75614-87-8Relevant articles and documents
Enzyme-catalyzed prodrug approaches for the histamine H3-receptor agonist (R)-α-methylhistamine
Stark, Holger,Krause, Michael,Rouleau, Agnes,Garbarg, Monique,Schwartz, Jean-Charles,Schunack, Walter
, p. 191 - 198 (2007/10/03)
Five novel prodrug types of the potent and selective histamine H3-receptor agonist (R)-α-methylhistamine (1) were prepared and pharmacologically tested in vitro as well as in vivo. In particular, an amide of fatty acid, mono- and dicarbamates, an (acyloxy)alkylcarbamate, and a diphthalidyl derivative were synthesized, all of which require initial prodrug activation through an enzyme-catalyzed reaction in contrast to formerly developed azomethine prodrugs which are cleaved by chemical hydrolysis only. Further drug liberation may ensue spontaneously in a cascade to give 1. Since they have diverse stabilities the prodrugs were investigated for drug liberation in vitro under neutral, acidic, and basic conditions at different temperatures as well as with liver homogenates. In vivo investigation of prodrugs after oral administration to mice proved that the fatty amide 2, the Nα-methylcarbamate 4a, and the Nα-(1-(acetyloxy)ethylcarbamate) 5 showed moderate to high plasma levels of 1. Compound 5 displayed even more than 2.5 times the AUC for 1 than that of the reference azomethine prodrug BP2.94 in the periphery and also displayed a detectable drug level in the central nervous system. It was shown that prodrug approaches based on an initial enzyme-catalyzed liberation step are successfully applicable to different pro-moieties for improved bioavailability and prolonged half-live. These approaches may also be used for other aminergic compounds of this class to optimize pharmacokinetic behavior.
Structure-activity relationships of novel azomethine prodrugs of the histamine H3-receptor agonist (R)-α-methylhistamine: From alkylaryl to substituted diaryl derivatives
Krause,Rouleau,Stark,Garbarg,Schwartz,Schunack
, p. 720 - 726 (2007/10/03)
This study was performed on the basis of recently developed prodrugs of the histamine H3-receptor agonist (R)-α-methylhistamine (1) to determine structure-activity relationships of azomethine prodrugs of 1, in which the primary amine functionality is bioreversibly linked to aromatic ketones. Therefore, the pro-moiety was systematically altered from alkylaryl over benzylaryl to diaryl substitution. Those compounds that emerged to be stable enough during preparation were tested for their in vitro hydrolysis rates. Apparently, bulky alkyl residues were capable of preventing previously observed intramolecular cyclization, but the obtained azomethines 12 a-c were far too unstable to serve as prodrugs. However, the benzylaryl imines 12d, e were stable compounds, but 12d decomposed too rapidly under in vitro conditions. Distinctly greater stability was provided by diaryl pro-moieties, even if strongly electron-withdrawing functionalities were introduced. Selected compounds were also tested in vivo following p.o. application to mice. Particularly the trifluoromethyl substituted imine 12i proved to be highly effective as stability and rate of conversion were well-balanced, so that brain penetration of 1 was strikingly facilitated. Thus 12i, a highly potent azomethine prodrug, may serve as an important pharmacological tool and, possibly, a therapeutic agent.
Structure-activity relationships of histamine analogues, XX: absolute configuration and histamine-like activity of the enantiomeric alpha-methylhistamines
Gerhard,Schunack
, p. 709 - 714 (2007/10/02)
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