Mildronate's protective effects in the peripheral nervous system : Stavudine-induced neuropathy and formalin-induced inflammation

Funding Information: This work was supported by the Latvian Council of Science Grant Nr. 05-1418; ESF Grant ESS2004/3; Contract No. 453, between the Latvian Institute of Organic Synthesis and the Joint Stock Company “Grindex”; Contract No. 2377, between the University of Latvia and the Joint Stock Company “Grindex”; and a L’ORÉAL Latvian “For Women In Science” fellowship with the support of the Latvian National Commission for UNESCO and the Latvian Academy of Sciences.Mildronate, previously known as a cardioprotective drug, recently was found to normalise mitochondrial processes by preventing the dysfunction of complex I in rat liver mitochondria. Previously we have shown also the ability of mildronate to prevent pathologies in the central nervous system by normalizing the expression of different signalling molecules in brain tissue. This allowed us to suggest that mildronate may possess a beneficial role also in peripheral nervous system pathologies. The present study was designed to assess the peripheral tissue damage caused by anti-HIV drug stavudine, as well as pain and inflammation caused by formalin. For this demonstration, we investigated the influence of mildronate: (1) on decreased myelin expression and increased neuron degeneration in rat sciatic nerve tissue caused by stavudine; and (2) on formalin-induced inflammation in mice. We found that mildronate protected the stavudine-induced degeneration of neurons in rat peripheral sciatic nerve without a significant influence on demyelination. In a formalin test, mildronate showed anti-inflammatory action comparable to that of indomethacin, a reference drug. The present results show that mildronate is capable of regulating peripheral nerve damage and peripheral inflammatory responses. We suggest that the multifunctional effects of mildronate can be attributed to its ability to regulate mitochondrial processes. The obtained data indicate protective effects of mildronate in different peripheral neurological pathologies.publishersversionPeer reviewe

Karboksilesteraza djelomice hidrolizira estere gama-butirobetaina u serumu štakora

Although described some time ago, gamma-butyrobetaine esters and related compounds have not gained much attention from researchers, and their physiological function remains obscure. Formerly we detected GBB-esterase enzymatic activity in rat blood serum using phenylated gamma-butyrobetaine as an artificial substrate of the enzyme and HPLC. The aim of the present work was to develop an assay that would enable spectrophotometric or colorimetric determination of the reaction products of GBB-esterase activity and to reveal individual proteins performing GBB-esterase activity in rat blood serum. For this purpose gammabutyrobetaine 1-naphthyl ester was synthesised. Hydrolysis of this ester releases 1-naphthol, which increases the optical absorbance at 322 nm. We have shown that the enzymatic hydrolysis of GBB 1-naphthyl ester to 1-naphthol in rat blood serum is due to GBB-esterase activity. An attempt was done to purify the enzyme from rat blood serum. By combining DEAE Sepharose at pH 4.2 and affinity chromatography with procainamide we achieved a 68-fold enrichment of GBB-esterase activity in our preparations. Separation of fraction proteins in 2D protein electrophoresis with following mass-spectrometry indicated that GBB esterase activity in rat blood serum is performed in part by carboxylesterase.Premda su poznati već neko vrijeme, esteri gama-butirobetaina (GBB) i srodni spojevi nisu dobili mnogo pozornosti u znanstvenoistraživačkoj zajednici, a njihova fiziološka funkcija i dalje je nerazjašnjena. U ranijem smo istraživanju HPLC-metodom otkrili enzimsku aktivnost GBB-esteraze u serumu štakora rabeći umjetni supstrat ovoga enzima, tj. fenilirani gama-butirobetain. Cilj ovoga istraživanja bio je razviti pretragu koja će omogućiti spektrofotometrijsko ili kolorimetrijsko određivanje reakcijskih produkata nastalih aktivnošću GBB-esteraze te utvrditi koji pojedinačni proteini u serumu štakora posjeduju aktivnost GBB-esteraze. U tu je svrhu sintetiziran gama-butirobetain 1-naftil ester. Njegovom hidrolizom otpušta se 1-naftol koji povećava optičku apsorbanciju na 322 nm. Pokazali smo da u hidrolizi GBB 1-naftil estera u 1-naftol u serumu štakora sudjeluje GBB-esteraza. Pokušali smo pročistiti enzim iz štakorskoga seruma. Kombinacijom DEAE sefaroze pri pH 4,2 i afinitetne kromatografije s prokainamidom dobili smo 68-erostruko povećanje aktivnosti ovoga enzima. Razdvajanjem bjelančevina iz frakcije s pomoću 2D elektroforeze te naknadnom spektrometrijom masa utvrđeno je da u serumu štakora esteraznu aktivnost prema gama-butirobetainu kao supstratu djelomice provodi karboksilesteraza

Synthesis of Hydroxamic Acids by Activation of Carboxylic Acids with N,N'-Carbonyldiimidazole: Exploring the Efficiency of the Method

Activation of carboxylic acids with N,N'-carbonyldiimidazole followed by the reaction with anhydrous or aqueous hydroxylamine hydrochloride was demonstrated to be an operationally simple method for the synthesis of hydroxamic acids in good yield and high purity after aqueous workup. The potential by-product, N,O-diacylhydroxylamine, is cleanly transformed to hydroxamic acid in these reaction conditions

Reactivity of Aziridine-2-Carboxamide (Leakadine) with Nucleophiles in Aqueous Solutions

We describe studies of aziridine-2-carboxamide (Leakadine) reactivity with N-, O-, and S-nucleophiles in aqueous solutions using NMR spectroscopy and chemical synthesis. The results show that nucleophilic ring opening reactions of Leakadine with N- and O-nucleophiles take place only in acidic solutions, while reactions with S-nucleophiles occur irrespective of the pH and at a significantly higher reaction rate. These data suggest that the antitumor and immunostimulating activity of Leakadine may be associated with inhibition of extracellular cysteine proteases of cancer cells

Mildronate, an Inhibitor of Carnitine Biosynthesis, Induces an Increase in Gamma-Butyrobetaine Contents and Cardioprotection in Isolated Rat Heart Infarction

The inhibition of gamma-butyrobetaine (GBB) hydroxylase, a key enzyme in the biosynthesis of carnitine, contributes to lay ground for the cardioprotective mechanism of action of mildronate. By inhibiting the biosynthesis of carnitine, mildronate is supposed to induce the accumulation of GBB, a substrate of GBB hydroxylase. This study describes the changes in content of carnitine and GBB in rat plasma and heart tissues during long-term (28 days) treatment of mildronate [i.p. (intraperitoneal) 100 mg/kg/daily]. Obtained data show that in concert with a decrease in carnitine concentration, the administration of mildronate caused a significant increase in GBB concentration. We detected about a 5-fold increase in GBB contents in the plasma and brain and a 7-fold increase in the heart. In addition, we tested the cardioprotective effect of mildronate in isolated rat heart infarction model after 3, 7, and 14 days of administration.We found a statistically significant decrease in necrotic area of infarcted rat hearts after 14 days of treatment with mildronate. The cardioprotective effect of mildronate correlated with an increase in GBB contents. In conclusion, our study, for the first time, provides experimental evidence that the long-term administration of mildronate not only decreases free carnitine concentration, but also causes a significant increase in GBB concentration, which correlates with the cardioprotection of mildronate