Abstract: This invention is directed to novel peptide derivatives. Said peptide derivatives are useful as a substrate for the activity assay of enzymes of the group EC 3. 4. 22, for example, cathepsin L, cathepsin B and cathepsin H. Said peptide derivatives which contain L-methionine radical are prepared according to the methods conventional in peptide chemistry. As typical examples are mentioned D-leucyl-L-tyrosyl-L-methionine-.beta.-naphthylamide formate, .beta.-alanyl-L-tyrosyl-L-methionine-.beta.-naphthylamide formate and succinyl-L-tyrosyl-L-methionine-p-nitroanilide.

Abstract: An epoxysuccinyl amino acid derivative of the formula ##STR1## wherein R.sup.1 is hydrogen, alkali metal, benzyl or cycloalkyl having 5 to 6 carbon atoms, R.sup.2 is alkyl having 3 to 4 carbon atoms, R.sup.3 is hydrogen, benzyloxycarbonyl, acetyl or benzoyl, and n is an integer of 2 to 7. The subject compounds exhibit inhibitory activity towards thiol protease, especially, calcium-activated neutral thiol protease which exists in excess in muscle tissues of mammals afflicted with muscular dystrophy.

Abstract: An epoxysuccinyl amino acid derivative of the formula ##STR1## wherein R.sup.1 is hydrogen or alkali metal, R.sup.2 is isobutyl, R.sup.3 is hydrogen or benzyloxycarbonyl, and n is an integer of 5 to 7. The subject compounds exhibit inhibitory activity towards thiol protease, especially, calcium-activated neutral thiol protease which exists in excess in muscle tissues of mammals afflicted with muscular dystrophy.

Abstract: The epoxysuccinic acid derivatives of this invention are prepared by esterification of an epoxysuccinic acid or a halide thereof, by partial hydrolysis of an epoxysuccinic acid diester, by amidation of an epoxysuccinic acid monoester, or by hydrolysis of an epoxysuccinic acid amide monoester. These epoxysuccinic acid derivatives have excellent thiol protease inhibitory activity and anti-inflammatory activity without the acceleration of vascular permeability.

Abstract: The epoxysuccinamic acid compounds of the present invention are prepared by reaction of monoesters of epoxysuccinic acid or monoesters of epoxysuccinic acid chloride with amino compounds. These epoxysuccinamic acid compounds have excellent anti-inflammatory activity, thiol protease inhibitory activity, muscular dystrophy inhibitory activity and anti-hypertensive activity without acceleration of vascular permeability.

Abstract: An epoxysuccinic acid derivative of the formula ##STR1## wherein R.sup.1 is hydrogen, alkali metal, alkyl having 1-2 carbon atoms, cycloalkyl having 5-6 carbon atoms or benzyl, R.sup.2 is alkyl having 3-4 carbon atoms or benzyl, R.sup.3 is hydrogen or methyl, and R.sup.4 is alkyl having 1-10 carbon atoms, phenyl, benzyl, phenethyl or cycloalkyl having 3-6 carbon atoms or R.sup.3 and R.sup.4 taken together with the nitrogen atom to which they are attached form a 5-6 membered heterocyclic ring, or said heterocyclic ring substituted with a protected carboxy.