Studies on the Enzymatic Oxidation of Wedelolactone Contained in Eclipta alba

(1) Blackening of Eclipta alba leaves is an enzymatic process. The oxidase concerned in this process is a polyphenoloxidase solely with catecholase activity and without cresolase activity. (2) Eclipta enzyme is not contaminated with ascorbic acid oxidase and peroxidase. (3) Leaf blackening is retarded by the presence of ascorbic acid. (4) Addition of cupric ion accelerated the oxidation of wedelolactone. (5) Blackening of the leaves is caused mainly by the enzymatic oxidation of a phenolic compound, wedelolactone, present in the plant body.