Patent ID: 7256286

Claim:
A compound having the structure represented by a formula: wherein: R 3 is H′, or OH; R 7 is absent or represents from 1 to 4 substituents on the ring to which it is attached, independently selected from: lower alkyl, hydroxyl, amino, alkoxyl, alkylamino, ═O, acylainino and acyloxy; R 20 is H, OH, or -T-U—V—R′ where: T is —O—, —S—, —N(H)— or —N(Me)-; U is absent or is —C(O)—, —C(S)—, —S(O)— or —S(O) 2 —; and V is absent or is —O—, —S—, —N(H)— or —N(Me)-, provided that V is absent when U is absent; R 21 is ═CR 3 R b or R 21 represents independent moieties R 6 and R d where: R a and R b are independently H, CO 2 R′, CONR a R d or R′; R c and R d are independently H, alkyl, alkenyl, alkynyl or (CH 2 ) p CO 2 R′; R 26 is H, OH or R′; R′ is independently selected from: H, C 1 –C 10 alkyl, naphthyl, anthracyl, phenanthryl, alkenyl, alkynyl, heteroaryl, aralkyl and heteroaralkyl; X is —CH 2 —, —O—, —S— or —N(R e )— where R e is COH, CO 2 R′ or SO 2 R′, Z is —O— or —N(H)—; p is 1, 2 or 3; or a pharmaceutically acceptable salt thereof, excluding the compounds of Formula 1998a where R 3 is H or OH and where R 20 is —O—C(O)—CH 3 , or —O—C(O)—(CH 2 ) 6 —CH 3