25 7122n12C1C2C31 2NN222NN1 4125 101 73 71 31 53 62122231 32 32 31225a25b241 32 32 31226a26b1 42 31 41 426a26b1 469231 123 205 207233 12N2N21 46 7 9 6792021a21b1011a11bAA1 41011b11a1011a11bz1011a11b2021a21bA1 42021b11a2021a21bzA compound of formula (I) or a pharmaceutically acceptable salt or solvate thereof wherein: R is of formula (IIa) formula (IIb) or formula (IIc): (a) where A is a C aryl group and either (i) Q is a single bond and Q is selected from a single bond and Z (CH) where Z is selected from a single bond O S and NH and n is from 1 to 3 or (ii) Q is CH=CH and Q is a single bond (b) where: R R and R are independently selected from H and unsubstituted C alkyl (c) where Q is selected from OH SH and NR and R is selected from H methyl and ethyl X is selected from the group comprising: OH SH COH COH N=C=O NHNH CONHNH (formula (x)) (formular (y) NHR wherein R is selected from the group comprising H and C alkyl and either: when there is a double bond present between C2 and C3 R is selected from the group consisting of: (ia) C aryl group optionally substituted by one or more substituents selected from the group comprising: halo nitro cyano ether carboxy ester C alkyl C heterocyclyl and bis oxy C alkylene (ib) C saturated aliphatic alkyl (ic) C saturated cycloalkyl (id) wherein each of R R and R are independently selected from H C saturated alkyl C alkenyl C alkynyl and cyclopropyl where the total number of carbon atoms in the R group is no more than 5 (ie) wherein one of R and R is H and the other is selected from: phenyl which phenyl is optionally substituted by a group selected from halo methyl methoxy pyridyl and thiophenyl and (if) where R is selected from: H C saturated alkyl C alkenyl C alkynyl cyclopropyl phenyl which phenyl is optionally substituted by a group selected from halo methyl methoxy pyridyl and thiophenyl when there is a single bond present between C2 and C3 R is (formula (z)) where R and R are independently selected from H F C saturated a
