Peptide derivatives having thiazolyl-alanine residue

A peptide derivative of the formula (I):

• wherein
• A is 4-thiazolyl or 5-thiazolyl wherein the nitrogen in the thiazolyl ring may be a quarternary nitrogen which is formed with an optionally substituted alkyl or alkenyl group,
• X is a bond, oxygen, or sulfur,
• m is an integer of 0 to 4,
• Y is an optionally substituted alkyl, an optionally substituted carboxy, a cyano, or a substituent represented by the formula:
• wherein R1 and R2 are independently a hydrogen or an optionally substituted alkyl group, or R1 and R2 taken together with may form a non-aromatic heterocyclic ring with the adjacent nitrogen, which may contain oxygen, nitrogen, or sulfur and may be substituted,
• Z is the substituent represented by the formula:
• wherein R3 is a hydrogen, an optionally substituted alkyl group, an optionally substituted carboxy group, or an optionally substituted acyl group, R4 and R5 are each independently a hydrogen or an optionally substituted alkyl group, and W is an oxygen, a sulfur, an optionally substituted imino, —(CH2)n- wherein n is 0, 1, 2, or 3, or the substituent represented by the formula:
• or an acceptable salt or hydrate thereof.