Scytonemin

Scytonemin is a ring assembly formed by 1,1'-coupling of two molecules of (3E)-3-[(4-hydroxyphenyl)methylidene]cyclopenta[b]indol-2(3H)-one. It is a UV-screening molecule produced by many cyanobacterial strains. It functions as a biological pigment, bacterial metabolite, and ultraviolet filter. It is an organic heterotricyclic compound, polyphenol, enone, organonitrogen heterocyclic compound, and ring assembly.