Characterization of the dehydrodicaffeic acid dilactone-forming enzyme and the enzymic and chemical synthesis of this mushroom product.

Abstract

Dehydrodicaffeic acid dilactone (DDACD) was found in a cultured mushroom by screening for catechol-O-methyltransferase inhibitors. The enzyme which converts two molecules of caffeic acid to DDCAD has been extracted from the mushroom and purified and the enzyme reaction has been studied. It was markedly inhibited by reducing agents, such as NADPH, NADH, glutathione and ascorbic acid but stimulated by Fe3+, Fe2+, Co2+, Ni2+, Cu2+, Cu+ and Zn2+ ions. Sodium diethyldithiocarbamate and sodium cyanide known to be copper chelating agents inactivated the enzyme, but activity was restored by addition of Cu2+ or Cu+. Although the enzymic reaction did not occur under anaerobic conditions, 18O-oxygen was not incorporated into DDCAD. o-Diphenol oxidase catalyzed DDCAD formation from caffeic acid and the DDCAD-forming enzyme catalyzed the formation of DOPAchrome from DOPA. Thus, the DDCAD-forming enzyme is a type of o-diphenol oxidase. Peroxidase and hydrogen peroxide produced DDCAD from caffeic acid.On the other hand,...