Box-Behnken experimental design for preparation and optimization of the intranasal gels of selegiline hydrochloride.

Selegiline hydrochloride (SL) is chosen as an adjunct for the control of clinical signs of Parkinsonian patients. The aim of the present work is to develop and optimize thermosensitive gels using Pluronic (F-127) for enhancing transport of SL into the brain through the nasal route. SL gels were prepared using a cold method and the Box-Behnken experimental design methodology. Drug (SL), gelling agent (F-127), and emulsifier (Propylene glycol, PG) were selected as independent variables, while the gelation temperature, gel strength, pH, gel content, and gel erosion were considered as dependent variables. For further understanding of the interaction between the various variables, contour plots and surface plots were also applied. Selected formulations, like S10 (contain 25 mg SL, 20 g F-127, and 1 g PG) and S14 (contain 50 mg SL, 18 g F-127 and 1 g PG), had a clear appearance in the sol form, with gelling temperature of the nasal gel ranging between 33 and 34, respectively. The gel strength of the formulations varied from 4.67 and 0.68 mm and the drug content was 100%. The pH of the formulations ranged between 6.71 and 7.11. Detachment force was acceptable (63.69-244.16 N/cm2) to provide prolonged adhesion. In vitro, drug release studies showed that the prepared formulations could release SL for up to 8 h. Permeation flux for the S10 gel was 0.0002 mg/min/cm2. Results demonstrated that the potential use of SL gels can enhance the therapeutic effect of SL through the intranasal administration.

Automated radiosynthesis of [(11)C]L-deprenyl-D2 and [(11)C]D-deprenyl using a commercial platform.

Two (11)C-labelled PET tracers, (R)-N-[(11)C]methyl-N-(3,3-dideuteropropargyl)-1-phenylpropan-2-amine ([(11)C]L-deprenyl-D2, [(11)C]DED) and (S)-N-[(11)C]methyl-N-propargyl-1-phenylpropan-2-amine ([(11)C]D-deprenyl, [(11)C]DDE) were synthesised. One step N-alkylation with [(11)C]MeI or [(11)C]MeOTf was performed using the automated platform TRACERlab® FX-C Pro. The labelled products were obtained with (37±15)% (n=10) (end of synthesis, decay corrected from [(11)C]MeI) radiochemical yields from [(11)C]MeI after 38±3min synthesis time. In all cases, radiochemical purity was over 99% when [(11)C]MeOTf was used. This synthesis using a commercial platform makes these tracers more accessible for clinical research purposes.

Synthesis and evaluation of selegiline derivatives as monoamine oxidase inhibitor, antioxidant and metal chelator against Alzheimer's disease.

A series of compounds with monoamine oxidase inhibition and biometal chelation activities were designed, synthesised and evaluated as agents against Alzheimer's disease. The in vitro assay shows that most target compounds exhibit good MAO-B activities with submicromolar IC50 values and antioxidant activity (1.49-5.67 ORAC-FL values). The selected compounds were used to determine the biometal chelating ability using UV-vis spectrometry and high-resolution mass spectrometry, which confirm that they can effectively interact with copper(II), iron(II) and zinc(II). The ThT fluorescence binding assay indicates that the synthetic compounds can inhibit Cu(II)-induced Aß1-42 aggregation. The parallel artificial membrane permeation assay shows that most target compounds can cross the BBB. Based on these results, compound 8a was selected as a potential multifunctional agent for the treatment of AD.

Synthesis of three novel fluorine-18 labeled analogues of L-deprenyl for positron emission tomography (PET) studies of monoamine oxidase B (MAO-B).

The aim in this project was to synthesize and to study fluorine-18 labeled analogues of l-deprenyl which bind selectively to the enzyme monoamine oxidase B (MAO-B). Three fluorinated l-deprenyl analogues have been generated in multistep organic syntheses. The most promising fluorine-18 compound N-[(2S)-1-[(18)F]fluoro-3-phenylpropan-2-yl]-N-methylprop-2-yn-1-amine (4c) was synthesized by a one-step fluorine-18 nucleophilic substitution reaction. Autoradiography on human brain tissue sections demonstrated specific binding for compound 4c to brain regions known to have a high content of MAO-B. In addition, the corresponding nonradioactive fluorine-19 compound (13) inhibited recombinant human MAO-B with an IC(50) of 170.5 ± 29 nM but did not inhibit recombinant human MAO-A (IC(50) > 2000 nM), demonstrating its specificity. Biodistribution of 4c in mice showed high initial brain uptake leveling at 5.2 ± 0.04%ID/g after 2 min post injection. In conclusion, compound 4c is a specific inhibitor of MAO-B with high initial brain uptake in mice and is, therefore, a candidate for further investigation in PET.

Ring opening of pymisyl-protected aziridines with organocuprates.

The pyrimidine-2-sulfonyl (pymisyl) group is introduced as a new protecting group that can be used to activate aziridines towards ring opening. It is readily introduced and removed under mild conditions. Regioselective ring opening of pymisyl-protected 2-methyl-aziridine with organocuprates gives the corresponding sulfonamides in high yields, and the pymisyl group can subsequently be removed upon treatment with a thiolate. The versatility of this new nitrogen protecting group is illustrated with a new synthesis of Selegiline, a monoamine oxidase-B inhibitor marketed for the treatment of Parkinson's disease.

Deprenyl: from chemical synthesis to neuroprotection.

During the last decades (-)-deprenyl has become the golden standard of MAO-B inhibitors. It possesses dopamine potentiating and antioxidant properties; however, its effects cannot be explained solely by the enzyme inhibitory action. (-)-Deprenyl prevents the toxicity of certain selective neurotoxins and recently it was demonstrated to increase cell-cell adhesion as well. The complexity of its pharmacological effects reflects the action of both the parent compound and the active metabolites. (-)-Deprenyl and related propargylamines (DRPs) show neuroprotective features in a variety of in vitro and in vivo models that is dependent on the propargyl moiety. The main presumptive targets to date include glyceraldehyde-3-phosphate dehydrogenase, poly(ADP-ribose) polymerase, some kinase cascades, as well as pro- and antiapoptotic proteins, beside the inhibition of MAO-B. The antiapoptotic activity of DRPs converges upon the maintenance of mitochondrial integrity, due to the initiation of a complex transcriptional program, the details of which are yet to be elucidated.

Investigations of acetonitrile solvent cluster formation in supercritical carbon dioxide, and its impact on microscale syntheses of carbon-11-labeled radiotracers for PET.

A new strategy has been developed for synthesizing positron emission tomography (PET) radiotracers using [11C]methyl iodide. This strategy relies on the ability of organic co-solvents to cluster within mixtures of supercritical fluids resulting in localized regions of high density which can serve as microscopic pockets for reaction. We've shown that acetonitrile will cluster about dilute solutes when mixtures of this co-solvent with carbon dioxide are forced to behave as a homogeneous fluid at the critical point. We applied this strategy in a systematic investigation of the conditions for optimized reaction between methyl iodide and L-alpha-methyl-N-2-propynyl phenethylamine (nordeprenyl) to yield L-deprenyl. Variables such as temperature, ultraviolet light exposure, co-solvent concentration, system pressure, and methyl iodide concentration were explored. The synthesis of radioactive [11C]-L-deprenyl using no-carrier-added concentrations of [11C]methyl iodide was also tested. Results showed that greater than 90% radiochemical yield of the desired product could be attained using 40 times less labeling substrate than in conventional PET tracer syntheses.

Synthesis of tools for target identification of the anti-apoptotic compound CGP 3466; Part I.

Immobilized compounds for BIAcore studies and affinity precipitation as well as a fluorescent-labeled compound were prepared in order to identify the molecular target of the anti-apoptotic, neurorescuing compound CGP 3466 (N-methyl-N-propargyl-10-aminomethyl-dibenzo[b,f]oxepin).

Improved synthesis of some commonly used PET radioligands by the use of [11C]methyl triflate.

[11C]Methyl triflate was compared with [11C]methyl iodide as a labelled precursor in the synthesis of some commonly used PET radioligands, L-[11C]deprenyl, [11C]m-hydroxyephedrine (MHED), [11C] beta-CIT, [11C] beta-CFT and [11C]SCH 39166 which have been prepared previously in comparatively low yields from [11C]methyl iodide. A new dopamine reuptake radioligand, [11C] alpha-CIT, was also prepared. The results demonstrate that higher yields are obtained with shorter reaction times, lower reaction temperatures and smaller amounts of precursors with [11C]methyl triflate.

[A drug ahead of its time: the success story of selegiline]. / Egy gyógyszer, amely megelözte korát: a selegilin siker története.

The racemic form of Selegiline was investigated in clinics a short time after its discovery in the sixties. However its fate seemed to be sealed by the so-called "cheese effect" associated with the applications of other MAO inhibitors. In the seventies the (-) enantiomer, called Selegiline was investigated again in European Clinics, and was finally introduced into therapy as an adjuvant of L-Dopa treatment for Parkinsonism. In the eighties its launch to the market of the USA was influenced by events known as the "MPTP Story" and the "Orphan Drug Act". Further clinical investigations of Selegiline are expected to clarify the real therapeutic value of Selegiline.

[Synthesis of selegiline, its potential impurities and metabolites]. / Selegilin, valamint lehetséges szennyezéseinek és metabolitjainak elöállítása.

Selegiline is prepared in a three-step synthesis starting from phenylacetone and methylamine. Its possible impurities may be the (+)-isomer and compounds formed in side reactions. The syntheses of selegiline's metabolites are also described.

The synthesis of no-carrier-added DL-4-[18F]fluorodeprenyl via the nucleophilic aromatic substitution reaction.

No-carrier-added DL-alpha-methyl-beta-4-[18F]fluorophenyl-N-methyl-N-propynylethylamin e (DL-4-[18F]fluorodeprenyl) was synthesized via the following 3-step procedure: (1) nucleophilic aromatic substitution by [18F]fluoride on 4-nitrobenzaldehyde to produce 4-[18F]fluorobenzaldehyde (yield 65%); (2) the reaction of 4-[18F]fluorobenzaldehyde with (1-chloro-1-(trimethylsilyl)ethyl)lithium followed by hydrolysis to give 4-[18F]fluorophenylacetone (yield 50%); and (3) reductive alkylation of 4-[18F]fluorophenylacetone with N-methyl-propynylamine in the presence of NaBH3CN (yield 35%) followed by HPLC purification to give a racemic mixture of 4-[18F]fluorodeprenyl. The overall yield was 11% (EOB corrected), the synthesis time was 90 min and the specific activity greater than 0.57 Ci/mumol (end of synthesis). This synthesis approach, the conversion of an aromatic aldehyde to a homologous methyl ketone, extends the flexibility of the nucleophilic aromatic substitution reaction by applying it to the synthesis of radiotracers which do not bear electron-withdrawing activating groups on the aromatic ring. The tissue distribution of DL-4-[18F]fluorodeprenyl in mice at 1, 10 and 60 min was also measured and showed that metabolic defluorination was not significant. Clearance of radioactivity from brain after injection of DL-4-[18F]fluorodeprenyl was more rapid than that previously observed for [11C]L-deprenyl.

Synthesis of (R)-(-)- and (S)-(+)-4-fluorodeprenyl and (R)-(-)- and (S)-(+)-[N-11C-methyl]-4-fluorodeprenyl and positron emission tomography studies in baboon brain.

(R)-(-)- and (S)-(+)-alpha-methyl-beta-4-(fluorophenyl)-N-methyl-N- propynylethylamine [R)-(-)- and (S)-(+)-4-fluorodeprenyl) were synthesized via the reaction of 4-fluorobenzaldehyde with nitroethane followed by reduction with lithium aluminum hydride to produce racemic 4-fluoroamphetamine, which was resolved by recrystallization with L- or D-N-acetylleucine to yield (R)-(-)-4-fluoroamphetamine or (S)-(+)-4-fluoroamphetamine in greater than 96% enantiomeric excesses and in yields of 42 and 39%, respectively. Alkylation with propargyl bromide gave (R)-(-)- or (S)-(+)-4-fluoronordeprenyl which was reductively methylated (Borch conditions) to produce (R)-(-)- or (S)-(+)-4-fluorodeprenyl. Alkylation of (R)-(-)- or (S)-(+)-4-fluoronordeprenyl with carbon-11 labeled methyl iodide gave (R)-(-)- or (S)-(+)-[N-11C-methyl]-4-fluorodeprenyl in a radiochemical yield of 30-40%. Comparative PET studies of the two labeled enantiomers in baboons showed a significantly lower retention of radioactivity in the striatum for the (S)-(+) enantiomer relative to the (R)-(-) enantiomer.