4-Hydroxyderricin, the major active ingredients of Angelica keiskei Koidzumi, is an orally active, potent selective MAO-B (Monoamine oxidase inhibitors) inhibitor with an IC50 of 3.43 µM. 4-Hydroxyderricin also mildly inhibits dopamine beta (DBH)-hydroxylase activity. 4-Hydroxyderricin has antidepressant activity, anti-allergic, anti-diabetic, anti-oxidant, and antitumor effects. 4-Hydroxyderricin promotes apoptosis and cell cycle arrest through regulating PI3K/AKT/mTOR pathway in hepatocellular cells. 4-Hydroxyderricin inhibits osteoclast formation and accelerates osteoblast differentiation[1]. 4-Hydroxyderricin is promising for research of inflammatory diseases[1][2][3][4][5].