Arcyriaflavin from Arcyria denudata

Fruit bodies of wild myxomycetes often have bright colors. In 1980 Steglich et al. isolated red and yellow pigments from methanol extracts of 2 g of the red fruit bodies of Arcyria denudata [7], Structure of these pigments were elucidated by spectral data as a series of bisindole maleimides, and they were named arcyriarubin B (1), C (2), arcyriaflavin B (3), C (4), and arcyrioxepin A (5). 1, 2, and 5 were red... 

Steglich et al. also studied the constituents of the fruit bodies of Lycogala epidendrum [17] and isolated not only lycogarubins A-C (31-33) but also lycogalic acid A (35) [18], staurosporinone (36) [19], and arcyriarubin A (6) and arcyriaflavin A (7) previously isolated from Arcyria denudata. 

Arcyria pigments (bisindolylmaleimides and in-dolo[2,3-a]carbazoles). The tiny fruit bodies of the slime molds Arcyria denudata, A. nutans, and related myxomycetes contain indole pigments of the bisindol-ylmaleinimide type. Parent compounds are the red ar-cyriarubins A, B, and C. Oxidative cyclization in the 2,2 -position furnishes the pale yellow and poorly soluble arcyriaflavins A, B, and C (table I). Indolocarba-zoles of this type are also known as active principles from streptomycetes ( rebeccamycin). 

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