Further structure-activity relationships study of hybrid 7-{[2-(4-phenylpiperazin-1-yl)ethyl]propylamino}-5,6,7,8-tetrahydronaphthalen-2-ol analogues: identification of a high-affinity D3-preferring agonist with potent in vivo activity with long duration of action.
This paper describes an extended structure-activity relationships study of aminotetralin-piperazine-based hybrid molecules developed earlier for dopamine D2/D3 receptors. Various analogues as positional isomers have been developed where location of the phenolic hydroxyl group has been varied on the aromatic ring. Between two catechol derivatives, compound 6e with a two methylene linker length exhibited higher affinity and selectivity for D3 over D2 receptors over compound 6f with four methylene linkers (D2/D3 = 50.6 vs 7.51 for 6e and 6f, respectively). In general, the (-)-isomer was more potent than the (+)-isomeric counterpart. Binding results indicated highest selectivity for D3 receptors in compound (-)- 10 ( K i = 0.35 nM; D2/D3 = 71). In the 5-hydroxy series, highest selectivity for D3 receptors was exhibited by compound (-)- 25 ( K i = 0.82 nM; D2/D3 = 31.5). Most potent compounds exhibited binding and functional affinities at the sub-nanomolar level for the D3 receptor. Binding assays were carried out with HEK-293 cells expressing either D2 or D3 receptors by using tritiated spiperone as radioligand for competition studies to evaluate inhibition constants ( K i). A functional assay of selected compounds for stimulating GTPgammaS binding was carried out with CHO cells expressing human D2 receptors and AtT-20 cells expressing human D3 receptors. The functional assay results indicated partial to full agonist characteristics of test compounds. Compound (-)- 25 was selected further for in vivo study to evaluate its potency in producing contralateral rotations in rats with unilateral lesion in the nigrostriatal region induced by neurotoxin 6-OHDA, a Parkinsonian animal model. Compound (-)- 25 at 5 micromol/kg exhibited rotational activity that lasted beyond 12 h, whereas at a 1 micromol/kg dose the rotations lasted beyond 8 h.
Biswas
Swati
S
Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48202, USA.
Zhang
Suhong
S
Fernandez
Fernando
F
Ghosh
Balaram
B
Zhen
Juan
J
Kuzhikandathil
Eldo
E
Reith
Maarten E A
ME
Dutta
Aloke K
AK
D000818:Animals; D000978:Antiparkinson Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D009284:Naphthols / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D016627:Oxidopamine; D020734:Parkinsonian Disorders / Q000139:chemically induced / Q000188:drug therapy / Q000523:psychology; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011437:Propylamines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011869:Radioligand Assay; D050637:Receptors, Dopamine D3 / Q000819:agonists*; D013237:Stereoisomerism; D013239:Stereotyped Behavior / Q000187:drug effects; D013329:Structure-Activity Relationship; D013764:Tetrahydronaphthalenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013997:Time Factors
C526803:6-((2-(4-phenylpiperazin-1-yl)ethyl)(propyl)amino)-5,6,7,8-tetrahydronaphthalen-1-ol; D000978:Antiparkinson Agents; D009284:Naphthols; D010879:Piperazines; D011437:Propylamines; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; D016627:Oxidopamine