Podophyllotoxin is a non-alkaloid lignan found in species of Podophyllum that exhibits anticancer and antiviral activities. Podophyllotoxin displays antimitotic action, binding tubulin and inhibiting mitotic spindle formation. Derivatives of this compound inhibit topoisomerase II. In gastric cancer cells, podophyllotoxin induces G2/M phase cell cycle arrest and apoptosis, decreases the mitochondrial membrane potential, increases cytochrome c release, and inhibits cellular proliferation. Podophyllotoxin is occasionally clinically used to treat human papilloma virus (HPV) infection, as it inhibits viral reproduction through inhibition of E2 protein activity.