Investigation of mitochondrial targeting ability of sydnones and sydnonimines and mitochondria-targeted delivery of celecoxib.

Mitochondria are considered to be a promising target in cancer diagnosis and therapeutics. Recently, sydnone and sydnonimine, as mesoionic bioorthogonal reagents, have been used in cell labeling and drug delivery. Here we investigated the mitochondrial targeting ability of sydnones and sydnonimines for the first time. Experimental results show that sydnone and sydnonimine themselves have high mitochondrial distribution. However, the introduction of a phenyl group into the C4 position of sydnone dramatically decreases the mitochondrial affinity. In addition, we took advantage of mitochondrial targeting ability and click-and-release reaction of sydnonimine to evaluate anticancer activities of in-mitochondria delivery of celecoxib against HeLa and HepG2 cells, indicating that celecoxib-induced cancer cell death may not involve mitochondria-related pathway.

Antiproliferative, apoptosis-inducing activity and molecular docking studies of sydnones compounds.

Objective: To evaluate the antiproliferative and apoptosis inducing activity of different sydnones on cancer cell lines and their interaction with cancer proteins by molecular docking studies. Material and Methods: Antiproliferative activity was carried out by MTT assay and apoptosis inducing activity was performed by DAPI and Annexin V and propidium iodide staining. Molecular docking studies were performed using AutoDock Tools 1.5.6. Pharmacokinetics properties like ADME and toxicity were analysed by pkCSM web server. Result: In this study, four new sydnone compounds 3-(4-nonylbiphenyl-4'-yl) sydnone (MC-182), 3-(4-propylbiphenyl-4'-yl) sydnone (MC-454), 3-(4-hexylbiphenyl-4'-yl) sydnone (MC-433), and 3-(4-methylbiphenyl-4'-yl) sydnone (MC-431) were screened for antiproliferative and apoptotic effect against BT-474 (human breast cancer), HeLa (human cervical cancer) and Jurkat (human myeloid leukemia) Mostly, all the sydnone compounds exhibited decent antiproliferative effectiveness, but compound MC-431, MC-433, and MC-454 showed more antiproliferative activity (IC50 1.71, 10.09 and 2.87 µM against BT-474, Hela and Jurkat cell line, respectively). The changes of morphological characteristics of cancer cells determined by staining techniques indicate the apoptotic cell death. The molecular docking and interaction studies were carried out between sydnones with cancer proteins (epidermal growth factor domain receptor tyrosine kinase [EGF-TK], tumor necrosis factor-alpha [TNF-α] and Caspase3. Among all four sydnone molecules, two compounds MC-454 and MC-431 showed good binding energy with targeted proteins. Drug-like property was predicted by ADME toxicity study. Conclusion: The results indicate sydnone compounds were found to exhibit anticancer activity by inducing apoptosis. The molecular docking study of sydnones with cancer proteins showed a decent interaction affinity. The results of absorption, distribution, metabolism, excretion and toxicity studies by the Insilco approach also proved that MC-454 sydnone showed better In-Vivo administration. Thus, the current research work indicates that these sydnone compounds would be prospective in developing anticancer medicines.

Novel trifluoromethyl sydnone derivatives: Design, synthesis and fungicidal activity.

Crop pathogens reduce the yield and quality of agricultural production. The development of new fungicides will help to sustain this protection and overcome fungicide resistance. Sydnone is a kind of mesoionic, which has a wide range of biological activities. The application of sydnones in agriculture is less, and the study of these compounds will lead to the discovery of new active compounds. In this study, we designed and synthesized a series of noval sydnone mesoionic derivatives by active substructure splicing. All compounds were characterized using 1H and 13C NMR spectroscopy. Among them, trifluoromethyl compound D17 showed good bioactivity against Pseudoperonospora cubensis (EC50 = 49 mg L-1) in vivo, the activity was similar to that of the control Kresoxim-methyl (EC50 = 44 mg L-1). However, the target of these compounds should not only be tyrosinase, and the mode of action needs to be further studied. In addition, the structure-activity relationship indicated that the trifluoromethyl group was more beneficial for antifungal activity. This is the first report that fluorine-containing N(3)-benzyl sydnone compounds have good fungicidal activity. These results will provide a basis for the development of sydnone mesoionic as new lead fungicidal agents.

Discovery of novel iminosydnone compounds with insecticidal activities based on the binding mode of triflumezopyrim.

Triflumezopyrim (TFM) is a new mesoionic insecticide developed by DuPont. Like other neonicotinoid insecticides, it binds to the orthosteric site of the nicotinic acetylcholine receptor (nAChR), but the binding mode has not been reported. Nicotinic acetylcholine binding proteins (nAChBPs) are ideal alternative structure for nAChRs. In this study, molecular docking, molecular dynamics (MD) simulations, binding free energy calculation, and per-residue binding free energy decomposition were used to study the binding modes of TFM and other 12 mesoionic insecticides. By comparing the binding free energy and the insecticidal activity, it was found that the sub-pocket around the benzyl group of the mesoionic insecticide is the key area for maintaining its activity, which is composed of A: Val116, A: Met124, A: Ile126, B: Trp155 and B: Val156. In order to verify the druggability of the sub-pocket, a series of iminosydnone compounds were designed and synthesized based on the structure of the sub-pocket. The lethality rate of compound 1 against Mythimna separata were 100% at 500 mg/L. Our research provides a basis for designing new mesoionic insecticides based on structure.

Evaluation of Sydnone-Based Analogues of Combretastatin A-4 Phosphate (CA4P) as Vascular Disrupting Agents for Use in Cancer Therapy.

The combretastatins have attracted significant interest as small-molecule therapies for cancer due to their ability to function as vascular disrupting agents. We have successfully prepared a range of combretastatin analogues that are based on a novel sydnone heterocycle core, and their potential as tubulin binders has been assessed in vitro and in vivo. The most potent candidate was found to disrupt microtubules and affect cellular morphology at sub-micromolar levels. Moreover, it was found to bind reversibly to tubulin and significantly increase endothelial cell monolayer permeability, in a similar manner to combretastatin A4. Surprisingly, the compound did not exhibit efficacy in vivo, possibly due to rapid metabolism.

[EFFECT OF MEDIATOR-TYPE DRUGS ON HUMAN PSYCHOPHYSIOLOGICAL STATUS DURING MODEL OPERATOR ACTIVITY].

In a placebo-controlled study, changes in psychophysiological status of operators (38 healthy male volunteers aged 23-35 years) performing 4-hour model operator activity were evaluated after a single oral administration of typical representatives of the different classes of drugs (haloperidol, proroxan, yohimbine hydrochloride, propranolol, mesocarb, isoprenaline, Belladonna extract, anabasine hydrochloride, valproate sodium, and phenazepam), which are used for the treatment, rehabilitation and prophylaxis of common diseases. It was found that all the drugs modified to a greater or lesser extent some components of the model operator activity. Isoprenaline and phenazepam had the most negative effect on the psychophysiological indicators and quality of the modeled operator activity. The results should be considered before administration of such drugs to working operators.

Design and synthesis of novel hybrid sydnonimine and prodrug useful for glaucomatous optic neuropathy.

Synthesis and bioactivity of novel dual acting nitric oxide releasing and reactive oxygen scavenging hybrid compound SA-2 is described. The hybrid molecule SA-2 significantly increased the superoxide dismutase enzyme level and protected the photoreceptor cells from H2O2 induced oxidative stress. Synthesis of ocular esterase sensitive aceloxy alkyl carbamate prodrug SA-4 with improved aqueous half-life is achieved to aid topical ocular formulation. This class of hybrid molecule and prodrug may have dual potential of improved IOP lowering and neuroprotection in glaucomatous optic neuropathy.

Sydnone 1: A Mesoionic Compound with Antitumoral and Haematological Effects In Vivo.

This study evaluated the antitumour activity of the mesoionic compound sydnone 1 (Syd-1) against Walker-256 carcinosarcoma. Tumour cells were subcutaneously inoculated in the hind limb in male Wistar rats. The animals were orally treated for 12 days with Syd-1 (75 mg/kg) or vehicle. At the end of treatment, considerable decreases in tumour volume and tumour weight were observed in treated animals. Samples of these tumours presented increases in apoptotic bodies and pro-apoptotic protein expression (Bax and p53), while the expression of the anti-apoptotic protein Bcl-2 was reduced. A decrease in reduced glutathione levels and an increase in glutathione peroxidase activity were observed in tumour after Syd-1 treatment. However, significant splenomegaly was evident in animals that received Syd-1, most likely attributable to the induction of haemolysis. This study demonstrated the antitumour activity of Syd-1 against Walker-256 carcinosarcoma. Its mechanism of action is linked to the activation of apoptotic pathways that lead to tumour cell death.

Regioselective reaction: synthesis, characterization and pharmacological activity of some new Mannich and Schiff bases containing sydnone.

A novel series of 1-substituted aminomethyl-3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino-1,2,4-triazol-5-thiones (9), was prepared from the 3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino 5-mercapto-1,2,4-triazoles (8) by aminomethylation with formaldehyde and secondary amine. The structures of Schiff bases (8) and Mannich bases (9) were characterized on the basis of IR, NMR, mass spectra1 data and elemental analysis. The newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Mannich bases (9) carrying piperidine and morpholine residues showed promising anti-inflammatory and analgesic activity.

Sydnones: a brief review.

Sydnones are mesoionic heterocyclic aromatic compounds. They have been widely studied for some important biological activities like antiviral, antitumor, antimicrobial, anti-inflammatory, anticancer, analgesic, anthelmintic and antihypertensive activities. The aim of the present article is to review the available information on sydnones and the derivatives of sydnones and also a look at the future perspectives.

Fluorine bearing sydnones with styryl ketone group: synthesis and their possible analgesic and anti-inflammatory activities.

In continuation of structure activity relationship studies, a panel of fluorine containing sydnones with styryl ketone group 4-[1-oxo-3-(substituted aryl)-2-propenyl]-3-(3-chloro-4-fluorophenyl)sydnones 2a-i, was synthesized as better analgesic and anti-inflammatory agents. The title compounds were formed by condensing 4-acetyl-3-(3-chloro-4-fluorophenyl)sydnone with various substituted aryl aldehydes, characterized by spectral studies and evaluated at 100 mg\kg b.w., p.o. for analgesic, anti-inflammatory and ulcerogenic activities. Compounds 2c and 2e showed good analgesic effect in acetic acid-induced writhing while none showed significant activity in hot plate assay in mice. In carrageenan-induced rat paw oedema test, compound 2c and 2f exhibited good anti-inflammatory effect at 3rd h, whereas compounds 2c, 2e, 2d, 2g and 2h showed activity in croton oil induced ear oedema assay in mice. Compounds 2c and 2e were less ulcerogenic than ibuprofen in rats, when tested by ulcer index method. Compounds with electron attracting substituents such as 2c and 2e were found to be promising in terms of the ratio of efficacy and adverse effect. These compounds generally exhibited better activity than those of earlier series signifying fluorine substitution.

Characterization of pharmacological and wake-promoting properties of the dopaminergic stimulant sydnocarb in rats.

Sydnocarb is a psychomotor stimulant structurally similar to d-amphetamine (D-AMPH) and is used in Russia for the treatment of a variety of neuropsychiatric comorbidities. The nature of sydnocarb-induced facilitation of dopamine (DA) neurotransmission [DA release versus DA transporter (DAT) inhibition] is not clear. The present study characterized the pharmacological actions and behavioral effects of intraperitoneal sydnocarb in male Sprague-Dawley rats. Where relevant, comparisons were made with intraperitoneal D-AMPH. Unlike D-AMPH, which causes release of DA from rat synaptosomes (EC(50) = 0.10 µM; 95% confidence limits, 0.06-0.18), sydnocarb (up to 100 µM) did not. Sydnocarb potently (K(i) = 8.3 ± 0.7 nM) blocked recombinant human DAT expressed in Chinese hamster ovary-K1 cells and less potently blocked the norepinephrine transporter (K(i) = 10.1 ± 1.5 µM). Sydnocarb at 10 µM did not bind to 64 other targets. In rats, 10 and 30 mg/kg sydnocarb showed a 2-fold longer half-life in plasma and brain and a 5-fold lower brain-to-plasma ratio compared with 0.3 and 1 mg/kg D-AMPH. In the Irwin assay, sydnocarb was well tolerated up to 30 mg/kg; D-AMPH-like stereotypic behaviors were evident at 100 mg/kg. Behavioral effects of 30 mg/kg sydnocarb and 0.3 mg/kg D-AMPH were comparable. In a sleep/wake assay, 10 mg/kg sydnocarb and 1 mg/kg D-AMPH increased wakefulness comparably; however, sydnocarb (up to 30 mg/kg) did not induce D-AMPH-like rebound hypersomnolence (RHS). Like D-AMPH, sydnocarb enhanced theta power, an electrophysiological measure of cognitive function. In conclusion, sydnocarb is a selective and potent DAT inhibitor that produces robust increases in the wake state without RHS, and with potential cognitive-enhancing properties.

The effects of d-amphetamine, methylphenidate, sydnocarb, and caffeine on prepulse inhibition of the startle reflex in DBA/2 mice.

RATIONALE: Dopamine (DA) agonists decrease prepulse inhibition (PPI) and are widely used in translational models for the sensorimotor gating deficits in schizophrenia. Reductions in PPI induced by DA agonists are routinely reversed by antipsychotics in these translational models. Nevertheless, under conditions of low-baseline PPI, DA agonists may increase PPI in humans and experimental animals. DBA/2 mice have naturally low-baseline PPI, which as in the drug-induced translational models, is increased by antipsychotics. OBJECTIVE: Determine whether DBA/2 mice respond like other models of low-baseline PPI by evaluating the effect of psychostimulants (caffeine, 30-100 mg/kg IP) and the indirect DA agonists d-amphetamine (0.3-10 mg/kg IP), methylphenidate (10-100 mg/kg IP), and sydnocarb (10-30 mg/kg IP), a selective DA transporter inhibitor on PPI. Furthermore, baseline PPI in DBA/2 mice was increased by noise exposure and the effect of d-amphetamine was assessed. RESULTS: PPI was increased at one dose for each of the psychostimulants when baseline PPI was low in naïve DBA/2 mice. Effective doses were 3 mg/kg of d-amphetamine, 30 mg/kg of methylphenidate, 30 mg/kg of sydnocarb, and 100 mg/kg of caffeine. Higher doses of d-amphetamine (10 mg/kg) and methylphenidate (100 mg/kg IP) decreased PPI. When the baseline PPI was increased by noise exposure, 10 mg/kg of d-amphetamine only reduced PPI. CONCLUSION: Lower doses of psychostimulants increased PPI in naïve DBA/2 mice in a manner consistent with their naturally low-baseline PPI, and higher doses decreased PPI, consistent with effects observed in most mouse strains.

[Role of the brain dopaminergic and serotoninergic systems in psychopharmacological effects of ladasten and sydnocarb].

The influence of ladasten and sydnocarb on dopamine and serotonin receptors and the biosynthesis and re-uptake of dopamine and serotonin has been studied. It is established that both drugs do not produce any direct effects on dopamine D1, D2, and D3 receptors in rat striatum as well as on serotonin 5-HT1A and 5-HT2A receptors in rat frontal cortex in vitro. Ladasten in a single dose of 50 mg/kg (i.p.) stimulated ex vivo dopamine biosynthesis and release in striatum, without any influence on serotonin formation neither in striatum nor in frontal cortex. On the contrary, sydnocarb (17.5 mg/kg, i.p.) decreased the level of serotonin synthesis both in striatum and frontal cortex, while not affecting the biosynthesis of dopamine. Both ladasten and sydnocarb inhibited the active transport of dopamine in rat striatal synaptosomes at IC50 = 3.56 microM and 28.66 nM, respectively, but failed to influence the serotonin re-uptake in rat frontal cortex.

Synthesis and antimicrobial activities of a new series of 4-S-[4(1)-amino-5(1)-oxo-6(1)-substituted benzyl-4(1),5(1)-dihydro-1(1),2(1),4(1)-triazin-3-yl]mercaptoacetyl-3-arylsydnones.

The synthesis of some 4-S-(4(1)-amino-5(1)-oxo-6(1)-substituted benzyl-4(1),5(1)-dihydro-1(1),2(1),4(1)-triazin-3-yl)mercaptoacetyl-3-arylsydnones by the reaction of 3-aryl-4-bromoacetylsydnones with 6-substituted-4-amino-3-mercapto-1,2,4-triazin-5-ones is described. The IR, (1)H NMR, mass spectra and elemental analysis characterized the newly synthesized compounds. The synthesized compounds were screened for their antimicrobial activity. All the compounds showed higher activity than that of standard drug during antimicrobial studies and the activity was comparable with the standard drug for antifungal activity.

Effect of sydnone SYD-1, a mesoionic compound, on energy-linked functions of rat liver mitochondria.

An important antitumour effect of SYD-1 (3-[4-chloro-3-nitrophenyl]-1,2,3-oxadiazolium-5-olate) has been shown. We now report the effects of this mesoionic compound on mitochondrial metabolism. SYD-1 (1.5 micromol mg(-1) protein) dose-dependently inhibited the respiratory rate by 65% and 40% in state 3 using sodium glutamate and succinate, respectively, as substrates. Phosphorylation efficiency was depressed by SYD-1, as evidenced by stimulation of the state 4 respiratory rate, which was more accentuated with glutamate ( approximately 180%) than with succinate ( approximately 40%), with 1.5 micromol mg(-1) protein of SYD-1. As a consequence of the effects on states 3 and 4, the RCC and ADP/O ratios were lowered by SYD-1 using both substrates, although this effect was stronger with glutamate. The formation of membrane electrical potential was inhibited by approximately 50% (1.5 micromol SYD-1mg(-1) protein). SYD-1 interfered with the permeability of the inner mitochondrial membrane, as demonstrated by assays of mitochondrial swelling in the presence of sodium acetate and valinomycin +K(+). SYD-1 (1.5 micromol mg(-1) protein) inhibited glutamate completely and succinate energized-mitochondrial swelling by 80% in preparations containing sodium acetate. The swelling of de-energized mitochondria induced by K(+) and valinomycin was inhibited by 20% at all concentrations of SYD-1. An analysis of the segments of the respiratory chain suggested that the SYD-1 inhibition site goes beyond the complex I and includes complexes III and IV. Glutamate dehydrogenase was inhibited by 20% with SYD-1 (1.5 micromol mg(-1) protein). The hydrolytic activity of complex F(1)F(o) ATPase in intact mitochondria was greatly increased ( approximately 450%) in the presence of SYD-1. Our results show that SYD-1 depresses the efficiency of electron transport and oxidative phosphorylation, suggesting that these effects may be involved in its antitumoural effect.

Experimental encephalomyelitis induces changes in DJ-1: implications for oxidative stress in multiple sclerosis.

DJ-1 plays an important role in oxidative stress, and is involved in various neurodegenerative diseases. Accumulating evidence suggests a central role for oxidative stress in multiple sclerosis (MS). The aim of this study was to examine whether changes occur in DJ-1 expression in an animal model of MS, experimental autoimmune encephalomyelitis (EAE). We found upregulation of DJ-1 mRNA and protein expression levels in EAE and a correlation between disease severity and increased DJ-1 levels. Although DJ-1 isoforms were more alkaline in controls, in EAE, a shift was noted toward acidic isoforms. ROS induced by SIN-I exposure led to an increase in DJ-1 mRNA and protein levels in human glioma U-87 cells. Immunocytochemical staining demonstrated that DJ-1 is present both in the cytoplasm and the nuclei of these cells. This is the first report of modulation of DJ-1 expression in EAE. Upregulation of DJ-1 was noted in EAE, and similar results were observed in glioma cells exposed to ROS. In view of the accumulating evidence on the central role of oxidative stress in MS, and the importance of DJ-1 in oxidative stress management by the CNS, we believe that DJ-1 will be found to have a central role in MS.

[Comparative study of the effect of Ladasten, Sydnocarb and their combination on physical work ability of laboratory animals].

The action of Ladasten, Sydnocarb and their combination used at doses of 10 and 20 mg/kg, produce on working ability of mice was evaluated in the swimming test. It was shown that single doses of tested drugs as compared to their combination produce more pronounced and prolonged positive action on physical work ability of animals used in the experiments.

[Thermoprotector properties of a combination of sydnocarb with ladasten].

Thermoprotector properties of a 1 : 1 combination of sydnocarb and ladasten (both in a dose of 10 or 20 mg/kg) along with its effect on the hemodynamics and respiration in experimental animals were studied. The combination of sydnocarb (20 mg/kg) and ladasten (20 mg/kg) produced a significant thermoprotector effect, enhanced the regional and local cerebral flow, and increased the respiration rate.

Esterase-activated chromane-sydnonimine prodrug hybrids.

The preparation and characterization of two vitamin E analogs-sydnonimine conjugates, delta-tocopheryloxycarbonyl-3-morpholinosydnonimine (2) and troloxoxycarbonyl-3-morpholinosydnonimine (3), in which the hydroxyl group of the tocopheryl moieties is linked via an enzymatically cleavable urethane group to the sydnone moiety is described. In the presence of porcine liver esterase, these tocopheryl-sydnonimine conjugates generated the expected antioxidant moieties, i.e., delta-tocopherol or Trolox, and were found to convert oxyhemoglobin to methemoglobin at 37 degrees C in 50 mM phosphate buffer at pH 7.4, thus providing evidence for nitric oxide release. Their potency as antioxidants was indirectly studied by associating the two products of the hydrolysis, SIN-1, and delta-tocopherol or Trolox. Our findings suggest that unlike the other members of the sydnonimine family these chromane-sydnonimine derivatives do not act as peroxynitrite donors, and require enzymatic bioactivation before nitric oxide or nitroxyl anion (NO(-)) can be released.