Anthraquinones

A family of quinone pigments widespread in plants and plant products, built on the 9,10-anthraquinone skeleton. They include the stimulant laxatives of senna, rhubarb root and aloe latex — aloin and sennosides among them — as well as historic natural dyes such as alizarin from madder root. In foods they turn up in rhubarb, herbal laxative teas and certain traditional colorants. Their double identity as pigments and pharmacologically active compounds means regulators watch their levels in herbal foods and supplements: the laxative members carry dose limits and warning requirements, distinguishing food use from medicinal use.