Trihydroxyanthraquinones

Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is an organic compound. Classified as an anthraquinone, it can be isolated from rhubarb, buckthorn, and Japanese knotweed (Reynoutria japonica syn. Polygonum cuspidatum). Emodin is particularly abundant in the roots of the Chinese rhubarb (Rheum palmatum), knotweed and knotgrass (Polygonum cuspidatum and Polygonum multiflorum) as well as Hawaii 'au'auko'i cassia seeds or coffee weed (Semen cassia). It is specifically isolated from Rheum palmatum L. It is also produced by many species of fungi, including members of the genera Aspergillus, Pyrenoch

1,2,4-Trihydroxyanthraquinone, commonly called purpurin, is an anthraquinone. It is a naturally occurring red/yellow dye. It is formally derived from 9,10-anthraquinone by replacement of three hydrogen atoms by hydroxyl (OH) groups.

Morindone is an anthraquinone compound obtained from various Morinda species, especially M. tinctoria, but also M. citrifolia. Its principal use is as a dye, but it has also been investigated for anticancer and microbial uses.

1,3,8-Trihydroxyanthraquinone is an organic compound. It is one of many trihydroxyanthraquinone isomers, formally derived from anthraquinone by replacement of three hydrogen atoms by hydroxyl (OH) groups.

Anthrapurpurin, or 1,2,7-trihydroxyanthraquinone, is a purple dye used in histology for the detection of calcium.