Compound of general formula: wherein - L is a linker comprising 1 to 10 optionally substituted backbone atoms selected from carbon, nitrogen and oxygen; and - R 1 and R 2 are each independently selected from hydrogen and C 1 - C 6 alkyl, or R 1 and R 2 are joined together to form a second linker between the amide nitrogen atom and the cationic nitrogen atom, or R 1 is joined with a backbone atom of the linker L in a cyclic structure and/or R 2 is joined with a backbone atom of the linker L in a cyclic structure; and - R 3 is selected from hydrogen and C 1 - C 6 alkyl, wherein the alkyl moiety may be substituted with one or more halogen atoms or (halo)alkoxy moieties, or R 3 is absent when the cationic nitrogen atom is part of an imine moiety; and - R 4 is selected from hydrogen and C 1 - C 6 alkyl, wherein the alkyl moiety may be substituted with one or more halogen atoms or (halo)alkoxy moieties; and - X - is a pharmaceutically acceptable anion, wherein the compound is not: (i) the compound of formula, wherein L = -(CH 2) 3 -(L 3), R 1 = H, R 2 = H, R 3 = H, R 4 = H and X = Cl; (ii) the compound of formula, wherein L = -(CH 2) 2 -CHR 1' -CH 2 -NH-(CH 2) 4 -, R 1 -R 1' = -(CH 2) 2 -(L 1), R 2 = H, R 3 = -(CH 2) 2 -CH 3, R 4 = H and X = Cl; (iii) the compound of formula, wherein L = -(CH 2) 3 -(L 3), R 1 = H, R 2 = H, R 3 = H, R 4 = H; X = TFA, which is in the S -configuration at the 2-position; (iv) 1-[2-(6-amino-4-methyl-2-pyridinyl)ethyl]-4-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2 H- -benzopyran-2-yl)carbonyl]-piperazine hydrochloride; (v) 1-[4-(2-amino-6-pyridinyl)-3-butynyl]-4-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2 H- -benzopyran-2-yl)carbonyl]-piperazine hydrochloride; or (vi) N- [4-(6-amino-4-methyl-2-pyridinyl)butyl]-6-hydroxy-2,5,7,8-tetramethyl-2-chromanecarboxamide fumarate. - L is a linker comprising 1 to 10 optionally substituted backbone atoms selected from carbon, nitrogen and oxygen; and - R 1 and R 2 are each independently selected from hydrogen and C 1 - C 6 alkyl, or R 1 and R 2 are joined together to form a second linker between the amide nitrogen atom and the cationic nitrogen atom, or R 1 is joined with a backbone atom of the linker L in a cyclic structure and/or R 2 is joined with a backbone atom of the linker L in a cyclic structure; and - R 3 is selected from hydrogen and C 1 - C 6 alkyl, wherein the alkyl moiety may be substituted with one or more halogen atoms or (halo)alkoxy moieties, or R 3 is absent when the cationic nitrogen atom is part of an imine moiety; and - R 4 is selected from hydrogen and C 1 - C 6 alkyl, wherein the alkyl moiety may be substituted with one or more halogen atoms or (halo)alkoxy moieties; and - X - is a pharmaceutically acceptable anion, (i) the compound of formula, wherein L = -(CH 2) 3 -(L 3), R 1 = H, R 2 = H, R 3 = H, R 4 = H and X = Cl; (ii) the compound of formula, wherein L = -(CH 2) 2 -CHR 1' -CH 2 -NH-(CH 2) 4 -, R 1 -R 1' = -(CH 2) 2 -(L 1), R 2 = H, R 3 = -(CH 2) 2 -CH 3, R 4 = H and X = Cl; (iii) the compound of formula, wherein L = -(CH 2) 3 -(L 3), R 1 = H, R 2 = H, R 3 = H, R 4 = H; X = TFA, which is in the S -configuration at the 2-position; (iv) 1-[2-(6-amino-4-methyl-2-pyridinyl)ethyl]-4-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2 H- -benzopyran-2-yl)carbonyl]-piperazine hydrochloride; (v) 1-[4-(2-amino-6-pyridinyl)-3-butynyl]-4-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2 H- -benzopyran-2-yl)carbonyl]-piperazine hydrochloride; or (vi) N- [4-(6-amino-4-methyl-2-pyridinyl)butyl]-6-hydroxy-2,5,7,8-tetramethyl-2-chromanecarboxamide fumarate.