Emodins

Emodins are plant-produced glycosides, of the organic family of anthraquinones. Several, including emodin and aloe-emodin, are present in traditional herbal medicines, and are being researched as antineoplastic agents.

Emodin
Emodin proper is a "purgative anthraquinone found in several plants, especially Rhamnus frangula. It was formerly used as a laxative, but is now used mainly as tool in toxicity studies."

Aloe emodin
This hydroanthraquinone compound comes from the aloe vera plant.