Patent ID: 6946482

Claim:
A compound having the formula (I) and the pharmaceutically acceptable salts, esters, and prodrug forms thereof, wherein R 1 is substituted or unsubstituted C 1 -C 10 alkyl, substituted or unsubstituted C 2 -C 10 alkenyl, substituted or unsubstituted C 2 -C 10 alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted heterocyclo; R 2 is H, substituted or unsubstituted C 1 -C 5 alkyl, substituted or unsubstituted C 2 -C 5 alkenyl, substituted or unsubstituted C 2 -C 5 alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted heterocyclo; R 3 is H or OH; and R 4 is H or OH, or R 3 and R 4 taken together form O—(C═O)—O; with the proviso that when (a) R 1 is ethyl and (b) R 3 is OH or R 3 and R 4 taken together form O—C(═O)—O, then R 2 is not H or methyl.