A compound of general formula wherein Q is a group of formula Q1, Q2, Q3, Q4, Q5 or Q6 Z is H or OH; Y is -(CH 2) n - wherein n is an integer between 1 and 12 or is a divalent group of formula Y1 wherein A1 and A2 are, each independently, absent or are selected from the group consisting of (C 1 -C 6)alkylene, (C 3 -C 8)cycloalkylene and (C 3 -C 8)heterocycloalkylene; B is absent or is selected from the group consisting of (C 3 -C 8)cycloalkylene, (C 3 -C 8)heterocycloalkylene, arylene and heteroarylene or is a group of formula B1 C is absent or is selected from the group consisting of -O-, -OCO-, -C O-, -S-, -S -, -S 2 - and -N(R 4)- or is one of the following groups C1-C10 wherein R 4 is H or is selected from the group consisting of (C 1 -C 8)alkyl, (C 3 -C 8)cycloalkyl, (C 3 -C 8)heterocycloalkyl, aryl and heteroaryl; D is selected from the group consisting of (C 1 -C 12)alkylene, (C 2 -C 12)alkenylene and (C 2 -C 6)alkynylene, optionally substituted by one or more (C 1 -C 6)alkyl; R is -H or (C 1 -C 4)alkyl; X is -O- or -S-; R 1 is H or is selected from the group consisting of (C 3 -C 8)cycloalkyl, aryl, heteroaryl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl and (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, optionally substituted by one or more (C 1 -C 4)alkoxy; R 2 is selected from the group consisting of (C 3 -C 8)cycloalkyl, aryl, heteroaryl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl and (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, optionally substituted by one or more halogen atoms or (C 1 -C 4)alkoxy; R 3 is H or is selected from the group consisting of -OH, hydroxy(C 1 -C 6)alkyl, -N(R 5 R 6) and -N(R 5)CO(R 6); R 5 and R 6 are independently H or (C 1 -C 6)alkyl; and pharmaceutically acceptable salts or solvates thereof. wherein Q is a group of formula Q1, Q2, Q3, Q4, Q5 or Q6 Z is H or OH; Y is -(CH 2) n - wherein n is an integer between 1 and 12 or is a divalent group of formula Y1 wherein A1 and A2 are, each independently, absent or are selected from the group consisting of (C 1 -C 6)alkylene, (C 3 -C 8)cycloalkylene and (C 3 -C 8)heterocycloalkylene; B is absent or is selected from the group consisting of (C 3 -C 8)cycloalkylene, (C 3 -C 8)heterocycloalkylene, arylene and heteroarylene or is a group of formula B1 C is absent or is selected from the group consisting of -O-, -OCO-, -C O-, -S-, -S -, -S 2 - and -N(R 4)- or is one of the following groups C1-C10 wherein R 4 is H or is selected from the group consisting of (C 1 -C 8)alkyl, (C 3 -C 8)cycloalkyl, (C 3 -C 8)heterocycloalkyl, aryl and heteroaryl; D is selected from the group consisting of (C 1 -C 12)alkylene, (C 2 -C 12)alkenylene and (C 2 -C 6)alkynylene, optionally substituted by one or more (C 1 -C 6)alkyl; R is -H or (C 1 -C 4)alkyl; X is -O- or -S-; R 1 is H or is selected from the group consisting of (C 3 -C 8)cycloalkyl, aryl, heteroaryl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl and (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, optionally substituted by one or more (C 1 -C 4)alkoxy; R 2 is selected from the group consisting of (C 3 -C 8)cycloalkyl, aryl, heteroaryl, aryl(C 1 -C 6)alkyl, heteroaryl(C 1 -C 6)alkyl and (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, optionally substituted by one or more halogen atoms or (C 1 -C 4)alkoxy; R 3 is H or is selected from the group consisting of -OH, hydroxy(C 1 -C 6)alkyl, -N(R 5 R 6) and -N(R 5)CO(R 6); R 5 and R 6 are independently H or (C 1 -C 6)alkyl; and pharmaceutically acceptable salts or solvates thereof.