The present invention relates to isolated or purified or partially purified peptide derived molecules having the following general formula: €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ X-[(Pro) n -His-Pro-His-Ala-Arg-Ile-Lys] m -Y€ƒ€ƒ€ƒ€ƒ€ƒ(S1) The peptides are for medical use, in particular as anti-tumoral agents.