Analogs of the natural product icariin

A compound represented by the following structural formula:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is —O-monosaccharide, hydroxy, hydrogen, halogen or carboxy, or —C(O)O(C1-C10)alkyl, —C(O)O(C1-C10)alkenyl or —C(O)O(C1-C10)alkynyl optionally substituted with one or more substituents independently selected from (C1-C5)alkylamino, (C1-C5)alkoxy, amino, cyano, (C1-C5)dialkylamino, halo(C1-C5)alkoxy, halogen, hydroxy, nitro, thio or thio(C1-C5)alkoxy;
• R2 is hydroxy, —O-monosaccharide, hydrogen, halogen or (C1-C10)alkoxy optionally substituted with one or more substituents independently selected from (C1-C5)alkylamino, (C1-C5)alkoxy, amino, cyano, (C1-C5)dialkylamino, halo(C1-C5)alkoxy, halogen, hydroxy, nitro, thio or thio(C1-C5)alkoxy;
• R3 is hydroxy(C1-C5)alkyl;
• Ring A is a (C3-C15)unsaturated or aromatic carbocyclyl or a (C3-C15)unsaturated or aromatic heterocyclyl;
• each R4 is independently (C1-C10)alkyl, (C1-C10)alkylamino, (C1-C10)alkenyl, (C1-C10)alkenoxy, (C1-C10)alkoxy, (C1-C10)alkynyl, (C1-C10)acyl, (C1-C10)alkanoyl, amido, amino, formyl, (C6-C15)aryl, (C6-C15)aryloxy, carboxy, cyano, (C3-C15)cycloalkyl, (C3-C15)cycloalkoxy, (C1-C10)dialkylamino, (C1-C10)ether, halo(C1-C10)alkyl, halo(C1-C10)alkoxy, halogen, (C5-C13)heteroaryl, (C5-C15)heteroaryloxy, (C3-C15)heterocyclyl, (C3-C15)heterocyclyloxy, hydroxy, nitro, phosphate, phosphonate, sulfate, sulfonyl, sulfonamide, sulfonate, thio or thio(C1-C10)alkoxy;
• and
• n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14.