Ein α‐Methylanthrachinon aus Streptomyceten

An α‐Methylanthraquinone from Streptomycetes From cultures of several streptomycete strains producing isochromanquinone antibiotics ( 4 , 5 ), 3,8‐dihydroxy‐1‐methylanthraquinone‐2‐carboxylic acid ( 2b ), one of the rare naturally occurring α‐methylanthraquinones, was isolated. Native compounds of this group became known only as insect pigments (e.g. 1d ) and later on as constituents of a few plants. A common biosynthesis of benzoisochromanquinones and α‐methylanthraquinones is discussed.