Emodin is an anthraquinone pigment widely distributed in fungi and plants with a long tradition of use in herbal medicines. Structurally, emodin is 1,3,8-trihydroxy-6-methylanthraquinone and, like many simple anthraquinones, demonstrates a broad biological profile with weak to moderate antimicrobial, insecticidal and antitumor activity. More recently, emodin has been identified as a potent inhibitor of Lck, 11β-hydroxysteroid dehydrogenase Type 1 and monoamine oxidase, among other pathways. Emodin has been extensively researched with over 6,000 citations in Scifinder. Emodin is an important standard for chemical and bioassay dereplication of microbial extracts.