The present invention provides a oxazole compound represented by Formula (1), or a salt thereof:
wherein R
1
is an aryl group which may have one or more substituents; R
2
is an aryl group or a nitrogen atom-containing heterocyclic group each of which may have one or more substituents; and W is a divalent group represented by —Y
1
-A
1
- or —Y
2
—C(═O)— wherein Y
1
is a group such as —C(═O)—, A
1
is a group such as a lower alkylene group, and Y
2
is a group such as a piperazinediyl group. The oxazole compound has a specific inhibitory action against phosphodiesterase 4.
3-substituted-6-aryl pyridines of Formula I are provided:
wherein R
1
, R
2
, R
3
, R
8
, R
9
, A and Ar are defined herein. Such compounds are ligands of C5a receptors. Preferred compounds of Formula I bind to C5a receptors with high affinity and exhibit neutral antagonist or inverse agonist activity at C5a receptors. The present invention also relates to pharmaceutical compositions comprising such compounds, and to the use of such compounds in treating a variety of inflammatory, cardiovascular, and immune system disorders. In addition, the present invention provides labeled 3-substituted-6-aryl pyridines, which are useful as probes for the localization of C5a receptors.
3-substituted-6-aryl pyridines of Formula I are provided:
wherein R
1
, R
2
, R
3
, R
8
, R
9
, A and Ar are defined herein. Such compounds are ligands of C5a receptors. Preferred compounds of Formula I bind to C5a receptors with high affinity and exhibit neutral antagonist or inverse agonist activity at C5a receptors. The present invention also relates to pharmaceutical compositions comprising such compounds, and to the use of such compounds in treating a variety of inflammatory, cardiovascular, and immune system disorders. In addition, the present invention provides labeled 3-substituted-6-aryl pyridines, which are useful as probes for the localization of C5a receptors.