Actinorhodin is a benzoisochromanequinone dimer polyketide antibiotic produced by Streptomyces coelicolor. The antibiotic effect of the substance was first noticed in 1947, when it was noted to inhibit the growth of S. aureus; with the full structure being described in 1966. The gene cluster responsible for actinorhodin production contains the biosynthetic enzymes and genes responsible for export of the antibiotic. The antibiotic also has the effect of being a pH indicator due to its pH-dependent color change. It is a product of a Type II polyketide synthase biosynthetic pathway.
References