flaviolin

Flaviolin is a natural 1,4-naphthoquinone derivative, chemically identified as 2,5,7-trihydroxy-1,4-naphthoquinone, produced by various microorganisms including *Aspergillus* species and *Streptomyces griseus*. It is a polyketide synthesized by type III polyketide synthases (such as RppA or ThnA) through the spontaneous oxidation of 1,3,6,8-tetrahydroxynaphthalene (THN). In the field of synthetic biology and metabolic engineering, flaviolin is widely employed as a colorimetric reporter to monitor malonyl-CoA levels due to its characteristic red pigmentation. Therapeutically, it has been investigated for its antineoplastic activity, particularly against multiple myeloma, where it induces S-phase cell-cycle arrest and triggers apoptosis through the mitochondrial pathway and caspase-9 activation. It also serves as a biosynthetic precursor or shunt product for other complex natural products, including meroterpenoids and melanins.

Other names

2,5,7-trihydroxy-1,4-naphthoquinone2,5,7-trihydroxynaphthalene-1,4-dione