Irene Giorgi

New 1,2,3-triazolo[1,5-a]quinoxalines: synthesis and binding to benzodiazepine and adenosine receptors. II.

On pursuing research about 1,2,3-triazolo[1,5-a]quinoxalines, in this paper we report synthesis and binding assays toward the benzodiazepine and A(1) and A(2A) adenosine receptors, of a new series of derivatives, bearing some structural changes (introduction of fluorine and trifluoromethyl in the seventh position, amino substituents in the fourth position, benzyl group in the fifth position and aroyl substituents in the third position). The biological tests have shown that only the 7-fluorosubstituted compounds 3a and 4a and the N-benzyl derivative 7 have a good affinity toward the benzodiazepine receptors, while only the 7-trifluoromethyl substituted compound 3b presents a moderate affinity with low selectivity toward the A(1) adenosine receptors. The other structural modifications strongly decreased biological activity.

Some structural changes on triazolyl-benzotriazoles and triazolyl-benzimidazolones as potential potassium channel activators. III

This paper reports the synthesis and pharmacological evaluation of some compounds, obtained by structural modifications of 1,2,3-triazolyl-benzotriazoles and 1,2,3-triazolyl-benzimidazolones, which had shown activity as potential activators of the big-conductance calcium-activated potassium channels (BK(Ca)). Changes have concerned the introduction of a hinderer substituent in the 5-position of the benzimidazolone (4a, b) and benzotriazole (5a, b) rings, opening of the benzimidazolone ring (7) and substitution of the 1,2,3-triazole ring with a 2-hydroxyphenyl ring (10). Furthermore a series of 3-aryl-benzotriazin-4-one derivatives (13a-e) has been studied, which appears as a modification and/or combination of the benzimidazolone and benzotriazole rings. Only compound 10 shows interesting activity, while the other structural modifications either do not increase (compounds 4 and 5) or reduce (compounds 7 and 13) the pharmacological activity. However, these results provide useful information about structure-activity relationships.

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.

Triazolyl-benzimidazolones and triazolyl-benzotriazoles: new potential potassium channel activators. II

This paper reports the synthesis and pharmacological evaluation of a series of 5-substituted-triazolyl benzotriazoles (2a-f) and the corresponding series of 5-substituted-triazolyl-benzimidazolones (6a-f), as potential activators of the big-conductance calcium-activated potassium channels (BK(Ca)). The synthesis and structure demonstration of the stock compounds of the two series have been described in our previous works, as well as the common starting compounds 4-carboxamido-5-(4-substituted-2amino-anilino)-1,2,3-triazoles (1a-f). The triazolyl-benzotriazoles were obtained by diazotization, while the triazolyl-benzimidazolones were obtained by thermal intramolecular cyclization of ethoxycarbonylamino derivatives or directly with phosgene. Benzimidazolone compounds generally showed little effect whilst the compounds with a benzotriazole ring showed full efficacy, with vasorelaxing properties and potency parameters a little lower than that of the reference compound NS 1619. These effects were significantly reduced by an increased membrane depolarization. This depolarization-sensitive response is in agreement with the pharmacodynamic hypothesis of activation of potassium channels.

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).

erythro- and threo-2-Hydroxynonyl substituted 2-phenyladenines and 2-phenyl-8-azaadenines: ligands for A1 adenosine receptors and adenosine deaminase

erythro-2-Phenyl-9-(2-hydroxy-3-nonyl)adenine and its 8-aza analog were prepared and showed a very high inhibitory activity towards adenosine deaminase (ADA), with Ki 0.55 and 1.67 nM, respectively, and high affinity for A1 adenosine receptors, with Ki 28 and 2.8 nM, respectively. To increase affinity for A1 receptors we introduced a substituent on the N6 position such as alkyl or cycloalkyl groups, which are present in effective agonists or antagonists. Furthermore, for some compounds, we prepared the two diastereoisomers erythro and threo to verify whether the binding with A1 receptors is stereoselective, as in ADA. Results show that some of the synthesised compounds are good inhibitors for ADA and good ligands for A1, and the erythro diastereoisomers are more active than the threo ones. The experimental evidence allows us to hypothesise some similarity in the three dimensional structures of the binding site of the two proteins, ADA and A1 adenosine receptor, in spite of lacking any homologies in the amino acid sequences.

New amino derivatives of 1,2,3-triazolo[4,5-d]pyrimidines and their affinity towards A1 and A2A adenosine receptors

Abstract Starting from the appropriate azides (4-chlorobenzyl-, 2-thiophenemethyl-, 2-fluorobenzyl-, and 4-fluorobenzylazides) in which the variation of the substituent is at the basis of the four series of derivatives ( a–d ), the 7-aminosubstituted 1,2,3-triazolo[4,5-d]pyrimidines 4 were prepared by a well known synthetic route. The biological activity of compounds 4 was expected on the basis of the presence of particular substituents on N(7), and these substituents were introduced by the reaction of the 7 lactamic carbonyl function, present on precursors 3 , with cycloalkyl-, aralkyl- and arylamines. Radioligand binding assays at bovine brain adenosine A 1 and A 2A receptors showed that some compounds possessed a high affinity and selectivity for the A 1 receptor subtype. Furthermore, biological results indicated that the p -chlorobenzyl substituent lowered receptor binding, compared with the previously prepared benzyl and 2-chlorobenzyl derivatives, suggesting certain particular steric requirements of the lipophilic region which interacts with the benzyl substituent. The thiophenemethyl substituent conferred more activity than the benzyl one. The presence of a fluorine atom on the benzyl group determined a high affinity, especially when it was in the ortho position. Compounds 4c.1 (R = 2-fluorobenzyl, R′ = cyclopentyl, Ki = 10.5 nM), 4c.2 (R = 2-fluorobenzyl, R′ = cyclohexyl, Ki = 19.5 nM) and 4d.1 (R = 4-fluorobenzyl, R′ = cyclopentyl, Ki = 26 nM) were the most active for A 1 receptors.

1,2,3-Triazol-carboxanilides and 1,2,3-triazol-(N-benzyl)-carboxamides as BK-potassium channel activators. XII

The chemical structures of many synthetic activators of large-conductance calcium-activated potassium channels (BK channels) satisfy a simple pharmacophore model, consisting of two appropriately substituted phenyl rings connected by a linker of a heterogeneous nature. In this paper, a series of new compounds with modifications of the linker portion of the above pharmacophore are described. In particular, in these new derivatives, the linker portion is represented by a 1,2,3-triazole-carboxamide group, which can be viewed as a combination of two different kinds of linker, independently used in previous series of BK-openers: the amide function and the 1,2,3-triazole ring. The overall finding of this study indicated that the triazole-carboxamide derivatives were generally poorly effective and that this structural modification of the linker is deleterious for activity on BK channels. Therefore, it can be hypothesized that the increase of the steric hindrance of the linker and/or the increase of the distance between the two aromatic portions are negative for the interaction with the biological target.

Antimicrobial Properties of Flavonoids

Flavonoids are a class of plant constituents that have received increasing interest over the last decades. This chapter deals with the antimicrobial activity of some natural flavonoids or extracts rich in these constituents reported in the literature during the last 5 years.

2-Alkyloxyalkylthiohypoxanthines as new potent inhibitors of xanthine oxidase.

The title compounds were prepared and tested as xanthine oxidase (XO) inhibitors. Results evidenced that potency was related to the position of the oxygen atom in the 2-linear chain and that it grew with distance from the sulfur atom until it became equipotent to 2-n-hexylthiohypoxanthine. Enzymatic oxidation on C(2) occurred in the 8-alkylthiohypoxanthines. On the contrary, oxidation on C(8) did not occur in the 2-alkythioderivatives, demonstrating that the chain forced these molecules to form a complex with molybdenum(VI) involving only the N(3) and N(9) nitrogen atoms.