Synthesis and pharmacological evaluation of piperidinoalkanoyl-1,2,3,4-tetrahydroisoquinoline derivatives as novel specific bradycardic agents

HCN Channels Modulators: The Need for Selectivity

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.

Synthesis and biological activity of some 1,3-dihydro-2H-3-benzazepin-2-ones with a piperazine moiety as bradycardic agents

A series of 1,3-dihydro-2H-3-benzazepin-2-ones with a piperazine moiety were designed and synthesized by treating the common intermediate of 1,3-dihydro-7,8-dimethoxy-3-[3-(1-piperazinyl)propyl]-2H-3-benzazepin-2-ones with a variety of N-aryl-2-chloroacetamides and acyl chlorides. Their structures have been characterized by (1)H-NMR, MS, and elemental analysis. The title compounds were evaluated for their bradycardic activity in vitro. Most of the synthesized compounds exhibited some vasorelaxant activity and heart-rate-reducing activity with bradycardic potency.

2,3-Diamino acid modifying 3S-tetrahydroisoquinoline-3-carboxylic acids: leading to a class of novel agents with highly unfolded conformation, selective in vitro anti-platelet aggregation and potent in vivo anti-thrombotic activity

In the preparation of anti-thrombotic agents the 2- and 3-positions of 3S-tetra-hydroisoquinoline-3-carboxylic acid (THIQA) were simultaneously modified with amino acids to form 20 novel N-(3S-N-aminoacyl-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)amino acids (8a-t). On an in vitro platelet aggregation model 8a-t selectively inhibit ADP-induced platelet aggregation and their IC(50) values are leas than 3.5 nM. On an extracorporeal circulation of arterioveinos cannula model of rats both orally and intraveously effective doses of 8a-t are less than 30 nmol/kg. Cerius(2) based stereoview of explores 8a-t having highly unfolded conformation. 3D QSAR analysis gives the importance of the unfolded conformation to high in vitro anti-platelet aggregation and in vivo anti-thrombotic potency rational understanding.

(3S)-N-(L-Aminoacyl)-1,2,3,4-tetrahydroisoquinolines, a class of novel antithrombotic agents: synthesis, bioassay, 3D QSAR, and ADME analysis

To increase antithrombotic activity, 3S-tetrahydroisoquinoline-3-carboxylic acid (1) was modified with natural amino acids to form 19 novel dipeptide analogs, 3S-tetrahydroisoquinoline-3-carboxyamino acids (5a-s), targeting the intestinal peptide transport system. In vitro assay of 5a-s indicated that their potencies for inhibiting adenosine diphosphate (ADP), arachidonic acid (AA), platelet-activating factor (PAF), and thrombin (TH)-induced platelet aggregations were higher than that of 1. Additionally, in vivo assay of 5a-s indicated that their potencies for inhibiting thrombogenesis in rats were also higher than that of 1. Among the candidates, 5h with Ser attachment showed the most impressive features for further development. According to molecular field analysis based Cerius(2) QSAR module, two equations (r, 0.961 and 0.988) correlating the structures with both in vitro and in vivo activities of 5a-s were established. ADMET calculations predict higher intestinal absorption for compounds 5a-s. Further investigation with 5h as a lead compound is underway.