José L. Marco

Relevance of benzyloxy group in 2-indolyl methylamines in the selective MAO-B inhibition.

Previous studies with indolyl derivatives as monoamine oxidase (MAO) inhibitors have shown the relevance of the indole structure for recognition by the active site of this enzyme. We now report a new series of molecules with structural features which determine the selectivity of MAO inhibition. A benzyloxy group attached at position 5 of the indole ring is critical for this selective behaviour. Amongst all of these benzyloxy‐indolyl methylamines, N‐(2‐propynyl)‐2‐(5‐benzyloxyindol)methylamine FA‐73 was the most potent MAO‐B ‘suicide’ inhibitor studied. The Ki values for MAO‐A and MAO‐B were 800±60 and 0.75±0.15 nM, respectively. These data represent a selectivity value of 1066 for MAO‐B, being 48 times more selective than L‐deprenyl (Ki values of 376±0.032 and 16.8±0.1 nM for MAO A and MAO‐B, respectively). The IC50 values for dopamine uptake in striatal synaptosomal fractions from rats were 150±8 μM for FA‐73 and 68±10 μM for L‐deprenyl whereas in human caudate tissue the IC50 values were 0.36±0.015 μM for FA‐73 and 0.10±0.007 μM for L‐deprenyl. Moreover, mouse brain MAO‐B activity was 90% ex vivo inhibited by both compounds 1 h after 4 mg kg−1 adminstration, MAO‐A activity was not affected. These novel molecules should provide a better understanding of the active site of monoamine oxidase and could be the starting point for the design of further selective, non‐amphetamine‐like MAO‐B inhibitors with therapeutic potential for the treatment of neurological disorders.

Synthesis and acetylcholinesterase/butyrylcholinesterase inhibition activity of new tacrine-like analogues

The synthesis and preliminary results for acetylcholinesterase and butyrylcholinesterase inhibition activity of a series of pyrano[2,3-b]quinolines (2, 3) and benzonaphthyridines (5, 6) derivatives are described. These molecules are tacrine-like analogues which have been prepared from readily available polyfunctionalized ethyl [6-amino-5-cyano-4H-pyrans and 6-amino-5-cyanopyridines]-3-carboxylates via Friedlander condensation with selected ketones. These compounds showed moderate acetylcholinesterase inhibition activity, the more potent (2e, 5b) being 6 times less active than tacrine. The butyrylcholinesterase activity of some of these molecules is also discussed.

The C-12 and C-20 configurations of some neo-clerodane diterpenoids isolated from Teucrium species

Abstract A convenient and conclusive method for determining the C-12 stereochemistry of neo-clerodan-20,12-olide derivatives, even when only one epimer is available, is by 1 H NMR NOE measurements. The C-12 configuration of 26 neo-clerodane diterpenoids isolated from Teucrium species has been re-examined by using this type of experiment. The results indicated that all the previous assignments were correct, except for teupyreinin, where the previously assigned C-12( S ) configuration must be amended to C-12( R ). This was confirmed by chemical transformations and additional 1 H and 13 C NMR studies. Furthermore, the NOE experiments allowed the assignment of a C-20( S ) configuration for teuflavin, the structure of which had previously been reported without this feature, and indicated that the previously assigned C-20( S ) configuration for teupyreinidin must be amended to C-20( R ). The validity of using NOE experiments to establish the C-12 and C-20 configurations in these neo-clerodane derivatives has been confirmed by applying it to compounds whose structure had already firmly established by X-ray diffraction analyses.

Novel tacrine derivatives that block neuronal calcium channels

A new series of tacrine (9-amino-1,2,3,4-tetrahydroacridine) derivatives were synthesized and their effects on 45Ca(2+) entry into bovine adrenal chromaffin cells stimulated with dimethylphenylpiperazinium (DMPP) or K(+), studied. At 3 microM, compound 1 did not affect (45)Ca(2+) uptake evoked by DMPP. Compounds 14, 15 and 17 inhibited the effects of DMPP by 30%. Compounds 3, 9 and tacrine blocked the DMPP signal by about 50%. Compounds 5 and 12 were the most potent blockers of DMPP-stimulated 45Ca(2+) entry (90%); the rest of the compounds inhibited the effects of DMPP by 70-80%. Compounds 1, 3, 4, 8, 10, 11, 13, 16, 17 and tacrine inhibited 45Ca(2+) uptake induced by K(+) about 20%. Compounds 6, 14 and 15 inhibited the K(+) effects by 10% or less. Compounds 7, 9, 12 and 18 blocked the K(+) signal by 30% and, finally, compounds 2 and 5 inhibited the K(+)-induced 45Ca(2+) entry by 50%. None of the new compounds was as effective as diltiazem (IC(50)=0.03 microM) in causing relaxation of the rat aorta precontracted with 35 mM K(+); the most potent was compound 7 (IC(50)=0.3 microM). Compounds 5, 6, 8, 9, 10 and 13 had IC(50)s around 10 microM and compounds 3, 4, 11 and 12 around 20 microM. Blockade of Ca(2+) entry through neuronal voltage-dependent Ca(2+) channels, without concomitant blockade of vascular Ca(2+) channels, suggests that some of these compounds might exhibit neuroprotectant effects but not undesirable hemodynamic effects.

Development of methods for the synthesis of chiral, highly functionalized 2-amino-4-aryl-4H-pyrans

The development of new methods for the asymmetric synthesis of highly functionalized 2-amino-4-aryl-4 H -pyrans is described. Two alternative synthetic routes: the 1,4-conjugate addition of chiral β-ketoesters 3 or the N -acetoacetyl sultam 11 to arylidenemalononitriles 6 , and the Michael addition of malononitrile to enantiomerically pure α-acetylcinnamates 5 , have been designed. Depending upon the chiral auxiliary, the resulting 4 H -pyrans were obtained in low [(−)-menthol, (−)-borneol, (−)-ethyl lactate] to good (Oppolzers sultam) diastereomeric excesses. The absolute configuration at the new stereocenter in the minor isomer of compound 12a was determined as S by X-ray diffraction analysis. Reductive cleavage of 4 H -pyrans 12 with lithium aluminiun hydride yielded the enantiomerically pure or enriched alcohols 14 .

Synthesis of asymmetric 1-amino-2-phenylcyclopropanecarboxylic acids by diastereoselective cyclopropanation of highly functionalized homochiral olefines

Abstract Homochiral benzylidenediketopiperazine and α-benzoylaminocinnamic esters react with diazomethane giving high to good diastereomeric ratios of spiropyrazoline derivatives which, on photolysis and acid hydrolysis of the resulting spirocyclopropyl compounds gave, respectively, (+)- and (−)-1-amino-2-phenylcyclopropanecarboxylic acids.

Anti‐apoptotic effect of Mao‐B inhibitor PF9601N [N‐(2‐propynyl)‐2‐(5‐benzyloxy‐indolyl) methylamine] is mediated by p53 pathway inhibition in MPP+‐treated SH‐SY5Y human dopaminergic cells

PF9601N [N‐(2‐propynyl) 2‐(5‐benzyloxyindol) methylamine] is a non‐amphetamine type MAO‐B inhibitor that has shown neuroprotective properties in vivo using different experimental models of Parkinson’s disease. The mechanisms underlying its neuroprotective effects are poorly understood, but appear to be independent of MAO‐B inhibition. We have studied its neuroprotective properties using the human SH‐SY5Y dopaminergic cell line exposed to 1‐methyl‐4‐phenylpyridinium (MPP+), a cellular model of Parkinson’s disease. PF9601N pre‐treatment significantly reduced MPP+‐induced cell death and decreased the activation of one of the main executioner caspases, caspase‐3. MPP+ induced stabilization of transcription factor p53, which led to increased levels of this transcription factor, its nuclear translocation and transactivation of p53 response elements. PF9601N prevented this increase, thus reducing its transcriptional activity. Additional results showed that p53 may mediate its pro‐apoptotic actions through caspase‐2 under our experimental conditions. PUMA‐α may also contribute to the p53‐induced cell death. Since PF9601N significantly reduced MPP+‐induced caspase‐2 activity and PUMA‐α levels, this reduction may lead to increased cell survival. Thus, PF9601N is a novel molecule with an apparently novel mechanism of action which has a promising potential as a therapeutic agent in the treatment of neurodegenerative diseases.

Synthesis of optically pure 1-(3-furyl)-1,2-dihydroxyethane derivatives

Abstract The synthesis of the enantiomerically pure 1-(3-furyl)-1,2-dihydroxyethane derivatives 1 - (R), 2 - (R), 3 - (S) and 3 - (R) is described.

Enantioselective synthesis of (+)-(1R,2S)-allocoronamic acid

Abstract The asymmetric synthesis of (+)-(1R,2S)-allocoronamic acid is reported. Diazomethane addition to (Z)-N-( tert -butoxycarbonyl)ethyldehydroalanyl-L-prolin-anhydride, easily prepared from (Z)-2-phenyl-4-propylidene-5(4H)-oxazolone and L-proline, gave in high diastereomeric excess the corresponding spiropyrazoline, which was transformed, on photolysis and acid hydrolysis of the resulting spirocyclopropane, into (+)-(1R,2S)-1-amino-2-ethyl-cyclopropanecarboxylic acid.

Synthesis and acetylcholinesterase/butyrylcholinesterase inhibition activity of 4-amino-2, 3-diaryl-5, 6, 7, 8-tetrahydrofuro(and thieno)[2, 3-b]-quinolines, and 4-amino-5, 6, 7, 8, 9-pentahydro-2, 3-diphenylcyclohepta[e]furo(and thieno)-[2, 3-b]pyridines.

The acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibition activities of a series of 4‐amino‐2, 3‐diaryl‐5, 6, 7, 8‐tetrahydrofuro[2, 3‐b]quinolines (10—12)/4‐amino‐5, 6, 7, 8‐tetrahydro‐2, 3‐diphenylthieno[2, 3‐b]quinoline (14) and 4‐amino‐5, 6, 7, 8, 9‐pentahydro‐2, 3‐diphenylcyclohepta[e]furo[2, 3‐b]pyridine (13)/4‐amino‐5, 6, 7, 8, 9‐pentahydro‐2, 3‐phenylcyclohepta[e]thieno[2, 3‐b]pyridine (15) are described. These compounds are tacrine (THA) analogues which have been prepared either from readily available 2‐amino‐3‐cyano‐4, 5‐diarylfurans (16—18) or from 2‐amino‐3‐cyano‐4, 5‐diphenylthiophene (19), via Friedländer condensation with cyclohexanone or cycloheptanone. These compounds are competitive inhibitors for acetylcholinesterase, the more potent being compound (13) which is three‐fold less active than tacrine. The butyrylcholinesterase inhibition activity is significant only in compounds 10 and133, which are ten‐fold less active than tacrine. It is found that the products 11 and 12 strongly inhibit acetylcholinesterase, and show excellent selectivity regarding butyrylcholinesterase.