Abstract: A compound according to formula 1 ##STR1## wherein R.sub.1 and R.sub.2 independently represent hydrogen, carbamoyl which is substituted by an alkyl of 1 to 4 carbon atoms, alkylcarbonyl of 2 to 5 carbon atoms or phenyl carbonyl, X represents halogen nitro or cyano and R.sub.3 represents ##STR2## wherein R.sub.4 represents cyano or alkylcarbonyl of 2 to 5 carbon atoms and R.sub.5 represents carbamoyl which is unsubstituted or substituted with alkyl of 1 to 8 carbon atoms or which is substituted with hydroxyalkyl of 1 to 8 carbon atoms or pharmaceutically acceptable esters and salts thereof, and a pharmaceutically acceptable carrier therefor, as well as pharmaceutical compositions containing said compounds as COMT inhibitors.

Abstract: Catechol compounds of formula I ##STR1## where R.sub.1, R.sub.2, R.sub.3 and X are as described herein are effective Catechol-O-methyltransferase inhibitors.

Abstract: The invention concerns a method for the treatment of Parkinson's Disease. The method comprises administering a catechol-O-methyl-transferase inhibiting amount of a compound having the formula I ##STR1## wherein R.sub.1 and R.sub.2 independently represent hydrogen, alkylcarbamoyl of 2 to 5 carbon atoms or alkylcarbonyl of 2 to 5 carbon atoms, X represents nitro or cyano and R.sub.3 represents ##STR2## wherein R.sub.4 represents cyano or alkylcarbonyl of 2 to 5 carbon atoms and R.sub.5 represents cyano; alkylcarbonyl of 2 to 5 carbon atoms; or carbamoyl which is unsubstituted or substituted with alkyl of 1 to 8 carbon atoms, or hydroxyalkyl of 1 to 8 carbon atoms or pharmaceutically acceptable salts or esters thereof; and a sufficient amount of levodopa to treat Parkinson's Disease. A peripheral decarboxylase inhibitor such as carbidopa or benzerazide is also preferably administered.