A compound for use in the treatment of vascular leak syndrome, the compound having the formula I: ** Formula ** in which R is an unsubstituted or substituted thiazolyl unit having the formula: ** Formula ** or ** Formula ** or ** Formula ** R2, R3, and R4 are each independently: i) hydrogen； ii) substituted or unsubstituted linear, branched or cyclic C1-C6 alkyl； iii) C2-C6 linear, branched or cyclic substituted or unsubstituted alkenyl； iv) substituted or unsubstituted linear or branched C2-C6 alkynyl； v) C6 or C10 substituted or unsubstituted aryl； vi) substituted or unsubstituted C1-C9 heteroaryl； vii) substituted or unsubstituted C1-C9 heterocyclic； or viii) R2 and R3 can be taken together to form a saturated or unsaturated ring having 5 to 7 atoms； wherein from 1 to 3 atoms may optionally be heteroatoms chosen from oxygen, nitrogen and sulfur； Z is a unit having the formula: - (L) n-R1 R1 is chosen from: i) hydrogen； ii) hydroxyl； iii) amino； iv) C1-C6 alkyl, linear, branched or substituted or unsubstituted cyclic； v) C1-C6, linear, branched or cyclic substituted or unsubstituted alkoxy； vi) C6 or C10 substituted or unsubstituted aryl； vii) substituted or unsubstituted C1-C9 heterocyclic rings； or viii) substituted or unsubstituted C1-C9 heteroaryl rings； L is a union unit having the formula: - [Q] and [C (R5aR5b)] x [Q1] z [C (R6aR6b)] w- Q and Q1 are each independently: i) -C (O) -； ii) -NH-； iii) -C (O) NH-； iv) -NHC (O) -； v) -NHC (O) NH-； vi) -NHC (O) O-； vii) -C (O) O-； viii) -C (O) NHC (O) -； ix) -O-； X) -S-； xi) -SO2-； xii) -C (>； = NH) -； xiii) -C (>； = NH) NH-； xiv) -NHC (>； = NH) -； or xv) -NHC (>； = NH) NH-； R5a and R5b are each independently: i) hydrogen； ii) hydroxy； iii) halogen； iv) substituted or unsubstituted linear or branched C1-C6 alkyl； or v) a unit having the formula: - [C (R7aR7b)] tR8 R7a and R7b are each independently: i) hydrogen； or ii) substituted or unsubstituted linear, branched or cyclic C1-C6 alkyl； R8 is: i) hydrogen； i
