Isosilybin is a diastereoisomeric mixture of flavonolignans isosilybin A and isosilybin B isolated from milk thistle (Silybum marianum) that exhibits hepatoprotective activity. Isosilybin potently inhibits Cytochrome P4502C8 (CYP2C8) activity in human liver microsomes. Also Isosilybin is an activator of PPARγ.