Substituted xanthines and methods of use thereof

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl, each of which is optionally substituted with 1-4 R3;
• R2 is C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 haloalkyl, halo, hydroxyl, C1-C6 alkoxy, C1-C6 heteroalkyl, C6-C10 aryloxy, C7-C16 arylalkoxy, amino, C1-C6 alkylamino, C2-C12 dialkylamino, —C(O)—, —S—, —S—C1-C6 alkyl, —S(O)—, —S(O)2—, —O—, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, nitro, cyano, wherein each of C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 haloalkyl, C1-C6 alkoxy, C1-C6 heteroalkyl, C6-C10 aryloxy, C7-C16 arylalkoxy, amino, C1-C6 alkylamino, C2-C12 dialkylamino, —S—, —S—C1-C6 alkyl, —S(O)—, —S(O)2—, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, is optionally substituted with 1-3 R3;
• each R3 is independently C1-C6 alkyl, C1-C6 heteroalkyl, halo, C1-C6 haloalkoxy, hydroxyl, C1-C6 alkoxy, amino, C1-C6 alkylamino, C2-C12 dialkylamino, cyano, nitro, amido, —S—, —S(O)2—, —C(O)—, —C(O)O—C1-C6 alkyl, —C(O)—C1-C6 alkyl, C3-C7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl, wherein each of C1-C6 alkyl, C1-C6 heteroalkyl, C1-C6 haloalkoxy, C1-C6 alkoxy, amino, C1-C6 alkylamino, C2-C12 dialkylamino, amido, —S—, —S(O)2—, —C(O)—, —C(O)O—C1-C6 alkyl, —C(O)—C1-C6 alkyl, C3-C7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl is optionally substituted with 1-3 R4;
• and
• each R4 is independently C1-C6 alkyl, C1-C6 heteroalkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C7 cycloalkyl, C1-C6 haloalkoxy, C1-C6 haloalkyl, heterocycloalkyl, C6-C10 aryl, heteroaryl, C4-C10 cycloalkylalkyl, heterocycloalkylalkyl, C7-C16 arylalkyl, heteroaryl-C1-C6 alkyl, halo, hydroxyl, C1-C6 alkoxy, C1-C6 hydroxyalkyl, C6-C10 aryloxy, C7-C16 arylalkoxy, C2-C8 alkoxyalkoxyl, amino, C1-C6 alkylamino, C2-C12 dialkylamino, —S—, —S—C1-C6 alkyl, —S(O)2—C1-C6 alkyl, sulfonamidyl, amido, urea, sulfonylurea, acyl, —C(O)—C6-C10 aryl, —NHC(O)—C6-C10 aryl, —C(O)NH—C6-C10 aryl, —C(O)OH, —C(O)O—C1-C6 alkyl, —C(O)—C1-C6 alkyl, acyl, nitro, or cyano.