Patent ID: 7534815

Claim:
A method for treating hypertension, which comprises administering to a patient in need thereof an effective amount of a composition comprising a compound of formula (1): wherein, R 1 and R 2 are the same or different and each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an alkoxyalkyl group, an aryl group, an alkylaryl group, an aralkyl group or an acyl group, R 3 represents an amino acid residue selected from the group consisting of glycine, alanine, valine, leucine, isoleucine, phenylalanine, proline, serine, threonine, cysteine, cystine, methionine, tyrosine, asparagine, glutamine, aspartic acid, glutamic acid, lysine, arginine and histidine; or a pharmaceutically acceptable salt thereof, wherein said compound is in isolated or purified form.