183155-66-0Relevant articles and documents
Synthesis and in vitro pharmacology of a series of new chiral histamine H3-receptor ligands: 2-(R and S)-amino-3-(1H-imidazol-4(5)-yl)propyl ether derivatives
Kovalainen, Jari T.,Christiaans, Johannes A. M.,Kotisaari, Sanna,Laitinen, Jarmo T.,M?nnist?, Pekka T.,Tuomisto, Leena,Gynther, Jukka
, p. 1193 - 1202 (2007/10/03)
To investigate stereospecificity and the mechanism of activation of the histamine H3-receptor, a series of 2-(R and S)-amino-3-(1H-imidazol-4(5)- yl)propyl ether derivatives were synthesized. In these compounds, the structures of the well-known antagonist iodoproxyfan and the full agonists R- or S-(α)-methylhistamine were combined in one molecule. The obtained 'hybrid' molecules were tested for H3-receptor affinity on rat cerebral cortex. Some selected compounds were further screened for H3-receptor functional activity with GTPγ[35S] autoradiography studies using rat brain tissue sections. The affinity of all the synthesized compounds (-log K(i) = 5.9-7.9) was lower than that found for iodoproxyfan or two of its analogues; however, the compounds showed stereospecificity. The S-configuration of the series of 2-amino-3-(1H-imidazol-4(5)-yl)propyl ether derivatives, which resembles the stereochemistry of R-(α)-methylhistamine, was more favorable. Incorporation of an amino group in the propyl chain of iodoproxyfan and analogues did not alter the antagonistic behavior for compounds with an aromatic side chain. However, when also the aromatic moiety was replaced by a cyclohexyl group, the compounds behaved as agonists. This indicates that an interaction between the side chain amino group and the H3-receptor protein is involved in H3-receptor activation. The 2-(S)-amino-3-(1H-imidazol-4(5)- yl)propyl cyclohexylmethyl ether (23) has H3-receptor agonistic properties with high affinity for the histamine H3-receptor (-log K(i) = 7.9 ± 0.2) and might serve as a useful tool for further studies concerning drug design and receptor-ligand interactions.
[125I]iodoproxyfan and related compounds: a reversible radioligand and novel classes of antagonists with high affinity and selectivity for the histamine H3 receptor.
Stark,Purand,Huels,Ligneau,Garbarg,Schwartz,Schunack
, p. 1220 - 1226 (2007/10/03)
The synthesis and biological evaluation of new histamine H3 receptor antagonists with an iodinated aryl partial structure are described as part of an extensive research program to find model compounds for the development of a new radioligand with high H3 receptor affinity and specific activity. All compounds were tested for their H3 receptor antagonist activity in a [3H]-histamine-release assay with synaptosomes from rat cerebral cortex. The new leads with potent H3 receptor antagonist activity belong to a series of derivatives of 3-(1H-imidazol-4-yl)propanol with carbamate (4-7), ester (8-16), and ether (17-22) as functional groups. Structure-activity relationships are discussed. The most active compound in the functional test (-log Ki = 8.3) and in binding studies with [3H]-(R)-alpha-methylhistamine on rat cerebral cortex (-log Ki = 9.0) in vitro was 3-(1H-imidazol-4-yl)propyl (4-iodophenyl)methyl ether (iodoproxyfan, 19) exhibiting no central H3 receptor antagonist activity in vivo. The potency of iodoproxyfan is more than 300 times lower at H1, H2, alpha1, alpha2, beta1, 5-HT2A, 5-HT3, and M3 receptors than at histamine H3 receptors. Because of the high potency and selectivity of 19, this compound has also been prepared in the [125I]-iodinated form by a nucleophilic halogen exchange reaction using the corresponding bromo derivative 22 as a precursor. The newly prepared [125I]iodoproxyfan (23) possesses advantageous pharmacological properties and fulfills all criteria of a useful radioligand.
