Orally active trifluoromethyl ketone inhibitors of human leukocyte elastase.

This paper describes the development a series of peptidyl trifluoromethyl ketone inhibitors of human leukocyte elastase which are found to have excellent pharmacological profiles. Methods have been developed that allow for the synthesis of these inhibitors in stereochemically pure form. Two of these compounds, 1k and 1l, have high levels of oral bioavailability in several species. Compound 1l has entered development as ZD8321 and is presently undergoing clinical evaluation. These compounds demonstrate that peptidyl trifluoromethyl ketone inhibitors can achieve high levels of oral activity and bioavailability, and therefore they may prove useful as therapeutic agents in the treatment of diseases in which elastase is implicated.

Nonpeptidic inhibitors of human leukocyte elastase. 5. Design, synthesis, and X-ray crystallography of a series of orally active 5-aminopyrimidin-6-one-containing trifluoromethyl ketones.

The effects of changes in substitution in a series of 5-amino-2-pyrimidin-6-ones on both in vitro activity and oral activity in an acute hemorrhagic assay have been explored. These compounds contained either a trifluoromethyl ketone or a boronic acid moiety to bind covalently to the Ser-195 hydroxyl of human leukocyte elastase (HLE). Boronic acid-containing inhibitors were found to be more potent than the corresponding trifluoromethyl ketones in vitro but were less active upon oral administration. Compound 13b was found to offer the best combination of oral potency, duration of action, and enzyme selectivity and, as such, was selected for further biological testing. X-ray crystallography of a cocrystallized complex of compound 19m and porcine pancreatic elastase demonstrated that the inhibitor is bound to the enzyme in a manner similar to that found previously for a closely related series of pyridone-containing inhibitors of HLE.

1,3,8-trisubstituted xanthines. Effects of substitution pattern upon adenosine receptor A1/A2 affinity.

A series of 11 8-substituted xanthines having three different substitution patterns on the 1- and 3-positions [pattern a (R1 = R3 = CH2CH2CH3), b (R1 = CH2CH2CH3, R3 = CH3), and c (R1 = CH3, R3 = CH2CH2CH3)] was prepared. These compounds were assessed for affinity and selectivity in binding to adenosine A1 and A2 receptors. Compounds with greatest affinity at the A1 receptor had the 1,3-substitution pattern a. With one exception, compounds with pattern a also exhibited the most potent binding at the A2 receptor; however, several compounds with pattern c were equipotent at the A2 receptor with those having pattern a. Additionally, the substituents on the 1- and 3-positions of these 8-substituted xanthines were equally important for determining maximum affinity to the A1 receptor, while the substituent at the 3-position is more important than the substituent at the 1-position for potency at the A2 receptor. As a result of this, it is possible to maximize selectivity for the A1 receptor by choice of the 1- and 3-position substituents. However, the R1/R3 substitution pattern required for maximum A1 selectivity is also dependent upon the substituent in the 8-position in a manner which is not fully understood.