The Pigments in the callus of Rubia akane and their dyeing properties

Abstract

The pigments in the callus which were produced by tissue culture of Rubia akane were investigated. The aqueous extracts prepared from the callus, in column chromatography on Sephadex LH-20 yielded four anthraquinone glycosides and three anthraquinone aglycons. After acid hydrolysis, anthraquinones of the glycosides were identified. Alizarin, purpurin, purpuroxanthin and 2-metyl-1, 3, 6-trihydoxyanthraquinone were found. The major constituents were purpurin and purpuroxanthin. Both the glycosides of purpurin and purpuroxanthin showed the presence of glucose and xylose by thin layer chromatography after hydrolysis. The three anthraquinone aglycons were alizarin, purpurin and 2-methyl-1, 3, 6-trihydroxy anthraquinone. Silk fabrics premordanted with aluminum salt were dyed with the glycosides of purpurin and purpuroxanthin. Surface color of dyed silk was shown on the a*b* diagram of the a*b*L* colorimetric system.