1,721,031 research outputs found
Synthesis of 4-amino-6-(hetero)arylalkylamino-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives as potent A(2A) adenosine receptor antagonists
No full textIn previous papers (Colotta, V. et al. Arch. Pharm. Pharm. Med. Chem. 1999, 332, 39. Colotta, V. et al. J. Med. Chem. 2000, 43, 1158) we reported the synthesis and binding affinity at bovine (b) A(1) and A(2A) and human (h) A(3) adenosine receptors (ARs) of the 4-amino-6-benzylamino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one (compound A) which resulted in a potent and selective A(2A) AR antagonist. Compound A provided the lead compound of a series of 6- or 8-(hetero)arylalkylamino-4-amino-2-phenyl- 1,2,4-triazolo[4,3-a]quinoxatin-1-one derivatives (compounds 1-20) which are the object of this paper. Most of the newly synthesized compounds are inactive at hA(3) ARs while they possess both nanomolar bA(2A) affinities and different degrees of bA(2A) versus bA(1) selectivity. The binding data show that hydrophilic substituents on the benzyl moiety are the most profitable for bA(2A) receptor affinity. Furthermore, their steric hindrance seems to play an important role for the bA(2A) AR interaction, thus suggesting that the 6-aralkylamino moiety of these ligands interacts with a size-limited binding pocket of this AR subtype. Thus, the SAR studies provided us some new insights about the structural requirements of the bA(2A) AR recognition site. (C) 2003 Elsevier Ltd. All rights reserved
Synthesis and structure-activity relationships of a new set of 1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives as adenosine receptor antagonists
No full textIn a previous paper (Colotta V. et al., J. Med. Chem. 2000, 43, 1158), we reported the synthesis and the binding activity of some 4-oxo (A) and 4-amino (B) substituted 1,2,4-triazolo[4,3-a]quinoxalin-1-ones, bearing different substituents on the appended 2-phenyl ring (region 1), some of which were potent and selective A(1) or A(3) antagonists. To further investigate the SAR in this class of antagonists, in the present paper some 2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives of both series A and B, bearing simple substituents on the benzofused moiety (region 2), are reported. The binding data at bovine A(1) (bA(1)) and A(2A)(bA(2A)) and at human A(3) (hA(3)) adenosine receptors (ARs) show that in series A (compounds 1, 4-11) the presence of substituents on the benzofused moiety is, in general, not advantageous for anchoring at all three AR subtypes, while within series B (compounds 12-21) it exerts a beneficial effect for both bA(1) and hA(3) AR affinities which span the low nanomolar range. In particular, among the 4-amino derivatives 12-21, the 8-chloro-6-nitro (compound 17) and the 6-nitro (compound 18) substitutions afford, respectively, the highest bA(1) and hA(3) AR affinity. Moreover, compound 18, additionally investigated in binding assays at human A(1) (hA(1)) receptors, shows a 183-fold selectivity for hA(3) versus hA(1) receptors. Finally, the SAR studies provide some new insights about the steric and lipophilic requirements of the hA(3) receptor binding pocket which accommodates the benzofused moiety of our 4-amino-triazoloquinoxalin-1-one derivatives. (C) 2003 Elsevier Ltd. All rights reserved
TRICYCLIC HETEROAROMATIC SYSTEMS - SYNTHESIS AND A(1) AND A(2A) ADENOSINE BINDING ACTIVITIES OF SOME 1-ARYL-1,4-DIHYDRO-3-METHYL[1]BENZOPYRANO[2,3-C]PYRAZOL-4-ONES, 1-ARYL-4,9-DIHYDRO-3-METHYL-1H-PYRAZOLO[3,4-B]QUINOLIN-4-ONES, AND 1-ARYL-1H-IMIDAZO[4,5-B]QUINOXALINES
No full textThe syntheses and A(1) and A(2a) adenosine binding activities of some new 1-aryl-1,4-dihydro-3-methyl[1]benzopyrano[2,3-c]pyrazol-4-ones, 1-aryl-4,9-dihydro-3-methyl-1H-pyrazolo[3,4-b]-quinolin-4-ones, and 1-aryl-1H-imidazo[4,5-b]quinoxalines are reported. Some compounds show A(1) adenosine receptor affinity and selectivity. Structure-activity relationships on these new classes of adenosine receptor ligands are defined
TRICYCLIC HETEROAROMATIC SYSTEMS - SYNTHESIS, [H-3]FLUNITRAZEPAM BRAIN MEMBRANE-BINDING INHIBITION, AND STRUCTURE ACTIVITY RELATIONSHIPS OF 2,3-DIHYDRO-2-ARYL-4-R-[1]BENZOPYRANO[4,3-C]PYRAZOLE-3-ONES
No full textWe report the synthesis and binding activity to the central benzodiazepine receptors of some 2,3-dihydro-2-aryl-4-R-[1]benzopyrano[4,3-c]pyrazole-3-ones, which are isosteres of the CGS series. Although the compounds of the CGS series are potent ligands of the benzodiazepine receptors, none of the isosteres tested showed any significant inhibiting potency. This may be due to the change in electronic properties brought about by the replacement of the NH of the CGS series with an oxygen atom
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
TRICYCLIC HETEROAROMATIC SYSTEMS - SYNTHESIS OF 1,3-DISUBSTITUTED [1]BENZOPYRANO(4,3-B)PYRROL-4-ONES AND 1,2-DISUBSTITUTED [1]BENZOPYRANO(4,3-B)PYRROL-4-ONES AND STRUCTURE-ACTIVITY-RELATIONSHIPS AS BENZODIAZEPINE RECEPTOR LIGANDS
No full textThe synthesis of some 1,3- and 1,2- disubstituted [1]benzopyrano-pyrrol-4-ones is reported as well as their benzodiazepine receptor affinity, as measured by the ability to displace [H-3]flunitrazepam from its specific central binding. The structure-activity relationships on the whole series of disubstituted [1]benzopyrano-pyrrol-4-ones show the imporantance of the presence of the 1-aryl substituent and the size limitation of the 3-substituent. The size of the latter seems also to be important for the ''in vitro'' efficacy
Synthesis, binding studies, and structure-activity relationships of 1-aryl-and 2-aryl[1]benzopyranopyrazol-4-ones, central benzodiazepine receptor ligands.
No full textNOVEL ADENOSINE RECEPTOR LIGANDS - 1,3-DISUBSTITUTED[1]BENZOPYRANO[2,3-C]PYRAZOL-4-ONES - SYNTHESIS AND STRUCTURE-ACTIVITY-RELATIONSHIPS
No full textA series of 1,3-disubstituted[1]benzopyrano[2,3-c]pyrazol-4-ones were synthesized and tested in vitro as A1 and A2 adenosine receptor ligands. The binding results and a molecular modelling study indicated that the presence of a proton donor group in the N6-H region of adenosine and the 7-NH region of xanthine, respectively and occupancy of the A2 lipophilic area by a moiety endowed with an electrostatic effect are essential for receptor affinity and A2-selectivity
Dipyrazolo[5,4-b:3',4'-d]pyridines. Synthesis, inhibition of benzodiazepine receptor binding and structure-activity relationships.
No full textSome 2,6,8-trisubstituted dipyrazolo[5,4-b:3',4'-d]pyridin-3-ones related to the CGS series were synthesized and tested for their ability to displace [3H]flunitrazepam binding from bovine brain membranes. However the affinity for the benzodiazepine receptor of the tested compounds was lower than that of the CGS series, although it was comparable to that of chlordiazepoxide. It follows that some structure-activity relationships on the tested compounds can be drawn
- …
