rat BCECs, RBEC1. Uptakes of L-[3H]carnitine and acetyl-L-[3H]carnitine by RBEC1 were sodium ion-dependent, saturable with K(m) values of 33.1 +/- 11.4 microM and 31.3 +/- 11.6 microM, respectively, and inhibited by carnitine analogs. These transport properties are consistent with those of carnitine transport by OCTN2. OCTN2 was confirmed to be expressed in rat and human BCECs by an RT-PCR method. Furthermore, the uptake of acetyl-L-[3H]carnitine by the BCECs of juvenile visceral steatosis (jvs) mouse, in which OCTN2 is functionally defective owing to a genetical missense mutation of one amino acid residue, was reduced. The brain distributions of L-[3H]carnitine and acetyl-L-[3H]carnitine in jvs mice were slightly lower than those of wild-type mice at 4 h after intravenous administration. These results suggest that OCTN2 is involved in transport of L-carnitine and acetyl-L-carnitine from the circulating blood to the brain across the BBB.

Stereoisomeric acylamidomorpholinium carnitine analogues: Selective inhibitors of carnitine palmitoyltransferase I and II

Acylamidomorpholinium carnitine analogues, 6-(tetradecanamidomethyl- and -hexadecanamidomethyl)-4,4-dimethylmorpholin-4-ium-2-acetate, 1, synthesized as complete sets of stereoisomers, were assayed as inhibitors for isozymes of carnitine palmitoyltransferase (CPT). Microsomal CPT isozymes showed modest discrimination among the stereoisomer; while rat-liver mitochondrial CPT-I and CPT-II showed distinct differences. The tetradecanamidomethyl analogue of (2R,6S)- 1 activated CPT-I but inhibited CPT-II.

Stereoselective synthesis of a conformationally defined cyclohexyl carnitine analogue that binds CPT-1 with high affinity

Carnitine (1, 3-hydroxy-4-trimethylammoniobutyrate) is important in mammalian tissue as a carrier of acyl groups. In order to explore the binding requirements of the carnitine acyltransferases for carnitine, we designed conformationally defined cyclohexyl carnitine analogues. These diastereomers contain the required gauche conformation between the trimethylammonium and hydroxy groups but vary the conformation between the hydroxy and carboxylic acid groups. Here we describe the synthesis and biological activity of the all-trans diastereomer (2) , which was prepared by the ring opening of trans-methyl 2,3-epoxycylohexanecarboxylate with NaN3. Racemic 2 was a competitive inhibitor of neonatal rat cardiac myocyte CPT-1 (Ki 0.5 mM for racemic 2; Km 0.2 mM for l-carnitine) and a noncompetitive inhibitor of neonatal rat cardiac myocyte CPT-2 (Ki 0.67 mM). These results suggest that 2 represents the bound conformation of carnitine for CPT-1.

Effect of carnitines on Lactobacillus plantarum subjected to osmotic stress

We investigated the effect of carnitine analogues on the physiology of Lactobacillus plantarum subjected to salt stress. Salt stressed cells of L. plantarum accumulated exogenously provided carnitine and its structural analogues acetylcarnitine and propionylcarnitine to maximum concentrations of 466, 122 and 75 μmol (g dry weight of cells) −1, respectively. Addition of these carnitines to osmotically stressed medium increased growth rate. Furthermore, the intracellular amino acid pool, consisting of mainly aspartate and glutamate, was reduced when carnitine, acetylcarnitine or propionylcarnitine were included in the medium. This is the first study demonstrating a role for β-substituted acylcarnitine esters in osmoadaptation of a lactic acid bacterium.

ChemInform Abstract: Synthesis and Enzymatic Evaluation of Conformationally Defined Carnitine Analogues.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Enzymic Evaluation of Conformationally Defined Carnitine Analogs

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Enzymic Evaluation of Conformationally Defined Carnitine AnalogsWayne J. Brouillette, Ashraf Saeed, Ahmed Abuelyaman, Tracy L. Hutchison, Paul E. Wolkowicz, and Jeanie B. McMillinCite this: J. Org. Chem. 1994, 59, 15, 4297–4303Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July 1994https://doi.org/10.1021/jo00094a049RIGHTS & PERMISSIONSArticle Views719Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (826 KB) Get e-Alerts Get e-Alerts

Effects of C-methylated carnitine analogs on rates of mitochondrial fatty acid oxidation

Carnitine analogs containing one and/or two methyl substituents on the α-, β-, or γ-carbon were evaluated in isolated rat liver mitochondria for their effects on fatty acid oxidation. Their abilities to either support, in the absence of carnitine, or inhibit, in the presence of carnitine, carnitine-dependent fatty acid oxidation were determined by the conversion of radiolabeled [1- 14C]palmitic acid to acid-soluble radiolabeled products. None of the methylcarnitine analogs were observed to be significant inhibitors of palmitate oxidation at concentrations (1.0 mM) up to ten times that for icarnitine. The two diastereomers of d,l-4-methylcarnitine, however, were able to support palmilate oxidation in the absence of carnitine, and rates were roughly 40% of that obtained with equimolar (0.1 mM) l-carnitine.

Acyl-CoA chain length affects the specificity of various carnitine palmitoyltransferases with respect to carnitine analogues. Possible application in the discrimination of different carnitine palmitoyltransferase activities

The activities of carnitine palmitoyltransferases (CPTs) of mitochondrial outer and inner membranes and of peroxisomes have been studied with carnitine analogues, namely DL-thiolcarnitine, DL-sulphocarnitine and L-aminocarnitine, using palmitoyl-CoA or octanoyl-CoA as co-substrate. With sulphocarnitine, both of the mitochondrial CPTs and the malonyl-CoA-sensitive CPT of peroxisomes showed appreciable activity with palmitoyl-CoA, but relatively lower activity when octanoyl-CoA was the co-substrate. The soluble CPT of peroxisomes did not show any activity with sulphocarnitine in the presence of either acyl-CoA. With thiolcarnitine, all of the CPTs showed more activity with palmitoyl-CoA than with octanoyl-CoA. None of the CPTs showed any activity with aminocarnitine and palmitoyl-CoA, but when the acyl donor was octanoyl-CoA, both of the malonyl-CoA-sensitive CPT enzymes showed considerable activity, unlike the malonyl-CoA-insensitive CPT isoenzymes. Aminocarnitine inhibited palmitoylcarnitine formation by both of the mitochondrial CPTs and by the CPT of gradient-purified peroxisomes, but the purified peroxisomal soluble CPT was not inhibited. These results show that the interaction of CPT enzymes with carnitine analogues, as substrates or inhibitors, is influenced by the chain length of the acyl-CoA substrate, and that the use of the appropriate carnitine analogue and acyl-CoA is likely to be useful for the discrimination of the various CPT activities in CPT deficiency disorders.

Synthesis and biological evaluation of cyclic analogues of 1-carnitine as potential agents in the treatment of myocardial ischemia.

A series of cyclic rigid analogues of l-carnitine has been synthesized and examined for activity as substrates for the carnitine-acylcarnitine translocase, the enzyme that mediates transport of fatty acids into the mitochondria. Synthetic steps to seven of these analogues are described in this paper. Bioassay of these compounds is conducted in a preparation of isolated heart mitochondria that have been previously loaded with [14C]-l-carnitine. Efflux of radioactivity from the mitochondria is then monitored in the presence of the compound being evaluated in order to assess the amount of enzyme activity initiated. The palmityl ester of l-N,N-dimethyl-trans-2-carboxy-4-hydroxypyrrolidinium chloride elicited a 13.63 and 63.07% efflux of [14C]-l-carnitine at concentrations of 3 and 50 mM, respectively. This represents the first instance in which a nonnaturally occurring analogue of l-carnitine has been shown to undergo transport via this mitochondrial translocase, suggesting the possibility that cyclic carnitine analogues may find utility as agents in the treatment of myocardial ischemia.

Purification and properties of carnitine acetyltransferases from bovine spermatozoa and heart

To investigate the physical and kinetic properties of sperm carnitine acetyltransferase, the enzyme was purified from bovine spermatozoa and heart muscle. Carnitine acetyltransferase was purified 580-fold from ejaculated bovine spermatozoa to a specific activity of 85 units/mg protein (95% homogeneity). Sperm carnitine acetyltransferase was characterized as a single polypeptide of M r 62,000 and p I 8.2. Heart carnitine acetyltransferase was purified 650-fold by the same procedure to a final specific activity of 71 units/mg protein. The kinetic properties of purified bovine sperm carnitine acetyltransferase were consistent with the proposed function of this enzyme in acetylcarnitine pool formation. Product inhibition by either acetyl- l-carnitine or CoASH was not sufficient to predict significant in vivo inhibition of acetyl transfer. At high concentrations of l-carnitine, bovine sperm and heart carnitine acetyltransferases were most active with propionyl- and butyryl-CoA substrates, although octanoyl-, iso-butyryl-, and iso-valeryl-CoA were acceptable substrates. Binding of one substrate was enhanced by the presence of the second substrate. Carnitine analogs that have significance in reproduction, such as phosphorylcholine and taurine, did not inhibit carnitine acetyltransferase. Bovine sperm and heart carnitine acetyltransferases were indistinguishable on the basis of purification behavior, p I, pH optima, kinetic properties, acyl-CoA specificity, and sensitivity to sulfhydryl reagents and divalent cations; thus there was no indication that bovine sperm carnitine acetyltransferase is a sperm-specific isozyme.

Effect of Carnitine Analogs on Carnitine Acetyltransferase

Carnitine analogs with various substituents on the nitrogen were tested for their effect on carnitine acetyltransferase from rat sperm and pigeon breast. A radiometric assay was used to measure the formation of acetylcarnitine in the presence of other enzymes that competed for acetyl coenzyme A in the sperm preparation. The apparent enzyme inhibition caused by the analogs was explained by the analogs serving as alternative substrates with higher Km and lower Vmax values. The analogs had no effect on whole sperm.

Synthesis and Biological Evaluation of Potential Hypoglycemic Agents I: Carnitine Analogs

A series of 4‐dialkylamino‐3‐hydroxybutyric acid hydrochlorides and methochlorides, analogs of carnitine, was synthesized by treatment of tert‐butyl 3, 4‐epoxybutyrate with the appropriate amine or amine hydrochloride in methanol followed by mild acid hydrolysis. The compounds had no effect on blood glucose or serum fatty acid levels in rats.