New natural anthraquinones from cochineal (Dactylopius coccus)

Abstract

Cochineal is one of most well known organic red dyes. Dactylopius coccus Costa (Dactylopiidae) is a scale insect that is used as the source of the dye known as Mexican cochineal. Cochineal is today a natural food colorant (E120) and is also used in cosmetics and in pharmaceutical industry. Although cochineal has been used in art objects (textiles and paintings) for centuries, its exact chemical consistency is not well clarified [1] except for carminic acid which is the major component and kermesic and flavokermesic acids. Several minor components (typically less than 5% of the coloring material) remain unknown even though their presence is characteristic for the origin of cochineal. Chemical investigation of the methanol extract of the dried insects, after subsequent HPLC chromatographic separations, led to the isolation and structure elucidation of two new anthraquinones (1 and 2), along with the known compounds karminic acid, kermesic acid and flavokermesic acid. The structures of the new compounds were elucidated on the basis of their NMR and MS data. Interestingly, the new compounds were detected as minor constituents of historical art objects.