| abstract |
The invention encompasses a novel compound of formula I: (see formula I) its pharmaceutically acceptable salts, hydrates, solvates, clathrates, enantiomers, diastereomers, racemates, or mixtures of stereoisomers, pharmaceutical compositions comprising a compound of formula I, wherein R1, R2, X1, X2, X3, X4, Y and Z are as defined herein, and methods of use of the compound of formula I and compositions comprising thereof in mammals for treatment or prevention of diseases associated with unregulated levels of PDE4. |