Cercosporin (CGP049090) is a perylenequinone reported in 1957 as the causative agent of soy bean purple speck disease due to the fungal pathogen, Cercsopsorium kikuchii, which is widely found in species of Cercosporium. Cercosporin phytotoxicity is light-activated and this process contributes to a wider biological profile as a photodynamic antiviral and antitumor active. Cercosporin is an antagonist of Tcf4/b-catenin signalling, inhibiting the expression of survivin and inducing apoptosis in several tumor cell lines.