 The identity of the chemical causing bluing upon tissue injury was reported in 1973 . The molecule , <unk> , is a highly oxidized bis @-@ phenol @-@ substituted <unk> that develops a blue color when it is oxidized . In contrast , the bluing of other boletes has been attributed to the oxidation of variegatic or xerocomic acid . <unk> is biosynthesized from intermediates supplied by the <unk> pathway , a metabolic route used by fungi for the synthesis of aromatic amino acids . 
