Clementina Manera

Synthesis and β-blocking activity of (R, S)-(E)-oximeethers of 2,3-dihydro-1,8-naphthyridine and 2,3-dihydrothiopyrano[2,3-b]pyridine : potential antihypertensive agents - Part IX

The synthesis of oximeethers of 2,3-dihydro-1,8-naphthyridine and 2, 3-dihydrothiopyrano[2,3-b]pyridine is described. These compounds exhibit a selective beta-blocking activity, with a selectivity towards beta(2)-receptors. Groups in the N(1) position giving rise to a considerable steric hindrance led to a higher beta(2)-blocking selectivity, whereas groups creating a moderate hindrance caused a weak but significant decrease in beta(2)-antagonist potency. Substitution of the N(1)-R group with a sulfur atom led to compounds possessing beta(1)-, beta(2)- and beta(3)-blocking properties. Compounds 9c(1) and 10a(1) showed a beta(3)-antagonist activity slightly lower than that of propranolol.

Microfluidic approach for fast labeling optimization and dose-on-demand implementation

INTRODUCTION The diffusion of PET as a pivotal molecular imaging modality has emphasized the need for new positron-emitting radiotracers to be used in diagnostic applications and research. Microfluidic represents an innovative approach, owing to its potential to increase radiochemical productivity in terms of yields, time reduction, precursor consumption and flexible experimental planning. METHODS We focused on fluorine-18 labeling and used a microfluidic platform to perform sequential reactions, by using the same batch of (18)F-labeling solution on one or more substrates, during the same experimental session. A solid-phase extraction (SPE) workup procedure was also implemented in the system to provide a repeatable purification step. RESULTS We were able to quickly optimize the conditions for labeling of ethyl and propyl ditosylate and of a new cannabinoid type 2 (CB2) receptor agonist, CB41. In all substrates, we obtained good incorporation yields (60% to 85%) in short (<90 s) reaction times. Single dosages of the CB2 ligand were sequentially prepared, upon request, in satisfactory quantities and purity for small animal PET scanning. CONCLUSION This work demonstrates the usefulness of a microfluidic-based system for a rapid optimization of temperature, flow rate of reactants and their relative ratio in the labeling of different precursors by using the same (18)F-fluoride batch. This approach was used to obtain in sequence several injectable doses of a novel CB2 ligand, thus providing the proof of principle that microfluidic systems permit a dose-on-demand production of new radiotracers.

Synthesis and evaluation of antimycobacterial activity of 4-phenyl-1,8-naphthyridine derivatives.

Some 4-phenyl-1,8-naphthyridine derivatives with a piperazino group in the 2- and/or 7-position have been synthesized and evaluated for their tuberculostatic activity. The compounds 1, 6, 10, 17b,c and 19i showed a marked activity against Mycobacterium tuberculosis H37Rv. For this series of compounds, submitted to biological screening, no structure-activity relationship can be deduced.

Indoles and Related Compounds as Cannabinoid Ligands

The discovery of the endocannabinoid system has lead to great strides in research development. At present, two cannabinoid receptors, CB1R and CB2R, are known. They belong to Class A rhodopsin-like GPCRs, and possess a different tissue distribution. Many synthetic compounds have been synthesized and tested for their cannabinoid activity. A particular class among them, the aminoalkylindole derivatives (typified by WIN55212-2) are hypothesized to interact in a binding site different from the main cannabinoid agonists. In this review we report the main aminoalkylindole derivatives, and other compounds which are hypothesized to interact in the same binding site. Furthermore we analyze the pharmacological profiles, the mutagenesis data and the computational models that describe their interaction in the cannabinoid receptors, evaluating the most important aspects for their activity and selectivity.

SUBSTITUTED 1,2,3-TRIAZOLO[1,5-A]QUINAZOLINES: SYNTHESIS AND BINDING TO BENZODIAZEPINE AND ADENOSINE RECEPTORS

This paper reports the synthesis and evaluation of the biological affinity towards benzodiazepine and A(1) and A(2A) adenosine receptors of some 3-ethoxycarbonyl or 3-phenyl-substituted 1,2, 3-triazolo[1,5-a]quinazolines. Starting from the appropriate chloro-substituted phenylazides, the series of 7 or 8 chloro-substituted triazoloquinazolines were prepared. Nitration reactions of the triazoloquinazoline ring and chlorination reactions of the hydroxyl group in the 5 position of the same ring are also reported. By nucleophilic displacement of halogen, the corresponding 5-amino derivatives and some analogous derivatives bearing cyclohexylamino and p-toluidino substituents were obtained. The binding assays showed a generalized decrease in the affinity towards the benzodiazepine receptors and confirmed a moderate affinity towards the A(1) adenosine receptors in comparison with the previously studied triazoloquinazoline derivatives.

Evaluation of tramadol and its main metabolites in horse plasma by high-performance liquid chromatography/fluorescence and liquid chromatography/electrospray ionization tandem mass spectrometry techniques

Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat pain in humans. The clinical response of tramadol is strictly correlated to its metabolism, because of the different analgesic activity of its metabolites. O-Desmethyltramadol (M1), its major active metabolite, is 200 times more potent at the micro-receptor than the parent drug. In recent years tramadol has been widely introduced in veterinary medicine but its use has been questioned in some species. The aim of the present study was to develop a new sensible method to detect the whole metabolic profile of the drug in horses, through plasma analyses by high-performance liquid chromatography (HPLC) coupled with fluorimetric (FL) and photodiode array electrospray ionization mass spectrometric (PDA-ESI-MS) detection, after its sustained release by oral administration (5 mg/kg). In HPLC/FL experiments the comparison of the horse plasma chromatogram profile with that of a standard mixture suggested the identification of the major peaks as tramadol and its metabolites M1 and N,O-desmethyltramadol (M5). LC/PDA-ESI-MS/MS analysis confirmed the results obtained by HPLC/FL and also provided the identification of two more metabolites, N-desmethyltramadol (M2), and N,N-didesmethyltramadol (M3). Another metabolite, M6, was also detected and identified. The present findings demonstrate the usefulness and the advantage of LC/ESI-MS/MS techniques in a search for tramadol metabolites in horse plasma samples.

Rational design, synthesis, and pharmacological properties of new 1,8-naphthyridin-2(1H)-on-3-carboxamide derivatives as highly selective cannabinoid-2 receptor agonists.

The CB(2) receptor activation can be exploited for the treatment of diseases such as chronic pain and tumors of immune origin, devoid of psychotropic activity. On the basis of our already reported 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives, new 1,8-naphthyridin-2(1H)-on-3-carboxamide derivatives were designed, synthesized, and tested for their affinities toward the human CB(1) and CB(2) cannabinoid receptors. Some of the reported compounds showed a subnanomolar CB(2) affinity with a CB(1)/CB(2) selectivity ratio greater than 200 (compounds 6, 12, cis-12, 13, and cis-13). Further studies revealed that compound 12, which presented benzyl and carboxy-4-methylcyclohexylamide substituents bound in the 1 and 3 positions, exerted a CB(2)-mediated inhibitory action on immunological human basophil activation. On the human T cell leukemia line Jurkat the same derivative induced a concentration-dependent decrease of cell viability. The obtained results suggest that 1,8-naphthyridin-2(1H)-on-3-carboxamides represent a new scaffold very suitable for the development of new promising CB(2) agonists.

Synthesis and antiplatelet activity of some 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives

Several 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives were synthesized and tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonic acid, collagen and ADP. Only five compounds showed any appreciable activity, and the results of all the active derivatives were similar to those of papaverine in the test with arachidonic acid and collagen. Moreover, the most active compounds were investigated in the test with ADP and again showed a significant activity. The tested compounds that possessed the best activity were also shown to increase the c-AMP level significantly without involving the adenylyl cyclase system.

1,2,3-Triazolo [1,5-a] [1,4]- and 1,2,3-triazolo [1,5-a]-[1,5]benzodiazepine derivatives : synthesis and benzodiazepine receptor binding

This paper reports the synthesis of new 1,2,3-triazolo[1,4]benzodiazepine and 1,2,3-triazolo[1,5]benzodiazepine derivatives and their evaluation toward benzodiazepine receptors. Receptor affinity gradually and remarkably increases by moving the nitrogen atom of the central ring from position 3 through 4 to position 5, to give the most effective compound 6a (Ki = 150 nM). N-methylation of the diazepine ring (7a) lowers receptorial binding. Introduction of a chlorine atom on the benzene ring doubles the Ki value (6b) which remains unaltered by the N-methylation (7b).

New quinolone- and 1,8-naphthyridine-3-carboxamides as selective CB2 receptor agonists with anticancer and immuno-modulatory activity.

Several recent studies suggest that selective CB2 receptor agonists may represent a valid pharmacological approach in the treatment of various diseases due to the absence of relevant psychoactive side effect. In this study, we synthesized and tested a series of new quinoline-2(1H)-one- and 4-hydroxy-2-oxo-1,2-dihydro-1,8-naphthyridine derivatives characterized by a 4-methylcyclohexylamido substituent in position 3 of the heterocyclic nucleus with high CB2 receptor affinity and selectivity. Two compounds showing the best binding and selectivity profile behaved as a full agonist and a partial agonist at the CB2 receptor and induced a concentration-dependent decrease of cell viability on LNCaP, a prostatic cancer cell line expressing CB2 receptor. Moreover considering that the CB2 receptor is mainly expressed in cells and organs of the immune system, the same compounds were studied for their potential immune-modulatory and anti-inflammatory effects in activated lymphocytes isolated from healthy controls and multiple sclerosis (MS) patients.