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-formingenzyme is a type of o-diphenol oxidase. Peroxidase and hydrogen peroxide produced DDCAD from caffeic acid.
On the other hand, DDCAD was non-enzymatically synthesized from caffeic acid in the presence of CuCl₂ in 64%. yield. In both enzymic and non-enzymic syntheses, both (+)-DDCAD and (-)-DDCAD were produced.

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