Patent ID: 8637664

Claim:
A compound of formula I: or a salt thereof, wherein: the dotted line indicates the optional presence of a double bond between C2 and C3; R 2 is selected from —H, —OH, ═O, ═CH 2 , —CN, —R, OR, halo, ═CH—R, O—SO 2 —R, CO 2 R and COR; R 7 is selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR′, nitro, Me 3 Sn and halo; where R and R′ are independently selected from optionally substituted C 1-7 alkyl, C 3-20 heterocyclyl and C 5-20 aryl groups; R 10 and R 11 either are selected from H and YR Y , where Y is selected from O, S and NH and R Y is H or C 1-7 alkyl or H and SO x M where x is 2 or 3, and M is a monovalent pharmaceutically acceptable cation or are absent and a double bond is formed between the atoms bearing R 10 and R 11 ; each X is an N-methyl substituted pyrrole; n is from 1 to 6; R E is C 1-4 alkyl.