A compound of the general formula I: in which: R 1 represents an aliphatic heterocyclyl group having 4, 5, 6 or 7 ring atoms, bonded to the phenyl group shown in formula I through a ring nitrogen atom, and optionally substituted by one or more substituents selected from halogen atoms; OH; =O; C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 2-4 alkenyl and C 2-4 alkynyl groups, each optionally substituted by one or more substituents independently selected from halogen atoms and NR 8 R b groups; NO 2; CN; NR a R b; COR c; O.CO.R c; CO 2 R a; NR a.COR c; NR a CO 2 R b; C(=NH)NH 2; SO 2 R c; NR a SO 2 R c; and CH(CF 3)NH 2; R 2 represents a heteroaryl group which is optionally substituted by one or more substituents independently selected from: halogen atoms; NR a R b; C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 2-4 alkenyl and C 2-4 alkynyl groups, each optionally substituted by one or more substituents independently selected from halogen atoms and NR a R b groups; and -(CH 2) p -R' in which p is 0, 1, 2, 3 or 4 and R' represents one of the following substituents: OH; NO 2; CN; COR c; O.CO.R c; CO 2 R 6; NR a.COR c; NR a CO 2 R b; C(=NH)NH 2; SO 2 R c; NR a SO 2 R c; and CH(CF 3)NH 2; and/or which is optionally substituted on adjacent ring atoms by a group -NR a.CO.(CH 2) n - or -(CH 2) n.CO.NR a - forming a fused ring; R a represents a hydrogen atom or a C 1-4 alkyl group; R b represents a hydrogen atom, a C 1-4 alkyl group optionally substituted by a group NR a R a, or a cycloalkyl group in which a CH 2 moiety may be replaced by an oxygen atom or an NR a group; R c represents a hydrogen atom, a group -NR a R b, or a C 1-4 alkyl group optionally substituted by a group NR 3 R b; or R a and R b together may, when attached to the same nitrogen atom, represent a -(CH 2) m - group in which a CH 2 moiety may be replaced by an oxygen atom or an -NR a - group; m represents 4 or 5; n represents 1 or 2; and each of R 3 and R 4 independently represents a hydrogen atom or a C 1-4 alkyl group; or a salt thereof. R 1 represents an aliphatic heterocyclyl group having 4, 5, 6 or 7 ring atoms, bonded to the phenyl group shown in formula I through a ring nitrogen atom, and optionally substituted by one or more substituents selected from halogen atoms; OH; =O; C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 2-4 alkenyl and C 2-4 alkynyl groups, each optionally substituted by one or more substituents independently selected from halogen atoms and NR 8 R b groups; NO 2; CN; NR a R b; COR c; O.CO.R c; CO 2 R a; NR a.COR c; NR a CO 2 R b; C(=NH)NH 2; SO 2 R c; NR a SO 2 R c; and CH(CF 3)NH 2; R 2 represents a heteroaryl group which is optionally substituted by one or more substituents independently selected from: halogen atoms; NR a R b; C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 2-4 alkenyl and C 2-4 alkynyl groups, each optionally substituted by one or more substituents independently selected from halogen atoms and NR a R b groups; and -(CH 2) p -R' in which p is 0, 1, 2, 3 or 4 and R' represents one of the following substituents: OH; NO 2; CN; COR c; O.CO.R c; CO 2 R 6; NR a.COR c; NR a CO 2 R b; halogen atoms; NR a R b; C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkoxyC 1-4 alkyl, C 2-4 alkenyl and C 2-4 alkynyl groups, each optionally substituted by one or more substituents independently selected from halogen atoms and NR a R b groups; and -(CH 2) p -R' in which p is 0, 1, 2, 3 or 4 and R' represents one of the following substituents: OH; NO 2; CN; COR c; O.CO.R c; CO 2 R 6; NR a.COR c; NR a CO 2 R b; C(=NH)NH 2; SO 2 R c; NR a SO 2 R c; and CH(CF 3)NH 2; and/or which is optionally substituted on adjacent ring atoms by a group -NR a.CO.(CH 2) n - or -(CH 2) n.CO.NR a - forming a fused ring; R a represents a hydrogen atom or a C 1-4 alkyl group; R b represents a hydrogen atom, a C 1-4 alkyl group optionally substituted by a group NR a R a, or a cycloalkyl group in which a CH 2 moiety may be replaced by an oxygen atom or an NR a group; R c represents a hydrogen atom, a group -NR a R b, or a C 1-4 alkyl group optionally substituted by a group NR 3 R b; or R a and R b together may, when attached to the same nitrogen atom, represent a -(CH 2) m - group in which a CH 2 moiety may be replaced by an oxygen atom or an -NR a - group; m represents 4 or 5; n represents 1 or 2; and each of R 3 and R 4 independently represents a hydrogen atom or a C 1-4 alkyl group;