Chlorination of anthraquinones by lichen and fungal enzymes
1997
Cohen, P.A. | Towers, G.H.N.
Chlorination of the anthraquinones, emodin and 7-chloroemodin, was studied with an enzyme preparation from the lichen Nephroma laevigatum, and a commercially available fungal chloroperoxidase (EC 1.11.1.10). The fungal enzyme converted emodin to a mixture of 5-chloro, 7-chloro and 5,7-dichloroemodin, while converting the 7-chloro isomer to 5,7-dichloroemodin in nearly quantitative yield. The lichen enzyme, however, chlorinated emodin only at C-7 and failed to chlorinate 7-chloroemodin further. In non-enzymic controls, emodin gave the same set of products as the fungal enzyme but 7-chloroemodin did not undergo further chlorination. The chemical structures of the products were confirmed from UV, EI-mass and 1H NMR spectral data.
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