ω-(5-Phenyl-2H-tetrazol-2-yl)alkyl-substituted glycine amides and related compounds as inhibitors of the amine oxidase vascular adhesion protein-1 (VAP-1).

Vascular adhesion protein-1 (VAP-1), also known as plasma amine oxidase or semicarbazide-sensitive amine oxidase, is an enzyme that degrades primary amines to aldehydes with the formation of hydrogen peroxide and ammonia. Among others, it plays a role in inflammatory processes as it can mediate the migration of leukocytes from the blood to the inflamed tissue. We prepared a series of ω-(5-phenyl-2H-tetrazol-2-yl)alkyl-substituted glycine amides and related compounds and tested them for inhibition of purified bovine plasma VAP-1. Compounds with submicromolar activity were obtained. Studies on the mechanism of action revealed that the glycine amides are substrate inhibitors, i.e., they are also converted to an aldehyde derivative. However, the reaction proceeds much more slowly than that of the substrate used in the assay, whose conversion is thus blocked. Examination of the selectivity of the synthesized glycine amides with respect to other amine oxidases showed that they inhibited diamine oxidase, which is structurally related to VAP-1, but only to a much lesser extent. In contrast, the activity of monoamine oxidase A and B was not affected. Selected compounds also inhibited VAP-1 in human plasma. The IC50 values measured were higher than those determined with the bovine enzyme. However, the structure-activity relationships obtained with the glycine amides were similar for both enzymes.

Metabolism of sumatriptan revisited.

Scientific literature describes that sumatriptan is metabolized by oxidative deamination of its dimethylaminoethyl residue by monoamine oxidase A (MAO A) and not by cytochrome P450 (CYP)-mediated demethylation, as is usual for such structural elements. Using recombinant human enzymes and HPLC-MS analysis, we found that CYP enzymes may also be involved in the metabolism of sumatriptan. The CYP1A2, CYP2C19, and CYP2D6 isoforms converted this drug into N-desmethyl sumatriptan, which was further demethylated to N,N-didesmethyl sumatriptan by CYP1A2 and CYP2D6. Otherwise, sumatriptan and its two desmethyl metabolites were metabolized by recombinant MAO A but not by MAO B to the corresponding acetaldehyde, with sumatriptan being only a poor substrate for MAO A compared to the N-demethylated and the N,N-didemethylated derivatives.

ω-(5-Phenyl-2H-tetrazol-2-yl)alkyl-substituted hydrazides and related compounds as inhibitors of amine oxidase copper containing 3 (AOC3).

Amine oxidase copper containing 3 (AOC3), also known as plasma amine oxidase, semicarbazide-sensitive amine oxidase, or vascular adhesion protein-1, catalyzes the oxidative deamination of primary amines to aldehydes using copper and a quinone as cofactors. Because it is involved in the transmigration of inflammatory cells through blood vessels into tissues, AOC3 is thought to play an important role in inflammatory diseases. Therefore, inhibitors of this enzyme could lead to new therapeutics for the treatment of inflammation-related diseases. Recently, 6-(5-phenyl-2H-tetrazol-2-yl)hexan-1-amine was found to be a tight-binding substrate of AOC3. To obtain novel inhibitors of the enzyme, the amino group of this substrate was replaced with functional groups that occur in known AOC3 inhibitors, such as hydrazide or glycine amide moieties. In addition, derivatives of the compounds obtained in this way were prepared. The obtained hydrazide 5, which proved to be the most effective, was subjected to further structural modifications. Selected hydrazides were evaluated for selectivity toward some other amine oxidases.