Abstract: Novel erythromycin A derivatives of the formula ##STR1## wherein R is hydrogen or methyl, and the pharmaceutically acceptable acid addition salts thereof are disclosed. They exhibit excellent antibacterial activity against erythromycin resistant bacteria, Gram-positive bacteria and Mycoplasma species.

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: 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, cycloalkyl having 3-6 carbon atoms or a group of the formula ##STR2## wherein R.sup.5 is hydrogen, alkyl having 1-4 carbon atoms or said alkyl substituted with hydroxy, methylmercapto, phenyl, hydroxyphenyl, indolyl, an optionally protected carboxy, an optionally protected amino or an optionally protected guanidino, and R.sup.6 is hydroxy, alkalimetaloxy, alkoxy having 1-2 carbon atoms, benzyloxy, amino or dimethylamino, 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.

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.

Abstract: Novel erythromycin compounds of the formula ##STR1## wherein R.sup.1 is hydrogen or methyl, and a pharmaceutically acceptable salt thereof are disclosed. They exhibit excellent antibacterial activity against Gram-positive bacteria, acid stability and in vivo activity.