Synthesis and benzodiazepine receptor affinity of derivatives of the new tricyclic heteroaromatic system pyrido[3',2':5,6]thiopyrano[4,3-c]pyridazin-3(2H,5H)-one.
Derivatives 7-13 of a new tricyclic heteroaromatic system, pyrido[3',2':5,6]thiopyrano[4,3-c]pyridazin-3(2H,5H)-one, were prepared as potential ligands at the benzodiazepine receptor, in view of their structural analogy with potent ligands such as the pyrazoloquinolines of the CGS series II, and especially with the benzothiopyrano[4,3-c]pyridazinones VI. They were obtained starting from the versatile ketones 2,3-dihydrothiopyrano[2,3-b]pyridin-4(4H)-one 1 and the corresponding 7-methyl derivative 2, via condensation with glyoxylic acid, and reaction of the intermediate acid mixtures with hydrazine or substituted phenylhydrazines. When evaluated for their binding affinity at the benzo diazepine receptor in bovine cortical membranes, the target compounds 8-13 displayed an affinity in the micromolar/submicromolar order. A hypothesis is presented to rationalize these results.
Primofiore
Giampaolo
G
Dipartimento di Scienze Farmaceutiche, Università di Pisa, Pisa, Italy. primofiore@farm.unipi.it
Da Settimo
Federico
F
Marini
Anna Maria
AM
Simorini
Francesca
F
La Motta
Concettina
C
Taliani
Sabrina
S
Laneri
Sonia
S
Trincavelli
Letizia
L
Martini
Claudia
C
D000818:Animals; D002417:Cattle; D008024:Ligands; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*; D013329:Structure-Activity Relationship
D008024:Ligands; D011724:Pyridazines; D011963:Receptors, GABA-A