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.