Patent ID: 7056952

Claim:
A compound of the formula I or formula II in which A is selected from the group consisting of one of R 1 and R 2 is selected from H, OH and OCH 3 , and the other of R 1 and R 2 is selected from OH and OCH 3 ; one of R 3 and R 4 is selected from H, OH and OCH 3 , and the other of R 3 and R 4 is selected from OH and OCH 3 ; provided that at least one of the pairs R 1 , R 2 and R 3 , R 4 are both OH; R 5 is selected from OH and OCH 3 ; and denotes a single or double bond; or a pharmaceutically acceptable salt or prodrug thereof; with the proviso that (a) when A is and R 3 and R 4 are both OH then R 2 is other than H; and (b) when A is and R 3 and R 4 are both OH and R 2 is OCH 3 , then R 1 is other than H or OCH 3 .