Patent ID: 7304091

Claim:
An isolated compound of formula (I) wherein R1 is OH, C 6 H 5 COO, or R6COO wherein R6 is C 1 –C 5 alkyl; R2 is H, C 1 –C 5 alkyl, or C 1 –C 5 acyl; R3 is H, C 1 –C 5 alkyl, or C 1 –C 5 acyl; R4 is H, C 1 –C 5 alkyl, or C 1 –C 5 acyl; R5 is H or CH 3; and X is a compound of formula (II) or (Ill) or a physiologically-hydrolyzable and pharmaceutically acceptable ester thereof or a pharmaceutically acceptable salt thereof.