A conjugate of formula (A) is provided: In this formula, D represents any one of D1 or D2 groups； Wherein the dashed line indicates that a double bond is optionally present between C2 and C3； When there is a double bond between C2 and C3, R <； 2 >； is selected from the group consisting of (ia) to (iig) (ia) halo, nitro, cyano, ether, carboxy, ester, C 1-7 alkyl, C 3-7 heterocyclyl and bis-oxy -C 1-3 one or more substituents selected from the group comprising alkylene Lt ； / RTI >； aryl groups optionally <； RTI ID = 0.0 >； (ib) C1-5 saturated aliphatic alkyl； (ic) C 3-6 saturated cycloalkyl； (id) Wherein each R 31 , R 32 and R 33 is independently selected from H, C 1-3 saturated alkyl, C 2-3 alkenyl, C 2-3 alkynyl and cyclopropyl, wherein the total carbon in the R 2 group The number of atoms is 5 or less)； (ie) Wherein one of R <； 35a >； and R <； 35b >； is H and the other is selected from phenyl, pyridyl and thiophenyl optionally substituted by a group selected from halo, methyl and methoxy； (if) Wherein R 34 is selected from the group consisting of H, C 1-3 saturated alkyl, C 2-3 alkenyl, C 2-3 alkynyl, cyclopropyl, halo, methyl, methoxy, ； And thiophenyl)； (ig) halo； When there is a single bond between C2 and C3, R 2 is , Wherein R 36a and R 36b are independently H, F, C 1-4 saturated alkyl, C 2-3 is selected from alkenyl, said alkyl and alkenyl groups are C 1-4 alkyl, amido and C 1- 4 alkyl <； / RTI >；ester； If R 16a and R 16b, or one of the H and the other is selected from nitrile and C 1-4 alkyl esters； D 'represents any one of the groups D'1 or D'2: Wherein the dashed line indicates that a double bond is optionally present between C2 'and C3'； R 6 and R 9 are independently selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR ', NO 2 , Me 3 Sn and halo； R 7 is independently selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR ', NO 2 , Me 3 Sn and halo； Y is selected from the following formulas A1, A2, A3, A4, A5 and A6: L is a linker lin
