A cyclic depsipeptide having the structure of formula: wherein an ester bond is formed between the carboxy group of A7 and the hydroxy group of A2, wherein the acyl residue X is CH 3 CH 2 CH(CH 3)CO or (CH 3) 2 CHCO, A 1 is glutamine, glutamic acid, or a derivative thereof, selected from glutamic nitrile, glutamic acid C 1-12 alkyl ester or glutamic acid C 6-24 aryl ester, A 2 is threonine, A 3 is leucine, A 4 is Ahp, wherein AHP is 3-amino-6-hydroxy-pipiridin-2-one, 3-amino-piperidine-2-one, proline, 5-hydroxy-proline or a derivative thereof, selected from 3-amino-3,4-dihydro-1H-pyridin-2-one, or wherein R is selected from the group consisting of (C 1-12)alkyl, (C 2-12)alkenyl, (C 2-12)alkynyl, halo(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkoxy(C 1-12)alkyl, hydroxy(C 1-12)alkyl, phenyl and phenyl(C 1 - 6)alkyl., A 5 is isoleucine, A 6 is tyrosine, N-Me-tyrosine or a derivative thereof, selected from N-Me-tyrosine where the OH group of the tyrosine or N-Me-tyrosine is OR, wherein R is selected from the group consisting of (C 1-12)alkyl, (C 2-12)alkenyl, (C 2-12)alkynyl, halo(C 1-12)alkyl, halo(C 2-12)alkenyl, halo(C 2-12)alkynyl, (C 1-12)alkoxycarbonyl, (C 1-12)alkoxy-carbonyl(C 1-12)alkyl, (C 1-12)alkylaminocarbonyl, wherein the alkyl, alkenyl and alkinyl moieties of groups R can be unsubstituted or further substituted by aryl, aryl(C 1-6)alkyl, aryl(C 2-12)alkenyl or aryl(C 2-12)alkynyl, heterocyclyl and heterocyclyl(C 1-12)alkyl, A 7 is isoleucine or valine, or a pharmaceutically acceptable salt thereof. wherein an ester bond is formed between the carboxy group of A7 and the hydroxy group of A2, wherein the acyl residue X is CH 3 CH 2 CH(CH 3)CO or (CH 3) 2 CHCO, A 1 is glutamine, glutamic acid, or a derivative thereof, selected from glutamic nitrile, glutamic acid C 1-12 alkyl ester or glutamic acid C 6-24 aryl ester, A 2 is threonine, A 3 is leucine, A 4 is Ahp, wherein AHP is 3-amino-6-hydroxy-pipiridin-2-one, 3-amino-piperidine-2-one, proline, 5-hydroxy-proline or a derivative thereof, selected from 3-amino-3,4-dihydro-1H-pyridin-2-one, or wherein R is selected from the group consisting of (C 1-12)alkyl, (C 2-12)alkenyl, (C 2-12)alkynyl, halo(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkoxy(C 1-12)alkyl, hydroxy(C 1-12)alkyl, phenyl and phenyl(C 1 - 6)alkyl., wherein R is selected from the group consisting of (C 1-12)alkyl, (C 2-12)alkenyl, (C 2-12)alkynyl, halo(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkyl, (C 1-12)alkoxy(C 1-12)alkoxy(C 1-12)alkyl, hydroxy(C 1-12)alkyl, phenyl and phenyl(C 1 - 6)alkyl., A 5 is isoleucine, A 6 is tyrosine, N-Me-tyrosine or a derivative thereof, selected from N-Me-tyrosine where the OH group of the tyrosine or N-Me-tyrosine is OR, wherein R is selected from the group consisting of (C 1-12)alkyl, (C 2-12)alkenyl, (C 2-12)alkynyl, halo(C 1-12)alkyl, halo(C 2-12)alkenyl, halo(C 2-12)alkynyl, (C 1-12)alkoxycarbonyl, (C 1-12)alkoxy-carbonyl(C 1-12)alkyl, (C 1-12)alkylaminocarbonyl, wherein the alkyl, alkenyl and alkinyl moieties of groups R can be unsubstituted or further substituted by aryl, aryl(C 1-6)alkyl, aryl(C 2-12)alkenyl or aryl(C 2-12)alkynyl, heterocyclyl and heterocyclyl(C 1-12)alkyl, A 7 is isoleucine or valine, or a pharmaceutically acceptable salt thereof.