Determination of memantine in human plasma by liquid chromatography–electrospray tandem mass spectrometry: Application to a bioequivalence study

A simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of memantine (I) in human plasma is presented. Sample preparation consisted of the addition of amantadine (II) as internal standard (IS), liquid-liquid extraction in basic conditions using a mixture of diethyl ether-chloroform (7:3, v/v) as extracting solvent, followed by centrifugation, solvent evaporation and sample reconstitution in methanol. Both I and II (internal standard) were analyzed using a C18 column and a mobile phase composed of methanol-water-formic acid (80:20:0.1, v/v/v). Eluted compounds were monitored using positive mode electrospray (ES) tandem mass spectrometry. The analyses were carried out by selected reaction monitoring (SRM) using the parent to daughter combinations of m/z 180>163 (memantine) and m/z 152>135 (amantadine). The peak areas from the analyte and IS were used for quantification of I. The achieved limit of quantification (LOQ) was 0.1 ng/mL; the assay exhibited a linear dynamic range of 0.1-50.0 ng/mL with a determination coefficient (r2) of at least 0.98. Validation results on linearity, specificity, accuracy, precision and stability, as well as on application to the analysis of samples taken up to 320 h after oral administration of 20mg (two 10mg capsules) of I in healthy volunteers demonstrated the applicability to bioequivalence studies.

[Apomorphine in off state--clinical experience]

Apomorphine, a non-ergot derivative, is a potent, directly acting dopamine receptor agonist with high affinity to D4, lower to D2, D3, D5, the lowest to D1-like dopamine receptors as well as to serotonin and adrenoreceptors. Subcutaneous apomorphine is currently used in Parkinson's disease as an add-on to levodopa therapy or monotherapy for management of sudden, unexpected and refractory to levodopa-induced off state and fluctuation in advanced stage of illness. Many clinical trials have shown markedly (about 50-72%) reduced time of off phases. Other indications include the challenge test for determining the dopaminergic responsiveness. Apomorphine is used subcutaneously either as intermittent rescue injections or continuous infusions. Several other routes - transdermal, sublingual, intranasal, rectal and intravenous infusion - have been tried. Oral administration is not recommended. Apomorphine has rapid onset of antiparkinsonian action, qualitatively comparable to that of levodopa, short duration of action and stable efficacy with usually mild adverse events similar to other dopamine agonists. Domperidone or trimethobenzamide should be introduced before starting apomorphine treatment to reduce occurrence of peripheral adverse events (nausea, vomiting, orthostatic hypotension). Dyskinesias, sleep disturbances, hallucinations, delusion, oedema and yawning can occur, but some side effects are connected only with a specific route (for example skin nodules appearing during subcutaneous administration). Despite its long history, apomorphine is registered and used in only a few countries. Apomorphine warrants wider application in treatment of advanced Parkinson disease but the high cost of the drug, the necessity of concomitant treatment for prevention of side effects and subcutaneous administration restrict its use.

Isolation and characterization of some potential impurities in ropinirole hydrochloride

Three impurities in ropinirole hydrochloride drug substance at levels approximately 0.06-0.15% were detected by reverse-phase high performance liquid chromatography (HPLC). These impurities were isolated from the drug substance. These impurities were analyzed using reverse-phase HPLC. Based on the spectral data (IR, NMR and MS), structures of these impurities were characterized as 4-[2-(propylamino) ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride (impurity-A), 5-[2-(diropylamino) ethyl]-1,4-dihydro-3H-benzoxazin-3-one hydrochloride (impurity-B) and 4-[2-(diropylamino) ethyl]-1H-indol-2,3-dione hydrochloride (impurity-C). Synthesis of these impurities is discussed.

The path from anti Parkinson drug selegiline and rasagiline to multifunctional neuroprotective anti Alzheimer drugs ladostigil and m30

The therapeutic use of enzyme inhibitors in treatment of neurodegenerative diseases has its origin in the anti Parkinson action of the selective monoamine oxidase (MAO) B inhibitor, l-deprenyl (selegiline ), a failed anti depressant in 1975. This led to further development of MAO- A and B, catechol-O-methyltansferase and cholinestrerase inhibitors as anti Parkinson and Alzheimer drugs. One of the main reasons for the cognitive deficit in dementia of the Alzheimer' type (AD) and in dementia with Lewy bodies (DLB) is degeneration of cholinergic cortical neurones and synaptic plasticity. This led to a correlation that similar to Parkinson's Disease (PD), cholinesterase inhibitors (ChEI) may also have therapeutic activity in AD. Significant percentage of AD and DLB subjects also nigrostriatal dopaminergic, locus ceruleous noradrenergic and raphe nucleus serotoninergic neurones. The present ChEI anti AD drugs have limited symptomatic activity and devoid of neuroprotective property that is needed for disease modifying action. It is becoming clear that there are no magic bullets for neurodegenerative disorders and shut gun approach is needed either as polypharmacology or drugs with multiple activity at different target sites in the CNS. The complex pathology of AD as well as cascade of events that leads to the neurodegenerative process has led us to develop several multifunctional neuroprotective drugs with several CNS targets with possible disease modifying activity. Employing the pharamcophore of our antiparkinson drug rasagiline (Azilect, Agilect, N-propagrgyl-1R-aminoindan) we have developed a novel multifunctional neuroprotective drug, ladostigil [TV-3326 (N-propargyl-3R-aminoindan-5yl)-ethyl methylcarbamate)], with both cholinesterase-butyrylesterase (Ch-BuE) and brain selective monoamine-oxidase (MAO) AB inhibitory activities possessing the neuroprotective-neurescue propargyl moiety, as potential treatment of AD and DLB and PD with dementias. Since brain MAO and iron increase in AD, PD and ageing, that could lead to iron dependent oxidative stress neurodegeneration, we have developed another series of multifunctional drugs (M30 HLA-20 series) which are brain permeable iron chelators- brain selective MAO inhibitors and possess the propargyl neuroprotective moiety. These series of drugs have the ability of regulating and processing APP (amyloid precursor protein) and reducing Abeta peptide, since APP is a metaloprotein, with an iron responsive element 5d'UTR similar to transferring and ferritin.

Simultaneous enantioseparation of antiparkinsonian medication Rotigotine and related chiral impurities by capillary zone electrophoresis using dual cyclodextrin system

A dual cyclodextrin (CD) system consisting of sulfated beta-CD (S-beta-CD) and methyl-beta-CD (M-beta-CD) modified capillary zone electrophoresis (CZE) method was proposed to separate the antiparkinsonian drug Rotigotine ((-)-(S)-2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin) and related chiral impurities (2-(N-propylamino)-5-hydroxytetralin, 2-(N-propylamino)-5-methoxytetralin). The method was optimized by varying the CD type, the buffer pH, individual CD concentration of the dual system and the ionic strength of background electrolyte. Under the optimum conditions, i.e. 2% (w/v) S-beta-CD and 2% (w/v) M-beta-CD in 100mM sodium phosphate (pH 2.5) as the running buffer, separation voltage -20 kV, detected at 200 nm and temperature controlled at 20 degrees C, a satisfactory separation of the six analytes was accomplished. The optimized method was validated for specificity, precision, linearity, accuracy and stability using sodium benzenesulfonate as the internal standard. The relative standard deviation for migration time was less than 0.58%, and 3.78% for peak area ratio. The linearity ranged from 0.005 to 0.25 mM. The recovery ranged from 95.9% to 108.3%. The limits of detection and limits of quantification for each enantiomer were 0.003 and 0.01 mM, respectively. This method was utilized for evaluating the chiral purity of five batches of Rotigotine.

Separation of enantiomers of deprenyl with various CDs in CE and the effect of enantiomer migration order on enantiomeric impurity determination of selegiline in active ingredients and tablets

Opposite affinity pattern of enantiomers of the antiparkinsonian chiral drug deprenyl (DEP) was observed towards various neutral and charged derivatives of -CD. The effect of the enantiomer migration order on the LOD of enantiomeric impurity of R-DEP (selegiline) was studied for the standard substances and in the tablets from three different suppliers. The influence of injection mode on the LOD of a minor enantiomeric impurity was also studied and the CE method was compared with the pharmacopoeial HPLC method using a commercially available chiral column Chiralcel OD-H. The optimized CE method was more suitable for low-level enantiomeric impurity determination in selegiline compared to the pharmacopoeial HPLC method.

Anti-fibrillogenic and fibril-destabilizing activities of anti-Parkinsonian agents for α-synuclein fibrils in vitro

The aggregation of alpha-synuclein (alphaS) in the brain has been implicated as a critical step in the development of Lewy body diseases (LBD) and multiple system atrophy (MSA). Among the antioxidant strategies proposed, increasing evidence points to the possibility of achieving neuroprotection by dopamine agonists, as well as monoamine oxidase B inhibitors. We showed previously that the anti-Parkinsonian agents dose-dependently inhibited beta-amyloid fibrils (fAbeta)(1-40) and fAbeta(1-42) formation as well as destabilized preformed fAbetas. Using fluorescence spectroscopy with thioflavin S, electron microscopy, and atomic force microscopy, we examined the effects of anti-Parkinsonian agents, selegiline, dopamine, pergolide, bromocriptine, and trihexyphenidyl on the formation of alphaS fibrils (falphaS) and on preformed falphaS. All molecules except for trihexyphenidyl, dose-dependently inhibited the formation of falphaS. Moreover, these molecules dose-dependently destabilized preformed falphaS. The overall activity of the molecules examined was in the order of: selegiline = dopamine > pergolide > bromocriptine. These agents and other compounds related structurally could be key molecules for the development of therapeutics for LBD and MSA.

Safinamide: From molecular targets to a new anti-Parkinson drug

Ideal treatment in Parkinson's disease (PD) aims at relieving symptoms and slowing disease progression. Of all remedies, levodopa remains the most effective for symptomatic relief, but the medical need for neuroprotectant drugs is still unfulfilled. Safinamide, currently in phase III clinical trials for the treatment of PD, is a unique molecule with multiple mechanisms of action and a very high therapeutic index. It combines potent, selective, and reversible inhibition of MAO-B with blockade of voltage-dependent Na+ and Ca2+ channels and inhibition of glutamate release. Safinamide has neuroprotective and neurorescuing effects in MPTP-treated mice, in the rat kainic acid, and in the gerbil ischemia model. Safinamide potentiates levodopa-mediated increase of DA levels in DA-depleted mice and reverses the waning motor response after prolonged levodopa treatment in 6-OHDA-lesioned rats. Safinamide has excellent bioavailability, linear kinetics, and is suitable for once-a-day administration. Therefore, safinamide may be used in PD to reduce l-dopa dosage and also represents a valuable therapeutic drug to test disease-modifying potential.

Apomorphine in Dopaminergic Therapy

Apomorphine is a potent molecule for the treatment of Parkinson's disease (PD). It can be obtained in both the R and S forms, and it is the former that is the therapeutically active form. Due to its structural similarity with 3,4-dihydroxyphenethylamine, dopamine, apomorphine can function as an agonist in the treatment of PD as it can stimulate both the D1 and D2 receptors of the striatum. The clinical efficacy of apomorphine is similar to that of 3,4-dihydroxyphenylalanine, levodopa (L-dopa), the cornerstone drug in dopaminergic therapy. (R)-Apomorphine is efficacious for one of the most challenging aspects in the management of PD, namely, managing the unpredictable "on-off" period as a rescue medication after oral administration of a therapeutic drug such as L-dopa. The effectiveness is due to its rapid control of the wearing-off period of the orally administered medicine. This short review will trace the progress of apomorphine use starting with its initial discovery and the first indications for which it was used, discovery of its "cure" for PD, and the studies that led to demonstrating its therapeutic efficacy. The key structural features of apomorphine responsible for its activity are illustrated along with major issues of chemical stability. From a drug delivery point of view, the current form of administration of apomorphine and some of the potential alternate methods of delivery are reviewed.

Rasagiline in the pharmacotherapy of Parkinson's disease--a review

Despite the current efficacious symptomatic approaches, the search is on for new therapies for Parkinson's disease that can control the cardinal symptoms of the disease (tremor, rigidity and bradykinesia), control/prevent motor complications induced by long-term levodopa, act on non-motor disease symptoms (dementia, dysautonomia, pain, insomnia, falls) and halt disease progression. Rasagiline is a monoamine oxidase-B inhibitor that has demonstrated efficacy against the cardinal symptoms of Parkinson's disease when used as monotherapy in early Parkinson's disease, and as an adjunct to levodopa in advanced disease stages. It reduces the duration and severity of poor symptom response episodes in fluctuating patients. Preliminary results allow discussion of putative effects of rasagiline on some non-motor signs and disease progression. This article outlines the evidence surrounding the efficacy and safety of rasagiline, and discusses its potential to address some of the currently unmet needs of Parkinson's disease therapy.

Istradefylline, a novel adenosine A2A receptor antagonist, for the treatment of Parkinson's disease

Dopamine replacement therapy effectively treats the early motor symptoms of Parkinson's disease (PD). However, its association with the development of motor complications limits its usefulness in late stages of the disease. Adenosine A(2A) receptors are localised to the indirect striatal output function and control motor behaviour. They are active in predictive experimental models of PD and appear to be promising as the first major non-dopaminergic therapy for PD. Istradefylline is a novel adenosine A(2A) receptor antagonist currently in Phase III clinical trials for efficacy in patients with PD; results from Phase II clinical trials demonstrated that it provides a clinically meaningful reduction in 'off' time and an increased 'on' time with non-troublesome dyskinesia in levodopa-treated patients with established motor complications, and is safe and well tolerated.

Enhancement in dissolution pattern of piribedil by molecular encapsulation with beta-cyclodextrin

The aim of this study was to improve the dissolution behavior of piribedil by molecular encapsulation with beta-cyclodextrin (beta-CD). Toward this aim, physical mixing, co-grinding, and spray-drying methods were used to prepare solid binary systems. Differential scanning calorimetry, X-ray diffractometry, and particle size analysis were used to characterize the binary systems obtained. Complexes of piribedil and beta-CD could be prepared using the spray-drying method. Dissolution of piribedil was improved to a great extent by the complex prepared.

3-Normeridamycin: A Potent Non-Immunosuppressive Immunophilin Ligand is Neuroprotective in Dopaminergic Neurons

3-Normeridamycin (1), isolated from fermentation extracts of the soil actinomycete Streptomyces sp. LL-C31037, demonstrated potent neuroprotective activity. When challenged with the neurotoxin 1-methyl-4-phenylpyridinium (MPP+), known to induce parkinsonism, 1 restored functional dopamine uptake in a concentration-dependent manner, with an EC50 of 110 nM in dopaminergic neurons. The structure of 1 was determined via spectroscopic methods, and the immunosuppressive and immunophilin binding properties of the compound were also measured.

Ropinirole, a non-ergoline dopamine agonist

Dopamine agonists have become indispensable in the treatment of Parkinson's disease. In every-day practice, however, the decision to select the best compound for an individual patient is rendered difficult because of the large number of substances available on the market. This review article provides a closer look at the experimental and clinical studies with ropinirole published so far. Ropinirole is a non-ergoline dopamine agonist which has been proven to be effective in both, monotherapy and combination therapy of idiopathic Parkinson's disease. In addition to ameliorating bradykinesia, rigor, and tremor, ropinirole facilitates the daily life and improves depressive moods of patients with Parkinson's disease. The long-term complications of levodopa are avoided, and problems commonly associated with levodopa treatment are reduced. Ropinirole appears to have a neuroprotective effect. In addition to Parkinson's disease, ropinirole has also been used successfully in the treatment of restless legs syndrome.

Drugs in development for Parkinson's disease: an update

The current development of emerging pharmacological treatments for Parkinson's disease (PD), front preclinical to launch, is summarized. Advances over the past year are highlighted, including the significant progress of several drugs through various stages of development. Several agents have been discontinued from development, either because of adverse effects or lack of clinical efficacy. The methyl-esterified form of L-DOPA (melevodopa) and the monoamine oxidase type B inhibitor rasagiline have both been launched. With regard to the monoamine re-uptake inhibitors, many changes have been witnessed, with new agents reaching preclinical development and pre-existing ones being discontinued or having no development reported. Of the dopamine agonists, many continue to progress successfully through clinical trials. Others have struggled to demonstrate a significant advantage over currently available treatments and have been discontinued. The field of non-dopaminergic treatments remains dynamic. The alpha2 adrenergic receptor antagonists and the adenosine A2A receptor antagonists remain in clinical trials. Trials of the neuronal' synchronization modulator levetiracetam are at an advanced stage, and there has also been a new addition to the class (ie, seletracetam). There has been a change in the landscape of neuroprotective agents that modulate disease progression. Candidates from the classes of growth factors and glyceraldehyde-3-phosphate dehydrogenase inhibitors have been discontinued, or no development has been reported, and the mixed lineage kinase inhibitor CEP-1347 has been discontinued for PD treatment. Other drugs in this field, such as neuroimmunophilins, estrogens and alpha-synuclein oligomerization inhibitors, remain in development.

Evaluation of Solid-Phase Sorbents for the Analysis of Ropinirole in Whole Blood

In this paper, the extraction and analysis of ropinirole from whole blood using solid-phase cartridges is presented. Previously published methods for the analysis of this drug have employed plasma samples using C(18) cartridges. Liquid-liquid extraction has been employed for analysis of postmortem samples. In the method, drug free blood was spiked with ropinirole (0 to 10 ng) and an internal standard (quinidine). The samples were buffered with distilled water and centrifuged. The supernatant liquid was applied to previously conditioned endcapped C(6), C(18), and C(8)/SCX solid-phase extraction columns. The columns were washed, dried, and eluted with various solvents systems. The eluants were collected and evaporated. The residue was dissolved in 100 microL of aqueous 0.1% trifluoroacetic acid and analyzed by liquid chromatography using a C(18) (4.6 x 150 mm, 5-microm particle size) column and monitored at 250 nm, using diode-array detection. A mobile phase consisting of methanol/0.1% TFA in distilled water (22:78 v/v) was employed. The data was collected and appraised. It was found that 3-mL 200-mg CEC06 C6 (Hexyl endcapped) solid-phase columns that had been washed with 3 x 3 mL water and 3 x 3 mL acetonitrile and eluted with a solvent system consisting of 95:5 v/v acetonitrile/ammonia performed best. The linear range for this analysis was found to be from 0 to 10 ng/mL. The limit of detection was determined to be 1 ng/mL with a limit of quantification of 2.5 ng/mL.

Trapping effect of eugenol on hydroxyl radicals induced by L-DOPA in vitro

Many researchers have stated that eugenol might inhibit lipid peroxidation at the stage of initiation, propagation, or both, and many attempts have been made to elucidate the mechanism of its antioxidant activity. Nevertheless, details of its mechanism are still obscure. This study was carried out to investigate the trapping effect of eugenol on hydroxyl radical generated from L-3,4-dihydroxyphenylalanine (DOPA) in MiliQ water and the generation mechanism of the hydroxyl radical by this system which uses no metallic factor. This was studied by adding L-DOPA and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to phosphate buffered saline (PBS) or MiliQ water, and the generation of hydroxyl radical was detected on an ESR spectrum. By this method, the effect of antioxidants was detected as a modification of ESR spectra. We found that the eugenol trapped hydroxyl radicals directly, because it had no iron chelating action, did not trap L-DOPA semiquinone radical and inhibited hydroxyl radicals with or without iron ion.

Pleuropulmonary fibrosis after long-term treatment with the dopamine agonist pergolide for Parkinson Disease

Dopamine agonists are increasingly used in the treatment of Parkinson disease, but they may cause serious adverse effects. In December 1983, symptoms of Parkinson disease developed in a 55-year-old man with no history of pulmonary disease, smoking, or asbestos exposure. He began treatment with dopamine agonists bromocriptine mesylate (in 1984) and pergolide mesylate (in 1989). In late 2000, pulmonary symptoms developed. Chest radiographs and computed tomographic findings showed a mass in the right upper lobe and effusion. A biopsy specimen showed pleural and parenchymal fibrosis. This syndrome resolved after cessation of pergolide therapy and a switch to pramipexole dihydrochloride. This case draws attention to the association of long-term ergot dopamine agonist therapy with pleuropulmonary fibrosis, which can develop as late as 11 years after the initiation of therapy. We also review evidence that the risk of this complication is substantially lower with the newer nonergot dopamine agonists.

Synthesis and Reactions of Some New Substituted Pyridine and Pyrimidine Derivatives as Analgesic, Anticonvulsant and Antiparkinsonian Agents

A series of substituted pyridine and pyrimidine derivatives were synthesized as analgesic, anti convulsant, and antiparkinsonian agents by using compounds 1, 2, and 9 as starting materials. Pyr idino-imide derivative 3 was prepared by condensation of 1 with tetrachlorophthalic anhydride and compounds 4 and 5 were also obtained by reaction of compound 1 with 1,2,4,5-benzene-tetra carboxylic dianhydride and 1,4,5,8-naphthalenetetracarboxylic dianhydride, respectively. Similarly, compound 2 was reacted with previous anhydrides to afford the corresponding imide 6 and bis-imide derivatives 7 and 8, respectively. Bis-arylmethylene derivatives 9 were treated with hydrogen peroxide to afford the corresponding bis-oxiranocycloalkanone derivatives 10, which condensed with thiourea to give the corresponding thioxopyrimidine derivatives 11. Treatment of compound 11 with chloroacetic acid in the presence of anhydrous sodium acetate afforded the corresponding thiazolopyrim idine derivative 12 which condensed with aromatic aldehydes in acetic acid/acetic anhydride to give arylmethylene derivative 13. Also, compounds 13 could be prepared by reaction of compounds 11 with chloroacetic acid, aromatic aldehydes, and sodium acetate in a mixture of acetic acid and acetic anhydride. The pharmacological screening showed that many of these obtained compounds have good analgesic, anticonvulsant, and antiparkinsonian activities comparable to Valdecoxib, Carbamazepine, and Benzatropine as reference drugs.

Novel diamino derivatives of [1,2,4]triazolo[1,5-a][1,3,5]triazine as potent and selective adenosine A2a receptor antagonists

Piperazine derivatives of 2-furanyl[1,2,4]triazolo[1,5-a][1,3,5]triazine have recently been demonstrated to be potent and selective adenosine A(2a) receptor antagonists with oral activity in rodent models of Parkinson's disease. We have replaced the piperazinyl group with a variety of linear, monocyclic, and bicyclic diamines. Of these diamines, (R)-2-(aminomethyl)pyrrolidine is a particularly potent and selective replacement for the piperazinyl group. With this diamine component, we have been able to prepare numerous analogues with low nanomolar affinity toward the A(2a) receptor and good selectivity with respect to the A(1) receptor (>200-fold in some cases). Selected analogues from this series of [1,2,4]triazolo[1,5-a][1,3,5]triazine have now been shown to be orally active in the mouse catalepsy model.

Evaluation of rat striatal L-dopa and DA concentration after intraperitoneal administration of L-dopa prodrugs in liposomal formulations

Parkinson's disease is a neurodegenerative disease and its symptoms are relieved by administration of L-dopa (LD), which is converted by neuronal aromatic L-aminoacid decarboxylase (AADC), restoring dopamine (DA) levels in surviving neurons. In order to minimize unfavourable side effects, we studied new dimeric LD derivatives, as potential prodrugs for Parkinson's therapeutic treatment. To improve the bioavailability of the synthesized prodrugs, they were encapsulated in unilamellar liposomes of dimiristoylphosphatidylcholine (DMPC) and cholesterol (CHOL). In vivo microdialysis was used to monitor the striatal LD and DA concentrations after i.p. administration of new delivery systems. Bioavailability evaluation was performed by means of the HPLC-EC method. The striatal levels of LD and DA were remarkably elevated after i.p. administration of liposomal formulation of prodrug (+)-1b ([(O,O-diacetyl)-L-dopa-methylester]-succinyldiamide). This formulation showed about 2.5-fold increase in the basal levels of DA in dialysate rat striatum, suggesting that liposomal formulation of (+)-1b significantly increases LD and DA concentrations with respect to equimolar administration of LD itself or free prodrug (+)-1b.

Agonism at 5-HT2B receptors is not a class effect of the ergolines

Restrictive cardiac valvulopathies observed in Parkinson patients treated with the ergoline dopamine agonist pergolide have recently been associated with the agonist efficacy of the drug at 5-hydroxytryptamine2B (5-HT2B) receptors. To evaluate whether agonism at 5-HT2B receptors is a phenomenon of the class of the ergolines, we studied 5-HT2B receptor-mediated relaxation in porcine pulmonary arteries to five ergolines which are used as antiparkinsonian drugs. Pergolide and cabergoline were potent full agonists in this tissue (pEC50 8.42 and 8.72). Bromocriptine acted as a partial agonist (pEC50 6.86). Lisuride and terguride, however, failed to relax the arteries but potently antagonized 5-HT-induced relaxation (pKB 10.32 and 8.49). Thus, agonism at 5-HT2B receptors seems not to be a class effect of the ergolines.

Pharmacological Study of the Novel Compound FLZ Against Experimental Parkinson's Models and Its Active Mechanism

FLZ is a synthetic new derivative of squamosamide. Pharmacological study found that FLZ given orally improved the abnormal behavior caused by the functional disturbance of dopaminergic and cholinergic neurons in mice. FLZ significantly increased the content of dopamine and its metabolites in striatum in MPTP model mice. FLZ also remarkably protected dopaminergic PC-12 cells against dopamine and MPP+ induced injury and apoptosis in vitro. The compound inhibited the formation of dopamine-melanin and protein polymers. Additionally, FLZ inhibited cytochrome-c release from mitochondria and caspase-3 activation by dopamine in PC-12 cells. The above results suggest that compound FLZ possesses anti-PD activity through neuroprotection.

3,4-Methylenedioxymethamphetamine counteracts akinesia enantioselectively in rat rotational behavior and catalepsy

We have shown recently that 3,4-methylenedioxymethamphetamine (MDMA) has symptomatic antiparkinsonian activity in rodent models of Parkinson's disease. In search of its mechanism of action, we further investigated the enantiomers of MDMA in the rotational behavioral model and catalepsy test. Catalepsy testing was done in drug-naive unlesioned animals. The parkinsonian symptoms rigor and akinesia (i.e., catalepsy) were induced by intraperitoneal administration of haloperidol 0.5 mg/kg and measured repeatedly as descent latency from a horizontal bar and a vertical grid. MDMA and both its enantiomers were effective in counteracting haloperidol-induced catalepsy, but if given as racemic, the effects were more pronounced than with the enantiomers. For testing of rotational behavior, male Sprague Dawley rats were lesioned unilaterally with 6-hydroxydopamine (6-OHDA) at the medial forebrain bundle. Administration of S-MDMA (5 mg/kg) produced ipsilateral rotations. R-MDMA was far less effective in inducing ipsilateral rotations in 6-OHDA unilaterally lesioned rats, but when S-MDMA was given additionally rotations immediately increased. Regarding their overall antiparkinsonian effects, the S-enantiomer of MDMA was more effective than its R-congener. R-MDMA was able to increase the actions of S-MDMA.

Indolalkylamines derivatives as antioxidant and neuroprotective agents in an experimental model of Parkinson's disease

BACKGROUND

The neuroprotective effect of N-(2-propynyl)2-(5-benzyloxy-indol)methylamine (PF 9601N), a novel MAO B inhibitor, and its metabolite FA 72 on the human neuroblastoma SHSY5Y cell line lesioned with (300 microM) dopamine was assessed and compared with that of 1-deprenyl assayed at identical experimental conditions.

MATERIAL/METHODS

Using this experimental model, PF 961N showed a neuroprotective effect in a dose-dependent manner, and at a concentration of 10 pM a 20% recovery of cell viability was observed. However, the metabolite FA72 assayed under the same experimental conditions showed an increase in cell viability of nearly 50%. In the case of l-deprenyl, a concentration of 100 microM was necessary to recover only 10% of cell viability.

RESULTS

This neuroprotective effect could be explained in terms of the antioxidant capacity of PF 9601N. In this context, the antioxidant capacities of the novel series of MAO inhibitors, PF 9601N and its analogues, were evaluated by their inhibition of the auto-oxidation of dopamine to melanin and by the dichlorofluorescein and 2-deoxyribose methods.

CONCLUSIONS

All of these compounds have the basic structure of an indole ring in common, but show different substituents at different positions in it. The corresponding structure-activity relationship studies allowed us to conclude that the presence of a benzyloxy group, or a hydroxy or methoxy group, at position 5 of the indol ring enhanced these antioxidant characteristics, presenting a decreasing order of antioxidant activity of the primary > secondary > tertiary amines. The antioxidant properties of PF 9601 N would explain its neuroprotective effect observed in SHSY5Y cells lesioned with dopamine.